content: /*
   * Copyright (C) 2018 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 com.android.server.wm;
  
  import static android.view.SurfaceControl.HIDDEN;
  
  import android.graphics.Point;
  import android.graphics.Rect;
  import android.os.Binder;
  import android.os.Process;
  import android.view.InputChannel;
  import android.view.InputEventReceiver;
  import android.view.InputWindowHandle;
  import android.view.SurfaceControl;
  import android.view.WindowManager;
  
  import com.android.server.UiThread;
  
  import java.util.function.Supplier;
  
  /**
   * Manages a set of {@link SurfaceControl}s to draw a black letterbox between an
   * outer rect and an inner rect.
   */
  public class Letterbox {
  
      private static final Rect EMPTY_RECT = new Rect();
      private static final Point ZERO_POINT = new Point(0, 0);
  
      private final Supplier<SurfaceControl.Builder> mFactory;
      private final Rect mOuter = new Rect();
      private final Rect mInner = new Rect();
      private final LetterboxSurface mTop = new LetterboxSurface("top");
      private final LetterboxSurface mLeft = new LetterboxSurface("left");
      private final LetterboxSurface mBottom = new LetterboxSurface("bottom");
      private final LetterboxSurface mRight = new LetterboxSurface("right");
      private final LetterboxSurface[] mSurfaces = { mLeft, mTop, mRight, mBottom };
  
      /**
       * Constructs a Letterbox.
       *
       * @param surfaceControlFactory a factory for creating the managed {@link SurfaceControl}s
       */
      public Letterbox(Supplier<SurfaceControl.Builder> surfaceControlFactory) {
          mFactory = surfaceControlFactory;
      }
  
      /**
       * Lays out the letterbox, such that the area between the outer and inner
       * frames will be covered by black color surfaces.
       *
       * The caller must use {@link #applySurfaceChanges} to apply the new layout to the surface.
       * @param outer the outer frame of the letterbox (this frame will be black, except the area
       *              that intersects with the {code inner} frame), in global coordinates
       * @param inner the inner frame of the letterbox (this frame will be clear), in global
       *              coordinates
       * @param surfaceOrigin the origin of the surface factory in global coordinates
       */
      public void layout(Rect outer, Rect inner, Point surfaceOrigin) {
          mOuter.set(outer);
          mInner.set(inner);
  
          mTop.layout(outer.left, outer.top, inner.right, inner.top, surfaceOrigin);
          mLeft.layout(outer.left, inner.top, inner.left, outer.bottom, surfaceOrigin);
          mBottom.layout(inner.left, inner.bottom, outer.right, outer.bottom, surfaceOrigin);
          mRight.layout(inner.right, outer.top, outer.right, inner.bottom, surfaceOrigin);
      }
  
  
      /**
       * Gets the insets between the outer and inner rects.
       */
      public Rect getInsets() {
          return new Rect(
                  mLeft.getWidth(),
                  mTop.getHeight(),
                  mRight.getWidth(),
                  mBottom.getHeight());
      }
  
      /** @return The frame that used to place the content. */
      Rect getInnerFrame() {
          return mInner;
      }
  
      /**
       * Returns true if any part of the letterbox overlaps with the given {@code rect}.
       */
      public boolean isOverlappingWith(Rect rect) {
          for (LetterboxSurface surface : mSurfaces) {
              if (surface.isOverlappingWith(rect)) {
                  return true;
              }
          }
          return false;
      }
  
      /**
       * Hides the letterbox.
       *
       * The caller must use {@link #applySurfaceChanges} to apply the new layout to the surface.
       */
      public void hide() {
          layout(EMPTY_RECT, EMPTY_RECT, ZERO_POINT);
      }
  
      /**
       * Destroys the managed {@link SurfaceControl}s.
       */
      public void destroy() {
          mOuter.setEmpty();
          mInner.setEmpty();
  
          for (LetterboxSurface surface : mSurfaces) {
              surface.remove();
          }
      }
  
      /** Returns whether a call to {@link #applySurfaceChanges} would change the surface. */
      public boolean needsApplySurfaceChanges() {
          for (LetterboxSurface surface : mSurfaces) {
              if (surface.needsApplySurfaceChanges()) {
                  return true;
              }
          }
          return false;
      }
  
      public void applySurfaceChanges(SurfaceControl.Transaction t) {
          for (LetterboxSurface surface : mSurfaces) {
              surface.applySurfaceChanges(t);
          }
      }
  
      /** Enables touches to slide into other neighboring surfaces. */
      void attachInput(WindowState win) {
          for (LetterboxSurface surface : mSurfaces) {
              surface.attachInput(win);
          }
      }
  
      void onMovedToDisplay(int displayId) {
          for (LetterboxSurface surface : mSurfaces) {
              if (surface.mInputInterceptor != null) {
                  surface.mInputInterceptor.mWindowHandle.displayId = displayId;
              }
          }
      }
  
      private static class InputInterceptor {
          final InputChannel mServerChannel;
          final InputChannel mClientChannel;
          final InputWindowHandle mWindowHandle;
          final InputEventReceiver mInputEventReceiver;
          final WindowManagerService mWmService;
          final Binder mToken = new Binder();
  
          InputInterceptor(String namePrefix, WindowState win) {
              mWmService = win.mWmService;
              final String name = namePrefix + (win.mAppToken != null ? win.mAppToken : win);
              final InputChannel[] channels = InputChannel.openInputChannelPair(name);
              mServerChannel = channels[0];
              mClientChannel = channels[1];
              mInputEventReceiver = new SimpleInputReceiver(mClientChannel);
  
              mWmService.mInputManager.registerInputChannel(mServerChannel, mToken);
  
              mWindowHandle = new InputWindowHandle(null /* inputApplicationHandle */,
                      null /* clientWindow */, win.getDisplayId());
              mWindowHandle.name = name;
              mWindowHandle.token = mToken;
              mWindowHandle.layoutParamsFlags = WindowManager.LayoutParams.FLAG_NOT_FOCUSABLE
                      | WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL
                      | WindowManager.LayoutParams.FLAG_SPLIT_TOUCH
                      | WindowManager.LayoutParams.FLAG_SLIPPERY;
              mWindowHandle.layoutParamsType = WindowManager.LayoutParams.TYPE_INPUT_CONSUMER;
              mWindowHandle.dispatchingTimeoutNanos =
                      WindowManagerService.DEFAULT_INPUT_DISPATCHING_TIMEOUT_NANOS;
              mWindowHandle.visible = true;
              mWindowHandle.ownerPid = Process.myPid();
              mWindowHandle.ownerUid = Process.myUid();
              mWindowHandle.scaleFactor = 1.0f;
          }
  
          void updateTouchableRegion(Rect frame) {
              if (frame.isEmpty()) {
                  // Use null token to indicate the surface doesn't need to receive input event (see
                  // the usage of Layer.hasInput in SurfaceFlinger), so InputDispatcher won't keep the
                  // unnecessary records.
                  mWindowHandle.token = null;
                  return;
              }
              mWindowHandle.token = mToken;
              mWindowHandle.touchableRegion.set(frame);
              mWindowHandle.touchableRegion.translate(-frame.left, -frame.top);
          }
  
          void dispose() {
              mWmService.mInputManager.unregisterInputChannel(mServerChannel);
              mInputEventReceiver.dispose();
              mServerChannel.dispose();
              mClientChannel.dispose();
          }
  
          private static class SimpleInputReceiver extends InputEventReceiver {
              SimpleInputReceiver(InputChannel inputChannel) {
                  super(inputChannel, UiThread.getHandler().getLooper());
              }
          }
      }
  
      private class LetterboxSurface {
  
          private final String mType;
          private SurfaceControl mSurface;
  
          private final Rect mSurfaceFrameRelative = new Rect();
          private final Rect mLayoutFrameGlobal = new Rect();
          private final Rect mLayoutFrameRelative = new Rect();
  
          private InputInterceptor mInputInterceptor;
  
          public LetterboxSurface(String type) {
              mType = type;
          }
  
          public void layout(int left, int top, int right, int bottom, Point surfaceOrigin) {
              mLayoutFrameGlobal.set(left, top, right, bottom);
              mLayoutFrameRelative.set(mLayoutFrameGlobal);
              mLayoutFrameRelative.offset(-surfaceOrigin.x, -surfaceOrigin.y);
          }
  
          private void createSurface() {
              mSurface = mFactory.get().setName("Letterbox - " + mType)
                      .setFlags(HIDDEN).setColorLayer().build();
              mSurface.setLayer(-1);
              mSurface.setColor(new float[]{0, 0, 0});
              mSurface.setColorSpaceAgnostic(true);
          }
  
          void attachInput(WindowState win) {
              if (mInputInterceptor != null) {
                  mInputInterceptor.dispose();
              }
              mInputInterceptor = new InputInterceptor("Letterbox_" + mType + "_", win);
          }
  
          public void remove() {
              if (mSurface != null) {
                  new SurfaceControl.Transaction().remove(mSurface).apply();
                  mSurface = null;
              }
              if (mInputInterceptor != null) {
                  mInputInterceptor.dispose();
                  mInputInterceptor = null;
              }
          }
  
          public int getWidth() {
              return Math.max(0, mLayoutFrameGlobal.width());
          }
  
          public int getHeight() {
              return Math.max(0, mLayoutFrameGlobal.height());
          }
  
          /**
           * Returns if the given {@code rect} overlaps with this letterbox piece.
           * @param rect the area to check for overlap in global coordinates
           */
          public boolean isOverlappingWith(Rect rect) {
              if (mLayoutFrameGlobal.isEmpty()) {
                  return false;
              }
              return Rect.intersects(rect, mLayoutFrameGlobal);
          }
  
          public void applySurfaceChanges(SurfaceControl.Transaction t) {
              if (mSurfaceFrameRelative.equals(mLayoutFrameRelative)) {
                  // Nothing changed.
                  return;
              }
              mSurfaceFrameRelative.set(mLayoutFrameRelative);
              if (!mSurfaceFrameRelative.isEmpty()) {
                  if (mSurface == null) {
                      createSurface();
                  }
                  t.setPosition(mSurface, mSurfaceFrameRelative.left, mSurfaceFrameRelative.top);
                  t.setWindowCrop(mSurface, mSurfaceFrameRelative.width(),
                          mSurfaceFrameRelative.height());
                  t.show(mSurface);
              } else if (mSurface != null) {
                  t.hide(mSurface);
              }
              if (mSurface != null && mInputInterceptor != null) {
                  mInputInterceptor.updateTouchableRegion(mSurfaceFrameRelative);
                  t.setInputWindowInfo(mSurface, mInputInterceptor.mWindowHandle);
              }
          }
  
          public boolean needsApplySurfaceChanges() {
              return !mSurfaceFrameRelative.equals(mLayoutFrameRelative);
          }
      }
  }
  