cc/trees/occlusion.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "cc/trees/occlusion.h"
   6
   7 #include "cc/base/math_util.h"
   8 #include "ui/gfx/geometry/rect.h"
   9
  10 namespace cc {
  11
  12 Occlusion::Occlusion() {
  13 }
  14
  15 Occlusion::Occlusion(const gfx::Transform& draw_transform,
  16                      const SimpleEnclosedRegion& occlusion_from_outside_target,
  17                      const SimpleEnclosedRegion& occlusion_from_inside_target)
  18     : draw_transform_(draw_transform),
  19       occlusion_from_outside_target_(occlusion_from_outside_target),
  20       occlusion_from_inside_target_(occlusion_from_inside_target) {
  21 }
  22
  23 Occlusion Occlusion::GetOcclusionWithGivenDrawTransform(
  24     const gfx::Transform& transform) const {
  25   return Occlusion(
  26       transform, occlusion_from_outside_target_, occlusion_from_inside_target_);
  27 }
  28
  29 bool Occlusion::HasOcclusion() const {
  30   return !occlusion_from_inside_target_.IsEmpty() ||
  31          !occlusion_from_outside_target_.IsEmpty();
  32 }
  33
  34 bool Occlusion::IsOccluded(const gfx::Rect& content_rect) const {
  35   if (content_rect.IsEmpty())
  36     return true;
  37
  38   if (!HasOcclusion())
  39     return false;
  40
  41   gfx::Rect unoccluded_rect_in_target_surface =
  42       GetUnoccludedRectInTargetSurface(content_rect);
  43   return unoccluded_rect_in_target_surface.IsEmpty();
  44 }
  45
  46 gfx::Rect Occlusion::GetUnoccludedContentRect(
  47     const gfx::Rect& content_rect) const {
  48   if (content_rect.IsEmpty())
  49     return content_rect;
  50
  51   if (!HasOcclusion())
  52     return content_rect;
  53
  54   gfx::Rect unoccluded_rect_in_target_surface =
  55       GetUnoccludedRectInTargetSurface(content_rect);
  56   if (unoccluded_rect_in_target_surface.IsEmpty())
  57     return gfx::Rect();
  58
  59   gfx::Transform inverse_draw_transform(gfx::Transform::kSkipInitialization);
  60   bool ok = draw_transform_.GetInverse(&inverse_draw_transform);
  61   DCHECK(ok);
  62
  63   gfx::Rect unoccluded_rect = MathUtil::ProjectEnclosingClippedRect(
  64       inverse_draw_transform, unoccluded_rect_in_target_surface);
  65   unoccluded_rect.Intersect(content_rect);
  66
  67   return unoccluded_rect;
  68 }
  69
  70 gfx::Rect Occlusion::GetUnoccludedRectInTargetSurface(
  71     const gfx::Rect& content_rect) const {
  72   // Take the ToEnclosingRect at each step, as we want to contain any unoccluded
  73   // partial pixels in the resulting Rect.
  74   gfx::Rect unoccluded_rect_in_target_surface =
  75       MathUtil::MapEnclosingClippedRect(draw_transform_, content_rect);
  76   DCHECK_LE(occlusion_from_inside_target_.GetRegionComplexity(), 1u);
  77   DCHECK_LE(occlusion_from_outside_target_.GetRegionComplexity(), 1u);
  78   // These subtract operations are more lossy than if we did both operations at
  79   // once.
  80   unoccluded_rect_in_target_surface.Subtract(
  81       occlusion_from_inside_target_.bounds());
  82   unoccluded_rect_in_target_surface.Subtract(
  83       occlusion_from_outside_target_.bounds());
  84
  85   return unoccluded_rect_in_target_surface;
  86 }
  87
  88 }  // namespace cc