Reland "Support downsampling in ViewResourceAdapter"

This is a reland of 2bc512d7

Original change's description:
> Support downsampling in ViewResourceAdapter
>
> Bug: 965609
> Change-Id: I148d5fe8b7371a529b612ed2e9b407ced0062f82
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1623139
> Commit-Queue: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
> Reviewed-by: David Trainor <dtrainor@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#662915}

Bug: 965609, 966859
TBR=dtrainor@chromium.org

Change-Id: I3da718de48413f22060f7504c78932d941929308
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1635431Reviewed-by: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
Commit-Queue: Wei-Yin Chen (陳威尹) <wychen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#664615}

ui/android/java/src/org/chromium/ui/resources/ResourceManager.java

@@ -138,8 +138,9 @@ public class ResourceManager implements ResourceLoaderCallback {
 
         if (mNativeResourceManagerPtr == 0) return;
 
-        nativeOnResourceReady(
-                mNativeResourceManagerPtr, resType, resId, bitmap, resource.createNativeResource());
+        nativeOnResourceReady(mNativeResourceManagerPtr, resType, resId, bitmap,
+                resource.getBitmapSize().width(), resource.getBitmapSize().height(),
+                resource.createNativeResource());
     }
 
     @Override
@@ -195,7 +196,7 @@ public class ResourceManager implements ResourceLoaderCallback {
     }
 
     private native void nativeOnResourceReady(long nativeResourceManagerImpl, int resType,
-            int resId, Bitmap bitmap, long nativeResource);
+            int resId, Bitmap bitmap, int width, int height, long nativeResource);
     private native void nativeRemoveResource(long nativeResourceManagerImpl, int resType,
             int resId);
     private native void nativeClearTintedResourceCache(long nativeResourceManagerImpl);

ui/android/java/src/org/chromium/ui/resources/dynamics/ViewResourceAdapter.java

@@ -27,7 +27,8 @@ public class ViewResourceAdapter extends DynamicResource implements OnLayoutChan
     private final Rect mDirtyRect = new Rect();
 
     private Bitmap mBitmap;
-    private Rect mBitmapSize = new Rect();
+    private Rect mViewSize = new Rect();
+    protected float mScale = 1;
 
     /**
      * Builds a {@link ViewResourceAdapter} instance around {@code view}.
@@ -71,7 +72,19 @@ public class ViewResourceAdapter extends DynamicResource implements OnLayoutChan
 
     @Override
     public Rect getBitmapSize() {
-        return mBitmapSize;
+        return mViewSize;
+    }
+
+    /**
+     * Set the downsampling scale. The rendered size is not affected.
+     * @param scale The scale to use. <1 means the Bitmap is smaller than the View.
+     */
+    public void setDownsamplingScale(float scale) {
+        assert scale <= 1;
+        if (mScale != scale) {
+            invalidate(null);
+        }
+        mScale = scale;
     }
 
     /**
@@ -143,7 +156,10 @@ public class ViewResourceAdapter extends DynamicResource implements OnLayoutChan
      * @param canvas The {@link Canvas} that will be drawn to.
      */
     protected void capture(Canvas canvas) {
+        canvas.save();
+        canvas.scale(mScale, mScale);
         mView.draw(canvas);
+        canvas.restore();
     }
 
     /**
@@ -156,8 +172,8 @@ public class ViewResourceAdapter extends DynamicResource implements OnLayoutChan
      * @return Whether |mBitmap| is corresponding to |mView| or not.
      */
     private boolean validateBitmap() {
-        int viewWidth = mView.getWidth();
-        int viewHeight = mView.getHeight();
+        int viewWidth = (int) (mView.getWidth() * mScale);
+        int viewHeight = (int) (mView.getHeight() * mScale);
         boolean isEmpty = viewWidth == 0 || viewHeight == 0;
         if (isEmpty) {
             viewWidth = 1;
@@ -172,8 +188,8 @@ public class ViewResourceAdapter extends DynamicResource implements OnLayoutChan
         if (mBitmap == null) {
             mBitmap = Bitmap.createBitmap(viewWidth, viewHeight, Bitmap.Config.ARGB_8888);
             mBitmap.setHasAlpha(true);
-            mDirtyRect.set(0, 0, viewWidth, viewHeight);
-            mBitmapSize.set(0, 0, mBitmap.getWidth(), mBitmap.getHeight());
+            mViewSize.set(0, 0, mView.getWidth(), mView.getHeight());
+            mDirtyRect.set(mViewSize);
         }
 
         return !isEmpty;

ui/android/junit/src/org/chromium/ui/resources/dynamics/ViewResourceAdapterTest.java

@@ -78,6 +78,19 @@ public class ViewResourceAdapterTest {
         assertEquals(bitmap.getHeight(), rect.height());
     }
 
+    @Test
+    public void testSetDownsamplingSize() {
+        float scale = 0.5f;
+        mAdapter.setDownsamplingScale(scale);
+        Bitmap bitmap = mAdapter.getBitmap();
+        assertEquals(mViewWidth * scale, bitmap.getWidth(), 1);
+        assertEquals(mViewHeight * scale, bitmap.getHeight(), 1);
+
+        Rect rect = mAdapter.getBitmapSize();
+        assertEquals(mViewWidth, rect.width());
+        assertEquals(mViewHeight, rect.height());
+    }
+
     @Test
     public void testIsDirty() {
         assertTrue(mAdapter.isDirty());
@@ -99,6 +112,21 @@ public class ViewResourceAdapterTest {
         assertEquals(2, dirtyRect.height());
     }
 
+    @Test
+    public void testOnLayoutChangeDownsampled() {
+        mAdapter.setDownsamplingScale(0.5f);
+
+        mAdapter.getBitmap();
+        assertFalse(mAdapter.isDirty());
+
+        mAdapter.onLayoutChange(mView, 0, 0, 1, 2, 0, 0, mViewWidth, mViewHeight);
+        assertTrue(mAdapter.isDirty());
+
+        Rect dirtyRect = mAdapter.getDirtyRect();
+        assertEquals(1, dirtyRect.width());
+        assertEquals(2, dirtyRect.height());
+    }
+
     @Test
     public void testInvalidate() {
         mAdapter.getBitmap();
@@ -123,6 +151,19 @@ public class ViewResourceAdapterTest {
         assertEquals(dirtyRect.toString(), mAdapter.getDirtyRect().toString());
     }
 
+    @Test
+    public void testInvalidateRectDownsampled() {
+        mAdapter.setDownsamplingScale(0.5f);
+
+        mAdapter.getBitmap();
+        assertFalse(mAdapter.isDirty());
+
+        Rect dirtyRect = new Rect(1, 2, 3, 4);
+        mAdapter.invalidate(dirtyRect);
+        assertTrue(mAdapter.isDirty());
+        assertEquals(dirtyRect.toString(), mAdapter.getDirtyRect().toString());
+    }
+
     @Test
     public void testInvalidateRectUnion() {
         mAdapter.getBitmap();
@@ -217,4 +258,18 @@ public class ViewResourceAdapterTest {
         assertEquals(mViewWidth, rect.width());
         assertEquals(mViewHeight, rect.height());
     }
+
+    @Test
+    public void testGetDirtyRectDownsampled() {
+        mAdapter.setDownsamplingScale(0.5f);
+
+        mAdapter.getBitmap();
+        Rect rect = mAdapter.getDirtyRect();
+        assertTrue(rect.isEmpty());
+
+        mAdapter.invalidate(null);
+        rect = mAdapter.getDirtyRect();
+        assertEquals(mViewWidth, rect.width());
+        assertEquals(mViewHeight, rect.height());
+    }
 }

ui/android/resources/resource_manager_impl.cc

@@ -205,6 +205,8 @@ void ResourceManagerImpl::OnResourceReady(JNIEnv* env,
                                           jint res_type,
                                           jint res_id,
                                           const JavaRef<jobject>& bitmap,
+                                          jint width,
+                                          jint height,
                                           jlong native_resource) {
   DCHECK_GE(res_type, ANDROID_RESOURCE_TYPE_FIRST);
   DCHECK_LE(res_type, ANDROID_RESOURCE_TYPE_LAST);
@@ -222,7 +224,7 @@ void ResourceManagerImpl::OnResourceReady(JNIEnv* env,
   resource->SetUIResource(
       cc::ScopedUIResource::Create(ui_resource_manager_,
                                    cc::UIResourceBitmap(skbitmap)),
-      jbitmap.size());
+      gfx::Size(width, height));
 }
 
 void ResourceManagerImpl::RemoveResource(

ui/android/resources/resource_manager_impl.h

@@ -49,6 +49,8 @@ class UI_ANDROID_EXPORT ResourceManagerImpl
                        jint res_type,
                        jint res_id,
                        const base::android::JavaRef<jobject>& bitmap,
+                       jint width,
+                       jint height,
                        jlong native_resource);
   void RemoveResource(
       JNIEnv* env,

ui/android/resources/resource_manager_impl_unittest.cc

@@ -55,7 +55,7 @@ class TestResourceManagerImpl : public ResourceManagerImpl {
     small_bitmap.setImmutable();
 
     OnResourceReady(nullptr, nullptr, res_type, res_id,
-                    gfx::ConvertToJavaBitmap(&small_bitmap),
+                    gfx::ConvertToJavaBitmap(&small_bitmap), 1, 1,
                     reinterpret_cast<intptr_t>(new Resource()));
   }