cc/base/math_util.cc

   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 #include "cc/base/math_util.h"
   6
   7 #include <algorithm>
   8 #include <cmath>
   9 #include <limits>
  10
  11 #include "base/values.h"
  12 #include "ui/gfx/quad_f.h"
  13 #include "ui/gfx/rect.h"
  14 #include "ui/gfx/rect_conversions.h"
  15 #include "ui/gfx/rect_f.h"
  16 #include "ui/gfx/transform.h"
  17 #include "ui/gfx/vector2d_f.h"
  18
  19 namespace cc {
  20
  21 const double MathUtil::kPiDouble = 3.14159265358979323846;
  22 const float MathUtil::kPiFloat = 3.14159265358979323846f;
  23
  24 static HomogeneousCoordinate ProjectHomogeneousPoint(
  25     const gfx::Transform& transform,
  26     const gfx::PointF& p) {
  27   // In this case, the layer we are trying to project onto is perpendicular to
  28   // ray (point p and z-axis direction) that we are trying to project. This
  29   // happens when the layer is rotated so that it is infinitesimally thin, or
  30   // when it is co-planar with the camera origin -- i.e. when the layer is
  31   // invisible anyway.
  32   if (!transform.matrix().get(2, 2))
  33     return HomogeneousCoordinate(0.0, 0.0, 0.0, 1.0);
  34
  35   SkMScalar z = -(transform.matrix().get(2, 0) * p.x() +
  36              transform.matrix().get(2, 1) * p.y() +
  37              transform.matrix().get(2, 3)) /
  38              transform.matrix().get(2, 2);
  39   HomogeneousCoordinate result(p.x(), p.y(), z, 1.0);
  40   transform.matrix().mapMScalars(result.vec, result.vec);
  41   return result;
  42 }
  43
  44 static HomogeneousCoordinate MapHomogeneousPoint(
  45     const gfx::Transform& transform,
  46     const gfx::Point3F& p) {
  47   HomogeneousCoordinate result(p.x(), p.y(), p.z(), 1.0);
  48   transform.matrix().mapMScalars(result.vec, result.vec);
  49   return result;
  50 }
  51
  52 static HomogeneousCoordinate ComputeClippedPointForEdge(
  53     const HomogeneousCoordinate& h1,
  54     const HomogeneousCoordinate& h2) {
  55   // Points h1 and h2 form a line in 4d, and any point on that line can be
  56   // represented as an interpolation between h1 and h2:
  57   //    p = (1-t) h1 + (t) h2
  58   //
  59   // We want to compute point p such that p.w == epsilon, where epsilon is a
  60   // small non-zero number. (but the smaller the number is, the higher the risk
  61   // of overflow)
  62   // To do this, we solve for t in the following equation:
  63   //    p.w = epsilon = (1-t) * h1.w + (t) * h2.w
  64   //
  65   // Once paramter t is known, the rest of p can be computed via
  66   //    p = (1-t) h1 + (t) h2.
  67
  68   // Technically this is a special case of the following assertion, but its a
  69   // good idea to keep it an explicit sanity check here.
  70   DCHECK_NE(h2.w(), h1.w());
  71   // Exactly one of h1 or h2 (but not both) must be on the negative side of the
  72   // w plane when this is called.
  73   DCHECK(h1.ShouldBeClipped() ^ h2.ShouldBeClipped());
  74
  75   // ...or any positive non-zero small epsilon
  76   SkMScalar w = 0.00001f;
  77   SkMScalar t = (w - h1.w()) / (h2.w() - h1.w());
  78
  79   SkMScalar x = (SK_MScalar1 - t) * h1.x() + t * h2.x();
  80   SkMScalar y = (SK_MScalar1 - t) * h1.y() + t * h2.y();
  81   SkMScalar z = (SK_MScalar1 - t) * h1.z() + t * h2.z();
  82
  83   return HomogeneousCoordinate(x, y, z, w);
  84 }
  85
  86 static inline void ExpandBoundsToIncludePoint(float* xmin,
  87                                               float* xmax,
  88                                               float* ymin,
  89                                               float* ymax,
  90                                               const gfx::PointF& p) {
  91   *xmin = std::min(p.x(), *xmin);
  92   *xmax = std::max(p.x(), *xmax);
  93   *ymin = std::min(p.y(), *ymin);
  94   *ymax = std::max(p.y(), *ymax);
  95 }
  96
  97 static inline void AddVertexToClippedQuad(const gfx::PointF& new_vertex,
  98                                           gfx::PointF clipped_quad[8],
  99                                           int* num_vertices_in_clipped_quad) {
 100   clipped_quad[*num_vertices_in_clipped_quad] = new_vertex;
 101   (*num_vertices_in_clipped_quad)++;
 102 }
 103
 104 gfx::Rect MathUtil::MapClippedRect(const gfx::Transform& transform,
 105                                    const gfx::Rect& src_rect) {
 106   return gfx::ToEnclosingRect(MapClippedRect(transform, gfx::RectF(src_rect)));
 107 }
 108
 109 gfx::RectF MathUtil::MapClippedRect(const gfx::Transform& transform,
 110                                     const gfx::RectF& src_rect) {
 111   if (transform.IsIdentityOrTranslation()) {
 112     return src_rect +
 113            gfx::Vector2dF(SkMScalarToFloat(transform.matrix().get(0, 3)),
 114                           SkMScalarToFloat(transform.matrix().get(1, 3)));
 115   }
 116
 117   // Apply the transform, but retain the result in homogeneous coordinates.
 118
 119   SkMScalar quad[4 * 2];  // input: 4 x 2D points
 120   quad[0] = src_rect.x();
 121   quad[1] = src_rect.y();
 122   quad[2] = src_rect.right();
 123   quad[3] = src_rect.y();
 124   quad[4] = src_rect.right();
 125   quad[5] = src_rect.bottom();
 126   quad[6] = src_rect.x();
 127   quad[7] = src_rect.bottom();
 128
 129   SkMScalar result[4 * 4];  // output: 4 x 4D homogeneous points
 130   transform.matrix().map2(quad, 4, result);
 131
 132   HomogeneousCoordinate hc0(result[0], result[1], result[2], result[3]);
 133   HomogeneousCoordinate hc1(result[4], result[5], result[6], result[7]);
 134   HomogeneousCoordinate hc2(result[8], result[9], result[10], result[11]);
 135   HomogeneousCoordinate hc3(result[12], result[13], result[14], result[15]);
 136   return ComputeEnclosingClippedRect(hc0, hc1, hc2, hc3);
 137 }
 138
 139 gfx::RectF MathUtil::ProjectClippedRect(const gfx::Transform& transform,
 140                                         const gfx::RectF& src_rect) {
 141   if (transform.IsIdentityOrTranslation()) {
 142     return src_rect +
 143            gfx::Vector2dF(SkMScalarToFloat(transform.matrix().get(0, 3)),
 144                           SkMScalarToFloat(transform.matrix().get(1, 3)));
 145   }
 146
 147   // Perform the projection, but retain the result in homogeneous coordinates.
 148   gfx::QuadF q = gfx::QuadF(src_rect);
 149   HomogeneousCoordinate h1 = ProjectHomogeneousPoint(transform, q.p1());
 150   HomogeneousCoordinate h2 = ProjectHomogeneousPoint(transform, q.p2());
 151   HomogeneousCoordinate h3 = ProjectHomogeneousPoint(transform, q.p3());
 152   HomogeneousCoordinate h4 = ProjectHomogeneousPoint(transform, q.p4());
 153
 154   return ComputeEnclosingClippedRect(h1, h2, h3, h4);
 155 }
 156
 157 void MathUtil::MapClippedQuad(const gfx::Transform& transform,
 158                               const gfx::QuadF& src_quad,
 159                               gfx::PointF clipped_quad[8],
 160                               int* num_vertices_in_clipped_quad) {
 161   HomogeneousCoordinate h1 =
 162       MapHomogeneousPoint(transform, gfx::Point3F(src_quad.p1()));
 163   HomogeneousCoordinate h2 =
 164       MapHomogeneousPoint(transform, gfx::Point3F(src_quad.p2()));
 165   HomogeneousCoordinate h3 =
 166       MapHomogeneousPoint(transform, gfx::Point3F(src_quad.p3()));
 167   HomogeneousCoordinate h4 =
 168       MapHomogeneousPoint(transform, gfx::Point3F(src_quad.p4()));
 169
 170   // The order of adding the vertices to the array is chosen so that
 171   // clockwise / counter-clockwise orientation is retained.
 172
 173   *num_vertices_in_clipped_quad = 0;
 174
 175   if (!h1.ShouldBeClipped()) {
 176     AddVertexToClippedQuad(
 177         h1.CartesianPoint2d(), clipped_quad, num_vertices_in_clipped_quad);
 178   }
 179
 180   if (h1.ShouldBeClipped() ^ h2.ShouldBeClipped()) {
 181     AddVertexToClippedQuad(
 182         ComputeClippedPointForEdge(h1, h2).CartesianPoint2d(),
 183         clipped_quad,
 184         num_vertices_in_clipped_quad);
 185   }
 186
 187   if (!h2.ShouldBeClipped()) {
 188     AddVertexToClippedQuad(
 189         h2.CartesianPoint2d(), clipped_quad, num_vertices_in_clipped_quad);
 190   }
 191
 192   if (h2.ShouldBeClipped() ^ h3.ShouldBeClipped()) {
 193     AddVertexToClippedQuad(
 194         ComputeClippedPointForEdge(h2, h3).CartesianPoint2d(),
 195         clipped_quad,
 196         num_vertices_in_clipped_quad);
 197   }
 198
 199   if (!h3.ShouldBeClipped()) {
 200     AddVertexToClippedQuad(
 201         h3.CartesianPoint2d(), clipped_quad, num_vertices_in_clipped_quad);
 202   }
 203
 204   if (h3.ShouldBeClipped() ^ h4.ShouldBeClipped()) {
 205     AddVertexToClippedQuad(
 206         ComputeClippedPointForEdge(h3, h4).CartesianPoint2d(),
 207         clipped_quad,
 208         num_vertices_in_clipped_quad);
 209   }
 210
 211   if (!h4.ShouldBeClipped()) {
 212     AddVertexToClippedQuad(
 213         h4.CartesianPoint2d(), clipped_quad, num_vertices_in_clipped_quad);
 214   }
 215
 216   if (h4.ShouldBeClipped() ^ h1.ShouldBeClipped()) {
 217     AddVertexToClippedQuad(
 218         ComputeClippedPointForEdge(h4, h1).CartesianPoint2d(),
 219         clipped_quad,
 220         num_vertices_in_clipped_quad);
 221   }
 222
 223   DCHECK_LE(*num_vertices_in_clipped_quad, 8);
 224 }
 225
 226 gfx::RectF MathUtil::ComputeEnclosingRectOfVertices(
 227     const gfx::PointF vertices[],
 228     int num_vertices) {
 229   if (num_vertices < 2)
 230     return gfx::RectF();
 231
 232   float xmin = std::numeric_limits<float>::max();
 233   float xmax = -std::numeric_limits<float>::max();
 234   float ymin = std::numeric_limits<float>::max();
 235   float ymax = -std::numeric_limits<float>::max();
 236
 237   for (int i = 0; i < num_vertices; ++i)
 238     ExpandBoundsToIncludePoint(&xmin, &xmax, &ymin, &ymax, vertices[i]);
 239
 240   return gfx::RectF(gfx::PointF(xmin, ymin),
 241                     gfx::SizeF(xmax - xmin, ymax - ymin));
 242 }
 243
 244 gfx::RectF MathUtil::ComputeEnclosingClippedRect(
 245     const HomogeneousCoordinate& h1,
 246     const HomogeneousCoordinate& h2,
 247     const HomogeneousCoordinate& h3,
 248     const HomogeneousCoordinate& h4) {
 249   // This function performs clipping as necessary and computes the enclosing 2d
 250   // gfx::RectF of the vertices. Doing these two steps simultaneously allows us
 251   // to avoid the overhead of storing an unknown number of clipped vertices.
 252
 253   // If no vertices on the quad are clipped, then we can simply return the
 254   // enclosing rect directly.
 255   bool something_clipped = h1.ShouldBeClipped() || h2.ShouldBeClipped() ||
 256                            h3.ShouldBeClipped() || h4.ShouldBeClipped();
 257   if (!something_clipped) {
 258     gfx::QuadF mapped_quad = gfx::QuadF(h1.CartesianPoint2d(),
 259                                         h2.CartesianPoint2d(),
 260                                         h3.CartesianPoint2d(),
 261                                         h4.CartesianPoint2d());
 262     return mapped_quad.BoundingBox();
 263   }
 264
 265   bool everything_clipped = h1.ShouldBeClipped() && h2.ShouldBeClipped() &&
 266                             h3.ShouldBeClipped() && h4.ShouldBeClipped();
 267   if (everything_clipped)
 268     return gfx::RectF();
 269
 270   float xmin = std::numeric_limits<float>::max();
 271   float xmax = -std::numeric_limits<float>::max();
 272   float ymin = std::numeric_limits<float>::max();
 273   float ymax = -std::numeric_limits<float>::max();
 274
 275   if (!h1.ShouldBeClipped())
 276     ExpandBoundsToIncludePoint(&xmin, &xmax, &ymin, &ymax,
 277                                h1.CartesianPoint2d());
 278
 279   if (h1.ShouldBeClipped() ^ h2.ShouldBeClipped())
 280     ExpandBoundsToIncludePoint(&xmin,
 281                                &xmax,
 282                                &ymin,
 283                                &ymax,
 284                                ComputeClippedPointForEdge(h1, h2)
 285                                    .CartesianPoint2d());
 286
 287   if (!h2.ShouldBeClipped())
 288     ExpandBoundsToIncludePoint(&xmin, &xmax, &ymin, &ymax,
 289                                h2.CartesianPoint2d());
 290
 291   if (h2.ShouldBeClipped() ^ h3.ShouldBeClipped())
 292     ExpandBoundsToIncludePoint(&xmin,
 293                                &xmax,
 294                                &ymin,
 295                                &ymax,
 296                                ComputeClippedPointForEdge(h2, h3)
 297                                    .CartesianPoint2d());
 298
 299   if (!h3.ShouldBeClipped())
 300     ExpandBoundsToIncludePoint(&xmin, &xmax, &ymin, &ymax,
 301                                h3.CartesianPoint2d());
 302
 303   if (h3.ShouldBeClipped() ^ h4.ShouldBeClipped())
 304     ExpandBoundsToIncludePoint(&xmin,
 305                                &xmax,
 306                                &ymin,
 307                                &ymax,
 308                                ComputeClippedPointForEdge(h3, h4)
 309                                    .CartesianPoint2d());
 310
 311   if (!h4.ShouldBeClipped())
 312     ExpandBoundsToIncludePoint(&xmin, &xmax, &ymin, &ymax,
 313                                h4.CartesianPoint2d());
 314
 315   if (h4.ShouldBeClipped() ^ h1.ShouldBeClipped())
 316     ExpandBoundsToIncludePoint(&xmin,
 317                                &xmax,
 318                                &ymin,
 319                                &ymax,
 320                                ComputeClippedPointForEdge(h4, h1)
 321                                    .CartesianPoint2d());
 322
 323   return gfx::RectF(gfx::PointF(xmin, ymin),
 324                     gfx::SizeF(xmax - xmin, ymax - ymin));
 325 }
 326
 327 gfx::QuadF MathUtil::MapQuad(const gfx::Transform& transform,
 328                              const gfx::QuadF& q,
 329                              bool* clipped) {
 330   if (transform.IsIdentityOrTranslation()) {
 331     gfx::QuadF mapped_quad(q);
 332     mapped_quad +=
 333         gfx::Vector2dF(SkMScalarToFloat(transform.matrix().get(0, 3)),
 334                        SkMScalarToFloat(transform.matrix().get(1, 3)));
 335     *clipped = false;
 336     return mapped_quad;
 337   }
 338
 339   HomogeneousCoordinate h1 =
 340       MapHomogeneousPoint(transform, gfx::Point3F(q.p1()));
 341   HomogeneousCoordinate h2 =
 342       MapHomogeneousPoint(transform, gfx::Point3F(q.p2()));
 343   HomogeneousCoordinate h3 =
 344       MapHomogeneousPoint(transform, gfx::Point3F(q.p3()));
 345   HomogeneousCoordinate h4 =
 346       MapHomogeneousPoint(transform, gfx::Point3F(q.p4()));
 347
 348   *clipped = h1.ShouldBeClipped() || h2.ShouldBeClipped() ||
 349             h3.ShouldBeClipped() || h4.ShouldBeClipped();
 350
 351   // Result will be invalid if clipped == true. But, compute it anyway just in
 352   // case, to emulate existing behavior.
 353   return gfx::QuadF(h1.CartesianPoint2d(),
 354                     h2.CartesianPoint2d(),
 355                     h3.CartesianPoint2d(),
 356                     h4.CartesianPoint2d());
 357 }
 358
 359 gfx::PointF MathUtil::MapPoint(const gfx::Transform& transform,
 360                                const gfx::PointF& p,
 361                                bool* clipped) {
 362   HomogeneousCoordinate h = MapHomogeneousPoint(transform, gfx::Point3F(p));
 363
 364   if (h.w() > 0) {
 365     *clipped = false;
 366     return h.CartesianPoint2d();
 367   }
 368
 369   // The cartesian coordinates will be invalid after dividing by w.
 370   *clipped = true;
 371
 372   // Avoid dividing by w if w == 0.
 373   if (!h.w())
 374     return gfx::PointF();
 375
 376   // This return value will be invalid because clipped == true, but (1) users of
 377   // this code should be ignoring the return value when clipped == true anyway,
 378   // and (2) this behavior is more consistent with existing behavior of WebKit
 379   // transforms if the user really does not ignore the return value.
 380   return h.CartesianPoint2d();
 381 }
 382
 383 gfx::Point3F MathUtil::MapPoint(const gfx::Transform& transform,
 384                                 const gfx::Point3F& p,
 385                                 bool* clipped) {
 386   HomogeneousCoordinate h = MapHomogeneousPoint(transform, p);
 387
 388   if (h.w() > 0) {
 389     *clipped = false;
 390     return h.CartesianPoint3d();
 391   }
 392
 393   // The cartesian coordinates will be invalid after dividing by w.
 394   *clipped = true;
 395
 396   // Avoid dividing by w if w == 0.
 397   if (!h.w())
 398     return gfx::Point3F();
 399
 400   // This return value will be invalid because clipped == true, but (1) users of
 401   // this code should be ignoring the return value when clipped == true anyway,
 402   // and (2) this behavior is more consistent with existing behavior of WebKit
 403   // transforms if the user really does not ignore the return value.
 404   return h.CartesianPoint3d();
 405 }
 406
 407 gfx::QuadF MathUtil::ProjectQuad(const gfx::Transform& transform,
 408                                  const gfx::QuadF& q,
 409                                  bool* clipped) {
 410   gfx::QuadF projected_quad;
 411   bool clipped_point;
 412   projected_quad.set_p1(ProjectPoint(transform, q.p1(), &clipped_point));
 413   *clipped = clipped_point;
 414   projected_quad.set_p2(ProjectPoint(transform, q.p2(), &clipped_point));
 415   *clipped |= clipped_point;
 416   projected_quad.set_p3(ProjectPoint(transform, q.p3(), &clipped_point));
 417   *clipped |= clipped_point;
 418   projected_quad.set_p4(ProjectPoint(transform, q.p4(), &clipped_point));
 419   *clipped |= clipped_point;
 420
 421   return projected_quad;
 422 }
 423
 424 gfx::PointF MathUtil::ProjectPoint(const gfx::Transform& transform,
 425                                    const gfx::PointF& p,
 426                                    bool* clipped) {
 427   HomogeneousCoordinate h = ProjectHomogeneousPoint(transform, p);
 428
 429   if (h.w() > 0) {
 430     // The cartesian coordinates will be valid in this case.
 431     *clipped = false;
 432     return h.CartesianPoint2d();
 433   }
 434
 435   // The cartesian coordinates will be invalid after dividing by w.
 436   *clipped = true;
 437
 438   // Avoid dividing by w if w == 0.
 439   if (!h.w())
 440     return gfx::PointF();
 441
 442   // This return value will be invalid because clipped == true, but (1) users of
 443   // this code should be ignoring the return value when clipped == true anyway,
 444   // and (2) this behavior is more consistent with existing behavior of WebKit
 445   // transforms if the user really does not ignore the return value.
 446   return h.CartesianPoint2d();
 447 }
 448
 449 gfx::RectF MathUtil::ScaleRectProportional(const gfx::RectF& input_outer_rect,
 450                                            const gfx::RectF& scale_outer_rect,
 451                                            const gfx::RectF& scale_inner_rect) {
 452   gfx::RectF output_inner_rect = input_outer_rect;
 453   float scale_rect_to_input_scale_x =
 454       scale_outer_rect.width() / input_outer_rect.width();
 455   float scale_rect_to_input_scale_y =
 456       scale_outer_rect.height() / input_outer_rect.height();
 457
 458   gfx::Vector2dF top_left_diff =
 459       scale_inner_rect.origin() - scale_outer_rect.origin();
 460   gfx::Vector2dF bottom_right_diff =
 461       scale_inner_rect.bottom_right() - scale_outer_rect.bottom_right();
 462   output_inner_rect.Inset(top_left_diff.x() / scale_rect_to_input_scale_x,
 463                           top_left_diff.y() / scale_rect_to_input_scale_y,
 464                           -bottom_right_diff.x() / scale_rect_to_input_scale_x,
 465                           -bottom_right_diff.y() / scale_rect_to_input_scale_y);
 466   return output_inner_rect;
 467 }
 468
 469 static inline float ScaleOnAxis(double a, double b, double c) {
 470   if (!b && !c)
 471     return a;
 472   if (!a && !c)
 473     return b;
 474   if (!a && !b)
 475     return c;
 476
 477   // Do the sqrt as a double to not lose precision.
 478   return static_cast<float>(std::sqrt(a * a + b * b + c * c));
 479 }
 480
 481 gfx::Vector2dF MathUtil::ComputeTransform2dScaleComponents(
 482     const gfx::Transform& transform,
 483     float fallback_value) {
 484   if (transform.HasPerspective())
 485     return gfx::Vector2dF(fallback_value, fallback_value);
 486   float x_scale = ScaleOnAxis(transform.matrix().getDouble(0, 0),
 487                               transform.matrix().getDouble(1, 0),
 488                               transform.matrix().getDouble(2, 0));
 489   float y_scale = ScaleOnAxis(transform.matrix().getDouble(0, 1),
 490                               transform.matrix().getDouble(1, 1),
 491                               transform.matrix().getDouble(2, 1));
 492   return gfx::Vector2dF(x_scale, y_scale);
 493 }
 494
 495 float MathUtil::SmallestAngleBetweenVectors(const gfx::Vector2dF& v1,
 496                                             const gfx::Vector2dF& v2) {
 497   double dot_product = gfx::DotProduct(v1, v2) / v1.Length() / v2.Length();
 498   // Clamp to compensate for rounding errors.
 499   dot_product = std::max(-1.0, std::min(1.0, dot_product));
 500   return static_cast<float>(Rad2Deg(std::acos(dot_product)));
 501 }
 502
 503 gfx::Vector2dF MathUtil::ProjectVector(const gfx::Vector2dF& source,
 504                                        const gfx::Vector2dF& destination) {
 505   float projected_length =
 506       gfx::DotProduct(source, destination) / destination.LengthSquared();
 507   return gfx::Vector2dF(projected_length * destination.x(),
 508                         projected_length * destination.y());
 509 }
 510
 511 scoped_ptr<base::Value> MathUtil::AsValue(gfx::Size s) {
 512   scoped_ptr<base::DictionaryValue> res(new base::DictionaryValue());
 513   res->SetDouble("width", s.width());
 514   res->SetDouble("height", s.height());
 515   return res.PassAs<base::Value>();
 516 }
 517
 518 scoped_ptr<base::Value> MathUtil::AsValue(const gfx::SizeF& s) {
 519   scoped_ptr<base::DictionaryValue> res(new base::DictionaryValue());
 520   res->SetDouble("width", s.width());
 521   res->SetDouble("height", s.height());
 522   return res.PassAs<base::Value>();
 523 }
 524
 525 scoped_ptr<base::Value> MathUtil::AsValue(const gfx::Rect& r) {
 526   scoped_ptr<base::ListValue> res(new base::ListValue());
 527   res->AppendInteger(r.x());
 528   res->AppendInteger(r.y());
 529   res->AppendInteger(r.width());
 530   res->AppendInteger(r.height());
 531   return res.PassAs<base::Value>();
 532 }
 533
 534 bool MathUtil::FromValue(const base::Value* raw_value, gfx::Rect* out_rect) {
 535   const base::ListValue* value = NULL;
 536   if (!raw_value->GetAsList(&value))
 537     return false;
 538
 539   if (value->GetSize() != 4)
 540     return false;
 541
 542   int x, y, w, h;
 543   bool ok = true;
 544   ok &= value->GetInteger(0, &x);
 545   ok &= value->GetInteger(1, &y);
 546   ok &= value->GetInteger(2, &w);
 547   ok &= value->GetInteger(3, &h);
 548   if (!ok)
 549     return false;
 550
 551   *out_rect = gfx::Rect(x, y, w, h);
 552   return true;
 553 }
 554
 555 scoped_ptr<base::Value> MathUtil::AsValue(const gfx::PointF& pt) {
 556   scoped_ptr<base::ListValue> res(new base::ListValue());
 557   res->AppendDouble(pt.x());
 558   res->AppendDouble(pt.y());
 559   return res.PassAs<base::Value>();
 560 }
 561
 562 scoped_ptr<base::Value> MathUtil::AsValue(const gfx::QuadF& q) {
 563   scoped_ptr<base::ListValue> res(new base::ListValue());
 564   res->AppendDouble(q.p1().x());
 565   res->AppendDouble(q.p1().y());
 566   res->AppendDouble(q.p2().x());
 567   res->AppendDouble(q.p2().y());
 568   res->AppendDouble(q.p3().x());
 569   res->AppendDouble(q.p3().y());
 570   res->AppendDouble(q.p4().x());
 571   res->AppendDouble(q.p4().y());
 572   return res.PassAs<base::Value>();
 573 }
 574
 575 scoped_ptr<base::Value> MathUtil::AsValue(const gfx::RectF& rect) {
 576   scoped_ptr<base::ListValue> res(new base::ListValue());
 577   res->AppendDouble(rect.x());
 578   res->AppendDouble(rect.y());
 579   res->AppendDouble(rect.width());
 580   res->AppendDouble(rect.height());
 581   return res.PassAs<base::Value>();
 582 }
 583
 584 scoped_ptr<base::Value> MathUtil::AsValue(const gfx::Transform& transform) {
 585   scoped_ptr<base::ListValue> res(new base::ListValue());
 586   const SkMatrix44& m = transform.matrix();
 587   for (int row = 0; row < 4; ++row) {
 588     for (int col = 0; col < 4; ++col)
 589       res->AppendDouble(m.getDouble(row, col));
 590   }
 591   return res.PassAs<base::Value>();
 592 }
 593
 594 scoped_ptr<base::Value> MathUtil::AsValue(const gfx::BoxF& box) {
 595   scoped_ptr<base::ListValue> res(new base::ListValue());
 596   res->AppendInteger(box.x());
 597   res->AppendInteger(box.y());
 598   res->AppendInteger(box.z());
 599   res->AppendInteger(box.width());
 600   res->AppendInteger(box.height());
 601   res->AppendInteger(box.depth());
 602   return res.PassAs<base::Value>();
 603 }
 604
 605 scoped_ptr<base::Value> MathUtil::AsValueSafely(double value) {
 606   return scoped_ptr<base::Value>(base::Value::CreateDoubleValue(
 607       std::min(value, std::numeric_limits<double>::max())));
 608 }
 609
 610 scoped_ptr<base::Value> MathUtil::AsValueSafely(float value) {
 611   return scoped_ptr<base::Value>(base::Value::CreateDoubleValue(
 612       std::min(value, std::numeric_limits<float>::max())));
 613 }
 614
 615 }  // namespace cc