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Issue 109433013: Move geometric types to a separate, more lightweight target. (Closed) Base URL: svn://svn.chromium.org/chrome/trunk/src
Patch Set: . Created 7 years ago
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1 // Copyright (c) 2012 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 "ui/gfx/quad_f.h"
6
7 #include <limits>
8
9 #include "base/strings/stringprintf.h"
10
11 namespace gfx {
12
13 void QuadF::operator=(const RectF& rect) {
14 p1_ = PointF(rect.x(), rect.y());
15 p2_ = PointF(rect.right(), rect.y());
16 p3_ = PointF(rect.right(), rect.bottom());
17 p4_ = PointF(rect.x(), rect.bottom());
18 }
19
20 std::string QuadF::ToString() const {
21 return base::StringPrintf("%s;%s;%s;%s",
22 p1_.ToString().c_str(),
23 p2_.ToString().c_str(),
24 p3_.ToString().c_str(),
25 p4_.ToString().c_str());
26 }
27
28 static inline bool WithinEpsilon(float a, float b) {
29 return std::abs(a - b) < std::numeric_limits<float>::epsilon();
30 }
31
32 bool QuadF::IsRectilinear() const {
33 return
34 (WithinEpsilon(p1_.x(), p2_.x()) && WithinEpsilon(p2_.y(), p3_.y()) &&
35 WithinEpsilon(p3_.x(), p4_.x()) && WithinEpsilon(p4_.y(), p1_.y())) ||
36 (WithinEpsilon(p1_.y(), p2_.y()) && WithinEpsilon(p2_.x(), p3_.x()) &&
37 WithinEpsilon(p3_.y(), p4_.y()) && WithinEpsilon(p4_.x(), p1_.x()));
38 }
39
40 bool QuadF::IsCounterClockwise() const {
41 // This math computes the signed area of the quad. Positive area
42 // indicates the quad is clockwise; negative area indicates the quad is
43 // counter-clockwise. Note carefully: this is backwards from conventional
44 // math because our geometric space uses screen coordiantes with y-axis
45 // pointing downards.
46 // Reference: http://mathworld.wolfram.com/PolygonArea.html
47
48 // Up-cast to double so this cannot overflow.
49 double determinant1 = static_cast<double>(p1_.x()) * p2_.y()
50 - static_cast<double>(p2_.x()) * p1_.y();
51 double determinant2 = static_cast<double>(p2_.x()) * p3_.y()
52 - static_cast<double>(p3_.x()) * p2_.y();
53 double determinant3 = static_cast<double>(p3_.x()) * p4_.y()
54 - static_cast<double>(p4_.x()) * p3_.y();
55 double determinant4 = static_cast<double>(p4_.x()) * p1_.y()
56 - static_cast<double>(p1_.x()) * p4_.y();
57
58 return determinant1 + determinant2 + determinant3 + determinant4 < 0;
59 }
60
61 static inline bool PointIsInTriangle(const PointF& point,
62 const PointF& r1,
63 const PointF& r2,
64 const PointF& r3) {
65 // Compute the barycentric coordinates of |point| relative to the triangle
66 // (r1, r2, r3). This algorithm comes from Christer Ericson's Real-Time
67 // Collision Detection.
68 Vector2dF v0 = r2 - r1;
69 Vector2dF v1 = r3 - r1;
70 Vector2dF v2 = point - r1;
71
72 double dot00 = DotProduct(v0, v0);
73 double dot01 = DotProduct(v0, v1);
74 double dot11 = DotProduct(v1, v1);
75 double dot20 = DotProduct(v2, v0);
76 double dot21 = DotProduct(v2, v1);
77
78 double denom = dot00 * dot11 - dot01 * dot01;
79
80 double v = (dot11 * dot20 - dot01 * dot21) / denom;
81 double w = (dot00 * dot21 - dot01 * dot20) / denom;
82 double u = 1 - v - w;
83
84 // Use the barycentric coordinates to test if |point| is inside the
85 // triangle (r1, r2, r2).
86 return (v >= 0) && (w >= 0) && (u >= 0);
87 }
88
89 bool QuadF::Contains(const PointF& point) const {
90 return PointIsInTriangle(point, p1_, p2_, p3_)
91 || PointIsInTriangle(point, p1_, p3_, p4_);
92 }
93
94 void QuadF::Scale(float x_scale, float y_scale) {
95 p1_.Scale(x_scale, y_scale);
96 p2_.Scale(x_scale, y_scale);
97 p3_.Scale(x_scale, y_scale);
98 p4_.Scale(x_scale, y_scale);
99 }
100
101 void QuadF::operator+=(const Vector2dF& rhs) {
102 p1_ += rhs;
103 p2_ += rhs;
104 p3_ += rhs;
105 p4_ += rhs;
106 }
107
108 void QuadF::operator-=(const Vector2dF& rhs) {
109 p1_ -= rhs;
110 p2_ -= rhs;
111 p3_ -= rhs;
112 p4_ -= rhs;
113 }
114
115 QuadF operator+(const QuadF& lhs, const Vector2dF& rhs) {
116 QuadF result = lhs;
117 result += rhs;
118 return result;
119 }
120
121 QuadF operator-(const QuadF& lhs, const Vector2dF& rhs) {
122 QuadF result = lhs;
123 result -= rhs;
124 return result;
125 }
126
127 } // namespace gfx
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