SkiaRenderer: Calculate clipping offset for backdrop filters

Needed when an RPDQ is partially offscreen

Bug: 968160, 948128
Change-Id: Ic9f400dafa9997d367fc3a93cac44e640f01ace0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1637778Reviewed-by: weiliangc <weiliangc@chromium.org>
Commit-Queue: Michael Ludwig <michaelludwig@google.com>
Cr-Commit-Position: refs/heads/master@{#665242}

cc/trees/layer_tree_host_pixeltest_filters.cc

@@ -81,14 +81,6 @@ INSTANTIATE_TEST_SUITE_P(,
                                            LayerTreeTest::RENDERER_SKIA_GL,
                                            LayerTreeTest::RENDERER_SOFTWARE));
 
-using LayerTreeHostFiltersPixelTestNonSkia = LayerTreeHostFiltersPixelTest;
-
-// TODO(crbug.com/948128): Enable these tests for Skia.
-INSTANTIATE_TEST_SUITE_P(,
-                         LayerTreeHostFiltersPixelTestNonSkia,
-                         ::testing::Values(LayerTreeTest::RENDERER_GL,
-                                           LayerTreeTest::RENDERER_SOFTWARE));
-
 using LayerTreeHostFiltersPixelTestGL = LayerTreeHostFiltersPixelTest;
 
 // TODO(crbug.com/948128): Enable these tests for Skia.
@@ -662,7 +654,7 @@ TEST_P(LayerTreeHostFiltersPixelTest, ImageRenderSurfaceScaled) {
           .InsertBeforeExtensionASCII(GetRendererSuffix()));
 }
 
-TEST_P(LayerTreeHostFiltersPixelTestNonSkia, ZoomFilter) {
+TEST_P(LayerTreeHostFiltersPixelTest, ZoomFilter) {
   scoped_refptr<SolidColorLayer> root =
       CreateSolidColorLayer(gfx::Rect(300, 300), SK_ColorWHITE);
 

components/viz/service/display/skia_renderer.cc

@@ -1632,8 +1632,19 @@ SkiaRenderer::DrawRPDQParams SkiaRenderer::CalculateRPDQParams(
   // Convert CC image filters for the backdrop into a SkImageFilter root node
   if (backdrop_filters) {
     DCHECK(!backdrop_filters->IsEmpty());
+
+    // Must account for clipping that occurs for backdrop filters, since their
+    // input content has already been clipped to the output rect.
+    gfx::Rect deviceRect = gfx::ToEnclosingRect(cc::MathUtil::MapClippedRect(
+        params->content_device_transform, gfx::RectF(quad->rect)));
+    gfx::Rect outRect = MoveFromDrawToWindowSpace(
+        current_frame()->current_render_pass->output_rect);
+    outRect.Intersect(deviceRect);
+    gfx::Vector2dF offset = (deviceRect.top_right() - outRect.top_right()) +
+                            (deviceRect.bottom_left() - outRect.bottom_left());
+
     auto bg_paint_filter = cc::RenderSurfaceFilters::BuildImageFilter(
-        *backdrop_filters, filter_size);
+        *backdrop_filters, gfx::SizeF(outRect.size()), offset);
     auto sk_bg_filter =
         bg_paint_filter ? bg_paint_filter->cached_sk_filter_ : nullptr;