v4/java/android/support/v4/view/ViewGroupCompat.java - platform/frameworks/support - Git at Google

 /*
  * 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 final 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 {
         boolean onRequestSendAccessibilityEvent(ViewGroup group, View child,
                 AccessibilityEvent event);
         void setMotionEventSplittingEnabled(ViewGroup group, boolean split);
         int getLayoutMode(ViewGroup group);
         void setLayoutMode(ViewGroup group, int mode);
         void setTransitionGroup(ViewGroup group, boolean isTransitionGroup);
         boolean isTransitionGroup(ViewGroup group);
         int getNestedScrollAxes(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;
         }

         @Override
         public int getNestedScrollAxes(ViewGroup group) {
             if (group instanceof NestedScrollingParent) {
                 return ((NestedScrollingParent) group).getNestedScrollAxes();
             }
             return ViewCompat.SCROLL_AXIS_NONE;
         }
     }

     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 ViewGroupCompatLollipopImpl extends ViewGroupCompatJellybeanMR2Impl {
         @Override
         public void setTransitionGroup(ViewGroup group, boolean isTransitionGroup) {
             ViewGroupCompatLollipop.setTransitionGroup(group, isTransitionGroup);
         }

         @Override
         public boolean isTransitionGroup(ViewGroup group) {
             return ViewGroupCompatLollipop.isTransitionGroup(group);
         }

         @Override
         public int getNestedScrollAxes(ViewGroup group) {
             return ViewGroupCompatLollipop.getNestedScrollAxes(group);
         }
     }

     static final ViewGroupCompatImpl IMPL;
     static {
         final int version = Build.VERSION.SDK_INT;
         if (version >= 21) {
             IMPL = new ViewGroupCompatLollipopImpl();
         } 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);
     }

     /**
      * Return the current axes of nested scrolling for this ViewGroup.
      *
      * <p>A ViewGroup returning something other than {@link ViewCompat#SCROLL_AXIS_NONE} is
      * currently acting as a nested scrolling parent for one or more descendant views in
      * the hierarchy.</p>
      *
      * @return Flags indicating the current axes of nested scrolling
      * @see ViewCompat#SCROLL_AXIS_HORIZONTAL
      * @see ViewCompat#SCROLL_AXIS_VERTICAL
      * @see ViewCompat#SCROLL_AXIS_NONE
      */
     public static int getNestedScrollAxes(ViewGroup group) {
         return IMPL.getNestedScrollAxes(group);
     }
 }
	/*
	* 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 final 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 {
	boolean onRequestSendAccessibilityEvent(ViewGroup group, View child,
	AccessibilityEvent event);
	void setMotionEventSplittingEnabled(ViewGroup group, boolean split);
	int getLayoutMode(ViewGroup group);
	void setLayoutMode(ViewGroup group, int mode);
	void setTransitionGroup(ViewGroup group, boolean isTransitionGroup);
	boolean isTransitionGroup(ViewGroup group);
	int getNestedScrollAxes(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;
	}

	@Override
	public int getNestedScrollAxes(ViewGroup group) {
	if (group instanceof NestedScrollingParent) {
	return ((NestedScrollingParent) group).getNestedScrollAxes();
	}
	return ViewCompat.SCROLL_AXIS_NONE;
	}
	}

	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 ViewGroupCompatLollipopImpl extends ViewGroupCompatJellybeanMR2Impl {
	@Override
	public void setTransitionGroup(ViewGroup group, boolean isTransitionGroup) {
	ViewGroupCompatLollipop.setTransitionGroup(group, isTransitionGroup);
	}

	@Override
	public boolean isTransitionGroup(ViewGroup group) {
	return ViewGroupCompatLollipop.isTransitionGroup(group);
	}

	@Override
	public int getNestedScrollAxes(ViewGroup group) {
	return ViewGroupCompatLollipop.getNestedScrollAxes(group);
	}
	}

	static final ViewGroupCompatImpl IMPL;
	static {
	final int version = Build.VERSION.SDK_INT;
	if (version >= 21) {
	IMPL = new ViewGroupCompatLollipopImpl();
	} 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);
	}

	/**
	* Return the current axes of nested scrolling for this ViewGroup.
	*
	* <p>A ViewGroup returning something other than {@link ViewCompat#SCROLL_AXIS_NONE} is
	* currently acting as a nested scrolling parent for one or more descendant views in
	* the hierarchy.</p>
	*
	* @return Flags indicating the current axes of nested scrolling
	* @see ViewCompat#SCROLL_AXIS_HORIZONTAL
	* @see ViewCompat#SCROLL_AXIS_VERTICAL
	* @see ViewCompat#SCROLL_AXIS_NONE
	*/
	public static int getNestedScrollAxes(ViewGroup group) {
	return IMPL.getNestedScrollAxes(group);
	}
	}