public
abstract
class
GridPagerAdapter
extends Object
java.lang.Object | |
↳ | android.support.wearable.view.GridPagerAdapter |
Known Direct Subclasses |
This component is responsible for providing views requested by a GridViewPager
.
Content is organized into rows and columns of pages, where each page is represented by a View. Each row may contain a different number of columns.
In addition to content views, this adapter is also queried for backgrounds to be displayed for each page. When the same background spans multiple pages, it's automatically zoomed and panned to create a parallax effect against the movement of the page content as it moves. By default, no background is provided.
Constants | |
---|---|
int |
OPTION_DISABLE_PARALLAX
Disables zooming and parallax scrolling of the background. |
int |
PAGE_DEFAULT_OPTIONS
Default background options. |
Fields | |
---|---|
public
static
final
Drawable |
BACKGROUND_NONE
This value indicates that no background should drawn. |
public
static
final
Point |
POSITION_NONE
|
public
static
final
Point |
POSITION_UNCHANGED
|
Public constructors | |
---|---|
GridPagerAdapter()
|
Public methods | |
---|---|
abstract
void
|
destroyItem(ViewGroup container, int row, int column, Object object)
Removes a page for the given position. |
void
|
finishUpdate(ViewGroup container)
Called when the a change in the shown pages has been completed. |
Drawable
|
getBackgroundForPage(int row, int column)
Provides content to be displayed as background for a specific page. |
Drawable
|
getBackgroundForRow(int row)
Provides content to be displayed as the default background for all pages on the given row. |
abstract
int
|
getColumnCount(int row)
Returns the maximum number of columns for each row. |
int
|
getCurrentColumnForRow(int row, int currentColumn)
Returns the column to arrive at when navigating vertically to the specified row. |
Point
|
getItemPosition(Object object)
Called when the host view is attempting to determine if an item's position has changed. |
int
|
getOptionsForPage(int row, int column)
Provides a set of features to apply to a page background. |
abstract
int
|
getRowCount()
Returns the number of rows available. |
abstract
Object
|
instantiateItem(ViewGroup container, int row, int column)
Creates the page for the given position. |
abstract
boolean
|
isViewFromObject(View view, Object object)
Determines whether a page View is associated with a specific key object as returned by
|
void
|
notifyDataSetChanged()
This method should be called by the application if the data backing this adapter has changed and associated views should update. |
void
|
notifyPageBackgroundChanged(int row, int column)
This method should be called if the value returned by |
void
|
notifyRowBackgroundChanged(int row)
This method should be called if the value returned by |
void
|
registerDataSetObserver(DataSetObserver observer)
Register an observer to receive callbacks related to the adapter's data changing. |
void
|
restoreState(Parcelable savedState, ClassLoader classLoader)
Restores the previously saved state of this adapter. |
Parcelable
|
saveState()
Saves the current state of this adapter. |
void
|
setCurrentColumnForRow(int row, int currentColumn)
Called to inform the adapter of which column is now current for the given row. |
void
|
startUpdate(ViewGroup container)
Called when a change in the shown pages is going to start being made. |
void
|
unregisterDataSetObserver(DataSetObserver observer)
Unregister an observer from callbacks related to the adapter's data changing. |
Protected methods | |
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void
|
applyItemPosition(Object object, Point position)
Called after |
Inherited methods | |
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From
class
java.lang.Object
|
int OPTION_DISABLE_PARALLAX
Disables zooming and parallax scrolling of the background.
Constant Value: 1 (0x00000001)
int PAGE_DEFAULT_OPTIONS
Default background options. Parallax scrolling is enabled.
Constant Value: 0 (0x00000000)
Drawable BACKGROUND_NONE
This value indicates that no background should drawn. See getBackgroundForRow(int)
and
getBackgroundForPage(int, int)
for specific effects.
Point POSITION_NONE
Point POSITION_UNCHANGED
GridPagerAdapter ()
void destroyItem (ViewGroup container, int row, int column, Object object)
Removes a page for the given position. The adapter is responsible for removing the view from
its container, although it only must ensure this is done by the time it returns from
finishUpdate(ViewGroup)
.
Parameters | |
---|---|
container |
ViewGroup :
The containing View from which the page will be removed. |
row |
int :
the row to be destroyed |
column |
int :
the column within the row to be destroyed |
object |
Object :
The same object that was returned by
instantiateItem(ViewGroup, int, int) .
|
void finishUpdate (ViewGroup container)
Called when the a change in the shown pages has been completed. At this point you must ensure that all of the pages have actually been added or removed from the container as appropriate.
Parameters | |
---|---|
container |
ViewGroup :
The containing View which is displaying this adapter's page views
|
Drawable getBackgroundForPage (int row, int column)
Provides content to be displayed as background for a specific page.
The return value BACKGROUND_NONE
indicates that there is no page-specific background.
and the row background should be used (if any).
The return value of this method can be cached. notifyPageBackgroundChanged(int, int)
may be
used to invalidate a previously returned value. getBackgroundForPage(int, int)
will then be
called to request the new value when necessary.
Parameters | |
---|---|
row |
int :
the row of the page |
column |
int :
the column of the page
|
Returns | |
---|---|
Drawable |
Drawable getBackgroundForRow (int row)
Provides content to be displayed as the default background for all pages on the given row.
The return value BACKGROUND_NONE
causes no background to be displayed, except for
those applied by getBackgroundForPage(int, int)
.
The return value of this method can be cached. notifyRowBackgroundChanged(int)
may be
used to invalidate a previously returned value. getBackgroundForRow(int)
will then be
called to request the new value when necessary.
Parameters | |
---|---|
row |
int :
the row of the page |
Returns | |
---|---|
Drawable |
a drawable to display for the row |
int getColumnCount (int row)
Returns the maximum number of columns for each row. The number of columns may vary by row.
Parameters | |
---|---|
row |
int
|
Returns | |
---|---|
int |
int getCurrentColumnForRow (int row, int currentColumn)
Returns the column to arrive at when navigating vertically to the specified row.
The default implementation simply returns 0.
Parameters | |
---|---|
row |
int :
the row in question |
currentColumn |
int :
the column which is currently centered |
Returns | |
---|---|
int |
the column to arrive at |
Point getItemPosition (Object object)
Called when the host view is attempting to determine if an item's position has changed.
Returns POSITION_UNCHANGED
if the position of the given item has not changed or
POSITION_NONE
if the item is no longer present in the adapter.
The default implementation assumes that all items have been removed and always returns
POSITION_NONE
. This causes all fragments to be detached and re-attached as needed.
Parameters | |
---|---|
object |
Object :
Object representing an item, previously returned by a call to
instantiateItem(ViewGroup, int, int) . |
Returns | |
---|---|
Point |
object's new position with row from [0, getRowCount()] and column from [0,
getColumnCount(row)], POSITION_UNCHANGED if the object's position has not
changed, or POSITION_NONE if the item is no longer present.
|
int getOptionsForPage (int row, int column)
Provides a set of features to apply to a page background. The return value should be a combination of one or more of the following, combined via bitwise-or:
The default return value isPAGE_DEFAULT_OPTIONS
.
Parameters | |
---|---|
row |
int :
the row of the page |
column |
int :
the column of the page |
Returns | |
---|---|
int |
a bitwise OR of all requested options |
int getRowCount ()
Returns the number of rows available.
Returns | |
---|---|
int |
Object instantiateItem (ViewGroup container, int row, int column)
Creates the page for the given position. The adapter is responsible for adding the view to
the container given here, although it only must ensure this is done by the time it returns
from finishUpdate(ViewGroup)
Parameters | |
---|---|
container |
ViewGroup :
containing View in which the page will be shown |
row |
int :
the row to be instantiated |
column |
int :
the column within the row to be instantiated |
Returns | |
---|---|
Object |
a an object representing the new page |
boolean isViewFromObject (View view, Object object)
Determines whether a page View is associated with a specific key object as returned by
instantiateItem(ViewGroup, int, int)
. This method is required for a PagerAdapter to
function properly.
Parameters | |
---|---|
view |
View :
Page View to check for association with object |
object |
Object :
Object to check for association with view |
Returns | |
---|---|
boolean |
true if view is associated with the key object object
|
void notifyDataSetChanged ()
This method should be called by the application if the data backing this adapter has changed and associated views should update.
void notifyPageBackgroundChanged (int row, int column)
This method should be called if the value returned by getBackgroundForPage(int, int)
or options returned by getOptionsForPage(int, int)
change. Any cached value are
removed and the the new value will be requested when necessary.
Parameters | |
---|---|
row |
int
|
column |
int
|
void notifyRowBackgroundChanged (int row)
This method should be called if the value returned by getBackgroundForRow(int)
changes. Any cached value is removed and the the new value will be requested when necessary.
Parameters | |
---|---|
row |
int
|
void registerDataSetObserver (DataSetObserver observer)
Register an observer to receive callbacks related to the adapter's data changing.
Parameters | |
---|---|
observer |
DataSetObserver :
The DataSetObserver which will receive callbacks.
|
void restoreState (Parcelable savedState, ClassLoader classLoader)
Restores the previously saved state of this adapter.
Parameters | |
---|---|
savedState |
Parcelable
|
classLoader |
ClassLoader
|
Parcelable saveState ()
Saves the current state of this adapter.
Returns | |
---|---|
Parcelable |
void setCurrentColumnForRow (int row, int currentColumn)
Called to inform the adapter of which column is now current for the given row. This
information could be stored and used to implement getCurrentColumnForRow(int, int)
.
The default implementation does nothing.
Parameters | |
---|---|
row |
int :
the row for the column change |
currentColumn |
int :
the column which is now current
|
void startUpdate (ViewGroup container)
Called when a change in the shown pages is going to start being made.
Parameters | |
---|---|
container |
ViewGroup :
The containing View which is displaying this adapter's page views.
|
void unregisterDataSetObserver (DataSetObserver observer)
Unregister an observer from callbacks related to the adapter's data changing.
Parameters | |
---|---|
observer |
DataSetObserver :
The DataSetObserver which will be unregistered.
|
void applyItemPosition (Object object, Point position)
Called after getItemPosition(Object)
to allow superclasses to update their
internal bookkeeping if a subclass has overridden getItemPosition(Object)
.
Parameters | |
---|---|
object |
Object :
Object representing the item passed to getItemPosition(Object) . |
position |
Point :
position which was returned from getItemPosition(Object) .
|