Start of hardware overlay support in CC with Ubercompositor.

cc/output/overlay_strategy_single_on_top.cc

Index: cc/output/overlay_strategy_single_on_top.cc
diff --git a/cc/output/overlay_strategy_single_on_top.cc b/cc/output/overlay_strategy_single_on_top.cc
new file mode 100644
index 0000000000000000000000000000000000000000..4c2064196ddbca9181d192cd94d51b6c4603f3f9
--- /dev/null
+++ b/cc/output/overlay_strategy_single_on_top.cc
@@ -0,0 +1,81 @@
+// Copyright 2014 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/overlay_strategy_single_on_top.h"
+
+#include "cc/output/output_surface.h"
+#include "cc/quads/draw_quad.h"
+#include "cc/quads/texture_draw_quad.h"
+#include "ui/gfx/rect_conversions.h"
+#include "ui/gfx/transform.h"
+
+namespace cc {
+
+OverlayStrategySingleOnTop::OverlayStrategySingleOnTop(
+    OverlayCandidateValidator* capability_checker,
+    ResourceProvider* resource_provider)
+    : capability_checker_(capability_checker),
+      resource_provider_(resource_provider) {}
+
+bool OverlayStrategySingleOnTop::Attempt(
+    RenderPassList* render_passes_in_draw_order) {
+  // Only attempt to handle very simple case for now.
+  if (!capability_checker_)
+    return false;
+
+  RenderPass* root_render_pass = render_passes_in_draw_order->back();
+  DCHECK(root_render_pass);
+
+  QuadList& quad_list = root_render_pass->quad_list;
+  const DrawQuad* candidate_quad = quad_list.front();
+  if (candidate_quad->material != DrawQuad::TEXTURE_CONTENT)
+    return false;
+
+  const TextureDrawQuad& quad = *TextureDrawQuad::MaterialCast(candidate_quad);
+  if (!resource_provider_->AllowOverlay(quad.resource_id))
+    return false;
+
+  // Simple quads only.
+  if (!quad.quadTransform().IsIdentityOrTranslation() || quad.needs_blending ||
+      quad.shared_quad_state->opacity != 1.f ||
+      quad.shared_quad_state->blend_mode != SkXfermode::kSrcOver_Mode ||
+      quad.premultiplied_alpha || quad.background_color != SK_ColorTRANSPARENT)
+    return false;
+
+  // Add our primary surface.
+  OverlayCandidateValidator::OverlayCandidateList candidates;
+  OverlayCandidate main_image;
+  main_image.display_rect = root_render_pass->output_rect;
+  main_image.format = RGBA_8888;
+  candidates.push_back(main_image);
+
+  // Add the overlay.
+  OverlayCandidate candidate;
+  gfx::RectF float_rect(quad.rect);
+  quad.quadTransform().TransformRect(&float_rect);
+  candidate.transform =
+      quad.flipped ? OverlayCandidate::FLIP_VERTICAL : OverlayCandidate::NONE;
+  candidate.display_rect = gfx::ToNearestRect(float_rect);
+  candidate.uv_rect = BoundingRect(quad.uv_top_left, quad.uv_bottom_right);
+  candidate.format = RGBA_8888;
+  candidates.push_back(candidate);
+
+  // Check for support.
+  capability_checker_->CheckOverlaySupport(&candidates);
+
+  // If the candidate can be handled by an overlay, create a pass for it.
+  if (candidates[1].overlay_handled) {
+    scoped_ptr<RenderPass> overlay_pass = RenderPass::Create();
+    overlay_pass->overlay_state = RenderPass::SIMPLE_OVERLAY;
+
+    scoped_ptr<DrawQuad> overlay_quad = quad_list.take(quad_list.begin());
+    quad_list.erase(quad_list.begin());
+    overlay_pass->quad_list.push_back(overlay_quad.Pass());
+    render_passes_in_draw_order->insert(render_passes_in_draw_order->begin(),
+                                        overlay_pass.Pass());
+  }
+  return candidates[1].overlay_handled;
+}
+
+}  // namespace cc