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/geometry/box_f.h"
  16 #include "ui/gfx/geometry/point3_f.h"
  17 #include "ui/gfx/geometry/point_f.h"
  18 #include "ui/gfx/geometry/scroll_offset.h"
  19 #include "ui/gfx/geometry/size.h"
  20 #include "ui/gfx/transform.h"
  21
  22 namespace base {
  23 class Value;
  24 namespace trace_event {
  25 class TracedValue;
  26 }
  27 }  // namespace base
  28
  29 namespace gfx {
  30 class QuadF;
  31 class Rect;
  32 class RectF;
  33 class Transform;
  34 class Vector2dF;
  35 class Vector2d;
  36 }
  37
  38 namespace cc {
  39
  40 struct HomogeneousCoordinate {
  41   HomogeneousCoordinate(SkMScalar x, SkMScalar y, SkMScalar z, SkMScalar w) {
  42     vec[0] = x;
  43     vec[1] = y;
  44     vec[2] = z;
  45     vec[3] = w;
  46   }
  47
  48   bool ShouldBeClipped() const { return w() <= 0.0; }
  49
  50   gfx::PointF CartesianPoint2d() const {
  51     if (w() == SK_MScalar1)
  52       return gfx::PointF(x(), y());
  53
  54     // For now, because this code is used privately only by MathUtil, it should
  55     // never be called when w == 0, and we do not yet need to handle that case.
  56     DCHECK(w());
  57     SkMScalar inv_w = SK_MScalar1 / w();
  58     return gfx::PointF(x() * inv_w, y() * inv_w);
  59   }
  60
  61   gfx::Point3F CartesianPoint3d() const {
  62     if (w() == SK_MScalar1)
  63       return gfx::Point3F(x(), y(), z());
  64
  65     // For now, because this code is used privately only by MathUtil, it should
  66     // never be called when w == 0, and we do not yet need to handle that case.
  67     DCHECK(w());
  68     SkMScalar inv_w = SK_MScalar1 / w();
  69     return gfx::Point3F(x() * inv_w, y() * inv_w, z() * inv_w);
  70   }
  71
  72   SkMScalar x() const { return vec[0]; }
  73   SkMScalar y() const { return vec[1]; }
  74   SkMScalar z() const { return vec[2]; }
  75   SkMScalar w() const { return vec[3]; }
  76
  77   SkMScalar vec[4];
  78 };
  79
  80 class CC_EXPORT MathUtil {
  81  public:
  82   static const double kPiDouble;
  83   static const float kPiFloat;
  84
  85   static double Deg2Rad(double deg) { return deg * kPiDouble / 180.0; }
  86   static double Rad2Deg(double rad) { return rad * 180.0 / kPiDouble; }
  87
  88   static float Deg2Rad(float deg) { return deg * kPiFloat / 180.0f; }
  89   static float Rad2Deg(float rad) { return rad * 180.0f / kPiFloat; }
  90
  91   static float Round(float f) {
  92     return (f > 0.f) ? std::floor(f + 0.5f) : std::ceil(f - 0.5f);
  93   }
  94   static double Round(double d) {
  95     return (d > 0.0) ? std::floor(d + 0.5) : std::ceil(d - 0.5);
  96   }
  97
  98   template <typename T> static T ClampToRange(T value, T min, T max) {
  99     return std::min(std::max(value, min), max);
 100   }
 101
 102   // Background: Existing transform code does not do the right thing in
 103   // MapRect / MapQuad / ProjectQuad when there is a perspective projection that
 104   // causes one of the transformed vertices to go to w < 0. In those cases, it
 105   // is necessary to perform clipping in homogeneous coordinates, after applying
 106   // the transform, before dividing-by-w to convert to cartesian coordinates.
 107   //
 108   // These functions return the axis-aligned rect that encloses the correctly
 109   // clipped, transformed polygon.
 110   static gfx::Rect MapEnclosingClippedRect(const gfx::Transform& transform,
 111                                            const gfx::Rect& rect);
 112   static gfx::RectF MapClippedRect(const gfx::Transform& transform,
 113                                    const gfx::RectF& rect);
 114   static gfx::Rect ProjectEnclosingClippedRect(const gfx::Transform& transform,
 115                                                const gfx::Rect& rect);
 116   static gfx::RectF ProjectClippedRect(const gfx::Transform& transform,
 117                                        const gfx::RectF& rect);
 118
 119   // This function is only valid when the transform preserves 2d axis
 120   // alignment and the resulting rect will not be clipped.
 121   static gfx::Rect MapEnclosedRectWith2dAxisAlignedTransform(
 122       const gfx::Transform& transform,
 123       const gfx::Rect& rect);
 124
 125   // Returns an array of vertices that represent the clipped polygon. After
 126   // returning, indexes from 0 to num_vertices_in_clipped_quad are valid in the
 127   // clipped_quad array. Note that num_vertices_in_clipped_quad may be zero,
 128   // which means the entire quad was clipped, and none of the vertices in the
 129   // array are valid.
 130   static void MapClippedQuad(const gfx::Transform& transform,
 131                              const gfx::QuadF& src_quad,
 132                              gfx::PointF clipped_quad[8],
 133                              int* num_vertices_in_clipped_quad);
 134   static bool MapClippedQuad3d(const gfx::Transform& transform,
 135                                const gfx::QuadF& src_quad,
 136                                gfx::Point3F clipped_quad[8],
 137                                int* num_vertices_in_clipped_quad);
 138
 139   static gfx::RectF ComputeEnclosingRectOfVertices(const gfx::PointF vertices[],
 140                                                    int num_vertices);
 141   static gfx::RectF ComputeEnclosingClippedRect(
 142       const HomogeneousCoordinate& h1,
 143       const HomogeneousCoordinate& h2,
 144       const HomogeneousCoordinate& h3,
 145       const HomogeneousCoordinate& h4);
 146
 147   // NOTE: These functions do not do correct clipping against w = 0 plane, but
 148   // they correctly detect the clipped condition via the boolean clipped.
 149   static gfx::QuadF MapQuad(const gfx::Transform& transform,
 150                             const gfx::QuadF& quad,
 151                             bool* clipped);
 152   static gfx::QuadF MapQuad3d(const gfx::Transform& transform,
 153                               const gfx::QuadF& q,
 154                               gfx::Point3F* p,
 155                               bool* clipped);
 156   static gfx::PointF MapPoint(const gfx::Transform& transform,
 157                               const gfx::PointF& point,
 158                               bool* clipped);
 159   static gfx::Point3F MapPoint(const gfx::Transform&,
 160                                const gfx::Point3F&,
 161                                bool* clipped);
 162   static gfx::QuadF ProjectQuad(const gfx::Transform& transform,
 163                                 const gfx::QuadF& quad,
 164                                 bool* clipped);
 165   static gfx::PointF ProjectPoint(const gfx::Transform& transform,
 166                                   const gfx::PointF& point,
 167                                   bool* clipped);
 168   // Identical to the above function, but coerces the homogeneous coordinate to
 169   // a 3d rather than a 2d point.
 170   static gfx::Point3F ProjectPoint3D(const gfx::Transform& transform,
 171                                      const gfx::PointF& point,
 172                                      bool* clipped);
 173
 174   static gfx::Vector2dF ComputeTransform2dScaleComponents(const gfx::Transform&,
 175                                                           float fallbackValue);
 176
 177   // Makes a rect that has the same relationship to input_outer_rect as
 178   // scale_inner_rect has to scale_outer_rect. scale_inner_rect should be
 179   // contained within scale_outer_rect, and likewise the rectangle that is
 180   // returned will be within input_outer_rect at a similar relative, scaled
 181   // position.
 182   static gfx::RectF ScaleRectProportional(const gfx::RectF& input_outer_rect,
 183                                           const gfx::RectF& scale_outer_rect,
 184                                           const gfx::RectF& scale_inner_rect);
 185
 186   // Returns the smallest angle between the given two vectors in degrees.
 187   // Neither vector is assumed to be normalized.
 188   static float SmallestAngleBetweenVectors(const gfx::Vector2dF& v1,
 189                                            const gfx::Vector2dF& v2);
 190
 191   // Projects the |source| vector onto |destination|. Neither vector is assumed
 192   // to be normalized.
 193   static gfx::Vector2dF ProjectVector(const gfx::Vector2dF& source,
 194                                       const gfx::Vector2dF& destination);
 195
 196   // Conversion to value.
 197   static scoped_ptr<base::Value> AsValue(const gfx::Size& s);
 198   static scoped_ptr<base::Value> AsValue(const gfx::Rect& r);
 199   static bool FromValue(const base::Value*, gfx::Rect* out_rect);
 200   static scoped_ptr<base::Value> AsValue(const gfx::PointF& q);
 201
 202   static void AddToTracedValue(const char* name,
 203                                const gfx::Size& s,
 204                                base::trace_event::TracedValue* res);
 205   static void AddToTracedValue(const char* name,
 206                                const gfx::SizeF& s,
 207                                base::trace_event::TracedValue* res);
 208   static void AddToTracedValue(const char* name,
 209                                const gfx::Rect& r,
 210                                base::trace_event::TracedValue* res);
 211   static void AddToTracedValue(const char* name,
 212                                const gfx::PointF& q,
 213                                base::trace_event::TracedValue* res);
 214   static void AddToTracedValue(const char* name,
 215                                const gfx::Point3F&,
 216                                base::trace_event::TracedValue* res);
 217   static void AddToTracedValue(const char* name,
 218                                const gfx::Vector2d& v,
 219                                base::trace_event::TracedValue* res);
 220   static void AddToTracedValue(const char* name,
 221                                const gfx::Vector2dF& v,
 222                                base::trace_event::TracedValue* res);
 223   static void AddToTracedValue(const char* name,
 224                                const gfx::ScrollOffset& v,
 225                                base::trace_event::TracedValue* res);
 226   static void AddToTracedValue(const char* name,
 227                                const gfx::QuadF& q,
 228                                base::trace_event::TracedValue* res);
 229   static void AddToTracedValue(const char* name,
 230                                const gfx::RectF& rect,
 231                                base::trace_event::TracedValue* res);
 232   static void AddToTracedValue(const char* name,
 233                                const gfx::Transform& transform,
 234                                base::trace_event::TracedValue* res);
 235   static void AddToTracedValue(const char* name,
 236                                const gfx::BoxF& box,
 237                                base::trace_event::TracedValue* res);
 238
 239   // Returns a base::Value representation of the floating point value.
 240   // If the value is inf, returns max double/float representation.
 241   static double AsDoubleSafely(double value);
 242   static float AsFloatSafely(float value);
 243 };
 244
 245 }  // namespace cc
 246
 247 #endif  // CC_BASE_MATH_UTIL_H_