From 8081f0940f727faf35394b71cdf602caf55b0f21 Mon Sep 17 00:00:00 2001
From: Selim Cinek <cinek@google.com>
Date: Fri, 1 May 2020 21:11:13 -0700
Subject: [PATCH] Fixed an issue where GONE Views would show during transitions

Because we're clipping children and MotionLayout doesn't hide them
when collapsed, views could flicker onto the screen

Test: add media notification, swipe down to shade and back, observe no flickering
Bug: 154137987
Change-Id: Ida591706e779215e13c6d3047be7e3b5318b4d19
---
 packages/SystemUI/res/xml/media_scene.xml     |  2 +
 .../systemui/media/GoneChildrenHideHelper.kt  | 52 +++++++++++++++++++
 .../systemui/media/MediaControlPanel.java     | 32 +++++++-----
 3 files changed, 73 insertions(+), 13 deletions(-)
 create mode 100644 packages/SystemUI/src/com/android/systemui/media/GoneChildrenHideHelper.kt

diff --git a/packages/SystemUI/res/xml/media_scene.xml b/packages/SystemUI/res/xml/media_scene.xml
index 6f99d9a675f12..f61b2b096d3c8 100644
--- a/packages/SystemUI/res/xml/media_scene.xml
+++ b/packages/SystemUI/res/xml/media_scene.xml
@@ -356,6 +356,7 @@
             android:id="@+id/media_progress_bar"
             android:layout_width="0dp"
             android:layout_height="wrap_content"
+            android:alpha="0.0"
             app:layout_constraintTop_toBottomOf="@id/album_art"
             app:layout_constraintStart_toStartOf="parent"
             app:layout_constraintEnd_toEndOf="@id/view_width"
@@ -364,6 +365,7 @@
 
         <Constraint
             android:id="@+id/notification_media_progress_time"
+            android:alpha="0.0"
             android:layout_width="0dp"
             android:layout_height="wrap_content"
             android:layout_marginTop="35dp"
diff --git a/packages/SystemUI/src/com/android/systemui/media/GoneChildrenHideHelper.kt b/packages/SystemUI/src/com/android/systemui/media/GoneChildrenHideHelper.kt
new file mode 100644
index 0000000000000..2fe0d9f4711fc
--- /dev/null
+++ b/packages/SystemUI/src/com/android/systemui/media/GoneChildrenHideHelper.kt
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2020 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.systemui.media
+
+import android.graphics.Rect
+import android.view.View
+import android.view.ViewGroup
+
+private val EMPTY_RECT = Rect(0,0,0,0)
+
+private val LAYOUT_CHANGE_LISTENER = object : View.OnLayoutChangeListener {
+
+    override fun onLayoutChange(v: View?, left: Int, top: Int, right: Int, bottom: Int,
+                                oldLeft: Int, oldTop: Int, oldRight: Int, oldBottom: Int) {
+        v?.let {
+            if (v.visibility == View.GONE) {
+                v.clipBounds = EMPTY_RECT
+            } else {
+                v.clipBounds = null
+            }
+        }
+    }
+}
+/**
+ * A helper class that clips all GONE children. Useful for transitions in motionlayout which
+ * don't clip its children.
+ */
+class GoneChildrenHideHelper private constructor() {
+    companion object {
+        @JvmStatic
+        fun clipGoneChildrenOnLayout(layout: ViewGroup) {
+            val childCount = layout.childCount
+            for (i in 0 until childCount) {
+                val child = layout.getChildAt(i)
+                child.addOnLayoutChangeListener(LAYOUT_CHANGE_LISTENER)
+            }
+        }
+    }
+}
\ No newline at end of file
diff --git a/packages/SystemUI/src/com/android/systemui/media/MediaControlPanel.java b/packages/SystemUI/src/com/android/systemui/media/MediaControlPanel.java
index 2a9ba8395ee75..72282714365b7 100644
--- a/packages/SystemUI/src/com/android/systemui/media/MediaControlPanel.java
+++ b/packages/SystemUI/src/com/android/systemui/media/MediaControlPanel.java
@@ -36,7 +36,6 @@ import android.media.session.MediaController.PlaybackInfo;
 import android.media.session.MediaSession;
 import android.media.session.PlaybackState;
 import android.service.media.MediaBrowserService;
-import android.util.DisplayMetrics;
 import android.util.Log;
 import android.view.LayoutInflater;
 import android.view.View;
@@ -181,6 +180,7 @@ public class MediaControlPanel {
         mMediaNotifView = (MotionLayout) inflater.inflate(R.layout.qs_media_panel, parent, false);
         mBackground = mMediaNotifView.findViewById(R.id.media_background);
         mLayoutAnimationHelper = new LayoutAnimationHelper(mMediaNotifView);
+        GoneChildrenHideHelper.clipGoneChildrenOnLayout(mMediaNotifView);
         mKeyFrames = mMediaNotifView.getDefinedTransitions().get(0).getKeyFrameList();
         mLocalMediaManager = routeManager;
         mForegroundExecutor = foregroundExecutor;
@@ -255,6 +255,9 @@ public class MediaControlPanel {
 
         mController = new MediaController(mContext, mToken);
 
+        ConstraintSet expandedSet = mMediaNotifView.getConstraintSet(R.id.expanded);
+        ConstraintSet collapsedSet = mMediaNotifView.getConstraintSet(R.id.collapsed);
+
         // Try to find a browser service component for this app
         // TODO also check for a media button receiver intended for restarting (b/154127084)
         // Only check if we haven't tried yet or the session token changed
@@ -323,6 +326,8 @@ public class MediaControlPanel {
         if (mSeamless != null) {
             if (mLocalMediaManager != null) {
                 mSeamless.setVisibility(View.VISIBLE);
+                setVisibleAndAlpha(collapsedSet, R.id.media_seamless, true /*visible */);
+                setVisibleAndAlpha(expandedSet, R.id.media_seamless, true /*visible */);
                 updateDevice(mLocalMediaManager.getCurrentConnectedDevice());
                 mSeamless.setOnClickListener(v -> {
                     final Intent intent = new Intent()
@@ -344,9 +349,6 @@ public class MediaControlPanel {
             Log.d(TAG, "PlaybackInfo was null. Defaulting to local playback.");
             mIsRemotePlayback = false;
         }
-
-        ConstraintSet expandedSet = mMediaNotifView.getConstraintSet(R.id.expanded);
-        ConstraintSet collapsedSet = mMediaNotifView.getConstraintSet(R.id.collapsed);
         List<Integer> actionsWhenCollapsed = data.getActionsToShowInCompact();
         // Media controls
         int i = 0;
@@ -376,15 +378,14 @@ public class MediaControlPanel {
             });
             boolean visibleInCompat = actionsWhenCollapsed.contains(i);
             updateKeyFrameVisibility(actionId, visibleInCompat);
-            collapsedSet.setVisibility(actionId,
-                    visibleInCompat ? ConstraintSet.VISIBLE : ConstraintSet.GONE);
-            expandedSet.setVisibility(actionId, ConstraintSet.VISIBLE);
+            setVisibleAndAlpha(collapsedSet, actionId, visibleInCompat);
+            setVisibleAndAlpha(expandedSet, actionId, true /*visible */);
         }
 
         // Hide any unused buttons
         for (; i < ACTION_IDS.length; i++) {
-            expandedSet.setVisibility(ACTION_IDS[i], ConstraintSet.GONE);
-            collapsedSet.setVisibility(ACTION_IDS[i], ConstraintSet.GONE);
+            setVisibleAndAlpha(expandedSet, ACTION_IDS[i], false /*visible */);
+            setVisibleAndAlpha(collapsedSet, ACTION_IDS[i], false /*visible */);
         }
 
         // Seek Bar
@@ -604,8 +605,8 @@ public class MediaControlPanel {
         ConstraintSet expandedSet = mMediaNotifView.getConstraintSet(R.id.expanded);
         ConstraintSet collapsedSet = mMediaNotifView.getConstraintSet(R.id.collapsed);
         for (int i = 1; i < ACTION_IDS.length; i++) {
-            expandedSet.setVisibility(ACTION_IDS[i], ConstraintSet.GONE);
-            collapsedSet.setVisibility(ACTION_IDS[i], ConstraintSet.GONE);
+            setVisibleAndAlpha(expandedSet, ACTION_IDS[i], false /*visible */);
+            setVisibleAndAlpha(collapsedSet, ACTION_IDS[i], false /*visible */);
         }
 
         // Add a restart button
@@ -631,8 +632,8 @@ public class MediaControlPanel {
         });
         btn.setImageDrawable(mContext.getResources().getDrawable(R.drawable.lb_ic_play));
         btn.setImageTintList(ColorStateList.valueOf(mForegroundColor));
-        expandedSet.setVisibility(ACTION_IDS[0], ConstraintSet.VISIBLE);
-        collapsedSet.setVisibility(ACTION_IDS[0], ConstraintSet.VISIBLE);
+        setVisibleAndAlpha(expandedSet, ACTION_IDS[0], true /*visible */);
+        setVisibleAndAlpha(collapsedSet, ACTION_IDS[0], true /*visible */);
 
         mSeekBarViewModel.clearController();
         // TODO: fix guts
@@ -647,6 +648,11 @@ public class MediaControlPanel {
         });
     }
 
+    private void setVisibleAndAlpha(ConstraintSet set, int actionId, boolean visible) {
+        set.setVisibility(actionId, visible? ConstraintSet.VISIBLE : ConstraintSet.GONE);
+        set.setAlpha(actionId, visible ? 1.0f : 0.0f);
+    }
+
     private void makeActive() {
         Assert.isMainThread();
         if (!mIsRegistered) {