Compute damage rect for Cast video compositing

cc/output/overlay_strategy_cast_underlay.cc

Index: cc/output/overlay_strategy_cast_underlay.cc
diff --git a/cc/output/overlay_strategy_cast_underlay.cc b/cc/output/overlay_strategy_cast_underlay.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c42511a11e258448c4b600b07138b5e299aab861
--- /dev/null
+++ b/cc/output/overlay_strategy_cast_underlay.cc
@@ -0,0 +1,72 @@
+// Copyright 2016 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_cast_underlay.h"
+
+#include "base/containers/adapters.h"
+#include "cc/quads/draw_quad.h"
+#include "cc/quads/solid_color_draw_quad.h"
+#include "ui/gfx/geometry/rect_conversions.h"
+
+namespace cc {
+
+OverlayStrategyCastUnderlay::OverlayStrategyCastUnderlay(
+    OverlayCandidateValidator* capability_checker)
+    : OverlayStrategyUnderlay(capability_checker),
+      have_swap_with_damage_rect_(false) {}
+
+OverlayStrategyCastUnderlay::~OverlayStrategyCastUnderlay() {}
+
+bool OverlayStrategyCastUnderlay::GetSwapWithDamageRect(gfx::Rect* rect) {
+  DCHECK(rect);
+  *rect = swap_with_damage_rect_;
+  return have_swap_with_damage_rect_;
+}
+
+bool OverlayStrategyCastUnderlay::Attempt(
+    ResourceProvider* resource_provider,
+    RenderPass* render_pass,
+    OverlayCandidateList* candidate_list) {
+  const QuadList& const_quad_list = render_pass->quad_list;
+  bool found_underlay = false;
+  gfx::Rect damage;
+  for (const auto* quad : base::Reversed(const_quad_list)) {
+    if (OverlayCandidate::IsInvisibleQuad(quad))
+      continue;
+
+    const auto& transform = quad->shared_quad_state->quad_to_target_transform;
+    gfx::RectF quad_rect = gfx::RectF(quad->rect);
+    transform.TransformRect(&quad_rect);
+
+    bool is_underlay = false;
+    if (!found_underlay) {
+      OverlayCandidate candidate;
+      is_underlay =
+          OverlayCandidate::FromDrawQuad(resource_provider, quad, &candidate);
+      found_underlay |= is_underlay;
+    }
+
+    if (!found_underlay && quad->material == DrawQuad::SOLID_COLOR) {
+      const SolidColorDrawQuad* solid = SolidColorDrawQuad::MaterialCast(quad);
+      if (solid->color == SK_ColorBLACK)
+        continue;
+    }
+
+    if (is_underlay) {
+      damage.Subtract(ToEnclosedRect(quad_rect));
+    } else {
+      damage.Union(ToEnclosingRect(quad_rect));
+    }
+  }
+
+  have_swap_with_damage_rect_ = found_underlay;
+  if (found_underlay) {
+    swap_with_damage_rect_ = damage;
+  }
+
+  return OverlayStrategyUnderlay::Attempt(resource_provider, render_pass,
+                                          candidate_list);
+}
+
+}  // namespace cc