Enable general CSS filters in the software compositor

cc/output/software_renderer.cc

Index: cc/output/software_renderer.cc
diff --git a/cc/output/software_renderer.cc b/cc/output/software_renderer.cc
index 4457607f72ef4c77cb67ae203ff095e6157081b0..edd7cb2f0af4b61c5b2f6881a15af3088bab20d2 100644
--- a/cc/output/software_renderer.cc
+++ b/cc/output/software_renderer.cc
@@ -435,22 +435,46 @@ void SoftwareRenderer::DrawRenderPassQuad(const DrawingFrame* frame,
                             SkMatrix::kFill_ScaleToFit);
 
   const SkBitmap* content = lock.sk_bitmap();
-  skia::RefPtr<SkShader> shader = skia::AdoptRef(
-      SkShader::CreateBitmapShader(*content,
-                                   SkShader::kClamp_TileMode,
-                                   SkShader::kClamp_TileMode));
-  shader->setLocalMatrix(content_mat);
-  current_paint_.setShader(shader.get());
 
-  // TODO(ajuma): Remove this condition once general CSS filters are working
-  // correctly (http://crbug.com/160302), and add corresponding pixel tests.
-  if (quad->filters.HasReferenceFilter()) {
+  SkBitmap filter_bitmap;
+  if (!quad->filters.IsEmpty()) {
     skia::RefPtr<SkImageFilter> filter = RenderSurfaceFilters::BuildImageFilter(
         quad->filters, content_texture->size());
-    if (filter)
-      current_paint_.setImageFilter(filter.get());
+    // TODO(ajuma): In addition origin translation, the canvas should also be
+    // scaled to accomodate device pixel ratio and pinch zoom. See
+    // crbug.com/281516 and crbug.com/281518.
+    // TODO(ajuma): Apply the filter in the same pass as the content where
+    // possible (e.g. when there's no origin offset). See crbug.com/308201.
+    if (filter) {
+      bool is_opaque = false;
+      skia::RefPtr<SkBaseDevice> device =
+          skia::AdoptRef(new SkBitmapDevice(SkBitmap::kARGB_8888_Config,

[ajuma, 2013/10/31 17:36:10]

Using createCompatibleDevice leads to a crash on Windows, since it creates a
BitmapPlatformDevice. As a result, when applying the filter during
canvas.drawSprite, the temporary device that's created in
SkColorFilterImageFilter::onFilterImage is also a BitmapPlatformDevice. Such a
device's pixel data cannot be assigned to another bitmap since the data is owned
by the device rather than being refcounted (see comments in
bitmap_platform_device_win.h). But onFilterImage does assign the device's pixel
data to *result, meaning we have a use-after-free when we later try to access
the result's pixel data.

Using an SkBitmapDevice avoids this issue.

+                                            content_texture->size().width(),
+                                            content_texture->size().height(),
+                                            is_opaque));
+      SkCanvas canvas(device.get());
+      SkPaint paint;
+      paint.setImageFilter(filter.get());
+      canvas.clear(SK_ColorTRANSPARENT);
+      canvas.translate(SkIntToScalar(-quad->rect.origin().x()),
+                       SkIntToScalar(-quad->rect.origin().y()));
+      canvas.drawSprite(*content, 0, 0, &paint);
+      bool will_change_pixels = false;
+      filter_bitmap = device->accessBitmap(will_change_pixels);
+    }
   }
 
+  skia::RefPtr<SkShader> shader;
+  if (filter_bitmap.isNull()) {
+    shader = skia::AdoptRef(SkShader::CreateBitmapShader(
+        *content, SkShader::kClamp_TileMode, SkShader::kClamp_TileMode));
+  } else {
+    shader = skia::AdoptRef(SkShader::CreateBitmapShader(
+        filter_bitmap, SkShader::kClamp_TileMode, SkShader::kClamp_TileMode));
+  }
+  shader->setLocalMatrix(content_mat);
+  current_paint_.setShader(shader.get());
+
   if (quad->mask_resource_id) {
     ResourceProvider::ScopedReadLockSoftware mask_lock(resource_provider_,
                                                        quad->mask_resource_id);