cc: Move UnoccludedContentRect to Occlusion.

cc/trees/occlusion.cc

 // 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/trees/occlusion.h"
 
 #include "cc/base/math_util.h"
 #include "ui/gfx/rect.h"
 
 namespace cc {
@@ skipping 11 matching lines @@
 
 bool Occlusion::IsOccluded(const gfx::Rect& content_rect) const {
   if (content_rect.IsEmpty())
     return true;
 
   if (occlusion_from_inside_target_.IsEmpty() &&
       occlusion_from_outside_target_.IsEmpty()) {
     return false;
   }
 
+  gfx::Rect unoccluded_rect_in_target_surface =
+      GetUnoccludedRectInTargetSurface(content_rect);
+  return unoccluded_rect_in_target_surface.IsEmpty();
+}
+
+gfx::Rect Occlusion::GetUnoccludedContentRect(
+    const gfx::Rect& content_rect) const {
+  if (content_rect.IsEmpty())
+    return content_rect;
+
+  if (occlusion_from_inside_target_.IsEmpty() &&
+      occlusion_from_outside_target_.IsEmpty()) {
+    return content_rect;
+  }
+
+  gfx::Rect unoccluded_rect_in_target_surface =
+      GetUnoccludedRectInTargetSurface(content_rect);
+  if (unoccluded_rect_in_target_surface.IsEmpty())
+    return gfx::Rect();
+
+  gfx::Transform inverse_draw_transform(gfx::Transform::kSkipInitialization);
+  bool ok = draw_transform_.GetInverse(&inverse_draw_transform);
+  DCHECK(ok);
+
+  gfx::Rect unoccluded_rect = MathUtil::ProjectEnclosingClippedRect(
+      inverse_draw_transform, unoccluded_rect_in_target_surface);
+  unoccluded_rect.Intersect(content_rect);
+
+  return unoccluded_rect;
+}
+
+gfx::Rect Occlusion::GetUnoccludedRectInTargetSurface(
+    const gfx::Rect& content_rect) const {
   // Take the ToEnclosingRect at each step, as we want to contain any unoccluded
   // partial pixels in the resulting Rect.
   gfx::Rect unoccluded_rect_in_target_surface =
       MathUtil::MapEnclosingClippedRect(draw_transform_, content_rect);
   DCHECK_LE(occlusion_from_inside_target_.GetRegionComplexity(), 1u);
   DCHECK_LE(occlusion_from_outside_target_.GetRegionComplexity(), 1u);
   // These subtract operations are more lossy than if we did both operations at
   // once.
   unoccluded_rect_in_target_surface.Subtract(
       occlusion_from_inside_target_.bounds());
   unoccluded_rect_in_target_surface.Subtract(
       occlusion_from_outside_target_.bounds());
 
-  return unoccluded_rect_in_target_surface.IsEmpty();
+  // TODO(vmpstr): Cache this.
+  return unoccluded_rect_in_target_surface;
 }
 
 }  // namespace cc