From b9c76f3224611396746261a25ecf44bac41c113d Mon Sep 17 00:00:00 2001
From: Michael Jurka <mikejurka@google.com>
Date: Wed, 9 Nov 2011 20:24:03 -0800
Subject: [PATCH] Fix occasional Home/All Apps slowdowns

Bug # 5581817

Change-Id: I0ee75ebe073325f89d89669b562ffc4db28f3004
---
 src/com/android/launcher2/PagedView.java | 41 ++++++++++++++++--------
 src/com/android/launcher2/Workspace.java | 22 +++++++++++--
 2 files changed, 47 insertions(+), 16 deletions(-)

diff --git a/src/com/android/launcher2/PagedView.java b/src/com/android/launcher2/PagedView.java
index 7be19bf23e..1c040babfb 100644
--- a/src/com/android/launcher2/PagedView.java
+++ b/src/com/android/launcher2/PagedView.java
@@ -123,6 +123,7 @@ public abstract class PagedView extends ViewGroup {
     protected boolean mCenterPagesVertically;
     protected boolean mAllowOverScroll = true;
     protected int mUnboundedScrollX;
+    protected int[] mTempVisiblePagesRange = new int[2];
 
     // parameter that adjusts the layout to be optimized for pages with that scale factor
     protected float mLayoutScale = 1.0f;
@@ -671,20 +672,7 @@ public abstract class PagedView extends ViewGroup {
         updateScrollingIndicator();
     }
 
-    @Override
-    protected void dispatchDraw(Canvas canvas) {
-        int halfScreenSize = getMeasuredWidth() / 2;
-        int screenCenter = mScrollX + halfScreenSize;
-
-        if (screenCenter != mLastScreenCenter) {
-            screenScrolled(screenCenter);
-            updateAdjacentPagesAlpha();
-            mLastScreenCenter = screenCenter;
-        }
-
-        // Find out which screens are visible; as an optimization we only call draw on them
-        // As an optimization, this code assumes that all pages have the same width as the 0th
-        // page.
+    protected void getVisiblePages(int[] range) {
         final int pageCount = getChildCount();
         if (pageCount > 0) {
             final int pageWidth = getScaledMeasuredWidth(getPageAt(0));
@@ -702,6 +690,31 @@ public abstract class PagedView extends ViewGroup {
                 x += getScaledMeasuredWidth(getPageAt(rightScreen)) + mPageSpacing;
             }
             rightScreen = Math.min(getChildCount() - 1, rightScreen);
+            range[0] = leftScreen;
+            range[1] = rightScreen;
+        } else {
+            range[0] = -1;
+            range[1] = -1;
+        }
+    }
+
+    @Override
+    protected void dispatchDraw(Canvas canvas) {
+        int halfScreenSize = getMeasuredWidth() / 2;
+        int screenCenter = mScrollX + halfScreenSize;
+
+        if (screenCenter != mLastScreenCenter) {
+            screenScrolled(screenCenter);
+            updateAdjacentPagesAlpha();
+            mLastScreenCenter = screenCenter;
+        }
+
+        // Find out which screens are visible; as an optimization we only call draw on them
+        final int pageCount = getChildCount();
+        if (pageCount > 0) {
+            getVisiblePages(mTempVisiblePagesRange);
+            final int leftScreen = mTempVisiblePagesRange[0];
+            final int rightScreen = mTempVisiblePagesRange[1];
 
             final long drawingTime = getDrawingTime();
             // Clip to the bounds
diff --git a/src/com/android/launcher2/Workspace.java b/src/com/android/launcher2/Workspace.java
index 209bd6ad29..44d0d943f9 100644
--- a/src/com/android/launcher2/Workspace.java
+++ b/src/com/android/launcher2/Workspace.java
@@ -1255,6 +1255,19 @@ public class Workspace extends SmoothPagedView
 
     @Override
     protected void dispatchDraw(Canvas canvas) {
+        if (mChildrenLayersEnabled) {
+            getVisiblePages(mTempVisiblePagesRange);
+            final int leftScreen = mTempVisiblePagesRange[0];
+            final int rightScreen = mTempVisiblePagesRange[1];
+            if (leftScreen != -1 && rightScreen != -1) {
+                // calling setChildrenLayersEnabled on a view that's not visible/rendered
+                // causes slowdowns on some graphics cards, so we set it here to be sure
+                // it's only called when it's safe (ie when the view will be rendered)
+                for (int i = leftScreen; i <= rightScreen; i++) {
+                    ((ViewGroup)getPageAt(i)).setChildrenLayersEnabled(true);
+                }
+            }
+        }
         super.dispatchDraw(canvas);
 
         if (mInScrollArea && !LauncherApplication.isScreenLarge()) {
@@ -1359,8 +1372,13 @@ public class Workspace extends SmoothPagedView
 
         if (enableChildrenLayers != mChildrenLayersEnabled) {
             mChildrenLayersEnabled = enableChildrenLayers;
-            for (int i = 0; i < getPageCount(); i++) {
-                ((ViewGroup)getChildAt(i)).setChildrenLayersEnabled(enableChildrenLayers);
+            // calling setChildrenLayersEnabled on a view that's not visible/rendered
+            // causes slowdowns on some graphics cards, so we only disable it here and leave
+            // the enabling to dispatchDraw
+            if (!enableChildrenLayers) {
+                for (int i = 0; i < getPageCount(); i++) {
+                    ((ViewGroup)getChildAt(i)).setChildrenLayersEnabled(false);
+                }
             }
         }
     }