cc/resources/layer_quad.cc

   1 // Copyright 2011 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/resources/layer_quad.h"
   6
   7 #include "base/logging.h"
   8 #include "ui/gfx/geometry/quad_f.h"
   9
  10 namespace cc {
  11
  12 LayerQuad::Edge::Edge(const gfx::PointF& p, const gfx::PointF& q) {
  13   if (p == q) {
  14     degenerate_ = true;
  15     return;
  16   }
  17   degenerate_ = false;
  18   gfx::Vector2dF tangent(p.y() - q.y(), q.x() - p.x());
  19   float cross2 = p.x() * q.y() - q.x() * p.y();
  20
  21   set(tangent.x(), tangent.y(), cross2);
  22   scale(1.0f / tangent.Length());
  23 }
  24
  25 gfx::PointF LayerQuad::Edge::Intersect(const LayerQuad::Edge& e) const {
  26   DCHECK(!degenerate());
  27   DCHECK(!e.degenerate());
  28
  29   return gfx::PointF((y() * e.z() - e.y() * z()) / (x() * e.y() - e.x() * y()),
  30                      (x() * e.z() - e.x() * z()) / (e.x() * y() - x() * e.y()));
  31 }
  32
  33 LayerQuad::LayerQuad(const gfx::QuadF& quad) {
  34   // Create edges.
  35   left_ = Edge(quad.p4(), quad.p1());
  36   right_ = Edge(quad.p2(), quad.p3());
  37   top_ = Edge(quad.p1(), quad.p2());
  38   bottom_ = Edge(quad.p3(), quad.p4());
  39
  40   float sign = quad.IsCounterClockwise() ? -1 : 1;
  41   left_.scale(sign);
  42   right_.scale(sign);
  43   top_.scale(sign);
  44   bottom_.scale(sign);
  45 }
  46
  47 LayerQuad::LayerQuad(const Edge& left,
  48                      const Edge& top,
  49                      const Edge& right,
  50                      const Edge& bottom)
  51     : left_(left),
  52       top_(top),
  53       right_(right),
  54       bottom_(bottom) {}
  55
  56 gfx::QuadF LayerQuad::ToQuadF() const {
  57   size_t num_degenerate_edges = left_.degenerate() + right_.degenerate() +
  58                                 top_.degenerate() + bottom_.degenerate();
  59   if (num_degenerate_edges > 1) {
  60     return gfx::QuadF();
  61   }
  62
  63   if (left_.degenerate()) {
  64     return gfx::QuadF(top_.Intersect(bottom_), top_.Intersect(right_),
  65                       right_.Intersect(bottom_), bottom_.Intersect(top_));
  66   }
  67   if (right_.degenerate()) {
  68     return gfx::QuadF(left_.Intersect(top_), top_.Intersect(bottom_),
  69                       bottom_.Intersect(top_), bottom_.Intersect(left_));
  70   }
  71   if (top_.degenerate()) {
  72     return gfx::QuadF(left_.Intersect(right_), right_.Intersect(left_),
  73                       right_.Intersect(bottom_), bottom_.Intersect(left_));
  74   }
  75   if (bottom_.degenerate()) {
  76     return gfx::QuadF(left_.Intersect(top_), top_.Intersect(right_),
  77                       right_.Intersect(left_), left_.Intersect(right_));
  78   }
  79   return gfx::QuadF(left_.Intersect(top_),
  80                     top_.Intersect(right_),
  81                     right_.Intersect(bottom_),
  82                     bottom_.Intersect(left_));
  83 }
  84
  85 void LayerQuad::ToFloatArray(float flattened[12]) const {
  86   if (left_.degenerate()) {
  87     flattened[0] = bottom_.x();
  88     flattened[1] = bottom_.y();
  89     flattened[2] = bottom_.z();
  90   } else {
  91     flattened[0] = left_.x();
  92     flattened[1] = left_.y();
  93     flattened[2] = left_.z();
  94   }
  95   if (top_.degenerate()) {
  96     flattened[3] = left_.x();
  97     flattened[4] = left_.y();
  98     flattened[5] = left_.z();
  99   } else {
 100     flattened[3] = top_.x();
 101     flattened[4] = top_.y();
 102     flattened[5] = top_.z();
 103   }
 104   if (right_.degenerate()) {
 105     flattened[6] = top_.x();
 106     flattened[7] = top_.y();
 107     flattened[8] = top_.z();
 108   } else {
 109     flattened[6] = right_.x();
 110     flattened[7] = right_.y();
 111     flattened[8] = right_.z();
 112   }
 113   if (bottom_.degenerate()) {
 114     flattened[9] = right_.x();
 115     flattened[10] = right_.y();
 116     flattened[11] = right_.z();
 117   } else {
 118     flattened[9] = bottom_.x();
 119     flattened[10] = bottom_.y();
 120     flattened[11] = bottom_.z();
 121   }
 122 }
 123
 124 }  // namespace cc