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/box_f.h"
  15 #include "ui/gfx/point3_f.h"
  16 #include "ui/gfx/point_f.h"
  17 #include "ui/gfx/size.h"
  18 #include "ui/gfx/transform.h"
  19
  20 namespace base { class Value; }
  21
  22 namespace gfx {
  23 class QuadF;
  24 class Rect;
  25 class RectF;
  26 class Transform;
  27 class Vector2dF;
  28 }
  29
  30 namespace cc {
  31
  32 struct HomogeneousCoordinate {
  33   HomogeneousCoordinate(SkMScalar x, SkMScalar y, SkMScalar z, SkMScalar w) {
  34     vec[0] = x;
  35     vec[1] = y;
  36     vec[2] = z;
  37     vec[3] = w;
  38   }
  39
  40   bool ShouldBeClipped() const { return w() <= 0.0; }
  41
  42   gfx::PointF CartesianPoint2d() const {
  43     if (w() == SK_MScalar1)
  44       return gfx::PointF(x(), y());
  45
  46     // For now, because this code is used privately only by MathUtil, it should
  47     // never be called when w == 0, and we do not yet need to handle that case.
  48     DCHECK(w());
  49     SkMScalar inv_w = SK_MScalar1 / w();
  50     return gfx::PointF(x() * inv_w, y() * inv_w);
  51   }
  52
  53   gfx::Point3F CartesianPoint3d() const {
  54     if (w() == SK_MScalar1)
  55       return gfx::Point3F(x(), y(), z());
  56
  57     // For now, because this code is used privately only by MathUtil, it should
  58     // never be called when w == 0, and we do not yet need to handle that case.
  59     DCHECK(w());
  60     SkMScalar inv_w = SK_MScalar1 / w();
  61     return gfx::Point3F(x() * inv_w, y() * inv_w, z() * inv_w);
  62   }
  63
  64   SkMScalar x() const { return vec[0]; }
  65   SkMScalar y() const { return vec[1]; }
  66   SkMScalar z() const { return vec[2]; }
  67   SkMScalar w() const { return vec[3]; }
  68
  69   SkMScalar vec[4];
  70 };
  71
  72 class CC_EXPORT MathUtil {
  73  public:
  74   static const double kPiDouble;
  75   static const float kPiFloat;
  76
  77   static double Deg2Rad(double deg) { return deg * kPiDouble / 180.0; }
  78   static double Rad2Deg(double rad) { return rad * 180.0 / kPiDouble; }
  79
  80   static float Deg2Rad(float deg) { return deg * kPiFloat / 180.0f; }
  81   static float Rad2Deg(float rad) { return rad * 180.0f / kPiFloat; }
  82
  83   static float Round(float f) {
  84     return (f > 0.f) ? std::floor(f + 0.5f) : std::ceil(f - 0.5f);
  85   }
  86   static double Round(double d) {
  87     return (d > 0.0) ? std::floor(d + 0.5) : std::ceil(d - 0.5);
  88   }
  89
  90   template <typename T> static T ClampToRange(T value, T min, T max) {
  91     return std::min(std::max(value, min), max);
  92   }
  93
  94   // Background: Existing transform code does not do the right thing in
  95   // MapRect / MapQuad / ProjectQuad when there is a perspective projection that
  96   // causes one of the transformed vertices to go to w < 0. In those cases, it
  97   // is necessary to perform clipping in homogeneous coordinates, after applying
  98   // the transform, before dividing-by-w to convert to cartesian coordinates.
  99   //
 100   // These functions return the axis-aligned rect that encloses the correctly
 101   // clipped, transformed polygon.
 102   static gfx::Rect MapClippedRect(const gfx::Transform& transform,
 103                                   const gfx::Rect& rect);
 104   static gfx::RectF MapClippedRect(const gfx::Transform& transform,
 105                                    const gfx::RectF& rect);
 106   static gfx::RectF ProjectClippedRect(const gfx::Transform& transform,
 107                                        const gfx::RectF& rect);
 108
 109   // Returns an array of vertices that represent the clipped polygon. After
 110   // returning, indexes from 0 to num_vertices_in_clipped_quad are valid in the
 111   // clipped_quad array. Note that num_vertices_in_clipped_quad may be zero,
 112   // which means the entire quad was clipped, and none of the vertices in the
 113   // array are valid.
 114   static void MapClippedQuad(const gfx::Transform& transform,
 115                              const gfx::QuadF& src_quad,
 116                              gfx::PointF clipped_quad[8],
 117                              int* num_vertices_in_clipped_quad);
 118
 119   static gfx::RectF ComputeEnclosingRectOfVertices(const gfx::PointF vertices[],
 120                                                    int num_vertices);
 121   static gfx::RectF ComputeEnclosingClippedRect(
 122       const HomogeneousCoordinate& h1,
 123       const HomogeneousCoordinate& h2,
 124       const HomogeneousCoordinate& h3,
 125       const HomogeneousCoordinate& h4);
 126
 127   // NOTE: These functions do not do correct clipping against w = 0 plane, but
 128   // they correctly detect the clipped condition via the boolean clipped.
 129   static gfx::QuadF MapQuad(const gfx::Transform& transform,
 130                             const gfx::QuadF& quad,
 131                             bool* clipped);
 132   static gfx::PointF MapPoint(const gfx::Transform& transform,
 133                               const gfx::PointF& point,
 134                               bool* clipped);
 135   static gfx::Point3F MapPoint(const gfx::Transform&,
 136                                const gfx::Point3F&,
 137                                bool* clipped);
 138   static gfx::QuadF ProjectQuad(const gfx::Transform& transform,
 139                                 const gfx::QuadF& quad,
 140                                 bool* clipped);
 141   static gfx::PointF ProjectPoint(const gfx::Transform& transform,
 142                                   const gfx::PointF& point,
 143                                   bool* clipped);
 144
 145   static gfx::Vector2dF ComputeTransform2dScaleComponents(const gfx::Transform&,
 146                                                           float fallbackValue);
 147
 148   // Makes a rect that has the same relationship to input_outer_rect as
 149   // scale_inner_rect has to scale_outer_rect. scale_inner_rect should be
 150   // contained within scale_outer_rect, and likewise the rectangle that is
 151   // returned will be within input_outer_rect at a similar relative, scaled
 152   // position.
 153   static gfx::RectF ScaleRectProportional(const gfx::RectF& input_outer_rect,
 154                                           const gfx::RectF& scale_outer_rect,
 155                                           const gfx::RectF& scale_inner_rect);
 156
 157   // Returns the smallest angle between the given two vectors in degrees.
 158   // Neither vector is assumed to be normalized.
 159   static float SmallestAngleBetweenVectors(const gfx::Vector2dF& v1,
 160                                            const gfx::Vector2dF& v2);
 161
 162   // Projects the |source| vector onto |destination|. Neither vector is assumed
 163   // to be normalized.
 164   static gfx::Vector2dF ProjectVector(const gfx::Vector2dF& source,
 165                                       const gfx::Vector2dF& destination);
 166
 167   // Conversion to value.
 168   static scoped_ptr<base::Value> AsValue(gfx::Size s);
 169   static scoped_ptr<base::Value> AsValue(const gfx::SizeF& s);
 170   static scoped_ptr<base::Value> AsValue(const gfx::Rect& r);
 171   static bool FromValue(const base::Value*, gfx::Rect* out_rect);
 172   static scoped_ptr<base::Value> AsValue(const gfx::PointF& q);
 173   static scoped_ptr<base::Value> AsValue(const gfx::QuadF& q);
 174   static scoped_ptr<base::Value> AsValue(const gfx::RectF& rect);
 175   static scoped_ptr<base::Value> AsValue(const gfx::Transform& transform);
 176   static scoped_ptr<base::Value> AsValue(const gfx::BoxF& box);
 177
 178   // Returns a base::Value representation of the floating point value.
 179   // If the value is inf, returns max double/float representation.
 180   static scoped_ptr<base::Value> AsValueSafely(double value);
 181   static scoped_ptr<base::Value> AsValueSafely(float value);
 182 };
 183
 184 }  // namespace cc
 185
 186 #endif  // CC_BASE_MATH_UTIL_H_