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 #include <vector>
  11
  12 #include "base/logging.h"
  13 #include "base/memory/scoped_ptr.h"
  14 #include "cc/base/cc_export.h"
  15 #include "ui/gfx/box_f.h"
  16 #include "ui/gfx/point3_f.h"
  17 #include "ui/gfx/point_f.h"
  18 #include "ui/gfx/size.h"
  19 #include "ui/gfx/transform.h"
  20
  21 namespace base {
  22 class Value;
  23 namespace debug {
  24 class TracedValue;
  25 }
  26 }
  27
  28 namespace gfx {
  29 class QuadF;
  30 class Rect;
  31 class RectF;
  32 class Transform;
  33 class Vector2dF;
  34 class Vector2d;
  35 }
  36
  37 namespace cc {
  38
  39 struct HomogeneousCoordinate {
  40   HomogeneousCoordinate(SkMScalar x, SkMScalar y, SkMScalar z, SkMScalar w) {
  41     vec[0] = x;
  42     vec[1] = y;
  43     vec[2] = z;
  44     vec[3] = w;
  45   }
  46
  47   bool ShouldBeClipped() const { return w() <= 0.0; }
  48
  49   gfx::PointF CartesianPoint2d() const {
  50     if (w() == SK_MScalar1)
  51       return gfx::PointF(x(), y());
  52
  53     // For now, because this code is used privately only by MathUtil, it should
  54     // never be called when w == 0, and we do not yet need to handle that case.
  55     DCHECK(w());
  56     SkMScalar inv_w = SK_MScalar1 / w();
  57     return gfx::PointF(x() * inv_w, y() * inv_w);
  58   }
  59
  60   gfx::Point3F CartesianPoint3d() const {
  61     if (w() == SK_MScalar1)
  62       return gfx::Point3F(x(), y(), z());
  63
  64     // For now, because this code is used privately only by MathUtil, it should
  65     // never be called when w == 0, and we do not yet need to handle that case.
  66     DCHECK(w());
  67     SkMScalar inv_w = SK_MScalar1 / w();
  68     return gfx::Point3F(x() * inv_w, y() * inv_w, z() * inv_w);
  69   }
  70
  71   SkMScalar x() const { return vec[0]; }
  72   SkMScalar y() const { return vec[1]; }
  73   SkMScalar z() const { return vec[2]; }
  74   SkMScalar w() const { return vec[3]; }
  75
  76   SkMScalar vec[4];
  77 };
  78
  79 class CC_EXPORT MathUtil {
  80  public:
  81   static const double kPiDouble;
  82   static const float kPiFloat;
  83
  84   static double Deg2Rad(double deg) { return deg * kPiDouble / 180.0; }
  85   static double Rad2Deg(double rad) { return rad * 180.0 / kPiDouble; }
  86
  87   static float Deg2Rad(float deg) { return deg * kPiFloat / 180.0f; }
  88   static float Rad2Deg(float rad) { return rad * 180.0f / kPiFloat; }
  89
  90   static float Round(float f) {
  91     return (f > 0.f) ? std::floor(f + 0.5f) : std::ceil(f - 0.5f);
  92   }
  93   static double Round(double d) {
  94     return (d > 0.0) ? std::floor(d + 0.5) : std::ceil(d - 0.5);
  95   }
  96
  97   template <typename T> static T ClampToRange(T value, T min, T max) {
  98     return std::min(std::max(value, min), max);
  99   }
 100
 101   // Background: Existing transform code does not do the right thing in
 102   // MapRect / MapQuad / ProjectQuad when there is a perspective projection that
 103   // causes one of the transformed vertices to go to w < 0. In those cases, it
 104   // is necessary to perform clipping in homogeneous coordinates, after applying
 105   // the transform, before dividing-by-w to convert to cartesian coordinates.
 106   //
 107   // These functions return the axis-aligned rect that encloses the correctly
 108   // clipped, transformed polygon.
 109   static gfx::Rect MapEnclosingClippedRect(const gfx::Transform& transform,
 110                                            const gfx::Rect& rect);
 111   static gfx::RectF MapClippedRect(const gfx::Transform& transform,
 112                                    const gfx::RectF& rect);
 113   static gfx::Rect ProjectEnclosingClippedRect(const gfx::Transform& transform,
 114                                                const gfx::Rect& rect);
 115   static gfx::RectF ProjectClippedRect(const gfx::Transform& transform,
 116                                        const gfx::RectF& rect);
 117
 118   // This function is only valid when the transform preserves 2d axis
 119   // alignment and the resulting rect will not be clipped.
 120   static gfx::Rect MapEnclosedRectWith2dAxisAlignedTransform(
 121       const gfx::Transform& transform,
 122       const gfx::Rect& rect);
 123
 124   // Returns an array of vertices that represent the clipped polygon. After
 125   // returning, indexes from 0 to num_vertices_in_clipped_quad are valid in the
 126   // clipped_quad array. Note that num_vertices_in_clipped_quad may be zero,
 127   // which means the entire quad was clipped, and none of the vertices in the
 128   // array are valid.
 129   static void MapClippedQuad(const gfx::Transform& transform,
 130                              const gfx::QuadF& src_quad,
 131                              gfx::PointF clipped_quad[8],
 132                              int* num_vertices_in_clipped_quad);
 133   static bool MapClippedQuad3d(const gfx::Transform& transform,
 134                                const gfx::QuadF& src_quad,
 135                                gfx::Point3F clipped_quad[8],
 136                                int* num_vertices_in_clipped_quad);
 137
 138   static gfx::RectF ComputeEnclosingRectOfVertices(const gfx::PointF vertices[],
 139                                                    int num_vertices);
 140   static gfx::RectF ComputeEnclosingClippedRect(
 141       const HomogeneousCoordinate& h1,
 142       const HomogeneousCoordinate& h2,
 143       const HomogeneousCoordinate& h3,
 144       const HomogeneousCoordinate& h4);
 145
 146   // NOTE: These functions do not do correct clipping against w = 0 plane, but
 147   // they correctly detect the clipped condition via the boolean clipped.
 148   static gfx::QuadF MapQuad(const gfx::Transform& transform,
 149                             const gfx::QuadF& quad,
 150                             bool* clipped);
 151   static gfx::QuadF MapQuad3d(const gfx::Transform& transform,
 152                               const gfx::QuadF& q,
 153                               gfx::Point3F* p,
 154                               bool* clipped);
 155   static gfx::PointF MapPoint(const gfx::Transform& transform,
 156                               const gfx::PointF& point,
 157                               bool* clipped);
 158   static gfx::Point3F MapPoint(const gfx::Transform&,
 159                                const gfx::Point3F&,
 160                                bool* clipped);
 161   static gfx::QuadF ProjectQuad(const gfx::Transform& transform,
 162                                 const gfx::QuadF& quad,
 163                                 bool* clipped);
 164   static gfx::PointF ProjectPoint(const gfx::Transform& transform,
 165                                   const gfx::PointF& point,
 166                                   bool* clipped);
 167   // Identical to the above function, but coerces the homogeneous coordinate to
 168   // a 3d rather than a 2d point.
 169   static gfx::Point3F ProjectPoint3D(const gfx::Transform& transform,
 170                                      const gfx::PointF& point,
 171                                      bool* clipped);
 172
 173   static gfx::Vector2dF ComputeTransform2dScaleComponents(const gfx::Transform&,
 174                                                           float fallbackValue);
 175
 176   // Makes a rect that has the same relationship to input_outer_rect as
 177   // scale_inner_rect has to scale_outer_rect. scale_inner_rect should be
 178   // contained within scale_outer_rect, and likewise the rectangle that is
 179   // returned will be within input_outer_rect at a similar relative, scaled
 180   // position.
 181   static gfx::RectF ScaleRectProportional(const gfx::RectF& input_outer_rect,
 182                                           const gfx::RectF& scale_outer_rect,
 183                                           const gfx::RectF& scale_inner_rect);
 184
 185   // Returns the smallest angle between the given two vectors in degrees.
 186   // Neither vector is assumed to be normalized.
 187   static float SmallestAngleBetweenVectors(const gfx::Vector2dF& v1,
 188                                            const gfx::Vector2dF& v2);
 189
 190   // Projects the |source| vector onto |destination|. Neither vector is assumed
 191   // to be normalized.
 192   static gfx::Vector2dF ProjectVector(const gfx::Vector2dF& source,
 193                                       const gfx::Vector2dF& destination);
 194
 195   // Conversion to value.
 196   static scoped_ptr<base::Value> AsValue(const gfx::Size& s);
 197   static scoped_ptr<base::Value> AsValue(const gfx::Rect& r);
 198   static bool FromValue(const base::Value*, gfx::Rect* out_rect);
 199   static scoped_ptr<base::Value> AsValue(const gfx::PointF& q);
 200
 201   static void AddToTracedValue(const gfx::Size& s,
 202                                base::debug::TracedValue* res);
 203   static void AddToTracedValue(const gfx::SizeF& s,
 204                                base::debug::TracedValue* res);
 205   static void AddToTracedValue(const gfx::Rect& r,
 206                                base::debug::TracedValue* res);
 207   static void AddToTracedValue(const gfx::PointF& q,
 208                                base::debug::TracedValue* res);
 209   static void AddToTracedValue(const gfx::Point3F&,
 210                                base::debug::TracedValue* res);
 211   static void AddToTracedValue(const gfx::Vector2d& v,
 212                                base::debug::TracedValue* res);
 213   static void AddToTracedValue(const gfx::Vector2dF& v,
 214                                base::debug::TracedValue* res);
 215   static void AddToTracedValue(const gfx::QuadF& q,
 216                                base::debug::TracedValue* res);
 217   static void AddToTracedValue(const gfx::RectF& rect,
 218                                base::debug::TracedValue* res);
 219   static void AddToTracedValue(const gfx::Transform& transform,
 220                                base::debug::TracedValue* res);
 221   static void AddToTracedValue(const gfx::BoxF& box,
 222                                base::debug::TracedValue* res);
 223
 224   // Returns a base::Value representation of the floating point value.
 225   // If the value is inf, returns max double/float representation.
 226   static double AsDoubleSafely(double value);
 227   static float AsFloatSafely(float value);
 228 };
 229
 230 }  // namespace cc
 231
 232 #endif  // CC_BASE_MATH_UTIL_H_