[Android WebView] Reduce jank of HW fallback

While we still have the SW draw fallback when rendering into a HW
Canvas, store a bitmap per WebContents in an android.util.LruCache rather than creating a new
Bitmap per frame. This drastically improves the performance of this
rendering mode.

Review URL: https://chromiumcodereview.appspot.com/18423002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@209645 0039d316-1c4b-4281-b951-d872f2087c98

5 files changed, 27 insertions, 10 deletions

diff --git a/android_webview/browser/browser_view_renderer.h b/android_webview/browser/browser_view_renderer.h
index 5be33e9..ab0a59e 100644
--- a/android_webview/browser/browser_view_renderer.h
+++ b/android_webview/browser/browser_view_renderer.h
@@ -55,7 +55,8 @@ class BrowserViewRenderer {
         JNIEnv* env,
         int width,
         int height,
-        const base::android::JavaRef<jobject>& jcanvas) = 0;
+        const base::android::JavaRef<jobject>& jcanvas,
+        void* owner_key) = 0;
 
     // Draws the provided Java Bitmap into the provided Java Canvas.
     virtual void DrawBitmapIntoCanvas(
diff --git a/android_webview/browser/in_process_view_renderer.cc b/android_webview/browser/in_process_view_renderer.cc
index 633dc51..cc7115c 100644
--- a/android_webview/browser/in_process_view_renderer.cc
+++ b/android_webview/browser/in_process_view_renderer.cc
@@ -448,7 +448,7 @@ bool InProcessViewRenderer::DrawSWInternal(jobject java_canvas,
   if (pixels == NULL) {
     TRACE_EVENT0("android_webview", "RenderToAuxBitmap");
     ScopedJavaLocalRef<jobject> jbitmap(java_helper_->CreateBitmap(
-        env, clip.width(), clip.height(), jcanvas));
+        env, clip.width(), clip.height(), jcanvas, web_contents_));
     if (!jbitmap.obj()) {
       TRACE_EVENT_INSTANT0("android_webview",
                            "EarlyOut_BitmapAllocFail",
@@ -540,7 +540,8 @@ InProcessViewRenderer::CapturePicture() {
   // for |canvas| as we don't have java canvas at this point (and it would be
   // software anyway).
   ScopedJavaLocalRef<jobject> jbitmap(java_helper_->CreateBitmap(
-      env, picture->width(), picture->height(), ScopedJavaLocalRef<jobject>()));
+      env, picture->width(), picture->height(), ScopedJavaLocalRef<jobject>(),
+      NULL));
   if (!jbitmap.obj())
     return ScopedJavaLocalRef<jobject>();
 
diff --git a/android_webview/java/src/org/chromium/android_webview/JavaBrowserViewRendererHelper.java b/android_webview/java/src/org/chromium/android_webview/JavaBrowserViewRendererHelper.java
index 54bb33d..4f3f9cb 100644
--- a/android_webview/java/src/org/chromium/android_webview/JavaBrowserViewRendererHelper.java
+++ b/android_webview/java/src/org/chromium/android_webview/JavaBrowserViewRendererHelper.java
@@ -8,6 +8,7 @@ import android.graphics.Bitmap;
 import android.graphics.Canvas;
 import android.graphics.Color;
 import android.graphics.Picture;
+import android.util.LruCache;
 
 import org.chromium.base.CalledByNative;
 import org.chromium.base.JNINamespace;
@@ -19,20 +20,31 @@ import org.chromium.content.common.TraceEvent;
 @JNINamespace("android_webview")
 public class JavaBrowserViewRendererHelper {
 
+    // Until the full HW path is ready, we limit to 5 AwContents on the screen at once.
+    private static LruCache<Integer, Bitmap> sBitmapCache = new LruCache<Integer, Bitmap>(5);
+
     /**
      * Provides a Bitmap object with a given width and height used for auxiliary rasterization.
      * |canvas| is optional and if supplied indicates the Canvas that this Bitmap will be
-     * drawn into. Note the Canvas will not be modified in any way.
+     * drawn into. Note the Canvas will not be modified in any way. If |ownerKey| is non-zero
+     * the Bitmap will be cached in sBitmapCache for future use.
      */
     @CalledByNative
-    private static Bitmap createBitmap(int width, int height, Canvas canvas) {
+    private static Bitmap createBitmap(int width, int height, Canvas canvas, int ownerKey) {
         if (canvas != null) {
             // When drawing into a Canvas, there is a maximum size imposed
             // on Bitmaps that can be drawn. Respect that limit.
             width = Math.min(width, canvas.getMaximumBitmapWidth());
             height = Math.min(height, canvas.getMaximumBitmapHeight());
         }
-        return Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
+        Bitmap bitmap = sBitmapCache.get(ownerKey);
+        if (bitmap == null || bitmap.getWidth() != width || bitmap.getHeight() != height) {
+            bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
+            if (ownerKey != 0) {
+                sBitmapCache.put(ownerKey, bitmap);
+            }
+        }
+        return bitmap;
     }
 
     /**
diff --git a/android_webview/native/java_browser_view_renderer_helper.cc b/android_webview/native/java_browser_view_renderer_helper.cc
index 8bbed36..0426bd1 100644
--- a/android_webview/native/java_browser_view_renderer_helper.cc
+++ b/android_webview/native/java_browser_view_renderer_helper.cc
@@ -22,11 +22,13 @@ ScopedJavaLocalRef<jobject> JavaBrowserViewRendererHelper::CreateBitmap(
     JNIEnv* env,
     int width,
     int height,
-    const base::android::JavaRef<jobject>& jcanvas) {
+    const base::android::JavaRef<jobject>& jcanvas,
+    void* owner_key) {
   TRACE_EVENT0("android_webview", "RendererHelper::CreateBitmap");
   return width <= 0 || height <= 0 ? ScopedJavaLocalRef<jobject>() :
-      Java_JavaBrowserViewRendererHelper_createBitmap(env, width, height,
-                                                      jcanvas.obj());
+      Java_JavaBrowserViewRendererHelper_createBitmap(
+          env, width, height, jcanvas.obj(),
+          reinterpret_cast<jint>(owner_key));
 }
 
 void JavaBrowserViewRendererHelper::DrawBitmapIntoCanvas(
diff --git a/android_webview/native/java_browser_view_renderer_helper.h b/android_webview/native/java_browser_view_renderer_helper.h
index 77860b3..2d1aadc 100644
--- a/android_webview/native/java_browser_view_renderer_helper.h
+++ b/android_webview/native/java_browser_view_renderer_helper.h
@@ -23,7 +23,8 @@ class JavaBrowserViewRendererHelper : public BrowserViewRenderer::JavaHelper {
       JNIEnv* env,
       int width,
       int height,
-      const base::android::JavaRef<jobject>& jcanvas) OVERRIDE;
+      const base::android::JavaRef<jobject>& jcanvas,
+      void* owner_key) OVERRIDE;
   virtual void DrawBitmapIntoCanvas(
       JNIEnv* env,
       const base::android::JavaRef<jobject>& jbitmap,