From eb701c636095791d6a6171836c0837a2dad7f02b Mon Sep 17 00:00:00 2001
From: Vadim Tryshev <vadimt@google.com>
Date: Mon, 14 May 2018 16:00:15 -0700
Subject: [PATCH] Scrolling on the most recent task upon Overview start

Fixes this problem:
1. Open a single task in Recents
2. Dismiss via Clear-all
3. Start a task
4. Press Home
5. Press square button
get Recents revealing Clear All button

Bug: 79117932
Test: Manual
Change-Id: I47bcc50cb72f1757025d2abac0196460e0bb3f36
---
 .../android/quickstep/views/RecentsView.java    | 13 +++----------
 src/com/android/launcher3/PagedView.java        | 17 ++++++++---------
 2 files changed, 11 insertions(+), 19 deletions(-)

diff --git a/quickstep/src/com/android/quickstep/views/RecentsView.java b/quickstep/src/com/android/quickstep/views/RecentsView.java
index a8e38a1ab0..ad85d9ed43 100644
--- a/quickstep/src/com/android/quickstep/views/RecentsView.java
+++ b/quickstep/src/com/android/quickstep/views/RecentsView.java
@@ -21,8 +21,8 @@ import static com.android.launcher3.anim.Interpolators.ACCEL;
 import static com.android.launcher3.anim.Interpolators.ACCEL_2;
 import static com.android.launcher3.anim.Interpolators.FAST_OUT_SLOW_IN;
 import static com.android.launcher3.anim.Interpolators.LINEAR;
-import static com.android.quickstep.TaskUtils.checkCurrentOrManagedUserId;
 import static com.android.launcher3.util.SystemUiController.UI_STATE_OVERVIEW;
+import static com.android.quickstep.TaskUtils.checkCurrentOrManagedUserId;
 
 import android.animation.Animator;
 import android.animation.AnimatorSet;
@@ -1038,14 +1038,7 @@ public abstract class RecentsView<T extends BaseActivity> extends PagedView impl
         }
         updateClearAllButtonAlpha();
 
-        if (!mShowEmptyMessage) return;
-
-        // The icon needs to be centered. Need to scoll to horizontal 0 because with Clear-All
-        // space on the right, it's not guaranteed that after deleting all tasks, the horizontal
-        // scroll position will be zero.
-        scrollTo(0, 0);
-
-        if (hasValidSize && mEmptyTextLayout == null) {
+        if (mShowEmptyMessage && hasValidSize && mEmptyTextLayout == null) {
             int availableWidth = mLastMeasureSize.x - mEmptyMessagePadding - mEmptyMessagePadding;
             mEmptyTextLayout = StaticLayout.Builder.obtain(mEmptyMessage, 0, mEmptyMessage.length(),
                     mEmptyMessagePaint, availableWidth)
@@ -1072,7 +1065,7 @@ public abstract class RecentsView<T extends BaseActivity> extends PagedView impl
             mTempRect.set(mInsets.left + getPaddingLeft(), mInsets.top + getPaddingTop(),
                     mInsets.right + getPaddingRight(), mInsets.bottom + getPaddingBottom());
             canvas.save();
-            canvas.translate((mTempRect.left - mTempRect.right) / 2,
+            canvas.translate(getScrollX() + (mTempRect.left - mTempRect.right) / 2,
                     (mTempRect.top - mTempRect.bottom) / 2);
             mEmptyIcon.draw(canvas);
             canvas.translate(mEmptyMessagePadding,
diff --git a/src/com/android/launcher3/PagedView.java b/src/com/android/launcher3/PagedView.java
index 87ee076f36..990132df58 100644
--- a/src/com/android/launcher3/PagedView.java
+++ b/src/com/android/launcher3/PagedView.java
@@ -92,7 +92,6 @@ public abstract class PagedView<T extends View & PageIndicator> extends ViewGrou
 
     @ViewDebug.ExportedProperty(category = "launcher")
     protected int mCurrentPage;
-    private int mChildCountOnLastLayout;
 
     @ViewDebug.ExportedProperty(category = "launcher")
     protected int mNextPage = INVALID_PAGE;
@@ -543,18 +542,19 @@ public abstract class PagedView<T extends View & PageIndicator> extends ViewGrou
     @Override
     protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
         mIsLayoutValid = true;
-        if (getChildCount() == 0) {
+        final int childCount = getChildCount();
+        boolean pageScrollChanged = false;
+        if (mPageScrolls == null || childCount != mPageScrolls.length) {
+            mPageScrolls = new int[childCount];
+            pageScrollChanged = true;
+        }
+
+        if (childCount == 0) {
             return;
         }
 
         if (DEBUG) Log.d(TAG, "PagedView.onLayout()");
-        final int childCount = getChildCount();
 
-        boolean pageScrollChanged = false;
-        if (mPageScrolls == null || childCount != mChildCountOnLastLayout) {
-            mPageScrolls = new int[childCount];
-            pageScrollChanged = true;
-        }
         if (getPageScrolls(mPageScrolls, true, SIMPLE_SCROLL_LOGIC)) {
             pageScrollChanged = true;
         }
@@ -591,7 +591,6 @@ public abstract class PagedView<T extends View & PageIndicator> extends ViewGrou
         if (mScroller.isFinished() && pageScrollChanged) {
             setCurrentPage(getNextPage());
         }
-        mChildCountOnLastLayout = childCount;
     }
 
     /**