/*
* 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.os.Build;
import android.view.View;
import android.view.ViewGroup;
import android.view.accessibility.AccessibilityEvent;
/**
* Helper for accessing features in {@link ViewGroup}
* introduced after API level 4 in a backwards compatible fashion.
*/
public class ViewGroupCompat {
/**
* This constant is a {@link #setLayoutMode(ViewGroup, int) layoutMode}.
* Clip bounds are the raw values of {@link android.view.View#getLeft() left},
* {@link android.view.View#getTop() top},
* {@link android.view.View#getRight() right} and {@link android.view.View#getBottom() bottom}.
*/
public static final int LAYOUT_MODE_CLIP_BOUNDS = 0;
/**
* This constant is a {@link #setLayoutMode(ViewGroup, int) layoutMode}.
* Optical bounds describe where a widget appears to be. They sit inside the clip
* bounds which need to cover a larger area to allow other effects,
* such as shadows and glows, to be drawn.
*/
public static final int LAYOUT_MODE_OPTICAL_BOUNDS = 1;
interface ViewGroupCompatImpl {
public boolean onRequestSendAccessibilityEvent(ViewGroup group, View child,
AccessibilityEvent event);
public void setMotionEventSplittingEnabled(ViewGroup group, boolean split);
public int getLayoutMode(ViewGroup group);
public void setLayoutMode(ViewGroup group, int mode);
public void setTransitionGroup(ViewGroup group, boolean isTransitionGroup);
public boolean isTransitionGroup(ViewGroup group);
}
static class ViewGroupCompatStubImpl implements ViewGroupCompatImpl {
public boolean onRequestSendAccessibilityEvent(
ViewGroup group, View child, AccessibilityEvent event) {
return true;
}
public void setMotionEventSplittingEnabled(ViewGroup group, boolean split) {
// no-op, didn't exist.
}
@Override
public int getLayoutMode(ViewGroup group) {
return LAYOUT_MODE_CLIP_BOUNDS;
}
@Override
public void setLayoutMode(ViewGroup group, int mode) {
// no-op, didn't exist. Views only support clip bounds.
}
@Override
public void setTransitionGroup(ViewGroup group, boolean isTransitionGroup) {
}
@Override
public boolean isTransitionGroup(ViewGroup group) {
return false;
}
}
static class ViewGroupCompatHCImpl extends ViewGroupCompatStubImpl {
@Override
public void setMotionEventSplittingEnabled(ViewGroup group, boolean split) {
ViewGroupCompatHC.setMotionEventSplittingEnabled(group, split);
}
}
static class ViewGroupCompatIcsImpl extends ViewGroupCompatHCImpl {
@Override
public boolean onRequestSendAccessibilityEvent(
ViewGroup group, View child, AccessibilityEvent event) {
return ViewGroupCompatIcs.onRequestSendAccessibilityEvent(group, child, event);
}
}
static class ViewGroupCompatJellybeanMR2Impl extends ViewGroupCompatIcsImpl {
@Override
public int getLayoutMode(ViewGroup group) {
return ViewGroupCompatJellybeanMR2.getLayoutMode(group);
}
@Override
public void setLayoutMode(ViewGroup group, int mode) {
ViewGroupCompatJellybeanMR2.setLayoutMode(group, mode);
}
}
static class ViewGroupCompatApi21Impl extends ViewGroupCompatJellybeanMR2Impl {
@Override
public void setTransitionGroup(ViewGroup group, boolean isTransitionGroup) {
ViewGroupCompatApi21.setTransitionGroup(group, isTransitionGroup);
}
@Override
public boolean isTransitionGroup(ViewGroup group) {
return ViewGroupCompatApi21.isTransitionGroup(group);
}
}
static final ViewGroupCompatImpl IMPL;
static {
final int version = Build.VERSION.SDK_INT;
if (version >= 21) {
IMPL = new ViewGroupCompatApi21Impl();
} else if (version >= 18) {
IMPL = new ViewGroupCompatJellybeanMR2Impl();
} else if (version >= 14) {
IMPL = new ViewGroupCompatIcsImpl();
} else if (version >= 11) {
IMPL = new ViewGroupCompatHCImpl();
} else {
IMPL = new ViewGroupCompatStubImpl();
}
}
/*
* Hide the constructor.
*/
private ViewGroupCompat() {
}
/**
* Called when a child has requested sending an {@link AccessibilityEvent} and
* gives an opportunity to its parent to augment the event.
* <p>
* If an {@link AccessibilityDelegateCompat} has been specified via calling
* {@link ViewCompat#setAccessibilityDelegate(View, AccessibilityDelegateCompat)} its
* {@link AccessibilityDelegateCompat#onRequestSendAccessibilityEvent(ViewGroup, View,
* AccessibilityEvent)} is responsible for handling this call.
* </p>
*
* @param group The group whose method to invoke.
* @param child The child which requests sending the event.
* @param event The event to be sent.
* @return True if the event should be sent.
*/
public static boolean onRequestSendAccessibilityEvent(ViewGroup group, View child,
AccessibilityEvent event) {
return IMPL.onRequestSendAccessibilityEvent(group, child, event);
}
/**
* Enable or disable the splitting of MotionEvents to multiple children during touch event
* dispatch. This behavior is enabled by default for applications that target an
* SDK version of 11 (Honeycomb) or newer. On earlier platform versions this feature
* was not supported and this method is a no-op.
*
* <p>When this option is enabled MotionEvents may be split and dispatched to different child
* views depending on where each pointer initially went down. This allows for user interactions
* such as scrolling two panes of content independently, chording of buttons, and performing
* independent gestures on different pieces of content.
*
* @param group ViewGroup to modify
* @param split <code>true</code> to allow MotionEvents to be split and dispatched to multiple
* child views. <code>false</code> to only allow one child view to be the target of
* any MotionEvent received by this ViewGroup.
*/
public static void setMotionEventSplittingEnabled(ViewGroup group, boolean split) {
IMPL.setMotionEventSplittingEnabled(group, split);
}
/**
* Returns the basis of alignment during layout operations on this ViewGroup:
* either {@link #LAYOUT_MODE_CLIP_BOUNDS} or {@link #LAYOUT_MODE_OPTICAL_BOUNDS}.
* <p>
* If no layoutMode was explicitly set, either programmatically or in an XML resource,
* the method returns the layoutMode of the view's parent ViewGroup if such a parent exists,
* otherwise the method returns a default value of {@link #LAYOUT_MODE_CLIP_BOUNDS}.
*
* @return the layout mode to use during layout operations
*
* @see #setLayoutMode(ViewGroup, int)
*/
public static int getLayoutMode(ViewGroup group) {
return IMPL.getLayoutMode(group);
}
/**
* Sets the basis of alignment during the layout of this ViewGroup.
* Valid values are either {@link #LAYOUT_MODE_CLIP_BOUNDS} or
* {@link #LAYOUT_MODE_OPTICAL_BOUNDS}.
*
* @param mode the layout mode to use during layout operations
*
* @see #getLayoutMode(ViewGroup)
*/
public static void setLayoutMode(ViewGroup group, int mode) {
IMPL.setLayoutMode(group, mode);
}
/**
* Changes whether or not this ViewGroup should be treated as a single entity during
* Activity Transitions.
* @param isTransitionGroup Whether or not the ViewGroup should be treated as a unit
* in Activity transitions. If false, the ViewGroup won't transition,
* only its children. If true, the entire ViewGroup will transition
* together.
*/
public static void setTransitionGroup(ViewGroup group, boolean isTransitionGroup) {
IMPL.setTransitionGroup(group, isTransitionGroup);
}
/**
* Returns true if this ViewGroup should be considered as a single entity for removal
* when executing an Activity transition. If this is false, child elements will move
* individually during the transition.
*/
public static boolean isTransitionGroup(ViewGroup group) {
return IMPL.isTransitionGroup(group);
}
}
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