cc/base/math_util.h

   1 // Copyright 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 #ifndef CC_BASE_MATH_UTIL_H_
   6 #define CC_BASE_MATH_UTIL_H_
   7
   8 #include <algorithm>
   9 #include <cmath>
  10
  11 #include "base/logging.h"
  12 #include "base/memory/scoped_ptr.h"
  13 #include "cc/base/cc_export.h"
  14 #include "ui/gfx/point3_f.h"
  15 #include "ui/gfx/point_f.h"
  16 #include "ui/gfx/size.h"
  17 #include "ui/gfx/transform.h"
  18
  19 namespace base { class Value; }
  20
  21 namespace gfx {
  22 class QuadF;
  23 class Rect;
  24 class RectF;
  25 class Transform;
  26 class Vector2dF;
  27 }
  28
  29 namespace cc {
  30
  31 struct HomogeneousCoordinate {
  32   HomogeneousCoordinate(SkMScalar x, SkMScalar y, SkMScalar z, SkMScalar w) {
  33     vec[0] = x;
  34     vec[1] = y;
  35     vec[2] = z;
  36     vec[3] = w;
  37   }
  38
  39   bool ShouldBeClipped() const { return w() <= 0.0; }
  40
  41   gfx::PointF CartesianPoint2d() const {
  42     if (w() == 1.0)
  43       return gfx::PointF(x(), y());
  44
  45     // For now, because this code is used privately only by MathUtil, it should
  46     // never be called when w == 0, and we do not yet need to handle that case.
  47     DCHECK(w());
  48     double inv_w = 1.0 / w();
  49     return gfx::PointF(x() * inv_w, y() * inv_w);
  50   }
  51
  52   gfx::Point3F CartesianPoint3d() const {
  53     if (w() == 1)
  54       return gfx::Point3F(x(), y(), z());
  55
  56     // For now, because this code is used privately only by MathUtil, it should
  57     // never be called when w == 0, and we do not yet need to handle that case.
  58     DCHECK(w());
  59     double inv_w = 1.0 / w();
  60     return gfx::Point3F(x() * inv_w, y() * inv_w, z() * inv_w);
  61   }
  62
  63   SkMScalar x() const { return vec[0]; }
  64   SkMScalar y() const { return vec[1]; }
  65   SkMScalar z() const { return vec[2]; }
  66   SkMScalar w() const { return vec[3]; }
  67
  68   SkMScalar vec[4];
  69 };
  70
  71 class CC_EXPORT MathUtil {
  72  public:
  73   static const double kPiDouble;
  74   static const float kPiFloat;
  75
  76   static double Deg2Rad(double deg) { return deg * kPiDouble / 180.0; }
  77   static double Rad2Deg(double rad) { return rad * 180.0 / kPiDouble; }
  78
  79   static float Deg2Rad(float deg) { return deg * kPiFloat / 180.0f; }
  80   static float Rad2Deg(float rad) { return rad * 180.0f / kPiFloat; }
  81
  82   static float Round(float f) {
  83     return (f > 0.f) ? std::floor(f + 0.5f) : std::ceil(f - 0.5f);
  84   }
  85   static double Round(double d) {
  86     return (d > 0.0) ? std::floor(d + 0.5) : std::ceil(d - 0.5);
  87   }
  88
  89   template <typename T> static T ClampToRange(T value, T min, T max) {
  90     return std::min(std::max(value, min), max);
  91   }
  92
  93   // Background: Existing transform code does not do the right thing in
  94   // MapRect / MapQuad / ProjectQuad when there is a perspective projection that
  95   // causes one of the transformed vertices to go to w < 0. In those cases, it
  96   // is necessary to perform clipping in homogeneous coordinates, after applying
  97   // the transform, before dividing-by-w to convert to cartesian coordinates.
  98   //
  99   // These functions return the axis-aligned rect that encloses the correctly
 100   // clipped, transformed polygon.
 101   static gfx::Rect MapClippedRect(const gfx::Transform& transform,
 102                                   gfx::Rect rect);
 103   static gfx::RectF MapClippedRect(const gfx::Transform& transform,
 104                                    const gfx::RectF& rect);
 105   static gfx::RectF ProjectClippedRect(const gfx::Transform& transform,
 106                                        const gfx::RectF& rect);
 107
 108   // Returns an array of vertices that represent the clipped polygon. After
 109   // returning, indexes from 0 to num_vertices_in_clipped_quad are valid in the
 110   // clipped_quad array. Note that num_vertices_in_clipped_quad may be zero,
 111   // which means the entire quad was clipped, and none of the vertices in the
 112   // array are valid.
 113   static void MapClippedQuad(const gfx::Transform& transform,
 114                              const gfx::QuadF& src_quad,
 115                              gfx::PointF clipped_quad[8],
 116                              int* num_vertices_in_clipped_quad);
 117
 118   static gfx::RectF ComputeEnclosingRectOfVertices(gfx::PointF vertices[],
 119                                                    int num_vertices);
 120   static gfx::RectF ComputeEnclosingClippedRect(
 121       const HomogeneousCoordinate& h1,
 122       const HomogeneousCoordinate& h2,
 123       const HomogeneousCoordinate& h3,
 124       const HomogeneousCoordinate& h4);
 125
 126   // NOTE: These functions do not do correct clipping against w = 0 plane, but
 127   // they correctly detect the clipped condition via the boolean clipped.
 128   static gfx::QuadF MapQuad(const gfx::Transform& transform,
 129                             const gfx::QuadF& quad,
 130                             bool* clipped);
 131   static gfx::PointF MapPoint(const gfx::Transform& transform,
 132                               gfx::PointF point,
 133                               bool* clipped);
 134   static gfx::Point3F MapPoint(const gfx::Transform&,
 135                                const gfx::Point3F&,
 136                                bool* clipped);
 137   static gfx::QuadF ProjectQuad(const gfx::Transform& transform,
 138                                 const gfx::QuadF& quad,
 139                                 bool* clipped);
 140   static gfx::PointF ProjectPoint(const gfx::Transform& transform,
 141                                   gfx::PointF point,
 142                                   bool* clipped);
 143
 144   static gfx::Vector2dF ComputeTransform2dScaleComponents(const gfx::Transform&,
 145                                                           float fallbackValue);
 146
 147   // Returns the smallest angle between the given two vectors in degrees.
 148   // Neither vector is assumed to be normalized.
 149   static float SmallestAngleBetweenVectors(gfx::Vector2dF v1,
 150                                            gfx::Vector2dF v2);
 151
 152   // Projects the |source| vector onto |destination|. Neither vector is assumed
 153   // to be normalized.
 154   static gfx::Vector2dF ProjectVector(gfx::Vector2dF source,
 155                                       gfx::Vector2dF destination);
 156
 157   // Conversion to value.
 158   static scoped_ptr<base::Value> AsValue(gfx::Size s);
 159   static scoped_ptr<base::Value> AsValue(gfx::SizeF s);
 160   static scoped_ptr<base::Value> AsValue(gfx::Rect r);
 161   static bool FromValue(const base::Value*, gfx::Rect* out_rect);
 162   static scoped_ptr<base::Value> AsValue(gfx::PointF q);
 163   static scoped_ptr<base::Value> AsValue(const gfx::QuadF& q);
 164   static scoped_ptr<base::Value> AsValue(const gfx::RectF& rect);
 165   static scoped_ptr<base::Value> AsValue(const gfx::Transform& transform);
 166
 167   // Returns a base::Value representation of the floating point value.
 168   // If the value is inf, returns max double/float representation.
 169   static scoped_ptr<base::Value> AsValueSafely(double value);
 170   static scoped_ptr<base::Value> AsValueSafely(float value);
 171 };
 172
 173 }  // namespace cc
 174
 175 #endif  // CC_BASE_MATH_UTIL_H_