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Commit 96eb6ca7 authored by George Mount's avatar George Mount
Browse files

Use transparent instead of null background during Activity Transitions 

Bug 32952142

When doing activity transitions, a window is temporarily translucent
during the transition. When a view hierarchy completely covers the
window, the background is never seen and applications can use a
null background to avoid overdraw. However, during the activity
transition, the underlying activity is seen during the transition.
With a null background, the buffer isn't properly cleared and
the uncleared buffer will show strange effects.

This CL forces a transparent background temporarily during the
activity transition to avoid this problem.

Test: manual testing using test application

Change-Id: I63f24dba3c2f810944bcbf07faf309f9f1c5889a
parent 7f9d210e

core/java/android/app/EnterTransitionCoordinator.java

+13 −2
Original line number Diff line number Diff line
@@ -19,6 +19,8 @@ import android.animation.Animator; 
import android.animation.AnimatorListenerAdapter;

import android.animation.ObjectAnimator;

import android.app.SharedElementCallback.OnSharedElementsReadyListener;

import android.graphics.Color;

import android.graphics.drawable.ColorDrawable;

import android.graphics.drawable.Drawable;

import android.os.Bundle;

import android.os.ResultReceiver;
@@ -61,6 +63,7 @@ class EnterTransitionCoordinator extends ActivityTransitionCoordinator { 
    private Transition mEnterViewsTransition;

    private OneShotPreDrawListener mViewsReadyListener;

    private final boolean mIsCrossTask;

    private Drawable mReplacedBackground;



    public EnterTransitionCoordinator(Activity activity, ResultReceiver resultReceiver,

            ArrayList<String> sharedElementNames, boolean isReturning, boolean isCrossTask) {
@@ -332,12 +335,15 @@ class EnterTransitionCoordinator extends ActivityTransitionCoordinator { 
        if (!mIsReturning) {

            mWasOpaque = mActivity.convertToTranslucent(null, null);

            Drawable background = decorView.getBackground();

            if (background != null) {

            if (background == null) {

                background = new ColorDrawable(Color.TRANSPARENT);

                mReplacedBackground = background;

            } else {

                getWindow().setBackgroundDrawable(null);

                background = background.mutate();

                background.setAlpha(0);

                getWindow().setBackgroundDrawable(background);

            }

            getWindow().setBackgroundDrawable(background);

        } else {

            mActivity = null; // all done with it now.

        }
@@ -553,6 +559,11 @@ class EnterTransitionCoordinator extends ActivityTransitionCoordinator { 
        final ViewGroup decorView = getDecor();

        if (decorView != null) {

            decorView.sendAccessibilityEvent(AccessibilityEvent.TYPE_WINDOW_CONTENT_CHANGED);



            Window window = getWindow();

            if (window != null && mReplacedBackground == decorView.getBackground()) {

                window.setBackgroundDrawable(null);

            }

        }

    }

core/java/android/app/ExitTransitionCoordinator.java

+1 −1
Original line number Diff line number Diff line
@@ -236,7 +236,7 @@ class ExitTransitionCoordinator extends ActivityTransitionCoordinator { 
            delayCancel();

            moveSharedElementsToOverlay();

            if (decorView != null && decorView.getBackground() == null) {

                getWindow().setBackgroundDrawable(new ColorDrawable(Color.BLACK));

                getWindow().setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));

            }

            final boolean targetsM = decorView == null || decorView.getContext()

                    .getApplicationInfo().targetSdkVersion >= VERSION_CODES.M;