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Commit 93a5ab7f authored by Jeff DeCew's avatar Jeff DeCew Committed by Yining Liu
Browse files

ViewFlipper: add inhibit state to prevent updates, even when started 

This internal state avoids a potential race condition in how SystemUI previously paused the ViewFlipper, which could have happened if the `setPaused` call was made before the view received the internal `onAttachedToView` update that would trigger auto-start.  This race was never confirmed, but this refactor should prevent it.

Test: manual with tracing
Bug: 409112153
Flag: EXEMPT refactor
Change-Id: Ie1d76a5eec753dd25b91fb29f7bb5dfed8a7b40c
parent a59184b4

core/java/android/widget/ViewFlipper.java

+21 −2
Original line number Diff line number Diff line
@@ -49,6 +49,9 @@ public class ViewFlipper extends ViewAnimator { 
    private boolean mStarted = false;

    private boolean mVisible = false;



    // Inhibiting prevents the view from actually animating, even if started or auto-started.

    private boolean mInhibited = false;



    public ViewFlipper(Context context) {

        super(context);

    }
@@ -127,6 +130,22 @@ public class ViewFlipper extends ViewAnimator { 
        updateRunning();

    }



    /**

     * Inhibits the view from actually animating, even if it is started or auto-started.

     *

     * <p>NOTE: This state is NOT reflected in the {@link #isFlipping()} method. That method

     * returns true if the view is started or auto-started, even if inhibited. There is no way to

     * inspect the inhibited state, and it is only intended to be a override to prevent the

     * ViewFlipper from updating in cases where the system knows the view is not visible, but the

     * view does not.

     *

     * @hide

     */

    public void setInhibited(boolean inhibited) {

        mInhibited = inhibited;

        updateRunning();

    }



    @Override

    public CharSequence getAccessibilityClassName() {

        return ViewFlipper.class.getName();
@@ -150,7 +169,7 @@ public class ViewFlipper extends ViewAnimator { 
     */

    @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)

    private void updateRunning(boolean flipNow) {

        boolean running = mVisible && mStarted;

        boolean running = mVisible && mStarted && !mInhibited;

        if (running != mRunning) {

            if (running) {

                showOnly(mWhichChild, flipNow);
@@ -162,7 +181,7 @@ public class ViewFlipper extends ViewAnimator { 
        }

        if (LOGD) {

            Log.d(TAG, "updateRunning() mVisible=" + mVisible + ", mStarted=" + mStarted

                    + ", mRunning=" + mRunning);

                    + ", mInhibited=" + mInhibited + ", mRunning=" + mRunning);

        }

    }

packages/SystemUI/src/com/android/systemui/statusbar/notification/row/ui/viewbinder/NotificationViewFlipperBinder.kt

+1 −9
Original line number Diff line number Diff line
@@ -42,13 +42,5 @@ object NotificationViewFlipperBinder { 
    suspend fun bind(

        viewFlipper: ViewFlipper,

        viewModel: NotificationViewFlipperViewModel,

    ) = coroutineScope { launch { viewModel.isPaused.collect { viewFlipper.setPaused(it) } } }



    private fun ViewFlipper.setPaused(paused: Boolean) {

        if (paused) {

            stopFlipping()

        } else if (isAutoStart) {

            startFlipping()

        }

    }

    ) = coroutineScope { launch { viewModel.isPaused.collect { viewFlipper.setInhibited(it) } } }

}