/*
* Copyright (C) 2013 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.animation.LayoutTransition;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import java.util.ArrayList;
/**
* An overlay is an extra layer that sits on top of a View (the "host view")
* which is drawn after all other content in that view (including children,
* if the view is a ViewGroup). Interaction with the overlay layer is done
* by adding and removing drawables.
*
* <p>An overlay requested from a ViewGroup is of type {@link ViewGroupOverlay},
* which also supports adding and removing views.</p>
*
* @see View#getOverlay() View.getOverlay()
* @see ViewGroup#getOverlay() ViewGroup.getOverlay()
* @see ViewGroupOverlay
*/
public class ViewOverlay {
/**
* The actual container for the drawables (and views, if it's a ViewGroupOverlay).
* All of the management and rendering details for the overlay are handled in
* OverlayViewGroup.
*/
OverlayViewGroup mOverlayViewGroup;
ViewOverlay(Context context, View hostView) {
mOverlayViewGroup = new OverlayViewGroup(context, hostView);
}
/**
* Used internally by View and ViewGroup to handle drawing and invalidation
* of the overlay
* @return
*/
ViewGroup getOverlayView() {
return mOverlayViewGroup;
}
/**
* Adds a Drawable to the overlay. The bounds of the drawable should be relative to
* the host view. Any drawable added to the overlay should be removed when it is no longer
* needed or no longer visible.
*
* @param drawable The Drawable to be added to the overlay. This drawable will be
* drawn when the view redraws its overlay.
* @see #remove(Drawable)
*/
public void add(Drawable drawable) {
mOverlayViewGroup.add(drawable);
}
/**
* Removes the specified Drawable from the overlay.
*
* @param drawable The Drawable to be removed from the overlay.
* @see #add(Drawable)
*/
public void remove(Drawable drawable) {
mOverlayViewGroup.remove(drawable);
}
/**
* Removes all content from the overlay.
*/
public void clear() {
mOverlayViewGroup.clear();
}
boolean isEmpty() {
return mOverlayViewGroup.isEmpty();
}
/**
* OverlayViewGroup is a container that View and ViewGroup use to host
* drawables and views added to their overlays ({@link ViewOverlay} and
* {@link ViewGroupOverlay}, respectively). Drawables are added to the overlay
* via the add/remove methods in ViewOverlay, Views are added/removed via
* ViewGroupOverlay. These drawable and view objects are
* drawn whenever the view itself is drawn; first the view draws its own
* content (and children, if it is a ViewGroup), then it draws its overlay
* (if it has one).
*
* <p>Besides managing and drawing the list of drawables, this class serves
* two purposes:
* (1) it noops layout calls because children are absolutely positioned and
* (2) it forwards all invalidation calls to its host view. The invalidation
* redirect is necessary because the overlay is not a child of the host view
* and invalidation cannot therefore follow the normal path up through the
* parent hierarchy.</p>
*
* @see View#getOverlay()
* @see ViewGroup#getOverlay()
*/
static class OverlayViewGroup extends ViewGroup {
/**
* The View for which this is an overlay. Invalidations of the overlay are redirected to
* this host view.
*/
View mHostView;
/**
* The set of drawables to draw when the overlay is rendered.
*/
ArrayList<Drawable> mDrawables = null;
OverlayViewGroup(Context context, View hostView) {
super(context);
mHostView = hostView;
mAttachInfo = mHostView.mAttachInfo;
mRight = hostView.getWidth();
mBottom = hostView.getHeight();
// pass right+bottom directly to RenderNode, since not going through setters
mRenderNode.setLeftTopRightBottom(0, 0, mRight, mBottom);
}
public void add(Drawable drawable) {
if (mDrawables == null) {
mDrawables = new ArrayList<Drawable>();
}
if (!mDrawables.contains(drawable)) {
// Make each drawable unique in the overlay; can't add it more than once
mDrawables.add(drawable);
invalidate(drawable.getBounds());
drawable.setCallback(this);
}
}
public void remove(Drawable drawable) {
if (mDrawables != null) {
mDrawables.remove(drawable);
invalidate(drawable.getBounds());
drawable.setCallback(null);
}
}
@Override
protected boolean verifyDrawable(Drawable who) {
return super.verifyDrawable(who) || (mDrawables != null && mDrawables.contains(who));
}
public void add(View child) {
if (child.getParent() instanceof ViewGroup) {
ViewGroup parent = (ViewGroup) child.getParent();
if (parent != mHostView && parent.getParent() != null &&
parent.mAttachInfo != null) {
// Moving to different container; figure out how to position child such that
// it is in the same location on the screen
int[] parentLocation = new int[2];
int[] hostViewLocation = new int[2];
parent.getLocationOnScreen(parentLocation);
mHostView.getLocationOnScreen(hostViewLocation);
child.offsetLeftAndRight(parentLocation[0] - hostViewLocation[0]);
child.offsetTopAndBottom(parentLocation[1] - hostViewLocation[1]);
}
parent.removeView(child);
if (parent.getLayoutTransition() != null) {
// LayoutTransition will cause the child to delay removal - cancel it
parent.getLayoutTransition().cancel(LayoutTransition.DISAPPEARING);
}
// fail-safe if view is still attached for any reason
if (child.getParent() != null) {
child.mParent = null;
}
}
super.addView(child);
}
public void remove(View view) {
super.removeView(view);
}
public void clear() {
removeAllViews();
if (mDrawables != null) {
mDrawables.clear();
}
}
boolean isEmpty() {
if (getChildCount() == 0 &&
(mDrawables == null || mDrawables.size() == 0)) {
return true;
}
return false;
}
@Override
public void invalidateDrawable(Drawable drawable) {
invalidate(drawable.getBounds());
}
@Override
protected void dispatchDraw(Canvas canvas) {
super.dispatchDraw(canvas);
final int numDrawables = (mDrawables == null) ? 0 : mDrawables.size();
for (int i = 0; i < numDrawables; ++i) {
mDrawables.get(i).draw(canvas);
}
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
// Noop: children are positioned absolutely
}
/*
The following invalidation overrides exist for the purpose of redirecting invalidation to
the host view. The overlay is not parented to the host view (since a View cannot be a
parent), so the invalidation cannot proceed through the normal parent hierarchy.
There is a built-in assumption that the overlay exactly covers the host view, therefore
the invalidation rectangles received do not need to be adjusted when forwarded to
the host view.
*/
@Override
public void invalidate(Rect dirty) {
super.invalidate(dirty);
if (mHostView != null) {
mHostView.invalidate(dirty);
}
}
@Override
public void invalidate(int l, int t, int r, int b) {
super.invalidate(l, t, r, b);
if (mHostView != null) {
mHostView.invalidate(l, t, r, b);
}
}
@Override
public void invalidate() {
super.invalidate();
if (mHostView != null) {
mHostView.invalidate();
}
}
@Override
void invalidate(boolean invalidateCache) {
super.invalidate(invalidateCache);
if (mHostView != null) {
mHostView.invalidate(invalidateCache);
}
}
@Override
void invalidateViewProperty(boolean invalidateParent, boolean forceRedraw) {
super.invalidateViewProperty(invalidateParent, forceRedraw);
if (mHostView != null) {
mHostView.invalidateViewProperty(invalidateParent, forceRedraw);
}
}
@Override
protected void invalidateParentCaches() {
super.invalidateParentCaches();
if (mHostView != null) {
mHostView.invalidateParentCaches();
}
}
@Override
protected void invalidateParentIfNeeded() {
super.invalidateParentIfNeeded();
if (mHostView != null) {
mHostView.invalidateParentIfNeeded();
}
}
/**
* @hide
*/
@Override
public void damageChild(View child, final Rect dirty) {
if (mHostView != null) {
// Note: This is not a "fast" invalidation. Would be nice to instead invalidate
// using DisplayList properties and a dirty rect instead of causing a real
// invalidation of the host view
int left = child.mLeft;
int top = child.mTop;
if (!child.getMatrix().isIdentity()) {
child.transformRect(dirty);
}
dirty.offset(left, top);
mHostView.invalidate(dirty);
}
}
/**
* @hide
*/
@Override
protected ViewParent damageChildInParent(int left, int top, Rect dirty) {
if (mHostView instanceof ViewGroup) {
return ((ViewGroup) mHostView).damageChildInParent(left, top, dirty);
}
return null;
}
@Override
public ViewParent invalidateChildInParent(int[] location, Rect dirty) {
if (mHostView != null) {
dirty.offset(location[0], location[1]);
if (mHostView instanceof ViewGroup) {
location[0] = 0;
location[1] = 0;
super.invalidateChildInParent(location, dirty);
return ((ViewGroup) mHostView).invalidateChildInParent(location, dirty);
} else {
invalidate(dirty);
}
}
return null;
}
}
}
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