public
class
WebView
extends AbsoluteLayout
implements
ViewTreeObserver.OnGlobalFocusChangeListener,
ViewGroup.OnHierarchyChangeListener
java.lang.Object | ||||
↳ | android.view.View | |||
↳ | android.view.ViewGroup | |||
↳ | android.widget.AbsoluteLayout | |||
↳ | android.webkit.WebView |
A View that displays web pages. This class is the basis upon which you can roll your own web browser or simply display some online content within your Activity. It uses the WebKit rendering engine to display web pages and includes methods to navigate forward and backward through a history, zoom in and out, perform text searches and more.
Note that, in order for your Activity to access the Internet and load web pages
in a WebView, you must add the INTERNET
permissions to your
Android Manifest file:
<uses-permission android:name="android.permission.INTERNET" />
This must be a child of the <manifest>
element.
For more information, read Building Web Apps in WebView.
By default, a WebView provides no browser-like widgets, does not enable JavaScript and web page errors are ignored. If your goal is only to display some HTML as a part of your UI, this is probably fine; the user won't need to interact with the web page beyond reading it, and the web page won't need to interact with the user. If you actually want a full-blown web browser, then you probably want to invoke the Browser application with a URL Intent rather than show it with a WebView. For example:
Uri uri = Uri.parse("http://www.example.com"); Intent intent = new Intent(Intent.ACTION_VIEW, uri); startActivity(intent);
See Intent
for more information.
To provide a WebView in your own Activity, include a <WebView>
in your layout,
or set the entire Activity window as a WebView during onCreate()
:
WebView webview = new WebView(this); setContentView(webview);
Then load the desired web page:
// Simplest usage: note that an exception will NOT be thrown // if there is an error loading this page (see below). webview.loadUrl("http://slashdot.org/"); // OR, you can also load from an HTML string: String summary = "<html><body>You scored <b>192</b> points.</body></html>"; webview.loadData(summary, "text/html", null); // ... although note that there are restrictions on what this HTML can do. // See the JavaDocs forloadData()
andloadDataWithBaseURL()
for more info.
A WebView has several customization points where you can add your own behavior. These are:
WebChromeClient
subclass.
This class is called when something that might impact a
browser UI happens, for instance, progress updates and
JavaScript alerts are sent here (see Debugging Tasks).
WebViewClient
subclass.
It will be called when things happen that impact the
rendering of the content, eg, errors or form submissions. You
can also intercept URL loading here (via shouldOverrideUrlLoading()
).WebSettings
, such as
enabling JavaScript with setJavaScriptEnabled()
. addJavascriptInterface(Object, String)
method. This
method allows you to inject Java objects into a page's JavaScript
context, so that they can be accessed by JavaScript in the page.Here's a more complicated example, showing error handling, settings, and progress notification:
// Let's display the progress in the activity title bar, like the // browser app does. getWindow().requestFeature(Window.FEATURE_PROGRESS); webview.getSettings().setJavaScriptEnabled(true); final Activity activity = this; webview.setWebChromeClient(new WebChromeClient() { public void onProgressChanged(WebView view, int progress) { // Activities and WebViews measure progress with different scales. // The progress meter will automatically disappear when we reach 100% activity.setProgress(progress * 1000); } }); webview.setWebViewClient(new WebViewClient() { public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) { Toast.makeText(activity, "Oh no! " + description, Toast.LENGTH_SHORT).show(); } }); webview.loadUrl("http://developer.android.com/");
To enable the built-in zoom, set
WebSettings
.setBuiltInZoomControls(boolean)
(introduced in API level CUPCAKE
).
NOTE: Using zoom if either the height or width is set to
WRAP_CONTENT
may lead to undefined behavior
and should be avoided.
For obvious security reasons, your application has its own cache, cookie store etc.—it does not share the Browser application's data.
By default, requests by the HTML to open new windows are
ignored. This is true whether they be opened by JavaScript or by
the target attribute on a link. You can customize your
WebChromeClient
to provide your own behaviour for opening multiple windows,
and render them in whatever manner you want.
The standard behavior for an Activity is to be destroyed and
recreated when the device orientation or any other configuration changes. This will cause
the WebView to reload the current page. If you don't want that, you
can set your Activity to handle the orientation
and keyboardHidden
changes, and then just leave the WebView alone. It'll automatically
re-orient itself as appropriate. Read Handling Runtime Changes for
more information about how to handle configuration changes during runtime.
The screen density of a device is based on the screen resolution. A screen with low density has fewer available pixels per inch, where a screen with high density has more — sometimes significantly more — pixels per inch. The density of a screen is important because, other things being equal, a UI element (such as a button) whose height and width are defined in terms of screen pixels will appear larger on the lower density screen and smaller on the higher density screen. For simplicity, Android collapses all actual screen densities into three generalized densities: high, medium, and low.
By default, WebView scales a web page so that it is drawn at a size that matches the default
appearance on a medium density screen. So, it applies 1.5x scaling on a high density screen
(because its pixels are smaller) and 0.75x scaling on a low density screen (because its pixels
are bigger).
Starting with API level ECLAIR
, WebView supports DOM, CSS,
and meta tag features to help you (as a web developer) target screens with different screen
densities.
Here's a summary of the features you can use to handle different screen densities:
window.devicePixelRatio
DOM property. The value of this property specifies the
default scaling factor used for the current device. For example, if the value of window.devicePixelRatio
is "1.0", then the device is considered a medium density (mdpi) device
and default scaling is not applied to the web page; if the value is "1.5", then the device is
considered a high density device (hdpi) and the page content is scaled 1.5x; if the
value is "0.75", then the device is considered a low density device (ldpi) and the content is
scaled 0.75x.-webkit-device-pixel-ratio
CSS media query. Use this to specify the screen
densities for which this style sheet is to be used. The corresponding value should be either
"0.75", "1", or "1.5", to indicate that the styles are for devices with low density, medium
density, or high density screens, respectively. For example:
<link rel="stylesheet" media="screen and (-webkit-device-pixel-ratio:1.5)" href="hdpi.css" />
The hdpi.css
stylesheet is only used for devices with a screen pixel ration of 1.5,
which is the high density pixel ratio.
In order to support inline HTML5 video in your application you need to have hardware acceleration turned on.
In order to support full screen — for video or other HTML content — you need to set a
WebChromeClient
and implement both
onShowCustomView(View, WebChromeClient.CustomViewCallback)
and onHideCustomView()
. If the implementation of either of these two methods is
missing then the web contents will not be allowed to enter full screen. Optionally you can implement
getVideoLoadingProgressView()
to customize the View displayed whilst a video
is loading.
For applications targeting Android N and later releases
(API level > M
) the geolocation api is only supported on
secure origins such as https. For such applications requests to geolocation api on non-secure
origins are automatically denied without invoking the corresponding
onGeolocationPermissionsShowPrompt(String, GeolocationPermissions.Callback)
method.
It is recommended to set the WebView layout height to a fixed value or to
MATCH_PARENT
instead of using
WRAP_CONTENT
.
When using MATCH_PARENT
for the height none of the WebView's parents should use a
WRAP_CONTENT
layout height since that could result in
incorrect sizing of the views.
Setting the WebView's height to WRAP_CONTENT
enables the following behaviors:
KITKAT
and earlier SDKs the
HTML viewport meta tag will be ignored in order to preserve backwards compatibility.
Using a layout width of WRAP_CONTENT
is not
supported. If such a width is used the WebView will attempt to use the width of the parent
instead.
WebView may upload anonymous diagnostic data to Google when the user has consented. This data helps Google improve WebView. Data is collected on a per-app basis for each app which has instantiated a WebView. An individual app can opt out of this feature by putting the following tag in its manifest:
<meta-data android:name="android.webkit.WebView.MetricsOptOut" android:value="true" />
Data will only be uploaded for a given app if the user has consented AND the app has not opted out.
Nested classes | |
---|---|
interface |
WebView.FindListener
Interface to listen for find results. |
class |
WebView.HitTestResult
|
interface |
WebView.PictureListener
This interface was deprecated in API level 12. This interface is now obsolete. |
class |
WebView.VisualStateCallback
Callback interface supplied to |
class |
WebView.WebViewTransport
Transportation object for returning WebView across thread boundaries. |
Inherited XML attributes | |
---|---|
From
class
android.view.ViewGroup
| |
From
class
android.view.View
|
Constants | |
---|---|
String |
SCHEME_GEO
URI scheme for map address. |
String |
SCHEME_MAILTO
URI scheme for email address. |
String |
SCHEME_TEL
URI scheme for telephone number. |
Inherited constants |
---|
From
class
android.view.ViewGroup
|
From
class
android.view.View
|
Inherited fields |
---|
From
class
android.view.View
|
Public constructors | |
---|---|
WebView(Context context)
Constructs a new WebView with a Context object. |
|
WebView(Context context, AttributeSet attrs)
Constructs a new WebView with layout parameters. |
|
WebView(Context context, AttributeSet attrs, int defStyleAttr)
Constructs a new WebView with layout parameters and a default style. |
|
WebView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes)
Constructs a new WebView with layout parameters and a default style. |
|
WebView(Context context, AttributeSet attrs, int defStyleAttr, boolean privateBrowsing)
This constructor was deprecated
in API level 17.
Private browsing is no longer supported directly via
WebView and will be removed in a future release. Prefer using
|
Public methods | |
---|---|
void
|
addJavascriptInterface(Object object, String name)
Injects the supplied Java object into this WebView. |
boolean
|
canGoBack()
Gets whether this WebView has a back history item. |
boolean
|
canGoBackOrForward(int steps)
Gets whether the page can go back or forward the given number of steps. |
boolean
|
canGoForward()
Gets whether this WebView has a forward history item. |
boolean
|
canZoomIn()
This method was deprecated
in API level 17.
This method is prone to inaccuracy due to race conditions
between the web rendering and UI threads; prefer
|
boolean
|
canZoomOut()
This method was deprecated
in API level 17.
This method is prone to inaccuracy due to race conditions
between the web rendering and UI threads; prefer
|
Picture
|
capturePicture()
This method was deprecated
in API level 19.
Use |
void
|
clearCache(boolean includeDiskFiles)
Clears the resource cache. |
static
void
|
clearClientCertPreferences(Runnable onCleared)
Clears the client certificate preferences stored in response to proceeding/cancelling client cert requests. |
void
|
clearFormData()
Removes the autocomplete popup from the currently focused form field, if present. |
void
|
clearHistory()
Tells this WebView to clear its internal back/forward list. |
void
|
clearMatches()
Clears the highlighting surrounding text matches created by
|
void
|
clearSslPreferences()
Clears the SSL preferences table stored in response to proceeding with SSL certificate errors. |
void
|
clearView()
This method was deprecated in API level 18. Use WebView.loadUrl("about:blank") to reliably reset the view state and release page resources (including any running JavaScript). |
void
|
computeScroll()
Called by a parent to request that a child update its values for mScrollX and mScrollY if necessary. |
WebBackForwardList
|
copyBackForwardList()
Gets the WebBackForwardList for this WebView. |
PrintDocumentAdapter
|
createPrintDocumentAdapter(String documentName)
Creates a PrintDocumentAdapter that provides the content of this Webview for printing. |
PrintDocumentAdapter
|
createPrintDocumentAdapter()
This method was deprecated
in API level 21.
Use |
WebMessagePort[]
|
createWebMessageChannel()
Creates a message channel to communicate with JS and returns the message ports that represent the endpoints of this message channel. |
void
|
destroy()
Destroys the internal state of this WebView. |
boolean
|
dispatchKeyEvent(KeyEvent event)
Dispatch a key event to the next view on the focus path. |
void
|
documentHasImages(Message response)
Queries the document to see if it contains any image references. |
static
void
|
enableSlowWholeDocumentDraw()
For apps targeting the L release, WebView has a new default behavior that reduces memory footprint and increases performance by intelligently choosing the portion of the HTML document that needs to be drawn. |
void
|
evaluateJavascript(String script, ValueCallback<String> resultCallback)
Asynchronously evaluates JavaScript in the context of the currently displayed page. |
static
String
|
findAddress(String addr)
Gets the first substring consisting of the address of a physical location. |
int
|
findAll(String find)
This method was deprecated
in API level 16.
|
void
|
findAllAsync(String find)
Finds all instances of find on the page and highlights them, asynchronously. |
View
|
findFocus()
Find the view in the hierarchy rooted at this view that currently has focus. |
void
|
findNext(boolean forward)
Highlights and scrolls to the next match found by
|
void
|
flingScroll(int vx, int vy)
|
void
|
freeMemory()
This method was deprecated in API level 19. Memory caches are automatically dropped when no longer needed, and in response to system memory pressure. |
CharSequence
|
getAccessibilityClassName()
Return the class name of this object to be used for accessibility purposes. |
AccessibilityNodeProvider
|
getAccessibilityNodeProvider()
Gets the provider for managing a virtual view hierarchy rooted at this View
and reported to |
SslCertificate
|
getCertificate()
Gets the SSL certificate for the main top-level page or null if there is no certificate (the site is not secure). |
int
|
getContentHeight()
Gets the height of the HTML content. |
Bitmap
|
getFavicon()
Gets the favicon for the current page. |
Handler
|
getHandler()
|
WebView.HitTestResult
|
getHitTestResult()
Gets a HitTestResult based on the current cursor node. |
String[]
|
getHttpAuthUsernamePassword(String host, String realm)
Retrieves HTTP authentication credentials for a given host and realm. |
String
|
getOriginalUrl()
Gets the original URL for the current page. |
int
|
getProgress()
Gets the progress for the current page. |
float
|
getScale()
This method was deprecated
in API level 17.
This method is prone to inaccuracy due to race conditions
between the web rendering and UI threads; prefer
|
WebSettings
|
getSettings()
Gets the WebSettings object used to control the settings for this WebView. |
String
|
getTitle()
Gets the title for the current page. |
String
|
getUrl()
Gets the URL for the current page. |
void
|
goBack()
Goes back in the history of this WebView. |
void
|
goBackOrForward(int steps)
Goes to the history item that is the number of steps away from the current item. |
void
|
goForward()
Goes forward in the history of this WebView. |
void
|
invokeZoomPicker()
Invokes the graphical zoom picker widget for this WebView. |
boolean
|
isPrivateBrowsingEnabled()
Gets whether private browsing is enabled in this WebView. |
void
|
loadData(String data, String mimeType, String encoding)
Loads the given data into this WebView using a 'data' scheme URL. |
void
|
loadDataWithBaseURL(String baseUrl, String data, String mimeType, String encoding, String historyUrl)
Loads the given data into this WebView, using baseUrl as the base URL for the content. |
void
|
loadUrl(String url)
Loads the given URL. |
void
|
loadUrl(String url, Map<String, String> additionalHttpHeaders)
Loads the given URL with the specified additional HTTP headers. |
void
|
onChildViewAdded(View parent, View child)
This method was deprecated in API level 8. WebView no longer needs to implement ViewGroup.OnHierarchyChangeListener. This method does nothing now. |
void
|
onChildViewRemoved(View p, View child)
This method was deprecated in API level 8. WebView no longer needs to implement ViewGroup.OnHierarchyChangeListener. This method does nothing now. |
InputConnection
|
onCreateInputConnection(EditorInfo outAttrs)
Create a new InputConnection for an InputMethod to interact with the view. |
boolean
|
onDragEvent(DragEvent event)
Handles drag events sent by the system following a call to
|
void
|
onFinishTemporaryDetach()
Called after |
boolean
|
onGenericMotionEvent(MotionEvent event)
Implement this method to handle generic motion events. |
void
|
onGlobalFocusChanged(View oldFocus, View newFocus)
This method was deprecated in API level 3. WebView should not have implemented ViewTreeObserver.OnGlobalFocusChangeListener. This method does nothing now. |
boolean
|
onHoverEvent(MotionEvent event)
Implement this method to handle hover events. |
boolean
|
onKeyDown(int keyCode, KeyEvent event)
Default implementation of |
boolean
|
onKeyMultiple(int keyCode, int repeatCount, KeyEvent event)
Default implementation of |
boolean
|
onKeyUp(int keyCode, KeyEvent event)
Default implementation of |
void
|
onPause()
Does a best-effort attempt to pause any processing that can be paused safely, such as animations and geolocation. |
void
|
onProvideVirtualStructure(ViewStructure structure)
Called when assist structure is being retrieved from a view as part of
|
void
|
onResume()
Resumes a WebView after a previous call to |
void
|
onStartTemporaryDetach()
This is called when a container is going to temporarily detach a child, with
|
boolean
|
onTouchEvent(MotionEvent event)
Implement this method to handle touch screen motion events. |
boolean
|
onTrackballEvent(MotionEvent event)
Implement this method to handle trackball motion events. |
void
|
onWindowFocusChanged(boolean hasWindowFocus)
Called when the window containing this view gains or loses focus. |
boolean
|
overlayHorizontalScrollbar()
This method was deprecated in API level 23. This method is now obsolete. |
boolean
|
overlayVerticalScrollbar()
This method was deprecated in API level 23. This method is now obsolete. |
boolean
|
pageDown(boolean bottom)
Scrolls the contents of this WebView down by half the page size. |
boolean
|
pageUp(boolean top)
Scrolls the contents of this WebView up by half the view size. |
void
|
pauseTimers()
Pauses all layout, parsing, and JavaScript timers for all WebViews. |
boolean
|
performLongClick()
Calls this view's OnLongClickListener, if it is defined. |
void
|
postUrl(String url, byte[] postData)
Loads the URL with postData using "POST" method into this WebView. |
void
|
postVisualStateCallback(long requestId, WebView.VisualStateCallback callback)
Posts a |
void
|
postWebMessage(WebMessage message, Uri targetOrigin)
Post a message to main frame. |
void
|
reload()
Reloads the current URL. |
void
|
removeJavascriptInterface(String name)
Removes a previously injected Java object from this WebView. |
boolean
|
requestChildRectangleOnScreen(View child, Rect rect, boolean immediate)
Called when a child of this group wants a particular rectangle to be positioned onto the screen. |
boolean
|
requestFocus(int direction, Rect previouslyFocusedRect)
Call this to try to give focus to a specific view or to one of its descendants
and give it hints about the direction and a specific rectangle that the focus
is coming from.
Looks for a view to give focus to respecting the setting specified by
|
void
|
requestFocusNodeHref(Message hrefMsg)
Requests the anchor or image element URL at the last tapped point. |
void
|
requestImageRef(Message msg)
Requests the URL of the image last touched by the user. |
WebBackForwardList
|
restoreState(Bundle inState)
Restores the state of this WebView from the given Bundle. |
void
|
resumeTimers()
Resumes all layout, parsing, and JavaScript timers for all WebViews. |
void
|
savePassword(String host, String username, String password)
This method was deprecated in API level 18. Saving passwords in WebView will not be supported in future versions. |
WebBackForwardList
|
saveState(Bundle outState)
Saves the state of this WebView used in
|
void
|
saveWebArchive(String filename)
Saves the current view as a web archive. |
void
|
saveWebArchive(String basename, boolean autoname, ValueCallback<String> callback)
Saves the current view as a web archive. |
void
|
setBackgroundColor(int color)
Sets the background color for this view. |
void
|
setCertificate(SslCertificate certificate)
This method was deprecated in API level 17. Calling this function has no useful effect, and will be ignored in future releases. |
void
|
setDownloadListener(DownloadListener listener)
Registers the interface to be used when content can not be handled by the rendering engine, and should be downloaded instead. |
void
|
setFindListener(WebView.FindListener listener)
Registers the listener to be notified as find-on-page operations progress. |
void
|
setHorizontalScrollbarOverlay(boolean overlay)
This method was deprecated in API level 23. This method has no effect. |
void
|
setHttpAuthUsernamePassword(String host, String realm, String username, String password)
Stores HTTP authentication credentials for a given host and realm. |
void
|
setInitialScale(int scaleInPercent)
Sets the initial scale for this WebView. |
void
|
setLayerType(int layerType, Paint paint)
Specifies the type of layer backing this view. |
void
|
setLayoutParams(ViewGroup.LayoutParams params)
Set the layout parameters associated with this view. |
void
|
setMapTrackballToArrowKeys(boolean setMap)
This method was deprecated in API level 17. Only the default case, true, will be supported in a future version. |
void
|
setNetworkAvailable(boolean networkUp)
Informs WebView of the network state. |
void
|
setOverScrollMode(int mode)
Set the over-scroll mode for this view. |
void
|
setPictureListener(WebView.PictureListener listener)
This method was deprecated in API level 12. This method is now obsolete. |
void
|
setScrollBarStyle(int style)
Specify the style of the scrollbars. |
void
|
setVerticalScrollbarOverlay(boolean overlay)
This method was deprecated in API level 23. This method has no effect. |
void
|
setWebChromeClient(WebChromeClient client)
Sets the chrome handler. |
static
void
|
setWebContentsDebuggingEnabled(boolean enabled)
Enables debugging of web contents (HTML / CSS / JavaScript) loaded into any WebViews of this application. |
void
|
setWebViewClient(WebViewClient client)
Sets the WebViewClient that will receive various notifications and requests. |
boolean
|
shouldDelayChildPressedState()
Return true if the pressed state should be delayed for children or descendants of this ViewGroup. |
boolean
|
showFindDialog(String text, boolean showIme)
This method was deprecated in API level 18. This method does not work reliably on all Android versions; implementing a custom find dialog using WebView.findAllAsync() provides a more robust solution. |
void
|
stopLoading()
Stops the current load. |
void
|
zoomBy(float zoomFactor)
Performs a zoom operation in this WebView. |
boolean
|
zoomIn()
Performs zoom in in this WebView. |
boolean
|
zoomOut()
Performs zoom out in this WebView. |
Protected methods | |
---|---|
int
|
computeHorizontalScrollOffset()
Compute the horizontal offset of the horizontal scrollbar's thumb within the horizontal range. |
int
|
computeHorizontalScrollRange()
Compute the horizontal range that the horizontal scrollbar represents. |
int
|
computeVerticalScrollExtent()
Compute the vertical extent of the vertical scrollbar's thumb within the vertical range. |
int
|
computeVerticalScrollOffset()
Compute the vertical offset of the vertical scrollbar's thumb within the horizontal range. |
int
|
computeVerticalScrollRange()
Compute the vertical range that the vertical scrollbar represents. |
void
|
dispatchDraw(Canvas canvas)
Called by draw to draw the child views. |
void
|
onAttachedToWindow()
This is called when the view is attached to a window. |
void
|
onConfigurationChanged(Configuration newConfig)
Called when the current configuration of the resources being used by the application have changed. |
void
|
onDraw(Canvas canvas)
Implement this to do your drawing. |
void
|
onFocusChanged(boolean focused, int direction, Rect previouslyFocusedRect)
Called by the view system when the focus state of this view changes. |
void
|
onMeasure(int widthMeasureSpec, int heightMeasureSpec)
Measure the view and its content to determine the measured width and the measured height. |
void
|
onOverScrolled(int scrollX, int scrollY, boolean clampedX, boolean clampedY)
Called by |
void
|
onScrollChanged(int l, int t, int oldl, int oldt)
This is called in response to an internal scroll in this view (i.e., the view scrolled its own contents). |
void
|
onSizeChanged(int w, int h, int ow, int oh)
This is called during layout when the size of this view has changed. |
void
|
onVisibilityChanged(View changedView, int visibility)
Called when the visibility of the view or an ancestor of the view has changed. |
void
|
onWindowVisibilityChanged(int visibility)
Called when the window containing has change its visibility
(between |
Inherited methods | |
---|---|
From
class
android.widget.AbsoluteLayout
| |
From
class
android.view.ViewGroup
| |
From
class
android.view.View
| |
From
class
java.lang.Object
| |
From
interface
android.view.ViewParent
| |
From
interface
android.view.ViewManager
| |
From
interface
android.graphics.drawable.Drawable.Callback
| |
From
interface
android.view.KeyEvent.Callback
| |
From
interface
android.view.accessibility.AccessibilityEventSource
| |
From
interface
android.view.ViewTreeObserver.OnGlobalFocusChangeListener
| |
From
interface
android.view.ViewGroup.OnHierarchyChangeListener
|
String SCHEME_GEO
URI scheme for map address.
Constant Value: "geo:0,0?q="
String SCHEME_MAILTO
URI scheme for email address.
Constant Value: "mailto:"
String SCHEME_TEL
URI scheme for telephone number.
Constant Value: "tel:"
WebView (Context context)
Constructs a new WebView with a Context object.
Parameters | |
---|---|
context |
Context :
a Context object used to access application assets
|
WebView (Context context, AttributeSet attrs)
Constructs a new WebView with layout parameters.
Parameters | |
---|---|
context |
Context :
a Context object used to access application assets |
attrs |
AttributeSet :
an AttributeSet passed to our parent
|
WebView (Context context, AttributeSet attrs, int defStyleAttr)
Constructs a new WebView with layout parameters and a default style.
Parameters | |
---|---|
context |
Context :
a Context object used to access application assets |
attrs |
AttributeSet :
an AttributeSet passed to our parent |
defStyleAttr |
int :
an attribute in the current theme that contains a
reference to a style resource that supplies default values for
the view. Can be 0 to not look for defaults.
|
WebView (Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes)
Constructs a new WebView with layout parameters and a default style.
Parameters | |
---|---|
context |
Context :
a Context object used to access application assets |
attrs |
AttributeSet :
an AttributeSet passed to our parent |
defStyleAttr |
int :
an attribute in the current theme that contains a
reference to a style resource that supplies default values for
the view. Can be 0 to not look for defaults. |
defStyleRes |
int :
a resource identifier of a style resource that
supplies default values for the view, used only if
defStyleAttr is 0 or can not be found in the theme. Can be 0
to not look for defaults.
|
WebView (Context context, AttributeSet attrs, int defStyleAttr, boolean privateBrowsing)
This constructor was deprecated
in API level 17.
Private browsing is no longer supported directly via
WebView and will be removed in a future release. Prefer using
WebSettings
, WebViewDatabase
, CookieManager
and WebStorage
for fine-grained control of privacy data.
Constructs a new WebView with layout parameters and a default style.
Parameters | |
---|---|
context |
Context :
a Context object used to access application assets |
attrs |
AttributeSet :
an AttributeSet passed to our parent |
defStyleAttr |
int :
an attribute in the current theme that contains a
reference to a style resource that supplies default values for
the view. Can be 0 to not look for defaults. |
privateBrowsing |
boolean :
whether this WebView will be initialized in
private mode |
void addJavascriptInterface (Object object, String name)
Injects the supplied Java object into this WebView. The object is
injected into the JavaScript context of the main frame, using the
supplied name. This allows the Java object's methods to be
accessed from JavaScript. For applications targeted to API
level JELLY_BEAN_MR1
and above, only public methods that are annotated with
JavascriptInterface
can be accessed from JavaScript.
For applications targeted to API level JELLY_BEAN
or below,
all public methods (including the inherited ones) can be accessed, see the
important security note below for implications.
Note that injected objects will not appear in JavaScript until the page is next (re)loaded. For example:
class JsObject { @JavascriptInterface public String toString() { return "injectedObject"; } } webView.addJavascriptInterface(new JsObject(), "injectedObject"); webView.loadData("", "text/html", null); webView.loadUrl("javascript:alert(injectedObject.toString())");
IMPORTANT:
JELLY_BEAN
or earlier.
Apps that target a version later than JELLY_BEAN
are still vulnerable if the app runs on a device running Android earlier than 4.2.
The most secure way to use this method is to target JELLY_BEAN_MR1
and to ensure the method is called only when running on Android 4.2 or later.
With these older versions, JavaScript could use reflection to access an
injected object's public fields. Use of this method in a WebView
containing untrusted content could allow an attacker to manipulate the
host application in unintended ways, executing Java code with the
permissions of the host application. Use extreme care when using this
method in a WebView which could contain untrusted content.LOLLIPOP
and above, methods of injected Java objects are enumerable from
JavaScript.Parameters | |
---|---|
object |
Object :
the Java object to inject into this WebView's JavaScript
context. Null values are ignored. |
name |
String :
the name used to expose the object in JavaScript
|
boolean canGoBack ()
Gets whether this WebView has a back history item.
Returns | |
---|---|
boolean |
true iff this WebView has a back history item |
boolean canGoBackOrForward (int steps)
Gets whether the page can go back or forward the given number of steps.
Parameters | |
---|---|
steps |
int :
the negative or positive number of steps to move the
history
|
Returns | |
---|---|
boolean |
boolean canGoForward ()
Gets whether this WebView has a forward history item.
Returns | |
---|---|
boolean |
true iff this Webview has a forward history item |
boolean canZoomIn ()
This method was deprecated
in API level 17.
This method is prone to inaccuracy due to race conditions
between the web rendering and UI threads; prefer
onScaleChanged(WebView, float, float)
.
Gets whether this WebView can be zoomed in.
Returns | |
---|---|
boolean |
true if this WebView can be zoomed in |
boolean canZoomOut ()
This method was deprecated
in API level 17.
This method is prone to inaccuracy due to race conditions
between the web rendering and UI threads; prefer
onScaleChanged(WebView, float, float)
.
Gets whether this WebView can be zoomed out.
Returns | |
---|---|
boolean |
true if this WebView can be zoomed out |
Picture capturePicture ()
This method was deprecated
in API level 19.
Use onDraw(Canvas)
to obtain a bitmap snapshot of the WebView, or
saveWebArchive(String)
to save the content to a file.
Gets a new picture that captures the current contents of this WebView. The picture is of the entire document being displayed, and is not limited to the area currently displayed by this WebView. Also, the picture is a static copy and is unaffected by later changes to the content being displayed.
Note that due to internal changes, for API levels between
HONEYCOMB
and
ICE_CREAM_SANDWICH
inclusive, the
picture does not include fixed position elements or scrollable divs.
Note that from JELLY_BEAN_MR1
the returned picture
should only be drawn into bitmap-backed Canvas - using any other type of Canvas will involve
additional conversion at a cost in memory and performance. Also the
createFromStream(InputStream)
and
writeToStream(OutputStream)
methods are not supported on the
returned object.
Returns | |
---|---|
Picture |
a picture that captures the current contents of this WebView |
void clearCache (boolean includeDiskFiles)
Clears the resource cache. Note that the cache is per-application, so this will clear the cache for all WebViews used.
Parameters | |
---|---|
includeDiskFiles |
boolean :
if false, only the RAM cache is cleared
|
void clearClientCertPreferences (Runnable onCleared)
Clears the client certificate preferences stored in response
to proceeding/cancelling client cert requests. Note that Webview
automatically clears these preferences when it receives a
ACTION_STORAGE_CHANGED
intent. The preferences are
shared by all the webviews that are created by the embedder application.
Parameters | |
---|---|
onCleared |
Runnable :
A runnable to be invoked when client certs are cleared.
The embedder can pass null if not interested in the
callback. The runnable will be called in UI thread.
|
void clearFormData ()
Removes the autocomplete popup from the currently focused form field, if
present. Note this only affects the display of the autocomplete popup,
it does not remove any saved form data from this WebView's store. To do
that, use clearFormData()
.
void clearHistory ()
Tells this WebView to clear its internal back/forward list.
void clearMatches ()
Clears the highlighting surrounding text matches created by
findAllAsync(String)
.
void clearSslPreferences ()
Clears the SSL preferences table stored in response to proceeding with SSL certificate errors.
void clearView ()
This method was deprecated
in API level 18.
Use WebView.loadUrl("about:blank") to reliably reset the view state
and release page resources (including any running JavaScript).
Clears this WebView so that onDraw() will draw nothing but white background, and onMeasure() will return 0 if MeasureSpec is not MeasureSpec.EXACTLY.
void computeScroll ()
Called by a parent to request that a child update its values for mScrollX
and mScrollY if necessary. This will typically be done if the child is
animating a scroll using a Scroller
object.
WebBackForwardList copyBackForwardList ()
Gets the WebBackForwardList for this WebView. This contains the back/forward list for use in querying each item in the history stack. This is a copy of the private WebBackForwardList so it contains only a snapshot of the current state. Multiple calls to this method may return different objects. The object returned from this method will not be updated to reflect any new state.
Returns | |
---|---|
WebBackForwardList |
PrintDocumentAdapter createPrintDocumentAdapter (String documentName)
Creates a PrintDocumentAdapter that provides the content of this Webview for printing.
The adapter works by converting the Webview contents to a PDF stream. The Webview cannot
be drawn during the conversion process - any such draws are undefined. It is recommended
to use a dedicated off screen Webview for the printing. If necessary, an application may
temporarily hide a visible WebView by using a custom PrintDocumentAdapter instance
wrapped around the object returned and observing the onStart and onFinish methods. See
PrintDocumentAdapter
for more information.
Parameters | |
---|---|
documentName |
String :
The user-facing name of the printed document. See
PrintDocumentInfo
|
Returns | |
---|---|
PrintDocumentAdapter |
PrintDocumentAdapter createPrintDocumentAdapter ()
This method was deprecated
in API level 21.
Use createPrintDocumentAdapter(String)
which requires user
to provide a print document name.
Returns | |
---|---|
PrintDocumentAdapter |
WebMessagePort[] createWebMessageChannel ()
Creates a message channel to communicate with JS and returns the message ports that represent the endpoints of this message channel. The HTML5 message channel functionality is described here
The returned message channels are entangled and already in started state.
Returns | |
---|---|
WebMessagePort[] |
the two message ports that form the message channel. |
void destroy ()
Destroys the internal state of this WebView. This method should be called after this WebView has been removed from the view system. No other methods may be called on this WebView after destroy.
boolean dispatchKeyEvent (KeyEvent event)
Dispatch a key event to the next view on the focus path. This path runs from the top of the view tree down to the currently focused view. If this view has focus, it will dispatch to itself. Otherwise it will dispatch the next node down the focus path. This method also fires any key listeners.
Parameters | |
---|---|
event |
KeyEvent :
The key event to be dispatched. |
Returns | |
---|---|
boolean |
True if the event was handled, false otherwise. |
void documentHasImages (Message response)
Queries the document to see if it contains any image references. The message object will be dispatched with arg1 being set to 1 if images were found and 0 if the document does not reference any images.
Parameters | |
---|---|
response |
Message :
the message that will be dispatched with the result
|
void enableSlowWholeDocumentDraw ()
For apps targeting the L release, WebView has a new default behavior that reduces memory footprint and increases performance by intelligently choosing the portion of the HTML document that needs to be drawn. These optimizations are transparent to the developers. However, under certain circumstances, an App developer may want to disable them:
onDraw(Canvas)
to do own drawing and accesses portions
of the page that is way outside the visible portion of the page.capturePicture()
to capture a very large HTML document.
Note that capturePicture is a deprecated API.void evaluateJavascript (String script, ValueCallback<String> resultCallback)
Asynchronously evaluates JavaScript in the context of the currently displayed page. If non-null, |resultCallback| will be invoked with any result returned from that execution. This method must be called on the UI thread and the callback will be made on the UI thread.
Compatibility note. Applications targeting N
or
later, JavaScript state from an empty WebView is no longer persisted across navigations like
loadUrl(String)
. For example, global variables and functions defined before calling
loadUrl(String)
will not exist in the loaded page. Applications should use
addJavascriptInterface(Object, String)
instead to persist JavaScript objects across navigations.
Parameters | |
---|---|
script |
String :
the JavaScript to execute. |
resultCallback |
ValueCallback :
A callback to be invoked when the script execution
completes with the result of the execution (if any).
May be null if no notificaion of the result is required.
|
String findAddress (String addr)
Gets the first substring consisting of the address of a physical location. Currently, only addresses in the United States are detected, and consist of:
Parameters | |
---|---|
addr |
String :
the string to search for addresses |
Returns | |
---|---|
String |
the address, or if no address is found, null |
int findAll (String find)
This method was deprecated
in API level 16.
findAllAsync(String)
is preferred.
Finds all instances of find on the page and highlights them.
Notifies any registered WebView.FindListener
.
Parameters | |
---|---|
find |
String :
the string to find |
Returns | |
---|---|
int |
the number of occurances of the String "find" that were found |
See also:
void findAllAsync (String find)
Finds all instances of find on the page and highlights them,
asynchronously. Notifies any registered WebView.FindListener
.
Successive calls to this will cancel any pending searches.
Parameters | |
---|---|
find |
String :
the string to find. |
See also:
View findFocus ()
Find the view in the hierarchy rooted at this view that currently has focus.
Returns | |
---|---|
View |
The view that currently has focus, or null if no focused view can be found. |
void findNext (boolean forward)
Highlights and scrolls to the next match found by
findAllAsync(String)
, wrapping around page boundaries as necessary.
Notifies any registered WebView.FindListener
. If findAllAsync(String)
has not been called yet, or if clearMatches()
has been called since the
last find operation, this function does nothing.
Parameters | |
---|---|
forward |
boolean :
the direction to search |
See also:
void freeMemory ()
This method was deprecated
in API level 19.
Memory caches are automatically dropped when no longer needed, and in response
to system memory pressure.
Informs this WebView that memory is low so that it can free any available memory.
CharSequence getAccessibilityClassName ()
Return the class name of this object to be used for accessibility purposes.
Subclasses should only override this if they are implementing something that
should be seen as a completely new class of view when used by accessibility,
unrelated to the class it is deriving from. This is used to fill in
AccessibilityNodeInfo.setClassName
.
Returns | |
---|---|
CharSequence |
AccessibilityNodeProvider getAccessibilityNodeProvider ()
Gets the provider for managing a virtual view hierarchy rooted at this View
and reported to AccessibilityService
s
that explore the window content.
If this method returns an instance, this instance is responsible for managing
AccessibilityNodeInfo
s describing the virtual sub-tree rooted at this
View including the one representing the View itself. Similarly the returned
instance is responsible for performing accessibility actions on any virtual
view or the root view itself.
If an View.AccessibilityDelegate
has been specified via calling
setAccessibilityDelegate(AccessibilityDelegate)
its
getAccessibilityNodeProvider(View)
is responsible for handling this call.
Returns | |
---|---|
AccessibilityNodeProvider |
The provider. |
SslCertificate getCertificate ()
Gets the SSL certificate for the main top-level page or null if there is no certificate (the site is not secure).
Returns | |
---|---|
SslCertificate |
the SSL certificate for the main top-level page |
int getContentHeight ()
Gets the height of the HTML content.
Returns | |
---|---|
int |
the height of the HTML content |
Bitmap getFavicon ()
Gets the favicon for the current page. This is the favicon of the current page until WebViewClient.onReceivedIcon is called.
Returns | |
---|---|
Bitmap |
the favicon for the current page |
Handler getHandler ()
Returns | |
---|---|
Handler |
A handler associated with the thread running the View. This handler can be used to pump events in the UI events queue. |
WebView.HitTestResult getHitTestResult ()
Gets a HitTestResult based on the current cursor node. If a HTML::a
tag is found and the anchor has a non-JavaScript URL, the HitTestResult
type is set to SRC_ANCHOR_TYPE and the URL is set in the "extra" field.
If the anchor does not have a URL or if it is a JavaScript URL, the type
will be UNKNOWN_TYPE and the URL has to be retrieved through
requestFocusNodeHref(Message)
asynchronously. If a HTML::img tag is
found, the HitTestResult type is set to IMAGE_TYPE and the URL is set in
the "extra" field. A type of
SRC_IMAGE_ANCHOR_TYPE indicates an anchor with a URL that has an image as
a child node. If a phone number is found, the HitTestResult type is set
to PHONE_TYPE and the phone number is set in the "extra" field of
HitTestResult. If a map address is found, the HitTestResult type is set
to GEO_TYPE and the address is set in the "extra" field of HitTestResult.
If an email address is found, the HitTestResult type is set to EMAIL_TYPE
and the email is set in the "extra" field of HitTestResult. Otherwise,
HitTestResult type is set to UNKNOWN_TYPE.
Returns | |
---|---|
WebView.HitTestResult |
String[] getHttpAuthUsernamePassword (String host, String realm)
Retrieves HTTP authentication credentials for a given host and realm.
This method is intended to be used with
onReceivedHttpAuthRequest(WebView, HttpAuthHandler, String, String)
.
Parameters | |
---|---|
host |
String :
the host to which the credentials apply |
realm |
String :
the realm to which the credentials apply |
Returns | |
---|---|
String[] |
the credentials as a String array, if found. The first element is the username and the second element is the password. Null if no credentials are found. |
String getOriginalUrl ()
Gets the original URL for the current page. This is not always the same as the URL passed to WebViewClient.onPageStarted because although the load for that URL has begun, the current page may not have changed. Also, there may have been redirects resulting in a different URL to that originally requested.
Returns | |
---|---|
String |
the URL that was originally requested for the current page |
int getProgress ()
Gets the progress for the current page.
Returns | |
---|---|
int |
the progress for the current page between 0 and 100 |
float getScale ()
This method was deprecated
in API level 17.
This method is prone to inaccuracy due to race conditions
between the web rendering and UI threads; prefer
onScaleChanged(WebView, float, float)
.
Gets the current scale of this WebView.
Returns | |
---|---|
float |
the current scale |
WebSettings getSettings ()
Gets the WebSettings object used to control the settings for this WebView.
Returns | |
---|---|
WebSettings |
a WebSettings object that can be used to control this WebView's settings |
String getTitle ()
Gets the title for the current page. This is the title of the current page until WebViewClient.onReceivedTitle is called.
Returns | |
---|---|
String |
the title for the current page |
String getUrl ()
Gets the URL for the current page. This is not always the same as the URL passed to WebViewClient.onPageStarted because although the load for that URL has begun, the current page may not have changed.
Returns | |
---|---|
String |
the URL for the current page |
void goBackOrForward (int steps)
Goes to the history item that is the number of steps away from the current item. Steps is negative if backward and positive if forward.
Parameters | |
---|---|
steps |
int :
the number of steps to take back or forward in the back
forward list
|
void invokeZoomPicker ()
Invokes the graphical zoom picker widget for this WebView. This will result in the zoom widget appearing on the screen to control the zoom level of this WebView.
boolean isPrivateBrowsingEnabled ()
Gets whether private browsing is enabled in this WebView.
Returns | |
---|---|
boolean |
void loadData (String data, String mimeType, String encoding)
Loads the given data into this WebView using a 'data' scheme URL.
Note that JavaScript's same origin policy means that script running in a
page loaded using this method will be unable to access content loaded
using any scheme other than 'data', including 'http(s)'. To avoid this
restriction, use loadDataWithBaseURL()
with an appropriate base URL.
The encoding parameter specifies whether the data is base64 or URL encoded. If the data is base64 encoded, the value of the encoding parameter must be 'base64'. For all other values of the parameter, including null, it is assumed that the data uses ASCII encoding for octets inside the range of safe URL characters and use the standard %xx hex encoding of URLs for octets outside that range. For example, '#', '%', '\', '?' should be replaced by %23, %25, %27, %3f respectively.
The 'data' scheme URL formed by this method uses the default US-ASCII
charset. If you need need to set a different charset, you should form a
'data' scheme URL which explicitly specifies a charset parameter in the
mediatype portion of the URL and call loadUrl(String)
instead.
Note that the charset obtained from the mediatype portion of a data URL
always overrides that specified in the HTML or XML document itself.
Parameters | |
---|---|
data |
String :
a String of data in the given encoding |
mimeType |
String :
the MIME type of the data, e.g. 'text/html' |
encoding |
String :
the encoding of the data
|
void loadDataWithBaseURL (String baseUrl, String data, String mimeType, String encoding, String historyUrl)
Loads the given data into this WebView, using baseUrl as the base URL for the content. The base URL is used both to resolve relative URLs and when applying JavaScript's same origin policy. The historyUrl is used for the history entry.
Note that content specified in this way can access local device files (via 'file' scheme URLs) only if baseUrl specifies a scheme other than 'http', 'https', 'ftp', 'ftps', 'about' or 'javascript'.
If the base URL uses the data scheme, this method is equivalent to
calling loadData()
and the
historyUrl is ignored, and the data will be treated as part of a data: URL.
If the base URL uses any other scheme, then the data will be loaded into
the WebView as a plain string (i.e. not part of a data URL) and any URL-encoded
entities in the string will not be decoded.
Note that the baseUrl is sent in the 'Referer' HTTP header when requesting subresources (images, etc.) of the page loaded using this method.
Parameters | |
---|---|
baseUrl |
String :
the URL to use as the page's base URL. If null defaults to
'about:blank'. |
data |
String :
a String of data in the given encoding |
mimeType |
String :
the MIMEType of the data, e.g. 'text/html'. If null,
defaults to 'text/html'. |
encoding |
String :
the encoding of the data |
historyUrl |
String :
the URL to use as the history entry. If null defaults
to 'about:blank'. If non-null, this must be a valid URL.
|
void loadUrl (String url)
Loads the given URL.
Also see compatibility note on evaluateJavascript(String, ValueCallback
.
Parameters | |
---|---|
url |
String :
the URL of the resource to load
|
void loadUrl (String url, Map<String, String> additionalHttpHeaders)
Loads the given URL with the specified additional HTTP headers.
Also see compatibility note on evaluateJavascript(String, ValueCallback
.
Parameters | |
---|---|
url |
String :
the URL of the resource to load |
additionalHttpHeaders |
Map :
the additional headers to be used in the
HTTP request for this URL, specified as a map from name to
value. Note that if this map contains any of the headers
that are set by default by this WebView, such as those
controlling caching, accept types or the User-Agent, their
values may be overriden by this WebView's defaults.
|
void onChildViewAdded (View parent, View child)
This method was deprecated
in API level 8.
WebView no longer needs to implement
ViewGroup.OnHierarchyChangeListener. This method does nothing now.
Called when a new child is added to a parent view.
Parameters | |
---|---|
parent |
View :
the view in which a child was added |
child |
View :
the new child view added in the hierarchy
|
void onChildViewRemoved (View p, View child)
This method was deprecated
in API level 8.
WebView no longer needs to implement
ViewGroup.OnHierarchyChangeListener. This method does nothing now.
Called when a child is removed from a parent view.
Parameters | |
---|---|
p |
View :
the view from which the child was removed |
child |
View :
the child removed from the hierarchy
|
InputConnection onCreateInputConnection (EditorInfo outAttrs)
Create a new InputConnection for an InputMethod to interact with the view. The default implementation returns null, since it doesn't support input methods. You can override this to implement such support. This is only needed for views that take focus and text input.
When implementing this, you probably also want to implement
onCheckIsTextEditor()
to indicate you will return a
non-null InputConnection.
Also, take good care to fill in the EditorInfo
object correctly and in its entirety, so that the connected IME can rely
on its values. For example, initialSelStart
and initialSelEnd
members
must be filled in with the correct cursor position for IMEs to work correctly
with your application.
Parameters | |
---|---|
outAttrs |
EditorInfo :
Fill in with attribute information about the connection.
|
Returns | |
---|---|
InputConnection |
boolean onDragEvent (DragEvent event)
Handles drag events sent by the system following a call to
startDragAndDrop()
.
When the system calls this method, it passes a
DragEvent
object. A call to
getAction()
returns one of the action type constants defined
in DragEvent. The method uses these to determine what is happening in the drag and drop
operation.
Parameters | |
---|---|
event |
DragEvent :
The DragEvent sent by the system.
The getAction() method returns an action type constant defined
in DragEvent, indicating the type of drag event represented by this object. |
Returns | |
---|---|
boolean |
true if the method was successful, otherwise false .
The method should return
The method should also return |
void onFinishTemporaryDetach ()
Called after onStartTemporaryDetach()
when the container is done
changing the view.
boolean onGenericMotionEvent (MotionEvent event)
Implement this method to handle generic motion events.
Generic motion events describe joystick movements, mouse hovers, track pad
touches, scroll wheel movements and other input events. The
source
of the motion event specifies
the class of input that was received. Implementations of this method
must examine the bits in the source before processing the event.
The following code example shows how this is done.
Generic motion events with source class SOURCE_CLASS_POINTER
are delivered to the view under the pointer. All other generic motion events are
delivered to the focused view.
public boolean onGenericMotionEvent(MotionEvent event) { if (event.isFromSource(InputDevice.SOURCE_CLASS_JOYSTICK)) { if (event.getAction() == MotionEvent.ACTION_MOVE) { // process the joystick movement... return true; } } if (event.isFromSource(InputDevice.SOURCE_CLASS_POINTER)) { switch (event.getAction()) { case MotionEvent.ACTION_HOVER_MOVE: // process the mouse hover movement... return true; case MotionEvent.ACTION_SCROLL: // process the scroll wheel movement... return true; } } return super.onGenericMotionEvent(event); }
Parameters | |
---|---|
event |
MotionEvent :
The generic motion event being processed. |
Returns | |
---|---|
boolean |
True if the event was handled, false otherwise. |
void onGlobalFocusChanged (View oldFocus, View newFocus)
This method was deprecated
in API level 3.
WebView should not have implemented
ViewTreeObserver.OnGlobalFocusChangeListener. This method does nothing now.
Callback method to be invoked when the focus changes in the view tree. When the view tree transitions from touch mode to non-touch mode, oldFocus is null. When the view tree transitions from non-touch mode to touch mode, newFocus is null. When focus changes in non-touch mode (without transition from or to touch mode) either oldFocus or newFocus can be null.
Parameters | |
---|---|
oldFocus |
View :
The previously focused view, if any. |
newFocus |
View :
The newly focused View, if any.
|
boolean onHoverEvent (MotionEvent event)
Implement this method to handle hover events.
This method is called whenever a pointer is hovering into, over, or out of the
bounds of a view and the view is not currently being touched.
Hover events are represented as pointer events with action
ACTION_HOVER_ENTER
, ACTION_HOVER_MOVE
,
or ACTION_HOVER_EXIT
.
ACTION_HOVER_ENTER
when the pointer enters the bounds of the view.ACTION_HOVER_MOVE
when the pointer has already entered the bounds of the view and has moved.ACTION_HOVER_EXIT
when the pointer has exited the bounds of the view or when the pointer is
about to go down due to a button click, tap, or similar user action that
causes the view to be touched.The view should implement this method to return true to indicate that it is handling the hover event, such as by changing its drawable state.
The default implementation calls setHovered(boolean)
to update the hovered state
of the view when a hover enter or hover exit event is received, if the view
is enabled and is clickable. The default implementation also sends hover
accessibility events.
Parameters | |
---|---|
event |
MotionEvent :
The motion event that describes the hover. |
Returns | |
---|---|
boolean |
True if the view handled the hover event. |
boolean onKeyDown (int keyCode, KeyEvent event)
Default implementation of KeyEvent.Callback.onKeyDown()
: perform press of the view
when KEYCODE_DPAD_CENTER
or KEYCODE_ENTER
is released, if the view is enabled and clickable.
Key presses in software keyboards will generally NOT trigger this listener, although some may elect to do so in some situations. Do not rely on this to catch software key presses.
Parameters | |
---|---|
keyCode |
int :
a key code that represents the button pressed, from
KeyEvent |
event |
KeyEvent :
the KeyEvent object that defines the button action
|
Returns | |
---|---|
boolean |
If you handled the event, return true. If you want to allow the event to be handled by the next receiver, return false. |
boolean onKeyMultiple (int keyCode, int repeatCount, KeyEvent event)
Default implementation of KeyEvent.Callback.onKeyMultiple()
: always returns false (doesn't handle
the event).
Key presses in software keyboards will generally NOT trigger this listener, although some may elect to do so in some situations. Do not rely on this to catch software key presses.
Parameters | |
---|---|
keyCode |
int :
A key code that represents the button pressed, from
KeyEvent . |
repeatCount |
int :
The number of times the action was made. |
event |
KeyEvent :
The KeyEvent object that defines the button action.
|
Returns | |
---|---|
boolean |
If you handled the event, return true. If you want to allow the event to be handled by the next receiver, return false. |
boolean onKeyUp (int keyCode, KeyEvent event)
Default implementation of KeyEvent.Callback.onKeyUp()
: perform clicking of the view
when KEYCODE_DPAD_CENTER
, KEYCODE_ENTER
or KEYCODE_SPACE
is released.
Key presses in software keyboards will generally NOT trigger this listener, although some may elect to do so in some situations. Do not rely on this to catch software key presses.
Parameters | |
---|---|
keyCode |
int :
A key code that represents the button pressed, from
KeyEvent . |
event |
KeyEvent :
The KeyEvent object that defines the button action.
|
Returns | |
---|---|
boolean |
If you handled the event, return true. If you want to allow the event to be handled by the next receiver, return false. |
void onPause ()
Does a best-effort attempt to pause any processing that can be paused
safely, such as animations and geolocation. Note that this call
does not pause JavaScript. To pause JavaScript globally, use
pauseTimers()
.
To resume WebView, call onResume()
.
void onProvideVirtualStructure (ViewStructure structure)
Called when assist structure is being retrieved from a view as part of
Activity.onProvideAssistData
to
generate additional virtual structure under this view. The defaullt implementation
uses getAccessibilityNodeProvider()
to try to generate this from the
view's virtual accessibility nodes, if any. You can override this for a more
optimal implementation providing this data.
Parameters | |
---|---|
structure |
ViewStructure
|
void onResume ()
Resumes a WebView after a previous call to onPause()
.
void onStartTemporaryDetach ()
This is called when a container is going to temporarily detach a child, with
ViewGroup.detachViewFromParent
.
It will either be followed by onFinishTemporaryDetach()
or
onDetachedFromWindow()
when the container is done.
boolean onTouchEvent (MotionEvent event)
Implement this method to handle touch screen motion events.
If this method is used to detect click actions, it is recommended that
the actions be performed by implementing and calling
performClick()
. This will ensure consistent system behavior,
including:
ACTION_CLICK
when
accessibility features are enabled
Parameters | |
---|---|
event |
MotionEvent :
The motion event. |
Returns | |
---|---|
boolean |
True if the event was handled, false otherwise. |
boolean onTrackballEvent (MotionEvent event)
Implement this method to handle trackball motion events. The
relative movement of the trackball since the last event
can be retrieve with MotionEvent.getX()
and
MotionEvent.getY()
. These are normalized so
that a movement of 1 corresponds to the user pressing one DPAD key (so
they will often be fractional values, representing the more fine-grained
movement information available from a trackball).
Parameters | |
---|---|
event |
MotionEvent :
The motion event. |
Returns | |
---|---|
boolean |
True if the event was handled, false otherwise. |
void onWindowFocusChanged (boolean hasWindowFocus)
Called when the window containing this view gains or loses focus. Note that this is separate from view focus: to receive key events, both your view and its window must have focus. If a window is displayed on top of yours that takes input focus, then your own window will lose focus but the view focus will remain unchanged.
Parameters | |
---|---|
hasWindowFocus |
boolean :
True if the window containing this view now has
focus, false otherwise.
|
boolean overlayHorizontalScrollbar ()
This method was deprecated
in API level 23.
This method is now obsolete.
Gets whether horizontal scrollbar has overlay style.
Returns | |
---|---|
boolean |
true |
boolean overlayVerticalScrollbar ()
This method was deprecated
in API level 23.
This method is now obsolete.
Gets whether vertical scrollbar has overlay style.
Returns | |
---|---|
boolean |
false |
boolean pageDown (boolean bottom)
Scrolls the contents of this WebView down by half the page size.
Parameters | |
---|---|
bottom |
boolean :
true to jump to bottom of page |
Returns | |
---|---|
boolean |
true if the page was scrolled |
boolean pageUp (boolean top)
Scrolls the contents of this WebView up by half the view size.
Parameters | |
---|---|
top |
boolean :
true to jump to the top of the page |
Returns | |
---|---|
boolean |
true if the page was scrolled |
void pauseTimers ()
Pauses all layout, parsing, and JavaScript timers for all WebViews. This is a global requests, not restricted to just this WebView. This can be useful if the application has been paused.
boolean performLongClick ()
Calls this view's OnLongClickListener, if it is defined. Invokes the context menu if the OnLongClickListener did not consume the event.
Returns | |
---|---|
boolean |
true if one of the above receivers consumed the event,
false otherwise
|
void postUrl (String url, byte[] postData)
Loads the URL with postData using "POST" method into this WebView. If url
is not a network URL, it will be loaded with loadUrl(String)
instead, ignoring the postData param.
Parameters | |
---|---|
url |
String :
the URL of the resource to load |
postData |
byte :
the data will be passed to "POST" request, which must be
be "application/x-www-form-urlencoded" encoded.
|
void postVisualStateCallback (long requestId, WebView.VisualStateCallback callback)
Posts a WebView.VisualStateCallback
, which will be called when
the current state of the WebView is ready to be drawn.
Because updates to the the DOM are processed asynchronously, updates to the DOM may not
immediately be reflected visually by subsequent onDraw(Canvas)
invocations. The
WebView.VisualStateCallback
provides a mechanism to notify the caller when the contents of
the DOM at the current time are ready to be drawn the next time the WebView
draws.
The next draw after the callback completes is guaranteed to reflect all the updates to the
DOM up to the the point at which the WebView.VisualStateCallback
was posted, but it may also
contain updates applied after the callback was posted.
The state of the DOM covered by this API includes the following:
To guarantee that the WebView
will successfully render the first frame
after the onComplete(long)
method has been called a set of conditions
must be met:
WebView
's visibility is set to VISIBLE
then
the WebView
must be attached to the view hierarchy.WebView
's visibility is set to INVISIBLE
then the WebView
must be attached to the view hierarchy and must be made
VISIBLE
from the onComplete(long)
method.WebView
's visibility is set to GONE
then the
WebView
must be attached to the view hierarchy and its
LayoutParams
's width and height need to be set to fixed
values and must be made VISIBLE
from the
onComplete(long)
method.When using this API it is also recommended to enable pre-rasterization if the WebView
is offscreen to avoid flickering. See setOffscreenPreRaster(boolean)
for
more details and do consider its caveats.
Parameters | |
---|---|
requestId |
long :
An id that will be returned in the callback to allow callers to match
requests with callbacks. |
callback |
WebView.VisualStateCallback :
The callback to be invoked.
|
void postWebMessage (WebMessage message, Uri targetOrigin)
Post a message to main frame. The embedded application can restrict the messages to a certain target origin. See HTML5 spec for how target origin can be used.
Parameters | |
---|---|
message |
WebMessage :
the WebMessage |
targetOrigin |
Uri :
the target origin. This is the origin of the page
that is intended to receive the message. For best security
practices, the user should not specify a wildcard (*) when
specifying the origin.
|
void removeJavascriptInterface (String name)
Removes a previously injected Java object from this WebView. Note that
the removal will not be reflected in JavaScript until the page is next
(re)loaded. See addJavascriptInterface(Object, String)
.
Parameters | |
---|---|
name |
String :
the name used to expose the object in JavaScript
|
boolean requestChildRectangleOnScreen (View child, Rect rect, boolean immediate)
Called when a child of this group wants a particular rectangle to be
positioned onto the screen. ViewGroup
s overriding this can trust
that:
ViewGroup
s overriding this should uphold the contract:
Parameters | |
---|---|
child |
View :
The direct child making the request. |
rect |
Rect :
The rectangle in the child's coordinates the child
wishes to be on the screen. |
immediate |
boolean :
True to forbid animated or delayed scrolling,
false otherwise |
Returns | |
---|---|
boolean |
Whether the group scrolled to handle the operation |
boolean requestFocus (int direction, Rect previouslyFocusedRect)
Call this to try to give focus to a specific view or to one of its descendants
and give it hints about the direction and a specific rectangle that the focus
is coming from. The rectangle can help give larger views a finer grained hint
about where focus is coming from, and therefore, where to show selection, or
forward focus change internally.
A view will not actually take focus if it is not focusable (isFocusable()
returns
false), or if it is focusable and it is not focusable in touch mode
(isFocusableInTouchMode()
) while the device is in touch mode.
A View will not take focus if it is not visible.
A View will not take focus if one of its parents has
getDescendantFocusability()
equal to
FOCUS_BLOCK_DESCENDANTS
.
See also focusSearch(int)
, which is what you call to say that you
have focus, and you want your parent to look for the next one.
You may wish to override this method if your custom View
has an internal
View
that it wishes to forward the request to.
Looks for a view to give focus to respecting the setting specified by
getDescendantFocusability()
.
Uses onRequestFocusInDescendants(int, android.graphics.Rect)
to
find focus within the children of this group when appropriate.
Parameters | |
---|---|
direction |
int :
One of FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, and FOCUS_RIGHT |
previouslyFocusedRect |
Rect :
The rectangle (in this View's coordinate system)
to give a finer grained hint about where focus is coming from. May be null
if there is no hint. |
Returns | |
---|---|
boolean |
Whether this view or one of its descendants actually took focus. |
void requestFocusNodeHref (Message hrefMsg)
Requests the anchor or image element URL at the last tapped point. If hrefMsg is null, this method returns immediately and does not dispatch hrefMsg to its target. If the tapped point hits an image, an anchor, or an image in an anchor, the message associates strings in named keys in its data. The value paired with the key may be an empty string.
Parameters | |
---|---|
hrefMsg |
Message :
the message to be dispatched with the result of the
request. The message data contains three keys. "url"
returns the anchor's href attribute. "title" returns the
anchor's text. "src" returns the image's src attribute.
|
void requestImageRef (Message msg)
Requests the URL of the image last touched by the user. msg will be sent to its target with a String representing the URL as its object.
Parameters | |
---|---|
msg |
Message :
the message to be dispatched with the result of the request
as the data member with "url" as key. The result can be null.
|
WebBackForwardList restoreState (Bundle inState)
Restores the state of this WebView from the given Bundle. This method is
intended for use in onRestoreInstanceState(Bundle)
and should be called to restore the state of this WebView. If
it is called after this WebView has had a chance to build state (load
pages, create a back/forward list, etc.) there may be undesirable
side-effects. Please note that this method no longer restores the
display data for this WebView.
Parameters | |
---|---|
inState |
Bundle :
the incoming Bundle of state |
Returns | |
---|---|
WebBackForwardList |
the restored back/forward list or null if restoreState failed |
void resumeTimers ()
Resumes all layout, parsing, and JavaScript timers for all WebViews. This will resume dispatching all timers.
void savePassword (String host, String username, String password)
This method was deprecated
in API level 18.
Saving passwords in WebView will not be supported in future versions.
Sets a username and password pair for the specified host. This data is used by the Webview to autocomplete username and password fields in web forms. Note that this is unrelated to the credentials used for HTTP authentication.
Parameters | |
---|---|
host |
String :
the host that required the credentials |
username |
String :
the username for the given host |
password |
String :
the password for the given host |
WebBackForwardList saveState (Bundle outState)
Saves the state of this WebView used in
onSaveInstanceState(Bundle)
. Please note that this
method no longer stores the display data for this WebView. The previous
behavior could potentially leak files if restoreState(Bundle)
was never
called.
Parameters | |
---|---|
outState |
Bundle :
the Bundle to store this WebView's state |
Returns | |
---|---|
WebBackForwardList |
the same copy of the back/forward list used to save the state. If saveState fails, the returned list will be null. |
void saveWebArchive (String filename)
Saves the current view as a web archive.
Parameters | |
---|---|
filename |
String :
the filename where the archive should be placed
|
void saveWebArchive (String basename, boolean autoname, ValueCallback<String> callback)
Saves the current view as a web archive.
Parameters | |
---|---|
basename |
String :
the filename where the archive should be placed |
autoname |
boolean :
if false, takes basename to be a file. If true, basename
is assumed to be a directory in which a filename will be
chosen according to the URL of the current page. |
callback |
ValueCallback :
called after the web archive has been saved. The
parameter for onReceiveValue will either be the filename
under which the file was saved, or null if saving the
file failed.
|
void setBackgroundColor (int color)
Sets the background color for this view.
Parameters | |
---|---|
color |
int :
the color of the background
|
void setCertificate (SslCertificate certificate)
This method was deprecated
in API level 17.
Calling this function has no useful effect, and will be
ignored in future releases.
Sets the SSL certificate for the main top-level page.
Parameters | |
---|---|
certificate |
SslCertificate
|
void setDownloadListener (DownloadListener listener)
Registers the interface to be used when content can not be handled by the rendering engine, and should be downloaded instead. This will replace the current handler.
Parameters | |
---|---|
listener |
DownloadListener :
an implementation of DownloadListener
|
void setFindListener (WebView.FindListener listener)
Registers the listener to be notified as find-on-page operations progress. This will replace the current listener.
Parameters | |
---|---|
listener |
WebView.FindListener :
an implementation of WebView.FindListener
|
void setHorizontalScrollbarOverlay (boolean overlay)
This method was deprecated
in API level 23.
This method has no effect.
Specifies whether the horizontal scrollbar has overlay style.
Parameters | |
---|---|
overlay |
boolean :
true if horizontal scrollbar should have overlay style
|
void setHttpAuthUsernamePassword (String host, String realm, String username, String password)
Stores HTTP authentication credentials for a given host and realm. This
method is intended to be used with
onReceivedHttpAuthRequest(WebView, HttpAuthHandler, String, String)
.
Parameters | |
---|---|
host |
String :
the host to which the credentials apply |
realm |
String :
the realm to which the credentials apply |
username |
String :
the username |
password |
String :
the password |
void setInitialScale (int scaleInPercent)
Sets the initial scale for this WebView. 0 means default.
The behavior for the default scale depends on the state of
getUseWideViewPort()
and
getLoadWithOverviewMode()
.
If the content fits into the WebView control by width, then
the zoom is set to 100%. For wide content, the behavor
depends on the state of getLoadWithOverviewMode()
.
If its value is true, the content will be zoomed out to be fit
by width into the WebView control, otherwise not.
If initial scale is greater than 0, WebView starts with this value
as initial scale.
Please note that unlike the scale properties in the viewport meta tag,
this method doesn't take the screen density into account.
Parameters | |
---|---|
scaleInPercent |
int :
the initial scale in percent
|
void setLayerType (int layerType, Paint paint)
Specifies the type of layer backing this view. The layer can be
LAYER_TYPE_NONE
, LAYER_TYPE_SOFTWARE
or
LAYER_TYPE_HARDWARE
.
A layer is associated with an optional Paint
instance that controls how the layer is composed on screen. The following
properties of the paint are taken into account when composing the layer:
If this view has an alpha value set to < 1.0 by calling
setAlpha(float)
, the alpha value of the layer's paint is superseded
by this view's alpha value.
Refer to the documentation of LAYER_TYPE_NONE
,
LAYER_TYPE_SOFTWARE
and LAYER_TYPE_HARDWARE
for more information on when and how to use layers.
Parameters | |
---|---|
layerType |
int :
The type of layer to use with this view, must be one of
LAYER_TYPE_NONE , LAYER_TYPE_SOFTWARE or
LAYER_TYPE_HARDWARE |
paint |
Paint :
The paint used to compose the layer. This argument is optional
and can be null. It is ignored when the layer type is
LAYER_TYPE_NONE |
void setLayoutParams (ViewGroup.LayoutParams params)
Set the layout parameters associated with this view. These supply parameters to the parent of this view specifying how it should be arranged. There are many subclasses of ViewGroup.LayoutParams, and these correspond to the different subclasses of ViewGroup that are responsible for arranging their children.
Parameters | |
---|---|
params |
ViewGroup.LayoutParams :
The layout parameters for this view, cannot be null
|
void setMapTrackballToArrowKeys (boolean setMap)
This method was deprecated
in API level 17.
Only the default case, true, will be supported in a future version.
Parameters | |
---|---|
setMap |
boolean
|
void setNetworkAvailable (boolean networkUp)
Informs WebView of the network state. This is used to set the JavaScript property window.navigator.isOnline and generates the online/offline event as specified in HTML5, sec. 5.7.7
Parameters | |
---|---|
networkUp |
boolean :
a boolean indicating if network is available
|
void setOverScrollMode (int mode)
Set the over-scroll mode for this view. Valid over-scroll modes are
OVER_SCROLL_ALWAYS
(default), OVER_SCROLL_IF_CONTENT_SCROLLS
(allow over-scrolling only if the view content is larger than the container),
or OVER_SCROLL_NEVER
.
Setting the over-scroll mode of a view will have an effect only if the
view is capable of scrolling.
Parameters | |
---|---|
mode |
int :
The new over-scroll mode for this view.
|
void setPictureListener (WebView.PictureListener listener)
This method was deprecated
in API level 12.
This method is now obsolete.
Sets the Picture listener. This is an interface used to receive notifications of a new Picture.
Parameters | |
---|---|
listener |
WebView.PictureListener :
an implementation of WebView.PictureListener |
void setScrollBarStyle (int style)
Specify the style of the scrollbars. The scrollbars can be overlaid or inset. When inset, they add to the padding of the view. And the scrollbars can be drawn inside the padding area or on the edge of the view. For example, if a view has a background drawable and you want to draw the scrollbars inside the padding specified by the drawable, you can use SCROLLBARS_INSIDE_OVERLAY or SCROLLBARS_INSIDE_INSET. If you want them to appear at the edge of the view, ignoring the padding, then you can use SCROLLBARS_OUTSIDE_OVERLAY or SCROLLBARS_OUTSIDE_INSET.
Parameters | |
---|---|
style |
int :
the style of the scrollbars. Should be one of
SCROLLBARS_INSIDE_OVERLAY, SCROLLBARS_INSIDE_INSET,
SCROLLBARS_OUTSIDE_OVERLAY or SCROLLBARS_OUTSIDE_INSET. |
void setVerticalScrollbarOverlay (boolean overlay)
This method was deprecated
in API level 23.
This method has no effect.
Specifies whether the vertical scrollbar has overlay style.
Parameters | |
---|---|
overlay |
boolean :
true if vertical scrollbar should have overlay style
|
void setWebChromeClient (WebChromeClient client)
Sets the chrome handler. This is an implementation of WebChromeClient for use in handling JavaScript dialogs, favicons, titles, and the progress. This will replace the current handler.
Parameters | |
---|---|
client |
WebChromeClient :
an implementation of WebChromeClient
|
void setWebContentsDebuggingEnabled (boolean enabled)
Enables debugging of web contents (HTML / CSS / JavaScript) loaded into any WebViews of this application. This flag can be enabled in order to facilitate debugging of web layouts and JavaScript code running inside WebViews. Please refer to WebView documentation for the debugging guide. The default is false.
Parameters | |
---|---|
enabled |
boolean :
whether to enable web contents debugging
|
void setWebViewClient (WebViewClient client)
Sets the WebViewClient that will receive various notifications and requests. This will replace the current handler.
Parameters | |
---|---|
client |
WebViewClient :
an implementation of WebViewClient
|
boolean shouldDelayChildPressedState ()
Return true if the pressed state should be delayed for children or descendants of this ViewGroup. Generally, this should be done for containers that can scroll, such as a List. This prevents the pressed state from appearing when the user is actually trying to scroll the content. The default implementation returns true for compatibility reasons. Subclasses that do not scroll should generally override this method and return false.
Returns | |
---|---|
boolean |
boolean showFindDialog (String text, boolean showIme)
This method was deprecated
in API level 18.
This method does not work reliably on all Android versions;
implementing a custom find dialog using WebView.findAllAsync()
provides a more robust solution.
Starts an ActionMode for finding text in this WebView. Only works if this WebView is attached to the view system.
Parameters | |
---|---|
text |
String :
if non-null, will be the initial text to search for.
Otherwise, the last String searched for in this WebView will
be used to start. |
showIme |
boolean :
if true, show the IME, assuming the user will begin typing.
If false and text is non-null, perform a find all. |
Returns | |
---|---|
boolean |
true if the find dialog is shown, false otherwise |
void zoomBy (float zoomFactor)
Performs a zoom operation in this WebView.
Parameters | |
---|---|
zoomFactor |
float :
the zoom factor to apply. The zoom factor will be clamped to the Webview's
zoom limits. This value must be in the range 0.01 to 100.0 inclusive.
|
boolean zoomIn ()
Performs zoom in in this WebView.
Returns | |
---|---|
boolean |
true if zoom in succeeds, false if no zoom changes |
boolean zoomOut ()
Performs zoom out in this WebView.
Returns | |
---|---|
boolean |
true if zoom out succeeds, false if no zoom changes |
int computeHorizontalScrollOffset ()
Compute the horizontal offset of the horizontal scrollbar's thumb within the horizontal range. This value is used to compute the position of the thumb within the scrollbar's track.
The range is expressed in arbitrary units that must be the same as the
units used by computeHorizontalScrollRange()
and
computeHorizontalScrollExtent()
.
The default offset is the scroll offset of this view.
Returns | |
---|---|
int |
the horizontal offset of the scrollbar's thumb |
int computeHorizontalScrollRange ()
Compute the horizontal range that the horizontal scrollbar represents.
The range is expressed in arbitrary units that must be the same as the
units used by computeHorizontalScrollExtent()
and
computeHorizontalScrollOffset()
.
The default range is the drawing width of this view.
Returns | |
---|---|
int |
the total horizontal range represented by the horizontal scrollbar |
int computeVerticalScrollExtent ()
Compute the vertical extent of the vertical scrollbar's thumb within the vertical range. This value is used to compute the length of the thumb within the scrollbar's track.
The range is expressed in arbitrary units that must be the same as the
units used by computeVerticalScrollRange()
and
computeVerticalScrollOffset()
.
The default extent is the drawing height of this view.
Returns | |
---|---|
int |
the vertical extent of the scrollbar's thumb |
int computeVerticalScrollOffset ()
Compute the vertical offset of the vertical scrollbar's thumb within the horizontal range. This value is used to compute the position of the thumb within the scrollbar's track.
The range is expressed in arbitrary units that must be the same as the
units used by computeVerticalScrollRange()
and
computeVerticalScrollExtent()
.
The default offset is the scroll offset of this view.
Returns | |
---|---|
int |
the vertical offset of the scrollbar's thumb |
int computeVerticalScrollRange ()
Compute the vertical range that the vertical scrollbar represents.
The range is expressed in arbitrary units that must be the same as the
units used by computeVerticalScrollExtent()
and
computeVerticalScrollOffset()
.
Returns | |
---|---|
int |
the total vertical range represented by the vertical scrollbar
The default range is the drawing height of this view. |
void dispatchDraw (Canvas canvas)
Called by draw to draw the child views. This may be overridden by derived classes to gain control just before its children are drawn (but after its own view has been drawn).
Parameters | |
---|---|
canvas |
Canvas :
the canvas on which to draw the view
|
void onAttachedToWindow ()
This is called when the view is attached to a window. At this point it
has a Surface and will start drawing. Note that this function is
guaranteed to be called before onDraw(android.graphics.Canvas)
,
however it may be called any time before the first onDraw -- including
before or after onMeasure(int, int)
.
void onConfigurationChanged (Configuration newConfig)
Called when the current configuration of the resources being used
by the application have changed. You can use this to decide when
to reload resources that can changed based on orientation and other
configuration characteristics. You only need to use this if you are
not relying on the normal Activity
mechanism of
recreating the activity instance upon a configuration change.
Parameters | |
---|---|
newConfig |
Configuration :
The new resource configuration.
|
void onDraw (Canvas canvas)
Implement this to do your drawing.
Parameters | |
---|---|
canvas |
Canvas :
the canvas on which the background will be drawn
|
void onFocusChanged (boolean focused, int direction, Rect previouslyFocusedRect)
Called by the view system when the focus state of this view changes. When the focus change event is caused by directional navigation, direction and previouslyFocusedRect provide insight into where the focus is coming from. When overriding, be sure to call up through to the super class so that the standard focus handling will occur.
Parameters | |
---|---|
focused |
boolean :
True if the View has focus; false otherwise. |
direction |
int :
The direction focus has moved when requestFocus()
is called to give this view focus. Values are
FOCUS_UP , FOCUS_DOWN , FOCUS_LEFT ,
FOCUS_RIGHT , FOCUS_FORWARD , or FOCUS_BACKWARD .
It may not always apply, in which case use the default. |
previouslyFocusedRect |
Rect :
The rectangle, in this view's coordinate
system, of the previously focused view. If applicable, this will be
passed in as finer grained information about where the focus is coming
from (in addition to direction). Will be null otherwise.
|
void onMeasure (int widthMeasureSpec, int heightMeasureSpec)
Measure the view and its content to determine the measured width and the
measured height. This method is invoked by measure(int, int)
and
should be overridden by subclasses to provide accurate and efficient
measurement of their contents.
CONTRACT: When overriding this method, you
must call setMeasuredDimension(int, int)
to store the
measured width and height of this view. Failure to do so will trigger an
IllegalStateException
, thrown by
measure(int, int)
. Calling the superclass'
onMeasure(int, int)
is a valid use.
The base class implementation of measure defaults to the background size,
unless a larger size is allowed by the MeasureSpec. Subclasses should
override onMeasure(int, int)
to provide better measurements of
their content.
If this method is overridden, it is the subclass's responsibility to make
sure the measured height and width are at least the view's minimum height
and width (getSuggestedMinimumHeight()
and
getSuggestedMinimumWidth()
).
Parameters | |
---|---|
widthMeasureSpec |
int :
horizontal space requirements as imposed by the parent.
The requirements are encoded with
View.MeasureSpec . |
heightMeasureSpec |
int :
vertical space requirements as imposed by the parent.
The requirements are encoded with
View.MeasureSpec . |
void onOverScrolled (int scrollX, int scrollY, boolean clampedX, boolean clampedY)
Called by overScrollBy(int, int, int, int, int, int, int, int, boolean)
to
respond to the results of an over-scroll operation.
Parameters | |
---|---|
scrollX |
int :
New X scroll value in pixels |
scrollY |
int :
New Y scroll value in pixels |
clampedX |
boolean :
True if scrollX was clamped to an over-scroll boundary |
clampedY |
boolean :
True if scrollY was clamped to an over-scroll boundary
|
void onScrollChanged (int l, int t, int oldl, int oldt)
This is called in response to an internal scroll in this view (i.e., the
view scrolled its own contents). This is typically as a result of
scrollBy(int, int)
or scrollTo(int, int)
having been
called.
Parameters | |
---|---|
l |
int :
Current horizontal scroll origin. |
t |
int :
Current vertical scroll origin. |
oldl |
int :
Previous horizontal scroll origin. |
oldt |
int :
Previous vertical scroll origin.
|
void onSizeChanged (int w, int h, int ow, int oh)
This is called during layout when the size of this view has changed. If you were just added to the view hierarchy, you're called with the old values of 0.
Parameters | |
---|---|
w |
int :
Current width of this view. |
h |
int :
Current height of this view. |
ow |
int :
Old width of this view. |
oh |
int :
Old height of this view.
|
void onVisibilityChanged (View changedView, int visibility)
Called when the visibility of the view or an ancestor of the view has changed.
Parameters | |
---|---|
changedView |
View :
The view whose visibility changed. May be
this or an ancestor view. |
visibility |
int :
The new visibility, one of VISIBLE ,
INVISIBLE or GONE .
|
void onWindowVisibilityChanged (int visibility)
Called when the window containing has change its visibility
(between GONE
, INVISIBLE
, and VISIBLE
). Note
that this tells you whether or not your window is being made visible
to the window manager; this does not tell you whether or not
your window is obscured by other windows on the screen, even if it
is itself visible.
Parameters | |
---|---|
visibility |
int :
The new visibility of the window.
|