Act on scrim visibility

The scrim visibility drives whether the launcher window is opaque or
not. We should track it and apply the flag instead of trying to catch it
through other Launcher life cycles.

Fixes: 195365607
Bug: 196403152
Test: tap on home button while launching app from overview
Change-Id: I2a00b86b602b5dd12c901433b92adcf0170be15e
(cherry picked from commit e4a9469156)

quickstep/src/com/android/launcher3/statehandlers/DepthController.java

@@ -108,6 +108,13 @@ public class DepthController implements StateHandler<LauncherState>,
         }
     };
 
+    private final Runnable mOpaquenessListener = new Runnable() {
+        @Override
+        public void run() {
+            dispatchTransactionSurface(mDepth);
+        }
+    };
+
     private final Launcher mLauncher;
     /**
      * Blur radius when completely zoomed out, in pixels.
@@ -150,23 +157,28 @@ public class DepthController implements StateHandler<LauncherState>,
                     if (windowToken != null) {
                         mWallpaperManager.setWallpaperZoomOut(windowToken, mDepth);
                     }
-                    CrossWindowBlurListeners.getInstance().addListener(mLauncher.getMainExecutor(),
-                            mCrossWindowBlurListener);
+                    onAttached();
                 }
 
                 @Override
                 public void onViewDetachedFromWindow(View view) {
                     CrossWindowBlurListeners.getInstance().removeListener(mCrossWindowBlurListener);
+                    mLauncher.getScrimView().removeOpaquenessListener(mOpaquenessListener);
                 }
             };
             mLauncher.getRootView().addOnAttachStateChangeListener(mOnAttachListener);
             if (mLauncher.getRootView().isAttachedToWindow()) {
-                CrossWindowBlurListeners.getInstance().addListener(mLauncher.getMainExecutor(),
-                        mCrossWindowBlurListener);
+                onAttached();
             }
         }
     }
 
+    private void onAttached() {
+        CrossWindowBlurListeners.getInstance().addListener(mLauncher.getMainExecutor(),
+                mCrossWindowBlurListener);
+        mLauncher.getScrimView().addOpaquenessListener(mOpaquenessListener);
+    }
+
     /**
      * Sets if the underlying activity is started or not
      */

src/com/android/launcher3/views/ScrimView.java

@@ -25,23 +25,27 @@ import android.graphics.drawable.ColorDrawable;
 import android.util.AttributeSet;
 import android.view.View;
 
+import androidx.annotation.NonNull;
 import androidx.core.graphics.ColorUtils;
 
 import com.android.launcher3.BaseActivity;
 import com.android.launcher3.Insettable;
 import com.android.launcher3.util.SystemUiController;
 
+import java.util.ArrayList;
+
 /**
  * Simple scrim which draws a flat color
  */
 public class ScrimView extends View implements Insettable {
     private static final float STATUS_BAR_COLOR_FORCE_UPDATE_THRESHOLD = 0.9f;
 
+    private final ArrayList<Runnable> mOpaquenessListeners = new ArrayList<>(1);
     private SystemUiController mSystemUiController;
-
     private ScrimDrawingController mDrawingController;
     private int mBackgroundColor;
     private boolean mIsVisible = true;
+    private boolean mLastDispatchedOpaqueness;
 
     public ScrimView(Context context, AttributeSet attrs) {
         super(context, attrs);
@@ -60,6 +64,7 @@ public class ScrimView extends View implements Insettable {
     @Override
     protected boolean onSetAlpha(int alpha) {
         updateSysUiColors();
+        dispatchVisibilityListenersIfNeeded();
         return super.onSetAlpha(alpha);
     }
 
@@ -67,6 +72,7 @@ public class ScrimView extends View implements Insettable {
     public void setBackgroundColor(int color) {
         mBackgroundColor = color;
         updateSysUiColors();
+        dispatchVisibilityListenersIfNeeded();
         super.setBackgroundColor(color);
     }
 
@@ -74,6 +80,7 @@ public class ScrimView extends View implements Insettable {
     public void onVisibilityAggregated(boolean isVisible) {
         super.onVisibilityAggregated(isVisible);
         mIsVisible = isVisible;
+        dispatchVisibilityListenersIfNeeded();
     }
 
     public boolean isFullyOpaque() {
@@ -108,6 +115,17 @@ public class ScrimView extends View implements Insettable {
         }
     }
 
+    private void dispatchVisibilityListenersIfNeeded() {
+        boolean fullyOpaque = isFullyOpaque();
+        if (mLastDispatchedOpaqueness == fullyOpaque) {
+            return;
+        }
+        mLastDispatchedOpaqueness = fullyOpaque;
+        for (int i = 0; i < mOpaquenessListeners.size(); i++) {
+            mOpaquenessListeners.get(i).run();
+        }
+    }
+
     private SystemUiController getSystemUiController() {
         if (mSystemUiController == null) {
             mSystemUiController = BaseActivity.fromContext(getContext()).getSystemUiController();
@@ -135,6 +153,22 @@ public class ScrimView extends View implements Insettable {
         }
     }
 
+    /**
+     * Registers a listener to be notified of whether the scrim is occluding other UI elements.
+     * @see #isFullyOpaque()
+     */
+    public void addOpaquenessListener(@NonNull Runnable listener) {
+        mOpaquenessListeners.add(listener);
+    }
+
+    /**
+     * Removes previously registered listener.
+     * @see #addOpaquenessListener(Runnable)
+     */
+    public void removeOpaquenessListener(@NonNull Runnable listener) {
+        mOpaquenessListeners.remove(listener);
+    }
+
     /**
      * A Utility interface allowing for other surfaces to draw on ScrimView
      */