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..3b209b3d5a350e4590b3fc89167b4928b2a6febd 100644
--- a/cc/output/software_renderer.cc
+++ b/cc/output/software_renderer.cc
@@ -435,22 +435,43 @@ 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.
+    if (filter) {
+      skia::RefPtr<SkBaseDevice> device =
+          skia::AdoptRef(current_canvas_->getDevice()->createCompatibleDevice(
+              SkBitmap::kARGB_8888_Config,
+              content_texture->size().width(),
+              content_texture->size().height(),
+              false));

[danakj, 2013/10/16 15:48:59]

can you use temporary variables so these boolean literals have names?

[ajuma, 2013/10/16 19:12:07]

Done.

+      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);
+      filter_bitmap = device->accessBitmap(false);

[Stephen White, 2013/10/15 19:49:19]

Might want to log a bug that there's a possible optimization here, when the
filter DAG is simple enough to apply in the same pass as the content (and
there's no origin offset to apply). Could at least do an
SkColorFilterImageFilter, probably more.

[ajuma, 2013/10/16 19:12:07]

Done and added a TODO for this too.

+    }
   }
 
+  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);