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authorJustin Klaassen <justinklaassen@google.com>2017-09-15 17:58:39 -0400
committerJustin Klaassen <justinklaassen@google.com>2017-09-15 17:58:39 -0400
commit10d07c88d69cc64f73a069163e7ea5ba2519a099 (patch)
tree8dbd149eb350320a29c3d10e7ad3201de1c5cbee /android/view/ViewParent.java
parent677516fb6b6f207d373984757d3d9450474b6b00 (diff)
downloadandroid-28-10d07c88d69cc64f73a069163e7ea5ba2519a099.tar.gz
Import Android SDK Platform PI [4335822]
/google/data/ro/projects/android/fetch_artifact \ --bid 4335822 \ --target sdk_phone_armv7-win_sdk \ sdk-repo-linux-sources-4335822.zip AndroidVersion.ApiLevel has been modified to appear as 28 Change-Id: Ic8f04be005a71c2b9abeaac754d8da8d6f9a2c32
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+/*
+ * Copyright (C) 2006 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.view;
+
+import android.annotation.NonNull;
+import android.graphics.Rect;
+import android.os.Bundle;
+import android.view.accessibility.AccessibilityEvent;
+
+/**
+ * Defines the responsibilities for a class that will be a parent of a View.
+ * This is the API that a view sees when it wants to interact with its parent.
+ *
+ */
+public interface ViewParent {
+ /**
+ * Called when something has changed which has invalidated the layout of a
+ * child of this view parent. This will schedule a layout pass of the view
+ * tree.
+ */
+ public void requestLayout();
+
+ /**
+ * Indicates whether layout was requested on this view parent.
+ *
+ * @return true if layout was requested, false otherwise
+ */
+ public boolean isLayoutRequested();
+
+ /**
+ * Called when a child wants the view hierarchy to gather and report
+ * transparent regions to the window compositor. Views that "punch" holes in
+ * the view hierarchy, such as SurfaceView can use this API to improve
+ * performance of the system. When no such a view is present in the
+ * hierarchy, this optimization in unnecessary and might slightly reduce the
+ * view hierarchy performance.
+ *
+ * @param child the view requesting the transparent region computation
+ *
+ */
+ public void requestTransparentRegion(View child);
+
+
+ /**
+ * The target View has been invalidated, or has had a drawing property changed that
+ * requires the hierarchy to re-render.
+ *
+ * This method is called by the View hierarchy to signal ancestors that a View either needs to
+ * re-record its drawing commands, or drawing properties have changed. This is how Views
+ * schedule a drawing traversal.
+ *
+ * This signal is generally only dispatched for attached Views, since only they need to draw.
+ *
+ * @param child Direct child of this ViewParent containing target
+ * @param target The view that needs to redraw
+ */
+ default void onDescendantInvalidated(@NonNull View child, @NonNull View target) {
+ if (getParent() != null) {
+ // Note: should pass 'this' as default, but can't since we may not be a View
+ getParent().onDescendantInvalidated(child, target);
+ }
+ }
+
+ /**
+ * All or part of a child is dirty and needs to be redrawn.
+ *
+ * @param child The child which is dirty
+ * @param r The area within the child that is invalid
+ *
+ * @deprecated Use {@link #onDescendantInvalidated(View, View)} instead.
+ */
+ @Deprecated
+ public void invalidateChild(View child, Rect r);
+
+ /**
+ * All or part of a child is dirty and needs to be redrawn.
+ *
+ * <p>The location array is an array of two int values which respectively
+ * define the left and the top position of the dirty child.</p>
+ *
+ * <p>This method must return the parent of this ViewParent if the specified
+ * rectangle must be invalidated in the parent. If the specified rectangle
+ * does not require invalidation in the parent or if the parent does not
+ * exist, this method must return null.</p>
+ *
+ * <p>When this method returns a non-null value, the location array must
+ * have been updated with the left and top coordinates of this ViewParent.</p>
+ *
+ * @param location An array of 2 ints containing the left and top
+ * coordinates of the child to invalidate
+ * @param r The area within the child that is invalid
+ *
+ * @return the parent of this ViewParent or null
+ *
+ * @deprecated Use {@link #onDescendantInvalidated(View, View)} instead.
+ */
+ @Deprecated
+ public ViewParent invalidateChildInParent(int[] location, Rect r);
+
+ /**
+ * Returns the parent if it exists, or null.
+ *
+ * @return a ViewParent or null if this ViewParent does not have a parent
+ */
+ public ViewParent getParent();
+
+ /**
+ * Called when a child of this parent wants focus
+ *
+ * @param child The child of this ViewParent that wants focus. This view
+ * will contain the focused view. It is not necessarily the view that
+ * actually has focus.
+ * @param focused The view that is a descendant of child that actually has
+ * focus
+ */
+ public void requestChildFocus(View child, View focused);
+
+ /**
+ * Tell view hierarchy that the global view attributes need to be
+ * re-evaluated.
+ *
+ * @param child View whose attributes have changed.
+ */
+ public void recomputeViewAttributes(View child);
+
+ /**
+ * Called when a child of this parent is giving up focus
+ *
+ * @param child The view that is giving up focus
+ */
+ public void clearChildFocus(View child);
+
+ /**
+ * Compute the visible part of a rectangular region defined in terms of a child view's
+ * coordinates.
+ *
+ * <p>Returns the clipped visible part of the rectangle <code>r</code>, defined in the
+ * <code>child</code>'s local coordinate system. <code>r</code> is modified by this method to
+ * contain the result, expressed in the global (root) coordinate system.</p>
+ *
+ * <p>The resulting rectangle is always axis aligned. If a rotation is applied to a node in the
+ * View hierarchy, the result is the axis-aligned bounding box of the visible rectangle.</p>
+ *
+ * @param child A child View, whose rectangular visible region we want to compute
+ * @param r The input rectangle, defined in the child coordinate system. Will be overwritten to
+ * contain the resulting visible rectangle, expressed in global (root) coordinates
+ * @param offset The input coordinates of a point, defined in the child coordinate system.
+ * As with the <code>r</code> parameter, this will be overwritten to contain the global (root)
+ * coordinates of that point.
+ * A <code>null</code> value is valid (in case you are not interested in this result)
+ * @return true if the resulting rectangle is not empty, false otherwise
+ */
+ public boolean getChildVisibleRect(View child, Rect r, android.graphics.Point offset);
+
+ /**
+ * Find the nearest view in the specified direction that wants to take focus
+ *
+ * @param v The view that currently has focus
+ * @param direction One of FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, and FOCUS_RIGHT
+ */
+ public View focusSearch(View v, int direction);
+
+ /**
+ * Find the nearest keyboard navigation cluster in the specified direction.
+ * This does not actually give focus to that cluster.
+ *
+ * @param currentCluster The starting point of the search. Null means the current cluster is not
+ * found yet
+ * @param direction Direction to look
+ *
+ * @return The nearest keyboard navigation cluster in the specified direction, or null if none
+ * can be found
+ */
+ View keyboardNavigationClusterSearch(View currentCluster, int direction);
+
+ /**
+ * Change the z order of the child so it's on top of all other children.
+ * This ordering change may affect layout, if this container
+ * uses an order-dependent layout scheme (e.g., LinearLayout). Prior
+ * to {@link android.os.Build.VERSION_CODES#KITKAT} this
+ * method should be followed by calls to {@link #requestLayout()} and
+ * {@link View#invalidate()} on this parent to force the parent to redraw
+ * with the new child ordering.
+ *
+ * @param child The child to bring to the top of the z order
+ */
+ public void bringChildToFront(View child);
+
+ /**
+ * Tells the parent that a new focusable view has become available. This is
+ * to handle transitions from the case where there are no focusable views to
+ * the case where the first focusable view appears.
+ *
+ * @param v The view that has become newly focusable
+ */
+ public void focusableViewAvailable(View v);
+
+ /**
+ * Shows the context menu for the specified view or its ancestors.
+ * <p>
+ * In most cases, a subclass does not need to override this. However, if
+ * the subclass is added directly to the window manager (for example,
+ * {@link ViewManager#addView(View, android.view.ViewGroup.LayoutParams)})
+ * then it should override this and show the context menu.
+ *
+ * @param originalView the source view where the context menu was first
+ * invoked
+ * @return {@code true} if the context menu was shown, {@code false}
+ * otherwise
+ * @see #showContextMenuForChild(View, float, float)
+ */
+ public boolean showContextMenuForChild(View originalView);
+
+ /**
+ * Shows the context menu for the specified view or its ancestors anchored
+ * to the specified view-relative coordinate.
+ * <p>
+ * In most cases, a subclass does not need to override this. However, if
+ * the subclass is added directly to the window manager (for example,
+ * {@link ViewManager#addView(View, android.view.ViewGroup.LayoutParams)})
+ * then it should override this and show the context menu.
+ * <p>
+ * If a subclass overrides this method it should also override
+ * {@link #showContextMenuForChild(View)}.
+ *
+ * @param originalView the source view where the context menu was first
+ * invoked
+ * @param x the X coordinate in pixels relative to the original view to
+ * which the menu should be anchored, or {@link Float#NaN} to
+ * disable anchoring
+ * @param y the Y coordinate in pixels relative to the original view to
+ * which the menu should be anchored, or {@link Float#NaN} to
+ * disable anchoring
+ * @return {@code true} if the context menu was shown, {@code false}
+ * otherwise
+ */
+ boolean showContextMenuForChild(View originalView, float x, float y);
+
+ /**
+ * Have the parent populate the specified context menu if it has anything to
+ * add (and then recurse on its parent).
+ *
+ * @param menu The menu to populate
+ */
+ public void createContextMenu(ContextMenu menu);
+
+ /**
+ * Start an action mode for the specified view with the default type
+ * {@link ActionMode#TYPE_PRIMARY}.
+ *
+ * <p>In most cases, a subclass does not need to override this. However, if the
+ * subclass is added directly to the window manager (for example,
+ * {@link ViewManager#addView(View, android.view.ViewGroup.LayoutParams)})
+ * then it should override this and start the action mode.</p>
+ *
+ * @param originalView The source view where the action mode was first invoked
+ * @param callback The callback that will handle lifecycle events for the action mode
+ * @return The new action mode if it was started, null otherwise
+ *
+ * @see #startActionModeForChild(View, android.view.ActionMode.Callback, int)
+ */
+ public ActionMode startActionModeForChild(View originalView, ActionMode.Callback callback);
+
+ /**
+ * Start an action mode of a specific type for the specified view.
+ *
+ * <p>In most cases, a subclass does not need to override this. However, if the
+ * subclass is added directly to the window manager (for example,
+ * {@link ViewManager#addView(View, android.view.ViewGroup.LayoutParams)})
+ * then it should override this and start the action mode.</p>
+ *
+ * @param originalView The source view where the action mode was first invoked
+ * @param callback The callback that will handle lifecycle events for the action mode
+ * @param type One of {@link ActionMode#TYPE_PRIMARY} or {@link ActionMode#TYPE_FLOATING}.
+ * @return The new action mode if it was started, null otherwise
+ */
+ public ActionMode startActionModeForChild(
+ View originalView, ActionMode.Callback callback, int type);
+
+ /**
+ * This method is called on the parent when a child's drawable state
+ * has changed.
+ *
+ * @param child The child whose drawable state has changed.
+ */
+ public void childDrawableStateChanged(View child);
+
+ /**
+ * Called when a child does not want this parent and its ancestors to
+ * intercept touch events with
+ * {@link ViewGroup#onInterceptTouchEvent(MotionEvent)}.
+ *
+ * <p>This parent should pass this call onto its parents. This parent must obey
+ * this request for the duration of the touch (that is, only clear the flag
+ * after this parent has received an up or a cancel.</p>
+ *
+ * @param disallowIntercept True if the child does not want the parent to
+ * intercept touch events.
+ */
+ public void requestDisallowInterceptTouchEvent(boolean disallowIntercept);
+
+ /**
+ * Called when a child of this group wants a particular rectangle to be
+ * positioned onto the screen. {@link ViewGroup}s overriding this can trust
+ * that:
+ * <ul>
+ * <li>child will be a direct child of this group</li>
+ * <li>rectangle will be in the child's content coordinates</li>
+ * </ul>
+ *
+ * <p>{@link ViewGroup}s overriding this should uphold the contract:</p>
+ * <ul>
+ * <li>nothing will change if the rectangle is already visible</li>
+ * <li>the view port will be scrolled only just enough to make the
+ * rectangle visible</li>
+ * <ul>
+ *
+ * @param child The direct child making the request.
+ * @param rectangle The rectangle in the child's coordinates the child
+ * wishes to be on the screen.
+ * @param immediate True to forbid animated or delayed scrolling,
+ * false otherwise
+ * @return Whether the group scrolled to handle the operation
+ */
+ public boolean requestChildRectangleOnScreen(View child, Rect rectangle,
+ boolean immediate);
+
+ /**
+ * Called by a child to request from its parent to send an {@link AccessibilityEvent}.
+ * The child has already populated a record for itself in the event and is delegating
+ * to its parent to send the event. The parent can optionally add a record for itself.
+ * <p>
+ * Note: An accessibility event is fired by an individual view which populates the
+ * event with a record for its state and requests from its parent to perform
+ * the sending. The parent can optionally add a record for itself before
+ * dispatching the request to its parent. A parent can also choose not to
+ * respect the request for sending the event. The accessibility event is sent
+ * by the topmost view in the view tree.</p>
+ *
+ * @param child The child which requests sending the event.
+ * @param event The event to be sent.
+ * @return True if the event was sent.
+ */
+ public boolean requestSendAccessibilityEvent(View child, AccessibilityEvent event);
+
+ /**
+ * Called when a child view now has or no longer is tracking transient state.
+ *
+ * <p>"Transient state" is any state that a View might hold that is not expected to
+ * be reflected in the data model that the View currently presents. This state only
+ * affects the presentation to the user within the View itself, such as the current
+ * state of animations in progress or the state of a text selection operation.</p>
+ *
+ * <p>Transient state is useful for hinting to other components of the View system
+ * that a particular view is tracking something complex but encapsulated.
+ * A <code>ListView</code> for example may acknowledge that list item Views
+ * with transient state should be preserved within their position or stable item ID
+ * instead of treating that view as trivially replaceable by the backing adapter.
+ * This allows adapter implementations to be simpler instead of needing to track
+ * the state of item view animations in progress such that they could be restored
+ * in the event of an unexpected recycling and rebinding of attached item views.</p>
+ *
+ * <p>This method is called on a parent view when a child view or a view within
+ * its subtree begins or ends tracking of internal transient state.</p>
+ *
+ * @param child Child view whose state has changed
+ * @param hasTransientState true if this child has transient state
+ */
+ public void childHasTransientStateChanged(View child, boolean hasTransientState);
+
+ /**
+ * Ask that a new dispatch of {@link View#fitSystemWindows(Rect)
+ * View.fitSystemWindows(Rect)} be performed.
+ */
+ public void requestFitSystemWindows();
+
+ /**
+ * Gets the parent of a given View for accessibility. Since some Views are not
+ * exposed to the accessibility layer the parent for accessibility is not
+ * necessarily the direct parent of the View, rather it is a predecessor.
+ *
+ * @return The parent or <code>null</code> if no such is found.
+ */
+ public ViewParent getParentForAccessibility();
+
+ /**
+ * Notifies a view parent that the accessibility state of one of its
+ * descendants has changed and that the structure of the subtree is
+ * different.
+ * @param child The direct child whose subtree has changed.
+ * @param source The descendant view that changed. May not be {@code null}.
+ * @param changeType A bit mask of the types of changes that occurred. One
+ * or more of:
+ * <ul>
+ * <li>{@link AccessibilityEvent#CONTENT_CHANGE_TYPE_CONTENT_DESCRIPTION}
+ * <li>{@link AccessibilityEvent#CONTENT_CHANGE_TYPE_SUBTREE}
+ * <li>{@link AccessibilityEvent#CONTENT_CHANGE_TYPE_TEXT}
+ * <li>{@link AccessibilityEvent#CONTENT_CHANGE_TYPE_UNDEFINED}
+ * </ul>
+ */
+ public void notifySubtreeAccessibilityStateChanged(
+ View child, @NonNull View source, int changeType);
+
+ /**
+ * Tells if this view parent can resolve the layout direction.
+ * See {@link View#setLayoutDirection(int)}
+ *
+ * @return True if this view parent can resolve the layout direction.
+ */
+ public boolean canResolveLayoutDirection();
+
+ /**
+ * Tells if this view parent layout direction is resolved.
+ * See {@link View#setLayoutDirection(int)}
+ *
+ * @return True if this view parent layout direction is resolved.
+ */
+ public boolean isLayoutDirectionResolved();
+
+ /**
+ * Return this view parent layout direction. See {@link View#getLayoutDirection()}
+ *
+ * @return {@link View#LAYOUT_DIRECTION_RTL} if the layout direction is RTL or returns
+ * {@link View#LAYOUT_DIRECTION_LTR} if the layout direction is not RTL.
+ */
+ public int getLayoutDirection();
+
+ /**
+ * Tells if this view parent can resolve the text direction.
+ * See {@link View#setTextDirection(int)}
+ *
+ * @return True if this view parent can resolve the text direction.
+ */
+ public boolean canResolveTextDirection();
+
+ /**
+ * Tells if this view parent text direction is resolved.
+ * See {@link View#setTextDirection(int)}
+ *
+ * @return True if this view parent text direction is resolved.
+ */
+ public boolean isTextDirectionResolved();
+
+ /**
+ * Return this view parent text direction. See {@link View#getTextDirection()}
+ *
+ * @return the resolved text direction. Returns one of:
+ *
+ * {@link View#TEXT_DIRECTION_FIRST_STRONG}
+ * {@link View#TEXT_DIRECTION_ANY_RTL},
+ * {@link View#TEXT_DIRECTION_LTR},
+ * {@link View#TEXT_DIRECTION_RTL},
+ * {@link View#TEXT_DIRECTION_LOCALE}
+ */
+ public int getTextDirection();
+
+ /**
+ * Tells if this view parent can resolve the text alignment.
+ * See {@link View#setTextAlignment(int)}
+ *
+ * @return True if this view parent can resolve the text alignment.
+ */
+ public boolean canResolveTextAlignment();
+
+ /**
+ * Tells if this view parent text alignment is resolved.
+ * See {@link View#setTextAlignment(int)}
+ *
+ * @return True if this view parent text alignment is resolved.
+ */
+ public boolean isTextAlignmentResolved();
+
+ /**
+ * Return this view parent text alignment. See {@link android.view.View#getTextAlignment()}
+ *
+ * @return the resolved text alignment. Returns one of:
+ *
+ * {@link View#TEXT_ALIGNMENT_GRAVITY},
+ * {@link View#TEXT_ALIGNMENT_CENTER},
+ * {@link View#TEXT_ALIGNMENT_TEXT_START},
+ * {@link View#TEXT_ALIGNMENT_TEXT_END},
+ * {@link View#TEXT_ALIGNMENT_VIEW_START},
+ * {@link View#TEXT_ALIGNMENT_VIEW_END}
+ */
+ public int getTextAlignment();
+
+ /**
+ * React to a descendant view initiating a nestable scroll operation, claiming the
+ * nested scroll operation if appropriate.
+ *
+ * <p>This method will be called in response to a descendant view invoking
+ * {@link View#startNestedScroll(int)}. Each parent up the view hierarchy will be
+ * given an opportunity to respond and claim the nested scrolling operation by returning
+ * <code>true</code>.</p>
+ *
+ * <p>This method may be overridden by ViewParent implementations to indicate when the view
+ * is willing to support a nested scrolling operation that is about to begin. If it returns
+ * true, this ViewParent will become the target view's nested scrolling parent for the duration
+ * of the scroll operation in progress. When the nested scroll is finished this ViewParent
+ * will receive a call to {@link #onStopNestedScroll(View)}.
+ * </p>
+ *
+ * @param child Direct child of this ViewParent containing target
+ * @param target View that initiated the nested scroll
+ * @param nestedScrollAxes Flags consisting of {@link View#SCROLL_AXIS_HORIZONTAL},
+ * {@link View#SCROLL_AXIS_VERTICAL} or both
+ * @return true if this ViewParent accepts the nested scroll operation
+ */
+ public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes);
+
+ /**
+ * React to the successful claiming of a nested scroll operation.
+ *
+ * <p>This method will be called after
+ * {@link #onStartNestedScroll(View, View, int) onStartNestedScroll} returns true. It offers
+ * an opportunity for the view and its superclasses to perform initial configuration
+ * for the nested scroll. Implementations of this method should always call their superclass's
+ * implementation of this method if one is present.</p>
+ *
+ * @param child Direct child of this ViewParent containing target
+ * @param target View that initiated the nested scroll
+ * @param nestedScrollAxes Flags consisting of {@link View#SCROLL_AXIS_HORIZONTAL},
+ * {@link View#SCROLL_AXIS_VERTICAL} or both
+ * @see #onStartNestedScroll(View, View, int)
+ * @see #onStopNestedScroll(View)
+ */
+ public void onNestedScrollAccepted(View child, View target, int nestedScrollAxes);
+
+ /**
+ * React to a nested scroll operation ending.
+ *
+ * <p>Perform cleanup after a nested scrolling operation.
+ * This method will be called when a nested scroll stops, for example when a nested touch
+ * scroll ends with a {@link MotionEvent#ACTION_UP} or {@link MotionEvent#ACTION_CANCEL} event.
+ * Implementations of this method should always call their superclass's implementation of this
+ * method if one is present.</p>
+ *
+ * @param target View that initiated the nested scroll
+ */
+ public void onStopNestedScroll(View target);
+
+ /**
+ * React to a nested scroll in progress.
+ *
+ * <p>This method will be called when the ViewParent's current nested scrolling child view
+ * dispatches a nested scroll event. To receive calls to this method the ViewParent must have
+ * previously returned <code>true</code> for a call to
+ * {@link #onStartNestedScroll(View, View, int)}.</p>
+ *
+ * <p>Both the consumed and unconsumed portions of the scroll distance are reported to the
+ * ViewParent. An implementation may choose to use the consumed portion to match or chase scroll
+ * position of multiple child elements, for example. The unconsumed portion may be used to
+ * allow continuous dragging of multiple scrolling or draggable elements, such as scrolling
+ * a list within a vertical drawer where the drawer begins dragging once the edge of inner
+ * scrolling content is reached.</p>
+ *
+ * @param target The descendent view controlling the nested scroll
+ * @param dxConsumed Horizontal scroll distance in pixels already consumed by target
+ * @param dyConsumed Vertical scroll distance in pixels already consumed by target
+ * @param dxUnconsumed Horizontal scroll distance in pixels not consumed by target
+ * @param dyUnconsumed Vertical scroll distance in pixels not consumed by target
+ */
+ public void onNestedScroll(View target, int dxConsumed, int dyConsumed,
+ int dxUnconsumed, int dyUnconsumed);
+
+ /**
+ * React to a nested scroll in progress before the target view consumes a portion of the scroll.
+ *
+ * <p>When working with nested scrolling often the parent view may want an opportunity
+ * to consume the scroll before the nested scrolling child does. An example of this is a
+ * drawer that contains a scrollable list. The user will want to be able to scroll the list
+ * fully into view before the list itself begins scrolling.</p>
+ *
+ * <p><code>onNestedPreScroll</code> is called when a nested scrolling child invokes
+ * {@link View#dispatchNestedPreScroll(int, int, int[], int[])}. The implementation should
+ * report how any pixels of the scroll reported by dx, dy were consumed in the
+ * <code>consumed</code> array. Index 0 corresponds to dx and index 1 corresponds to dy.
+ * This parameter will never be null. Initial values for consumed[0] and consumed[1]
+ * will always be 0.</p>
+ *
+ * @param target View that initiated the nested scroll
+ * @param dx Horizontal scroll distance in pixels
+ * @param dy Vertical scroll distance in pixels
+ * @param consumed Output. The horizontal and vertical scroll distance consumed by this parent
+ */
+ public void onNestedPreScroll(View target, int dx, int dy, int[] consumed);
+
+ /**
+ * Request a fling from a nested scroll.
+ *
+ * <p>This method signifies that a nested scrolling child has detected suitable conditions
+ * for a fling. Generally this means that a touch scroll has ended with a
+ * {@link VelocityTracker velocity} in the direction of scrolling that meets or exceeds
+ * the {@link ViewConfiguration#getScaledMinimumFlingVelocity() minimum fling velocity}
+ * along a scrollable axis.</p>
+ *
+ * <p>If a nested scrolling child view would normally fling but it is at the edge of
+ * its own content, it can use this method to delegate the fling to its nested scrolling
+ * parent instead. The parent may optionally consume the fling or observe a child fling.</p>
+ *
+ * @param target View that initiated the nested scroll
+ * @param velocityX Horizontal velocity in pixels per second
+ * @param velocityY Vertical velocity in pixels per second
+ * @param consumed true if the child consumed the fling, false otherwise
+ * @return true if this parent consumed or otherwise reacted to the fling
+ */
+ public boolean onNestedFling(View target, float velocityX, float velocityY, boolean consumed);
+
+ /**
+ * React to a nested fling before the target view consumes it.
+ *
+ * <p>This method siginfies that a nested scrolling child has detected a fling with the given
+ * velocity along each axis. Generally this means that a touch scroll has ended with a
+ * {@link VelocityTracker velocity} in the direction of scrolling that meets or exceeds
+ * the {@link ViewConfiguration#getScaledMinimumFlingVelocity() minimum fling velocity}
+ * along a scrollable axis.</p>
+ *
+ * <p>If a nested scrolling parent is consuming motion as part of a
+ * {@link #onNestedPreScroll(View, int, int, int[]) pre-scroll}, it may be appropriate for
+ * it to also consume the pre-fling to complete that same motion. By returning
+ * <code>true</code> from this method, the parent indicates that the child should not
+ * fling its own internal content as well.</p>
+ *
+ * @param target View that initiated the nested scroll
+ * @param velocityX Horizontal velocity in pixels per second
+ * @param velocityY Vertical velocity in pixels per second
+ * @return true if this parent consumed the fling ahead of the target view
+ */
+ public boolean onNestedPreFling(View target, float velocityX, float velocityY);
+
+ /**
+ * React to an accessibility action delegated by a target descendant view before the target
+ * processes it.
+ *
+ * <p>This method may be called by a target descendant view if the target wishes to give
+ * a view in its parent chain a chance to react to the event before normal processing occurs.
+ * Most commonly this will be a scroll event such as
+ * {@link android.view.accessibility.AccessibilityNodeInfo#ACTION_SCROLL_FORWARD}.
+ * A ViewParent that supports acting as a nested scrolling parent should override this
+ * method and act accordingly to implement scrolling via accesibility systems.</p>
+ *
+ * @param target The target view dispatching this action
+ * @param action Action being performed; see
+ * {@link android.view.accessibility.AccessibilityNodeInfo}
+ * @param arguments Optional action arguments
+ * @return true if the action was consumed by this ViewParent
+ */
+ public boolean onNestedPrePerformAccessibilityAction(View target, int action, Bundle arguments);
+}