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 class Vector2d;
  29 }
  30
  31 namespace cc {
  32
  33 struct HomogeneousCoordinate {
  34   HomogeneousCoordinate(SkMScalar x, SkMScalar y, SkMScalar z, SkMScalar w) {
  35     vec[0] = x;
  36     vec[1] = y;
  37     vec[2] = z;
  38     vec[3] = w;
  39   }
  40
  41   bool ShouldBeClipped() const { return w() <= 0.0; }
  42
  43   gfx::PointF CartesianPoint2d() const {
  44     if (w() == SK_MScalar1)
  45       return gfx::PointF(x(), y());
  46
  47     // For now, because this code is used privately only by MathUtil, it should
  48     // never be called when w == 0, and we do not yet need to handle that case.
  49     DCHECK(w());
  50     SkMScalar inv_w = SK_MScalar1 / w();
  51     return gfx::PointF(x() * inv_w, y() * inv_w);
  52   }
  53
  54   gfx::Point3F CartesianPoint3d() const {
  55     if (w() == SK_MScalar1)
  56       return gfx::Point3F(x(), y(), z());
  57
  58     // For now, because this code is used privately only by MathUtil, it should
  59     // never be called when w == 0, and we do not yet need to handle that case.
  60     DCHECK(w());
  61     SkMScalar inv_w = SK_MScalar1 / w();
  62     return gfx::Point3F(x() * inv_w, y() * inv_w, z() * inv_w);
  63   }
  64
  65   SkMScalar x() const { return vec[0]; }
  66   SkMScalar y() const { return vec[1]; }
  67   SkMScalar z() const { return vec[2]; }
  68   SkMScalar w() const { return vec[3]; }
  69
  70   SkMScalar vec[4];
  71 };
  72
  73 class CC_EXPORT MathUtil {
  74  public:
  75   static const double kPiDouble;
  76   static const float kPiFloat;
  77
  78   static double Deg2Rad(double deg) { return deg * kPiDouble / 180.0; }
  79   static double Rad2Deg(double rad) { return rad * 180.0 / kPiDouble; }
  80
  81   static float Deg2Rad(float deg) { return deg * kPiFloat / 180.0f; }
  82   static float Rad2Deg(float rad) { return rad * 180.0f / kPiFloat; }
  83
  84   static float Round(float f) {
  85     return (f > 0.f) ? std::floor(f + 0.5f) : std::ceil(f - 0.5f);
  86   }
  87   static double Round(double d) {
  88     return (d > 0.0) ? std::floor(d + 0.5) : std::ceil(d - 0.5);
  89   }
  90
  91   template <typename T> static T ClampToRange(T value, T min, T max) {
  92     return std::min(std::max(value, min), max);
  93   }
  94
  95   // Background: Existing transform code does not do the right thing in
  96   // MapRect / MapQuad / ProjectQuad when there is a perspective projection that
  97   // causes one of the transformed vertices to go to w < 0. In those cases, it
  98   // is necessary to perform clipping in homogeneous coordinates, after applying
  99   // the transform, before dividing-by-w to convert to cartesian coordinates.
 100   //
 101   // These functions return the axis-aligned rect that encloses the correctly
 102   // clipped, transformed polygon.
 103   static gfx::Rect MapEnclosingClippedRect(const gfx::Transform& transform,
 104                                            const gfx::Rect& rect);
 105   static gfx::RectF MapClippedRect(const gfx::Transform& transform,
 106                                    const gfx::RectF& rect);
 107   static gfx::Rect ProjectEnclosingClippedRect(const gfx::Transform& transform,
 108                                                const gfx::Rect& rect);
 109   static gfx::RectF ProjectClippedRect(const gfx::Transform& transform,
 110                                        const gfx::RectF& rect);
 111
 112   // Returns an array of vertices that represent the clipped polygon. After
 113   // returning, indexes from 0 to num_vertices_in_clipped_quad are valid in the
 114   // clipped_quad array. Note that num_vertices_in_clipped_quad may be zero,
 115   // which means the entire quad was clipped, and none of the vertices in the
 116   // array are valid.
 117   static void MapClippedQuad(const gfx::Transform& transform,
 118                              const gfx::QuadF& src_quad,
 119                              gfx::PointF clipped_quad[8],
 120                              int* num_vertices_in_clipped_quad);
 121
 122   static gfx::RectF ComputeEnclosingRectOfVertices(const gfx::PointF vertices[],
 123                                                    int num_vertices);
 124   static gfx::RectF ComputeEnclosingClippedRect(
 125       const HomogeneousCoordinate& h1,
 126       const HomogeneousCoordinate& h2,
 127       const HomogeneousCoordinate& h3,
 128       const HomogeneousCoordinate& h4);
 129
 130   // NOTE: These functions do not do correct clipping against w = 0 plane, but
 131   // they correctly detect the clipped condition via the boolean clipped.
 132   static gfx::QuadF MapQuad(const gfx::Transform& transform,
 133                             const gfx::QuadF& quad,
 134                             bool* clipped);
 135   static gfx::PointF MapPoint(const gfx::Transform& transform,
 136                               const gfx::PointF& point,
 137                               bool* clipped);
 138   static gfx::Point3F MapPoint(const gfx::Transform&,
 139                                const gfx::Point3F&,
 140                                bool* clipped);
 141   static gfx::QuadF ProjectQuad(const gfx::Transform& transform,
 142                                 const gfx::QuadF& quad,
 143                                 bool* clipped);
 144   static gfx::PointF ProjectPoint(const gfx::Transform& transform,
 145                                   const gfx::PointF& point,
 146                                   bool* clipped);
 147   // Identical to the above function, but coerces the homogeneous coordinate to
 148   // a 3d rather than a 2d point.
 149   static gfx::Point3F ProjectPoint3D(const gfx::Transform& transform,
 150                                      const gfx::PointF& point,
 151                                      bool* clipped);
 152
 153   static gfx::Vector2dF ComputeTransform2dScaleComponents(const gfx::Transform&,
 154                                                           float fallbackValue);
 155
 156   // Makes a rect that has the same relationship to input_outer_rect as
 157   // scale_inner_rect has to scale_outer_rect. scale_inner_rect should be
 158   // contained within scale_outer_rect, and likewise the rectangle that is
 159   // returned will be within input_outer_rect at a similar relative, scaled
 160   // position.
 161   static gfx::RectF ScaleRectProportional(const gfx::RectF& input_outer_rect,
 162                                           const gfx::RectF& scale_outer_rect,
 163                                           const gfx::RectF& scale_inner_rect);
 164
 165   // Returns the smallest angle between the given two vectors in degrees.
 166   // Neither vector is assumed to be normalized.
 167   static float SmallestAngleBetweenVectors(const gfx::Vector2dF& v1,
 168                                            const gfx::Vector2dF& v2);
 169
 170   // Projects the |source| vector onto |destination|. Neither vector is assumed
 171   // to be normalized.
 172   static gfx::Vector2dF ProjectVector(const gfx::Vector2dF& source,
 173                                       const gfx::Vector2dF& destination);
 174
 175   // Conversion to value.
 176   static scoped_ptr<base::Value> AsValue(const gfx::Size& s);
 177   static scoped_ptr<base::Value> AsValue(const gfx::SizeF& s);
 178   static scoped_ptr<base::Value> AsValue(const gfx::Rect& r);
 179   static bool FromValue(const base::Value*, gfx::Rect* out_rect);
 180   static scoped_ptr<base::Value> AsValue(const gfx::PointF& q);
 181   static scoped_ptr<base::Value> AsValue(const gfx::Point3F&);
 182   static scoped_ptr<base::Value> AsValue(const gfx::Vector2d& v);
 183   static scoped_ptr<base::Value> AsValue(const gfx::QuadF& q);
 184   static scoped_ptr<base::Value> AsValue(const gfx::RectF& rect);
 185   static scoped_ptr<base::Value> AsValue(const gfx::Transform& transform);
 186   static scoped_ptr<base::Value> AsValue(const gfx::BoxF& box);
 187
 188   // Returns a base::Value representation of the floating point value.
 189   // If the value is inf, returns max double/float representation.
 190   static scoped_ptr<base::Value> AsValueSafely(double value);
 191   static scoped_ptr<base::Value> AsValueSafely(float value);
 192 };
 193
 194 }  // namespace cc
 195
 196 #endif  // CC_BASE_MATH_UTIL_H_