Java tutorial
/* * Copyright (C) 2016 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.transition; import static android.support.annotation.RestrictTo.Scope.LIBRARY_GROUP; import android.content.Context; import android.graphics.Canvas; import android.graphics.Rect; import android.graphics.drawable.Drawable; import android.support.annotation.NonNull; import android.support.annotation.RequiresApi; import android.support.annotation.RestrictTo; import android.support.v4.view.ViewCompat; import android.view.MotionEvent; import android.view.View; import android.view.ViewGroup; import android.view.ViewParent; import java.lang.reflect.InvocationTargetException; import java.lang.reflect.Method; import java.util.ArrayList; @RequiresApi(14) class ViewOverlayApi14 implements ViewOverlayImpl { /** * 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. */ protected OverlayViewGroup mOverlayViewGroup; ViewOverlayApi14(Context context, ViewGroup hostView, View requestingView) { mOverlayViewGroup = new OverlayViewGroup(context, hostView, requestingView, this); } static ViewGroup getContentView(View view) { View parent = view; while (parent != null) { if (parent.getId() == android.R.id.content && parent instanceof ViewGroup) { return (ViewGroup) parent; } if (parent.getParent() instanceof ViewGroup) { parent = (ViewGroup) parent.getParent(); } } return null; } static ViewOverlayApi14 createFrom(View view) { ViewGroup contentView = getContentView(view); if (contentView != null) { final int numChildren = contentView.getChildCount(); for (int i = 0; i < numChildren; ++i) { View child = contentView.getChildAt(i); if (child instanceof OverlayViewGroup) { return ((OverlayViewGroup) child).mViewOverlay; } } return new ViewGroupOverlayApi14(contentView.getContext(), contentView, view); } return null; } /** * Used internally by View and ViewGroup to handle drawing and invalidation * of the overlay */ ViewGroup getOverlayView() { return mOverlayViewGroup; } @Override public void add(@NonNull Drawable drawable) { mOverlayViewGroup.add(drawable); } @Override public void clear() { mOverlayViewGroup.clear(); } @Override public void remove(@NonNull Drawable drawable) { mOverlayViewGroup.remove(drawable); } boolean isEmpty() { return mOverlayViewGroup.isEmpty(); } /** * OverlayViewGroup is a container that View and ViewGroup use to host * drawables and views added to their overlays ({@code ViewOverlay} and * {@code 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 { static Method sInvalidateChildInParentFastMethod; static { try { sInvalidateChildInParentFastMethod = ViewGroup.class .getDeclaredMethod("invalidateChildInParentFast", int.class, int.class, Rect.class); } catch (NoSuchMethodException e) { } } /** * The View for which this is an overlay. Invalidations of the overlay are redirected to * this host view. */ ViewGroup mHostView; View mRequestingView; /** * The set of drawables to draw when the overlay is rendered. */ ArrayList<Drawable> mDrawables = null; /** * Reference to the hosting overlay object */ ViewOverlayApi14 mViewOverlay; OverlayViewGroup(Context context, ViewGroup hostView, View requestingView, ViewOverlayApi14 viewOverlay) { super(context); mHostView = hostView; mRequestingView = requestingView; setRight(hostView.getWidth()); setBottom(hostView.getHeight()); hostView.addView(this); mViewOverlay = viewOverlay; } @Override public boolean dispatchTouchEvent(MotionEvent ev) { // Intercept and noop all touch events - overlays do not allow touch events return false; } public void add(Drawable drawable) { if (mDrawables == null) { mDrawables = new ArrayList<>(); } 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(@NonNull 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 && ViewCompat.isAttachedToWindow(parent)) { // 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); ViewCompat.offsetLeftAndRight(child, parentLocation[0] - hostViewLocation[0]); ViewCompat.offsetTopAndBottom(child, 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) { parent.removeView(child); } } super.addView(child, getChildCount() - 1); } public void remove(View view) { super.removeView(view); if (isEmpty()) { mHostView.removeView(this); } } public void clear() { removeAllViews(); if (mDrawables != null) { mDrawables.clear(); } } boolean isEmpty() { return getChildCount() == 0 && (mDrawables == null || mDrawables.size() == 0); } @Override public void invalidateDrawable(@NonNull Drawable drawable) { invalidate(drawable.getBounds()); } @Override protected void dispatchDraw(Canvas canvas) { int[] contentViewLocation = new int[2]; int[] hostViewLocation = new int[2]; mHostView.getLocationOnScreen(contentViewLocation); mRequestingView.getLocationOnScreen(hostViewLocation); canvas.translate(hostViewLocation[0] - contentViewLocation[0], hostViewLocation[1] - contentViewLocation[1]); canvas.clipRect(new Rect(0, 0, mRequestingView.getWidth(), mRequestingView.getHeight())); 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. */ private void getOffset(int[] offset) { int[] contentViewLocation = new int[2]; int[] hostViewLocation = new int[2]; mHostView.getLocationOnScreen(contentViewLocation); mRequestingView.getLocationOnScreen(hostViewLocation); offset[0] = hostViewLocation[0] - contentViewLocation[0]; offset[1] = hostViewLocation[1] - contentViewLocation[1]; } public void invalidateChildFast(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.getLeft(); int top = child.getTop(); int[] offset = new int[2]; getOffset(offset); // TODO: implement transforms // if (!child.getMatrix().isIdentity()) { // child.transformRect(dirty); // } dirty.offset(left + offset[0], top + offset[1]); mHostView.invalidate(dirty); } } /** * @hide */ @RestrictTo(LIBRARY_GROUP) protected ViewParent invalidateChildInParentFast(int left, int top, Rect dirty) { if (mHostView instanceof ViewGroup && sInvalidateChildInParentFastMethod != null) { try { int[] offset = new int[2]; getOffset(offset); sInvalidateChildInParentFastMethod.invoke(mHostView, left, top, dirty); } catch (IllegalAccessException e) { e.printStackTrace(); } catch (InvocationTargetException e) { e.printStackTrace(); } } return null; } @SuppressWarnings("deprecation") @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; int[] offset = new int[2]; getOffset(offset); dirty.offset(offset[0], offset[1]); return super.invalidateChildInParent(location, dirty); // return ((ViewGroup) mHostView).invalidateChildInParent(location, dirty); } else { invalidate(dirty); } } return null; } static class TouchInterceptor extends View { TouchInterceptor(Context context) { super(context); } } } }