ClippedData is a complex type containing one or Item instances, * each of which can hold one or more representations of an item of data. * For display to the user, it also has a label and iconic representation.
* *A ClipData contains a {@link ClipDescription}, which describes * important meta-data about the clip. In particular, its * {@link ClipDescription#getMimeType(int) getDescription().getMimeType(int)} * must return correct MIME type(s) describing the data in the clip. For help * in correctly constructing a clip with the correct MIME type, use * {@link #newPlainText(CharSequence, CharSequence)}, * {@link #newUri(ContentResolver, CharSequence, Uri)}, and * {@link #newIntent(CharSequence, Intent)}. * *
Each Item instance can be one of three main classes of data: a simple * CharSequence of text, a single Intent object, or a Uri. See {@link Item} * for more details. * *
For more information about using the clipboard framework, read the * Copy and Paste * developer guide.
*To implement a paste or drop of a ClippedData object into an application, * the application must correctly interpret the data for its use. If the {@link Item} * it contains is simple text or an Intent, there is little to be done: text * can only be interpreted as text, and an Intent will typically be used for * creating shortcuts (such as placing icons on the home screen) or other * actions. * *
If all you want is the textual representation of the clipped data, you * can use the convenience method {@link Item#coerceToText Item.coerceToText}. * In this case there is generally no need to worry about the MIME types * reported by {@link ClipDescription#getMimeType(int) getDescription().getMimeType(int)}, * since any clip item an always be converted to a string. * *
More complicated exchanges will be done through URIs, in particular * "content:" URIs. A content URI allows the recipient of a ClippedData item * to interact closely with the ContentProvider holding the data in order to * negotiate the transfer of that data. The clip must also be filled in with * the available MIME types; {@link #newUri(ContentResolver, CharSequence, Uri)} * will take care of correctly doing this. * *
For example, here is the paste function of a simple NotePad application. * When retrieving the data from the clipboard, it can do either two things: * if the clipboard contains a URI reference to an existing note, it copies * the entire structure of the note into a new note; otherwise, it simply * coerces the clip into text and uses that as the new note's contents. * * {@sample development/samples/NotePad/src/com/example/android/notepad/NoteEditor.java * paste} * *
In many cases an application can paste various types of streams of data. For * example, an e-mail application may want to allow the user to paste an image * or other binary data as an attachment. This is accomplished through the * ContentResolver {@link ContentResolver#getStreamTypes(Uri, String)} and * {@link ContentResolver#openTypedAssetFileDescriptor(Uri, String, android.os.Bundle)} * methods. These allow a client to discover the type(s) of data that a particular * content URI can make available as a stream and retrieve the stream of data. * *
For example, the implementation of {@link Item#coerceToText Item.coerceToText} * itself uses this to try to retrieve a URI clip as a stream of text: * * {@sample frameworks/base/core/java/android/content/ClipData.java coerceToText} * * *
To be the source of a clip, the application must construct a ClippedData * object that any recipient can interpret best for their context. If the clip * is to contain a simple text, Intent, or URI, this is easy: an {@link Item} * containing the appropriate data type can be constructed and used. * *
More complicated data types require the implementation of support in * a ContentProvider for describing and generating the data for the recipient. * A common scenario is one where an application places on the clipboard the * content: URI of an object that the user has copied, with the data at that * URI consisting of a complicated structure that only other applications with * direct knowledge of the structure can use. * *
For applications that do not have intrinsic knowledge of the data structure, * the content provider holding it can make the data available as an arbitrary * number of types of data streams. This is done by implementing the * ContentProvider {@link ContentProvider#getStreamTypes(Uri, String)} and * {@link ContentProvider#openTypedAssetFile(Uri, String, android.os.Bundle)} * methods. * *
Going back to our simple NotePad application, this is the implementation * it may have to convert a single note URI (consisting of a title and the note * text) into a stream of plain text data. * * {@sample development/samples/NotePad/src/com/example/android/notepad/NotePadProvider.java * stream} * *
The copy operation in our NotePad application is now just a simple matter * of making a clip containing the URI of the note being copied: * * {@sample development/samples/NotePad/src/com/example/android/notepad/NotesList.java * copy} * *
Note if a paste operation needs this clip as text (for example to paste
* into an editor), then {@link Item#coerceToText(Context)} will ask the content
* provider for the clip URI as text and successfully paste the entire note.
*/
public class ClipData implements Parcelable {
static final String[] MIMETYPES_TEXT_PLAIN = new String[] {
ClipDescription.MIMETYPE_TEXT_PLAIN };
static final String[] MIMETYPES_TEXT_URILIST = new String[] {
ClipDescription.MIMETYPE_TEXT_URILIST };
static final String[] MIMETYPES_TEXT_INTENT = new String[] {
ClipDescription.MIMETYPE_TEXT_INTENT };
final ClipDescription mClipDescription;
final Bitmap mIcon;
final ArrayList The types than an individual item can currently contain are: The algorithm for deciding what text to return is:
*
*
*/
public static class Item {
final CharSequence mText;
final Intent mIntent;
final Uri mUri;
/**
* Create an Item consisting of a single block of (possibly styled) text.
*/
public Item(CharSequence text) {
mText = text;
mIntent = null;
mUri = null;
}
/**
* Create an Item consisting of an arbitrary Intent.
*/
public Item(Intent intent) {
mText = null;
mIntent = intent;
mUri = null;
}
/**
* Create an Item consisting of an arbitrary URI.
*/
public Item(Uri uri) {
mText = null;
mIntent = null;
mUri = uri;
}
/**
* Create a complex Item, containing multiple representations of
* text, intent, and/or URI.
*/
public Item(CharSequence text, Intent intent, Uri uri) {
mText = text;
mIntent = intent;
mUri = uri;
}
/**
* Retrieve the raw text contained in this Item.
*/
public CharSequence getText() {
return mText;
}
/**
* Retrieve the raw Intent contained in this Item.
*/
public Intent getIntent() {
return mIntent;
}
/**
* Retrieve the raw URI contained in this Item.
*/
public Uri getUri() {
return mUri;
}
/**
* Turn this item into text, regardless of the type of data it
* actually contains.
*
*
*
*
* @param context The caller's Context, from which its ContentResolver
* and other things can be retrieved.
* @return Returns the item's textual representation.
*/
//BEGIN_INCLUDE(coerceToText)
public CharSequence coerceToText(Context context) {
// If this Item has an explicit textual value, simply return that.
if (mText != null) {
return mText;
}
// If this Item has a URI value, try using that.
if (mUri != null) {
// First see if the URI can be opened as a plain text stream
// (of any sub-type). If so, this is the best textual
// representation for it.
FileInputStream stream = null;
try {
// Ask for a stream of the desired type.
AssetFileDescriptor descr = context.getContentResolver()
.openTypedAssetFileDescriptor(mUri, "text/*", null);
stream = descr.createInputStream();
InputStreamReader reader = new InputStreamReader(stream, "UTF-8");
// Got it... copy the stream into a local string and return it.
StringBuilder builder = new StringBuilder(128);
char[] buffer = new char[8192];
int len;
while ((len=reader.read(buffer)) > 0) {
builder.append(buffer, 0, len);
}
return builder.toString();
} catch (FileNotFoundException e) {
// Unable to open content URI as text... not really an
// error, just something to ignore.
} catch (IOException e) {
// Something bad has happened.
Log.w("ClippedData", "Failure loading text", e);
return e.toString();
} finally {
if (stream != null) {
try {
stream.close();
} catch (IOException e) {
}
}
}
// If we couldn't open the URI as a stream, then the URI itself
// probably serves fairly well as a textual representation.
return mUri.toString();
}
// Finally, if all we have is an Intent, then we can just turn that
// into text. Not the most user-friendly thing, but it's something.
if (mIntent != null) {
return mIntent.toUri(Intent.URI_INTENT_SCHEME);
}
// Shouldn't get here, but just in case...
return "";
}
//END_INCLUDE(coerceToText)
}
/**
* Create a new clip.
*
* @param label Label to show to the user describing this clip.
* @param mimeTypes An array of MIME types this data is available as.
* @param item The contents of the first item in the clip.
*/
public ClipData(CharSequence label, String[] mimeTypes, Item item) {
mClipDescription = new ClipDescription(label, mimeTypes);
if (item == null) {
throw new NullPointerException("item is null");
}
mIcon = null;
mItems.add(item);
}
/**
* Create a new clip.
*
* @param description The ClipDescription describing the clip contents.
* @param item The contents of the first item in the clip.
*/
public ClipData(ClipDescription description, Item item) {
mClipDescription = description;
if (item == null) {
throw new NullPointerException("item is null");
}
mIcon = null;
mItems.add(item);
}
/**
* Create a new ClipData holding data of the type
* {@link ClipDescription#MIMETYPE_TEXT_PLAIN}.
*
* @param label User-visible label for the clip data.
* @param text The actual text in the clip.
* @return Returns a new ClipData containing the specified data.
*/
static public ClipData newPlainText(CharSequence label, CharSequence text) {
Item item = new Item(text);
return new ClipData(label, MIMETYPES_TEXT_PLAIN, item);
}
/**
* Create a new ClipData holding an Intent with MIME type
* {@link ClipDescription#MIMETYPE_TEXT_INTENT}.
*
* @param label User-visible label for the clip data.
* @param intent The actual Intent in the clip.
* @return Returns a new ClipData containing the specified data.
*/
static public ClipData newIntent(CharSequence label, Intent intent) {
Item item = new Item(intent);
return new ClipData(label, MIMETYPES_TEXT_INTENT, item);
}
/**
* Create a new ClipData holding a URI. If the URI is a content: URI,
* this will query the content provider for the MIME type of its data and
* use that as the MIME type. Otherwise, it will use the MIME type
* {@link ClipDescription#MIMETYPE_TEXT_URILIST}.
*
* @param resolver ContentResolver used to get information about the URI.
* @param label User-visible label for the clip data.
* @param uri The URI in the clip.
* @return Returns a new ClipData containing the specified data.
*/
static public ClipData newUri(ContentResolver resolver, CharSequence label,
Uri uri) {
Item item = new Item(uri);
String[] mimeTypes = null;
if ("content".equals(uri.getScheme())) {
String realType = resolver.getType(uri);
mimeTypes = resolver.getStreamTypes(uri, "*/*");
if (mimeTypes == null) {
if (realType != null) {
mimeTypes = new String[] { realType, ClipDescription.MIMETYPE_TEXT_URILIST };
}
} else {
String[] tmp = new String[mimeTypes.length + (realType != null ? 2 : 1)];
int i = 0;
if (realType != null) {
tmp[0] = realType;
i++;
}
System.arraycopy(mimeTypes, 0, tmp, i, mimeTypes.length);
tmp[i + mimeTypes.length] = ClipDescription.MIMETYPE_TEXT_URILIST;
mimeTypes = tmp;
}
}
if (mimeTypes == null) {
mimeTypes = MIMETYPES_TEXT_URILIST;
}
return new ClipData(label, mimeTypes, item);
}
/**
* Create a new ClipData holding an URI with MIME type
* {@link ClipDescription#MIMETYPE_TEXT_URILIST}.
* Unlike {@link #newUri(ContentResolver, CharSequence, Uri)}, nothing
* is inferred about the URI -- if it is a content: URI holding a bitmap,
* the reported type will still be uri-list. Use this with care!
*
* @param label User-visible label for the clip data.
* @param uri The URI in the clip.
* @return Returns a new ClipData containing the specified data.
*/
static public ClipData newRawUri(CharSequence label, Uri uri) {
Item item = new Item(uri);
return new ClipData(label, MIMETYPES_TEXT_URILIST, item);
}
/**
* Return the {@link ClipDescription} associated with this data, describing
* what it contains.
*/
public ClipDescription getDescription() {
return mClipDescription;
}
/**
* Add a new Item to the overall ClipData container.
*/
public void addItem(Item item) {
if (item == null) {
throw new NullPointerException("item is null");
}
mItems.add(item);
}
/** @hide */
public Bitmap getIcon() {
return mIcon;
}
/**
* Return the number of items in the clip data.
*/
public int getItemCount() {
return mItems.size();
}
/**
* Return a single item inside of the clip data. The index can range
* from 0 to {@link #getItemCount()}-1.
*/
public Item getItemAt(int index) {
return mItems.get(index);
}
@Override
public int describeContents() {
return 0;
}
@Override
public void writeToParcel(Parcel dest, int flags) {
mClipDescription.writeToParcel(dest, flags);
if (mIcon != null) {
dest.writeInt(1);
mIcon.writeToParcel(dest, flags);
} else {
dest.writeInt(0);
}
final int N = mItems.size();
dest.writeInt(N);
for (int i=0; i