From e00e8a78374cdcf01a25bd6327d2b94944b2bc3f Mon Sep 17 00:00:00 2001
From: Adam Powell <adamp@google.com>
Date: Sun, 11 Sep 2011 17:48:42 -0700
Subject: [PATCH] Pause WebKit drawing when WebView loses window focus.

This prevents animations and other live page content from consuming
too many resources while the user is interacting with a popup window.

Bug 5300522

Change-Id: I40fb6d16d56b540c431172052a1ae7fead7109be
---
 core/java/android/webkit/WebSettings.java |  8 ++++----
 core/java/android/webkit/WebView.java     | 15 +++++++++++++++
 core/java/android/webkit/WebViewCore.java |  4 ++++
 3 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/core/java/android/webkit/WebSettings.java b/core/java/android/webkit/WebSettings.java
index 77f67765c44fd..9c44138f03e5c 100644
--- a/core/java/android/webkit/WebSettings.java
+++ b/core/java/android/webkit/WebSettings.java
@@ -643,10 +643,10 @@ public class WebSettings {
 
     /**
      * Set whether the WebView will enable smooth transition while panning or
-     * zooming. If it is true, WebView will choose a solution to maximize the
-     * performance. e.g. the WebView's content may not be updated during the
-     * transition. If it is false, WebView will keep its fidelity. The default
-     * value is false.
+     * zooming or while the window hosting the WebView does not have focus.
+     * If it is true, WebView will choose a solution to maximize the performance.
+     * e.g. the WebView's content may not be updated during the transition.
+     * If it is false, WebView will keep its fidelity. The default value is false.
      */
     public void setEnableSmoothTransition(boolean enable) {
         mEnableSmoothTransition = enable;
diff --git a/core/java/android/webkit/WebView.java b/core/java/android/webkit/WebView.java
index 47abbc2e6d2d5..065beb1e58a1d 100644
--- a/core/java/android/webkit/WebView.java
+++ b/core/java/android/webkit/WebView.java
@@ -908,6 +908,9 @@ public class WebView extends AbsoluteLayout
     // used for serializing asynchronously handled touch events.
     private final TouchEventQueue mTouchEventQueue = new TouchEventQueue();
 
+    // Used to track whether picture updating was paused due to a window focus change.
+    private boolean mPictureUpdatePausedForFocusChange = false;
+
     // Used to notify listeners of a new picture.
     private PictureListener mPictureListener;
     /**
@@ -5570,8 +5573,20 @@ public class WebView extends AbsoluteLayout
         setActive(hasWindowFocus);
         if (hasWindowFocus) {
             JWebCoreJavaBridge.setActiveWebView(this);
+            if (mPictureUpdatePausedForFocusChange) {
+                WebViewCore.resumeUpdatePicture(mWebViewCore);
+                nativeSetIsScrolling(false);
+                mPictureUpdatePausedForFocusChange = false;
+            }
         } else {
             JWebCoreJavaBridge.removeActiveWebView(this);
+            final WebSettings settings = getSettings();
+            if (settings != null && settings.enableSmoothTransition() &&
+                    mWebViewCore != null && !WebViewCore.isUpdatePicturePaused(mWebViewCore)) {
+                WebViewCore.pauseUpdatePicture(mWebViewCore);
+                nativeSetIsScrolling(true);
+                mPictureUpdatePausedForFocusChange = true;
+            }
         }
         super.onWindowFocusChanged(hasWindowFocus);
     }
diff --git a/core/java/android/webkit/WebViewCore.java b/core/java/android/webkit/WebViewCore.java
index c61bd4868dce4..843a62405ef8a 100644
--- a/core/java/android/webkit/WebViewCore.java
+++ b/core/java/android/webkit/WebViewCore.java
@@ -2107,6 +2107,10 @@ public final class WebViewCore {
         }
     }
 
+    static boolean isUpdatePicturePaused(WebViewCore core) {
+        return core != null ? core.mDrawIsPaused : false;
+    }
+
     //////////////////////////////////////////////////////////////////////////
 
     private void restoreState(int index) {