Enable general CSS filters in the software compositor

cc/output/software_renderer.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/output/software_renderer.h"
 
 #include "base/debug/trace_event.h"
 #include "cc/base/math_util.h"
 #include "cc/output/compositor_frame.h"
 #include "cc/output/compositor_frame_ack.h"
@@ skipping 417 matching lines @@
   SkRect dest_rect = gfx::RectFToSkRect(QuadVertexRect());
   SkRect dest_visible_rect = gfx::RectFToSkRect(MathUtil::ScaleRectProportional(
       QuadVertexRect(), quad->rect, quad->visible_rect));
   SkRect content_rect = SkRect::MakeWH(quad->rect.width(), quad->rect.height());
 
   SkMatrix content_mat;
   content_mat.setRectToRect(content_rect, dest_rect,
                             SkMatrix::kFill_ScaleToFit);
 
   const SkBitmap* content = lock.sk_bitmap();
-  skia::RefPtr<SkShader> shader = skia::AdoptRef(
-      SkShader::CreateBitmapShader(*content,
-                                   SkShader::kClamp_TileMode,
-                                   SkShader::kClamp_TileMode));
+
+  SkBitmap filter_bitmap;
+  if (!quad->filters.IsEmpty()) {
+    skia::RefPtr<SkImageFilter> filter = RenderSurfaceFilters::BuildImageFilter(
+        quad->filters, content_texture->size());
+    // 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());
 
-  // 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()) {
-    skia::RefPtr<SkImageFilter> filter = RenderSurfaceFilters::BuildImageFilter(
-        quad->filters, content_texture->size());
-    if (filter)
-      current_paint_.setImageFilter(filter.get());
-  }
-
   if (quad->mask_resource_id) {
     ResourceProvider::ScopedReadLockSoftware mask_lock(resource_provider_,
                                                        quad->mask_resource_id);
 
     const SkBitmap* mask = mask_lock.sk_bitmap();
 
     SkRect mask_rect = SkRect::MakeXYWH(
         quad->mask_uv_rect.x() * mask->width(),
         quad->mask_uv_rect.y() * mask->height(),
         quad->mask_uv_rect.width() * mask->width(),
@@ skipping 92 matching lines @@
     EnsureBackbuffer();
   else
     DiscardBackbuffer();
 }
 
 void SoftwareRenderer::SetDiscardBackBufferWhenNotVisible(bool discard) {
   // The software renderer always discards the backbuffer when not visible.
 }
 
 }  // namespace cc