[Predictive Back] Swipe back within taskbar all apps should only scale down content view, rather than whole all apps sheet

Bug: 335467443
Test: manual - took a video
Flag: aconfig com.android.launcher3.enable_predictive_back_gesture TRUNKFOOD
Change-Id: I45980329f70ac1a8a8fc0e84be007f3385e40f58

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

@@ -287,6 +287,13 @@ public abstract class AbstractSlideInView<T extends Context & ActivityContext>
         return true;
     }
 
+    @Override
+    @RequiresApi(Build.VERSION_CODES.UPSIDE_DOWN_CAKE)
+    public void onBackStarted(BackEvent backEvent) {
+        super.onBackStarted(backEvent);
+        mViewToAnimateInSwipeToDismiss = shouldAnimateContentViewInBackSwipe() ? mContent : this;
+    }
+
     @Override
     @RequiresApi(Build.VERSION_CODES.UPSIDE_DOWN_CAKE)
     public void onBackProgressed(BackEvent backEvent) {
@@ -295,6 +302,18 @@ public abstract class AbstractSlideInView<T extends Context & ActivityContext>
         mSwipeToDismissProgress.updateValue(deceleratedProgress);
     }
 
+    /**
+     * During predictive back swipe, the default behavior is to scale {@link AbstractSlideInView}
+     * during back swipe. This method allow subclass to scale {@link #mContent}, typically to exit
+     * search mode.
+     *
+     * <p>Note that this method can be expensive, and should only be called from
+     * {@link #onBackStarted(BackEvent)}, not from {@link #onBackProgressed(BackEvent)}.
+     */
+    protected boolean shouldAnimateContentViewInBackSwipe() {
+        return false;
+    }
+
     protected void onUserSwipeToDismissProgressChanged() {
         float progress = mSwipeToDismissProgress.value;
         mIsDismissInProgress = progress > 0f;

src/com/android/launcher3/widget/picker/WidgetsFullSheet.java

@@ -46,7 +46,6 @@ import android.view.animation.Interpolator;
 import android.widget.Button;
 import android.widget.LinearLayout;
 import android.widget.TextView;
-import android.window.BackEvent;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
@@ -903,22 +902,23 @@ public class WidgetsFullSheet extends BaseWidgetSheet
         return isFoldUnFold || useDifferentLayoutOnOrientationChange;
     }
 
+    /**
+     * In widget search mode, we should scale down content inside widget bottom sheet, rather
+     * than the whole bottom sheet, to indicate we will navigate back within the widget
+     * bottom sheet.
+     */
     @Override
-    public void onBackStarted(BackEvent backEvent) {
-        super.onBackStarted(backEvent);
-        // In widget search mode, we should scale down content inside widget bottom sheet, rather
-        // than the whole bottom sheet, to indicate we will navigate back within the widget
-        // bottom sheet.
-        if (mIsInSearchMode) {
-            mViewToAnimateInSwipeToDismiss = mContent;
-        }
+    public boolean shouldAnimateContentViewInBackSwipe() {
+        return mIsInSearchMode;
     }
 
     @Override
     public void onBackInvoked() {
         if (mIsInSearchMode) {
             mSearchBar.reset();
-            animateSwipeToDismissProgressToStart();
+            // Posting animation to next frame will let widget sheet finish updating UI first, and
+            // make animation smoother.
+            post(this::animateSwipeToDismissProgressToStart);
         } else {
             super.onBackInvoked();
         }