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/*
* Copyright (C) 2011 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.support.v4.view;
import android.graphics.Rect;
import android.support.v4.view.accessibility.AccessibilityNodeInfoCompat;
import android.view.View;
import android.view.accessibility.AccessibilityEvent;
/**
* Helper for accessing features in {@link View} introduced after API
* level 4 in a backwards compatible fashion.
*/
public class ViewCompat {
/**
* Always allow a user to over-scroll this view, provided it is a
* view that can scroll.
*/
public static final int OVER_SCROLL_ALWAYS = 0;
/**
* Allow a user to over-scroll this view only if the content is large
* enough to meaningfully scroll, provided it is a view that can scroll.
*/
public static final int OVER_SCROLL_IF_CONTENT_SCROLLS = 1;
/**
* Never allow a user to over-scroll this view.
*/
public static final int OVER_SCROLL_NEVER = 2;
interface ViewCompatImpl {
public boolean canScrollHorizontally(View v, int direction);
public boolean canScrollVertically(View v, int direction);
public int getOverScrollMode(View v);
public void setOverScrollMode(View v, int mode);
public void onInitializeAccessibilityEvent(View v, AccessibilityEvent event);
public void onPopulateAccessibilityEvent(View v, AccessibilityEvent event);
public void onInitializeAccessibilityNodeInfo(View v, AccessibilityNodeInfoCompat info);
public void setAccessibilityDelegate(View v, AccessibilityDelegateCompat delegate);
}
static class BaseViewCompatImpl implements ViewCompatImpl {
public boolean canScrollHorizontally(View v, int direction) {
return false;
}
public boolean canScrollVertically(View v, int direction) {
return false;
}
public int getOverScrollMode(View v) {
return OVER_SCROLL_NEVER;
}
public void setOverScrollMode(View v, int mode) {
// Do nothing; API doesn't exist
}
public void setAccessibilityDelegate(View v, AccessibilityDelegateCompat delegate) {
// Do nothing; API doesn't exist
}
public void onPopulateAccessibilityEvent(View v, AccessibilityEvent event) {
// Do nothing; API doesn't exist
}
public void onInitializeAccessibilityEvent(View v, AccessibilityEvent event) {
// Do nothing; API doesn't exist
}
public void onInitializeAccessibilityNodeInfo(View v, AccessibilityNodeInfoCompat info) {
// Do nothing; API doesn't exist
}
}
static class GBViewCompatImpl extends BaseViewCompatImpl {
@Override
public int getOverScrollMode(View v) {
return ViewCompatGingerbread.getOverScrollMode(v);
}
@Override
public void setOverScrollMode(View v, int mode) {
ViewCompatGingerbread.setOverScrollMode(v, mode);
}
}
static class ICSViewCompatImpl extends GBViewCompatImpl {
@Override
public boolean canScrollHorizontally(View v, int direction) {
return ViewCompatICS.canScrollHorizontally(v, direction);
}
@Override
public boolean canScrollVertically(View v, int direction) {
return ViewCompatICS.canScrollVertically(v, direction);
}
@Override
public void onPopulateAccessibilityEvent(View v, AccessibilityEvent event) {
ViewCompatICS.onPopulateAccessibilityEvent(v, event);
}
@Override
public void onInitializeAccessibilityEvent(View v, AccessibilityEvent event) {
ViewCompatICS.onInitializeAccessibilityEvent(v, event);
}
@Override
public void onInitializeAccessibilityNodeInfo(View v, AccessibilityNodeInfoCompat info) {
ViewCompatICS.onInitializeAccessibilityNodeInfo(v, info.getImpl());
}
@Override
public void setAccessibilityDelegate(View v, AccessibilityDelegateCompat delegate) {
ViewCompatICS.setAccessibilityDelegate(v, delegate.getBridge());
}
}
static final ViewCompatImpl IMPL;
static {
final int version = android.os.Build.VERSION.SDK_INT;
if (version >= 14) {
IMPL = new ICSViewCompatImpl();
} else if (version >= 9) {
IMPL = new GBViewCompatImpl();
} else {
IMPL = new BaseViewCompatImpl();
}
}
/**
* Check if this view can be scrolled horizontally in a certain direction.
*
* @param v The View against which to invoke the method.
* @param direction Negative to check scrolling left, positive to check scrolling right.
* @return true if this view can be scrolled in the specified direction, false otherwise.
*/
public static boolean canScrollHorizontally(View v, int direction) {
return IMPL.canScrollHorizontally(v, direction);
}
/**
* Check if this view can be scrolled vertically in a certain direction.
*
* @param v The View against which to invoke the method.
* @param direction Negative to check scrolling up, positive to check scrolling down.
* @return true if this view can be scrolled in the specified direction, false otherwise.
*/
public static boolean canScrollVertically(View v, int direction) {
return IMPL.canScrollVertically(v, direction);
}
/**
* Returns the over-scroll mode for this view. The result will be
* one of {@link #OVER_SCROLL_ALWAYS} (default), {@link #OVER_SCROLL_IF_CONTENT_SCROLLS}
* (allow over-scrolling only if the view content is larger than the container),
* or {@link #OVER_SCROLL_NEVER}.
*
* @param v The View against which to invoke the method.
* @return This view's over-scroll mode.
*/
public static int getOverScrollMode(View v) {
return IMPL.getOverScrollMode(v);
}
/**
* Set the over-scroll mode for this view. Valid over-scroll modes are
* {@link #OVER_SCROLL_ALWAYS} (default), {@link #OVER_SCROLL_IF_CONTENT_SCROLLS}
* (allow over-scrolling only if the view content is larger than the container),
* or {@link #OVER_SCROLL_NEVER}.
*
* Setting the over-scroll mode of a view will have an effect only if the
* view is capable of scrolling.
*
* @param v The View against which to invoke the method.
* @param overScrollMode The new over-scroll mode for this view.
*/
public static void setOverScrollMode(View v, int overScrollMode) {
IMPL.setOverScrollMode(v, overScrollMode);
}
/**
* Called from {@link View#dispatchPopulateAccessibilityEvent(AccessibilityEvent)}
* giving a chance to this View to populate the accessibility event with its
* text content. While this method is free to modify event
* attributes other than text content, doing so should normally be performed in
* {@link View#onInitializeAccessibilityEvent(AccessibilityEvent)}.
*
* Example: Adding formatted date string to an accessibility event in addition
* to the text added by the super implementation:
*
public void onPopulateAccessibilityEvent(AccessibilityEvent event) {
* super.onPopulateAccessibilityEvent(event);
* final int flags = DateUtils.FORMAT_SHOW_DATE | DateUtils.FORMAT_SHOW_WEEKDAY;
* String selectedDateUtterance = DateUtils.formatDateTime(mContext,
* mCurrentDate.getTimeInMillis(), flags);
* event.getText().add(selectedDateUtterance);
* }
*
* If an {@link android.view.View.AccessibilityDelegate} has been specified via calling
* {@link View#setAccessibilityDelegate(android.view.View.AccessibilityDelegate)} its
* {@link android.view.View.AccessibilityDelegate#onPopulateAccessibilityEvent(View,
* AccessibilityEvent)}
* is responsible for handling this call.
*
* Note: Always call the super implementation before adding
* information to the event, in case the default implementation has basic information to add.
*
*
* @param v The View against which to invoke the method.
* @param event The accessibility event which to populate.
*
* @see View#sendAccessibilityEvent(int)
* @see View#dispatchPopulateAccessibilityEvent(AccessibilityEvent)
*/
public static void onPopulateAccessibilityEvent(View v, AccessibilityEvent event) {
IMPL.onPopulateAccessibilityEvent(v, event);
}
/**
* Initializes an {@link AccessibilityEvent} with information about
* this View which is the event source. In other words, the source of
* an accessibility event is the view whose state change triggered firing
* the event.
*
* Example: Setting the password property of an event in addition
* to properties set by the super implementation:
*
public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
* super.onInitializeAccessibilityEvent(event);
* event.setPassword(true);
* }
*
* If an {@link android.view.View.AccessibilityDelegate} has been specified via calling
* {@link View#setAccessibilityDelegate(android.view.View.AccessibilityDelegate)} its
* {@link android.view.View.AccessibilityDelegate#onInitializeAccessibilityEvent(View,
* AccessibilityEvent)}
* is responsible for handling this call.
*
* Note: Always call the super implementation before adding
* information to the event, in case the default implementation has basic information to add.
*
*
* @param v The View against which to invoke the method.
* @param event The event to initialize.
*
* @see View#sendAccessibilityEvent(int)
* @see View#dispatchPopulateAccessibilityEvent(AccessibilityEvent)
*/
public static void onInitializeAccessibilityEvent(View v, AccessibilityEvent event) {
IMPL.onInitializeAccessibilityEvent(v, event);
}
/**
* Initializes an {@link android.view.accessibility.AccessibilityNodeInfo} with information
* about this view. The base implementation sets:
*
* - {@link android.view.accessibility.AccessibilityNodeInfo#setParent(View)},
* - {@link android.view.accessibility.AccessibilityNodeInfo#setBoundsInParent(Rect)},
* - {@link android.view.accessibility.AccessibilityNodeInfo#setBoundsInScreen(Rect)},
* - {@link android.view.accessibility.AccessibilityNodeInfo#setPackageName(CharSequence)},
* - {@link android.view.accessibility.AccessibilityNodeInfo#setClassName(CharSequence)},
* - {@link android.view.accessibility.AccessibilityNodeInfo#setContentDescription(CharSequence)},
* - {@link android.view.accessibility.AccessibilityNodeInfo#setEnabled(boolean)},
* - {@link android.view.accessibility.AccessibilityNodeInfo#setClickable(boolean)},
* - {@link android.view.accessibility.AccessibilityNodeInfo#setFocusable(boolean)},
* - {@link android.view.accessibility.AccessibilityNodeInfo#setFocused(boolean)},
* - {@link android.view.accessibility.AccessibilityNodeInfo#setLongClickable(boolean)},
* - {@link android.view.accessibility.AccessibilityNodeInfo#setSelected(boolean)},
*
*
* Subclasses should override this method, call the super implementation,
* and set additional attributes.
*
*
* If an {@link android.view.View.AccessibilityDelegate} has been specified via calling
* {@link View#setAccessibilityDelegate(android.view.View.AccessibilityDelegate)} its
* {@link android.view.View.AccessibilityDelegate#onInitializeAccessibilityNodeInfo(View,
* android.view.accessibility.AccessibilityNodeInfo)}
* is responsible for handling this call.
*
*
* @param v The View against which to invoke the method.
* @param info The instance to initialize.
*/
public static void onInitializeAccessibilityNodeInfo(View v, AccessibilityNodeInfoCompat info) {
IMPL.onInitializeAccessibilityNodeInfo(v, info);
}
/**
* Sets a delegate for implementing accessibility support via compositon as
* opposed to inheritance. The delegate's primary use is for implementing
* backwards compatible widgets. For more details see
* {@link android.view.View.AccessibilityDelegate}.
*
* @param v The View against which to invoke the method.
* @param delegate The delegate instance.
*
* @see android.view.View.AccessibilityDelegate
*/
public static void setAccessibilityDelegate(View v, AccessibilityDelegateCompat delegate) {
IMPL.setAccessibilityDelegate(v, delegate);
}
}
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