cc/base/tiling_data.cc

   1 // Copyright 2010 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/tiling_data.h"
   6
   7 #include <algorithm>
   8
   9 #include "ui/gfx/geometry/rect.h"
  10 #include "ui/gfx/geometry/vector2d.h"
  11
  12 namespace cc {
  13
  14 static int ComputeNumTiles(int max_texture_size,
  15                            int total_size,
  16                            int border_texels) {
  17   if (max_texture_size - 2 * border_texels <= 0)
  18     return total_size > 0 && max_texture_size >= total_size ? 1 : 0;
  19
  20   int num_tiles = std::max(1,
  21                            1 + (total_size - 1 - 2 * border_texels) /
  22                            (max_texture_size - 2 * border_texels));
  23   return total_size > 0 ? num_tiles : 0;
  24 }
  25
  26 TilingData::TilingData()
  27     : border_texels_(0) {
  28   RecomputeNumTiles();
  29 }
  30
  31 TilingData::TilingData(const gfx::Size& max_texture_size,
  32                        const gfx::Size& tiling_size,
  33                        bool has_border_texels)
  34     : max_texture_size_(max_texture_size),
  35       tiling_size_(tiling_size),
  36       border_texels_(has_border_texels ? 1 : 0) {
  37   RecomputeNumTiles();
  38 }
  39
  40 TilingData::TilingData(const gfx::Size& max_texture_size,
  41                        const gfx::Size& tiling_size,
  42                        int border_texels)
  43     : max_texture_size_(max_texture_size),
  44       tiling_size_(tiling_size),
  45       border_texels_(border_texels) {
  46   RecomputeNumTiles();
  47 }
  48
  49 void TilingData::SetTilingSize(const gfx::Size& tiling_size) {
  50   tiling_size_ = tiling_size;
  51   RecomputeNumTiles();
  52 }
  53
  54 void TilingData::SetMaxTextureSize(const gfx::Size& max_texture_size) {
  55   max_texture_size_ = max_texture_size;
  56   RecomputeNumTiles();
  57 }
  58
  59 void TilingData::SetHasBorderTexels(bool has_border_texels) {
  60   border_texels_ = has_border_texels ? 1 : 0;
  61   RecomputeNumTiles();
  62 }
  63
  64 void TilingData::SetBorderTexels(int border_texels) {
  65   border_texels_ = border_texels;
  66   RecomputeNumTiles();
  67 }
  68
  69 int TilingData::TileXIndexFromSrcCoord(int src_position) const {
  70   if (num_tiles_x_ <= 1)
  71     return 0;
  72
  73   DCHECK_GT(max_texture_size_.width() - 2 * border_texels_, 0);
  74   int x = (src_position - border_texels_) /
  75       (max_texture_size_.width() - 2 * border_texels_);
  76   return std::min(std::max(x, 0), num_tiles_x_ - 1);
  77 }
  78
  79 int TilingData::TileYIndexFromSrcCoord(int src_position) const {
  80   if (num_tiles_y_ <= 1)
  81     return 0;
  82
  83   DCHECK_GT(max_texture_size_.height() - 2 * border_texels_, 0);
  84   int y = (src_position - border_texels_) /
  85       (max_texture_size_.height() - 2 * border_texels_);
  86   return std::min(std::max(y, 0), num_tiles_y_ - 1);
  87 }
  88
  89 int TilingData::FirstBorderTileXIndexFromSrcCoord(int src_position) const {
  90   if (num_tiles_x_ <= 1)
  91     return 0;
  92
  93   DCHECK_GT(max_texture_size_.width() - 2 * border_texels_, 0);
  94   int inner_tile_size = max_texture_size_.width() - 2 * border_texels_;
  95   int x = (src_position - 2 * border_texels_) / inner_tile_size;
  96   return std::min(std::max(x, 0), num_tiles_x_ - 1);
  97 }
  98
  99 int TilingData::FirstBorderTileYIndexFromSrcCoord(int src_position) const {
 100   if (num_tiles_y_ <= 1)
 101     return 0;
 102
 103   DCHECK_GT(max_texture_size_.height() - 2 * border_texels_, 0);
 104   int inner_tile_size = max_texture_size_.height() - 2 * border_texels_;
 105   int y = (src_position - 2 * border_texels_) / inner_tile_size;
 106   return std::min(std::max(y, 0), num_tiles_y_ - 1);
 107 }
 108
 109 int TilingData::LastBorderTileXIndexFromSrcCoord(int src_position) const {
 110   if (num_tiles_x_ <= 1)
 111     return 0;
 112
 113   DCHECK_GT(max_texture_size_.width() - 2 * border_texels_, 0);
 114   int inner_tile_size = max_texture_size_.width() - 2 * border_texels_;
 115   int x = src_position / inner_tile_size;
 116   return std::min(std::max(x, 0), num_tiles_x_ - 1);
 117 }
 118
 119 int TilingData::LastBorderTileYIndexFromSrcCoord(int src_position) const {
 120   if (num_tiles_y_ <= 1)
 121     return 0;
 122
 123   DCHECK_GT(max_texture_size_.height() - 2 * border_texels_, 0);
 124   int inner_tile_size = max_texture_size_.height() - 2 * border_texels_;
 125   int y = src_position / inner_tile_size;
 126   return std::min(std::max(y, 0), num_tiles_y_ - 1);
 127 }
 128
 129 gfx::Rect TilingData::ExpandRectIgnoringBordersToTileBounds(
 130     const gfx::Rect& rect) const {
 131   if (rect.IsEmpty() || has_empty_bounds())
 132     return gfx::Rect();
 133   if (rect.x() > tiling_size_.width() || rect.y() > tiling_size_.height())
 134     return gfx::Rect();
 135   int index_x = TileXIndexFromSrcCoord(rect.x());
 136   int index_y = TileYIndexFromSrcCoord(rect.y());
 137   int index_right = TileXIndexFromSrcCoord(rect.right() - 1);
 138   int index_bottom = TileYIndexFromSrcCoord(rect.bottom() - 1);
 139
 140   gfx::Rect rect_top_left(TileBounds(index_x, index_y));
 141   gfx::Rect rect_bottom_right(TileBounds(index_right, index_bottom));
 142
 143   return gfx::UnionRects(rect_top_left, rect_bottom_right);
 144 }
 145
 146 gfx::Rect TilingData::ExpandRectToTileBounds(const gfx::Rect& rect) const {
 147   if (rect.IsEmpty() || has_empty_bounds())
 148     return gfx::Rect();
 149   if (rect.x() > tiling_size_.width() || rect.y() > tiling_size_.height())
 150     return gfx::Rect();
 151   int index_x = FirstBorderTileXIndexFromSrcCoord(rect.x());
 152   int index_y = FirstBorderTileYIndexFromSrcCoord(rect.y());
 153   int index_right = LastBorderTileXIndexFromSrcCoord(rect.right() - 1);
 154   int index_bottom = LastBorderTileYIndexFromSrcCoord(rect.bottom() - 1);
 155
 156   gfx::Rect rect_top_left(TileBounds(index_x, index_y));
 157   gfx::Rect rect_bottom_right(TileBounds(index_right, index_bottom));
 158
 159   return gfx::UnionRects(rect_top_left, rect_bottom_right);
 160 }
 161
 162 gfx::Rect TilingData::TileBounds(int i, int j) const {
 163   AssertTile(i, j);
 164   int max_texture_size_x = max_texture_size_.width() - 2 * border_texels_;
 165   int max_texture_size_y = max_texture_size_.height() - 2 * border_texels_;
 166
 167   int lo_x = max_texture_size_x * i;
 168   if (i != 0)
 169     lo_x += border_texels_;
 170
 171   int lo_y = max_texture_size_y * j;
 172   if (j != 0)
 173     lo_y += border_texels_;
 174
 175   int hi_x = max_texture_size_x * (i + 1) + border_texels_;
 176   if (i + 1 == num_tiles_x_)
 177     hi_x += border_texels_;
 178
 179   int hi_y = max_texture_size_y * (j + 1) + border_texels_;
 180   if (j + 1 == num_tiles_y_)
 181     hi_y += border_texels_;
 182
 183   hi_x = std::min(hi_x, tiling_size_.width());
 184   hi_y = std::min(hi_y, tiling_size_.height());
 185
 186   int x = lo_x;
 187   int y = lo_y;
 188   int width = hi_x - lo_x;
 189   int height = hi_y - lo_y;
 190   DCHECK_GE(x, 0);
 191   DCHECK_GE(y, 0);
 192   DCHECK_GE(width, 0);
 193   DCHECK_GE(height, 0);
 194   DCHECK_LE(x, tiling_size_.width());
 195   DCHECK_LE(y, tiling_size_.height());
 196   return gfx::Rect(x, y, width, height);
 197 }
 198
 199 gfx::Rect TilingData::TileBoundsWithBorder(int i, int j) const {
 200   AssertTile(i, j);
 201   int max_texture_size_x = max_texture_size_.width() - 2 * border_texels_;
 202   int max_texture_size_y = max_texture_size_.height() - 2 * border_texels_;
 203
 204   int lo_x = max_texture_size_x * i;
 205   int lo_y = max_texture_size_y * j;
 206
 207   int hi_x = lo_x + max_texture_size_x + 2 * border_texels_;
 208   int hi_y = lo_y + max_texture_size_y + 2 * border_texels_;
 209
 210   hi_x = std::min(hi_x, tiling_size_.width());
 211   hi_y = std::min(hi_y, tiling_size_.height());
 212
 213   int x = lo_x;
 214   int y = lo_y;
 215   int width = hi_x - lo_x;
 216   int height = hi_y - lo_y;
 217   DCHECK_GE(x, 0);
 218   DCHECK_GE(y, 0);
 219   DCHECK_GE(width, 0);
 220   DCHECK_GE(height, 0);
 221   DCHECK_LE(x, tiling_size_.width());
 222   DCHECK_LE(y, tiling_size_.height());
 223   return gfx::Rect(x, y, width, height);
 224 }
 225
 226 int TilingData::TilePositionX(int x_index) const {
 227   DCHECK_GE(x_index, 0);
 228   DCHECK_LT(x_index, num_tiles_x_);
 229
 230   int pos = (max_texture_size_.width() - 2 * border_texels_) * x_index;
 231   if (x_index != 0)
 232     pos += border_texels_;
 233
 234   return pos;
 235 }
 236
 237 int TilingData::TilePositionY(int y_index) const {
 238   DCHECK_GE(y_index, 0);
 239   DCHECK_LT(y_index, num_tiles_y_);
 240
 241   int pos = (max_texture_size_.height() - 2 * border_texels_) * y_index;
 242   if (y_index != 0)
 243     pos += border_texels_;
 244
 245   return pos;
 246 }
 247
 248 int TilingData::TileSizeX(int x_index) const {
 249   DCHECK_GE(x_index, 0);
 250   DCHECK_LT(x_index, num_tiles_x_);
 251
 252   if (!x_index && num_tiles_x_ == 1)
 253     return tiling_size_.width();
 254   if (!x_index && num_tiles_x_ > 1)
 255     return max_texture_size_.width() - border_texels_;
 256   if (x_index < num_tiles_x_ - 1)
 257     return max_texture_size_.width() - 2 * border_texels_;
 258   if (x_index == num_tiles_x_ - 1)
 259     return tiling_size_.width() - TilePositionX(x_index);
 260
 261   NOTREACHED();
 262   return 0;
 263 }
 264
 265 int TilingData::TileSizeY(int y_index) const {
 266   DCHECK_GE(y_index, 0);
 267   DCHECK_LT(y_index, num_tiles_y_);
 268
 269   if (!y_index && num_tiles_y_ == 1)
 270     return tiling_size_.height();
 271   if (!y_index && num_tiles_y_ > 1)
 272     return max_texture_size_.height() - border_texels_;
 273   if (y_index < num_tiles_y_ - 1)
 274     return max_texture_size_.height() - 2 * border_texels_;
 275   if (y_index == num_tiles_y_ - 1)
 276     return tiling_size_.height() - TilePositionY(y_index);
 277
 278   NOTREACHED();
 279   return 0;
 280 }
 281
 282 gfx::Vector2d TilingData::TextureOffset(int x_index, int y_index) const {
 283   int left = (!x_index || num_tiles_x_ == 1) ? 0 : border_texels_;
 284   int top = (!y_index || num_tiles_y_ == 1) ? 0 : border_texels_;
 285
 286   return gfx::Vector2d(left, top);
 287 }
 288
 289 void TilingData::RecomputeNumTiles() {
 290   num_tiles_x_ = ComputeNumTiles(
 291       max_texture_size_.width(), tiling_size_.width(), border_texels_);
 292   num_tiles_y_ = ComputeNumTiles(
 293       max_texture_size_.height(), tiling_size_.height(), border_texels_);
 294 }
 295
 296 TilingData::BaseIterator::BaseIterator() : index_x_(-1), index_y_(-1) {
 297 }
 298
 299 TilingData::Iterator::Iterator() {
 300   done();
 301 }
 302
 303 TilingData::Iterator::Iterator(const TilingData* tiling_data,
 304                                const gfx::Rect& consider_rect,
 305                                bool include_borders)
 306     : left_(-1), right_(-1), bottom_(-1) {
 307   if (tiling_data->num_tiles_x() <= 0 || tiling_data->num_tiles_y() <= 0) {
 308     done();
 309     return;
 310   }
 311
 312   gfx::Rect tiling_bounds_rect(tiling_data->tiling_size());
 313   gfx::Rect rect(consider_rect);
 314   rect.Intersect(tiling_bounds_rect);
 315
 316   gfx::Rect top_left_tile;
 317   if (include_borders) {
 318     index_x_ = tiling_data->FirstBorderTileXIndexFromSrcCoord(rect.x());
 319     index_y_ = tiling_data->FirstBorderTileYIndexFromSrcCoord(rect.y());
 320     right_ = tiling_data->LastBorderTileXIndexFromSrcCoord(rect.right() - 1);
 321     bottom_ = tiling_data->LastBorderTileYIndexFromSrcCoord(rect.bottom() - 1);
 322     top_left_tile = tiling_data->TileBoundsWithBorder(index_x_, index_y_);
 323   } else {
 324     index_x_ = tiling_data->TileXIndexFromSrcCoord(rect.x());
 325     index_y_ = tiling_data->TileYIndexFromSrcCoord(rect.y());
 326     right_ = tiling_data->TileXIndexFromSrcCoord(rect.right() - 1);
 327     bottom_ = tiling_data->TileYIndexFromSrcCoord(rect.bottom() - 1);
 328     top_left_tile = tiling_data->TileBounds(index_x_, index_y_);
 329   }
 330   left_ = index_x_;
 331
 332   // Index functions always return valid indices, so explicitly check
 333   // for non-intersecting rects.
 334   if (!top_left_tile.Intersects(rect))
 335     done();
 336 }
 337
 338 TilingData::Iterator& TilingData::Iterator::operator++() {
 339   if (!*this)
 340     return *this;
 341
 342   index_x_++;
 343   if (index_x_ > right_) {
 344     index_x_ = left_;
 345     index_y_++;
 346     if (index_y_ > bottom_)
 347       done();
 348   }
 349
 350   return *this;
 351 }
 352
 353 TilingData::DifferenceIterator::DifferenceIterator(
 354     const TilingData* tiling_data,
 355     const gfx::Rect& consider_rect,
 356     const gfx::Rect& ignore_rect)
 357     : consider_left_(-1),
 358       consider_top_(-1),
 359       consider_right_(-1),
 360       consider_bottom_(-1),
 361       ignore_left_(-1),
 362       ignore_top_(-1),
 363       ignore_right_(-1),
 364       ignore_bottom_(-1) {
 365   if (tiling_data->num_tiles_x() <= 0 || tiling_data->num_tiles_y() <= 0) {
 366     done();
 367     return;
 368   }
 369
 370   gfx::Rect tiling_bounds_rect(tiling_data->tiling_size());
 371   gfx::Rect consider(consider_rect);
 372   gfx::Rect ignore(ignore_rect);
 373   consider.Intersect(tiling_bounds_rect);
 374   ignore.Intersect(tiling_bounds_rect);
 375   if (consider.IsEmpty()) {
 376     done();
 377     return;
 378   }
 379
 380   consider_left_ = tiling_data->TileXIndexFromSrcCoord(consider.x());
 381   consider_top_ = tiling_data->TileYIndexFromSrcCoord(consider.y());
 382   consider_right_ = tiling_data->TileXIndexFromSrcCoord(consider.right() - 1);
 383   consider_bottom_ = tiling_data->TileYIndexFromSrcCoord(consider.bottom() - 1);
 384
 385   if (!ignore.IsEmpty()) {
 386     ignore_left_ = tiling_data->TileXIndexFromSrcCoord(ignore.x());
 387     ignore_top_ = tiling_data->TileYIndexFromSrcCoord(ignore.y());
 388     ignore_right_ = tiling_data->TileXIndexFromSrcCoord(ignore.right() - 1);
 389     ignore_bottom_ = tiling_data->TileYIndexFromSrcCoord(ignore.bottom() - 1);
 390
 391     // Clamp ignore indices to consider indices.
 392     ignore_left_ = std::max(ignore_left_, consider_left_);
 393     ignore_top_ = std::max(ignore_top_, consider_top_);
 394     ignore_right_ = std::min(ignore_right_, consider_right_);
 395     ignore_bottom_ = std::min(ignore_bottom_, consider_bottom_);
 396   }
 397
 398   if (ignore_left_ == consider_left_ && ignore_right_ == consider_right_ &&
 399       ignore_top_ == consider_top_ && ignore_bottom_ == consider_bottom_) {
 400     done();
 401     return;
 402   }
 403
 404   index_x_ = consider_left_;
 405   index_y_ = consider_top_;
 406
 407   if (in_ignore_rect())
 408     ++(*this);
 409 }
 410
 411 TilingData::DifferenceIterator& TilingData::DifferenceIterator::operator++() {
 412   if (!*this)
 413     return *this;
 414
 415   index_x_++;
 416   if (in_ignore_rect())
 417     index_x_ = ignore_right_ + 1;
 418
 419   if (index_x_ > consider_right_) {
 420     index_x_ = consider_left_;
 421     index_y_++;
 422
 423     if (in_ignore_rect()) {
 424       index_x_ = ignore_right_ + 1;
 425       // If the ignore rect spans the whole consider rect horizontally, then
 426       // ignore_right + 1 will be out of bounds.
 427       if (in_ignore_rect() || index_x_ > consider_right_) {
 428         index_y_ = ignore_bottom_ + 1;
 429         index_x_ = consider_left_;
 430       }
 431     }
 432
 433     if (index_y_ > consider_bottom_)
 434       done();
 435   }
 436
 437   return *this;
 438 }
 439
 440 TilingData::SpiralDifferenceIterator::SpiralDifferenceIterator() {
 441   done();
 442 }
 443
 444 TilingData::SpiralDifferenceIterator::SpiralDifferenceIterator(
 445     const TilingData* tiling_data,
 446     const gfx::Rect& consider_rect,
 447     const gfx::Rect& ignore_rect,
 448     const gfx::Rect& center_rect)
 449     : consider_left_(-1),
 450       consider_top_(-1),
 451       consider_right_(-1),
 452       consider_bottom_(-1),
 453       ignore_left_(-1),
 454       ignore_top_(-1),
 455       ignore_right_(-1),
 456       ignore_bottom_(-1),
 457       direction_(RIGHT),
 458       delta_x_(1),
 459       delta_y_(0),
 460       current_step_(0),
 461       horizontal_step_count_(0),
 462       vertical_step_count_(0) {
 463   if (tiling_data->num_tiles_x() <= 0 || tiling_data->num_tiles_y() <= 0) {
 464     done();
 465     return;
 466   }
 467
 468   gfx::Rect tiling_bounds_rect(tiling_data->tiling_size());
 469   gfx::Rect consider(consider_rect);
 470   gfx::Rect ignore(ignore_rect);
 471   gfx::Rect center(center_rect);
 472   consider.Intersect(tiling_bounds_rect);
 473   ignore.Intersect(tiling_bounds_rect);
 474   if (consider.IsEmpty()) {
 475     done();
 476     return;
 477   }
 478
 479   consider_left_ = tiling_data->TileXIndexFromSrcCoord(consider.x());
 480   consider_top_ = tiling_data->TileYIndexFromSrcCoord(consider.y());
 481   consider_right_ = tiling_data->TileXIndexFromSrcCoord(consider.right() - 1);
 482   consider_bottom_ = tiling_data->TileYIndexFromSrcCoord(consider.bottom() - 1);
 483
 484   if (!ignore.IsEmpty()) {
 485     ignore_left_ = tiling_data->TileXIndexFromSrcCoord(ignore.x());
 486     ignore_top_ = tiling_data->TileYIndexFromSrcCoord(ignore.y());
 487     ignore_right_ = tiling_data->TileXIndexFromSrcCoord(ignore.right() - 1);
 488     ignore_bottom_ = tiling_data->TileYIndexFromSrcCoord(ignore.bottom() - 1);
 489
 490     // Clamp ignore indices to consider indices.
 491     ignore_left_ = std::max(ignore_left_, consider_left_);
 492     ignore_top_ = std::max(ignore_top_, consider_top_);
 493     ignore_right_ = std::min(ignore_right_, consider_right_);
 494     ignore_bottom_ = std::min(ignore_bottom_, consider_bottom_);
 495   }
 496
 497   if (ignore_left_ == consider_left_ && ignore_right_ == consider_right_ &&
 498       ignore_top_ == consider_top_ && ignore_bottom_ == consider_bottom_) {
 499     done();
 500     return;
 501   }
 502
 503   // Determine around left, such that it is between -1 and num_tiles_x.
 504   int around_left = 0;
 505   if (center.x() < 0 || center.IsEmpty())
 506     around_left = -1;
 507   else if (center.x() >= tiling_data->tiling_size().width())
 508     around_left = tiling_data->num_tiles_x();
 509   else
 510     around_left = tiling_data->TileXIndexFromSrcCoord(center.x());
 511
 512   // Determine around top, such that it is between -1 and num_tiles_y.
 513   int around_top = 0;
 514   if (center.y() < 0 || center.IsEmpty())
 515     around_top = -1;
 516   else if (center.y() >= tiling_data->tiling_size().height())
 517     around_top = tiling_data->num_tiles_y();
 518   else
 519     around_top = tiling_data->TileYIndexFromSrcCoord(center.y());
 520
 521   // Determine around right, such that it is between -1 and num_tiles_x.
 522   int right_src_coord = center.right() - 1;
 523   int around_right = 0;
 524   if (right_src_coord < 0 || center.IsEmpty()) {
 525     around_right = -1;
 526   } else if (right_src_coord >= tiling_data->tiling_size().width()) {
 527     around_right = tiling_data->num_tiles_x();
 528   } else {
 529     around_right = tiling_data->TileXIndexFromSrcCoord(right_src_coord);
 530   }
 531
 532   // Determine around bottom, such that it is between -1 and num_tiles_y.
 533   int bottom_src_coord = center.bottom() - 1;
 534   int around_bottom = 0;
 535   if (bottom_src_coord < 0 || center.IsEmpty()) {
 536     around_bottom = -1;
 537   } else if (bottom_src_coord >= tiling_data->tiling_size().height()) {
 538     around_bottom = tiling_data->num_tiles_y();
 539   } else {
 540     around_bottom = tiling_data->TileYIndexFromSrcCoord(bottom_src_coord);
 541   }
 542
 543   vertical_step_count_ = around_bottom - around_top + 1;
 544   horizontal_step_count_ = around_right - around_left + 1;
 545   current_step_ = horizontal_step_count_ - 1;
 546
 547   index_x_ = around_right;
 548   index_y_ = around_bottom;
 549
 550   // The current index is the bottom right of the around rect, which is also
 551   // ignored. So we have to advance.
 552   ++(*this);
 553 }
 554
 555 TilingData::SpiralDifferenceIterator& TilingData::SpiralDifferenceIterator::
 556 operator++() {
 557   int cannot_hit_consider_count = 0;
 558   while (cannot_hit_consider_count < 4) {
 559     if (needs_direction_switch())
 560       switch_direction();
 561
 562     index_x_ += delta_x_;
 563     index_y_ += delta_y_;
 564     ++current_step_;
 565
 566     if (in_consider_rect()) {
 567       cannot_hit_consider_count = 0;
 568
 569       if (!in_ignore_rect())
 570         break;
 571
 572       // Steps needed to reach the very edge of the ignore rect, while remaining
 573       // inside (so that the continue would take us outside).
 574       int steps_to_edge = 0;
 575       switch (direction_) {
 576         case UP:
 577           steps_to_edge = index_y_ - ignore_top_;
 578           break;
 579         case LEFT:
 580           steps_to_edge = index_x_ - ignore_left_;
 581           break;
 582         case DOWN:
 583           steps_to_edge = ignore_bottom_ - index_y_;
 584           break;
 585         case RIGHT:
 586           steps_to_edge = ignore_right_ - index_x_;
 587           break;
 588       }
 589
 590       // We need to switch directions in |max_steps|.
 591       int max_steps = current_step_count() - current_step_;
 592
 593       int steps_to_take = std::min(steps_to_edge, max_steps);
 594       DCHECK_GE(steps_to_take, 0);
 595
 596       index_x_ += steps_to_take * delta_x_;
 597       index_y_ += steps_to_take * delta_y_;
 598       current_step_ += steps_to_take;
 599     } else {
 600       int max_steps = current_step_count() - current_step_;
 601       int steps_to_take = max_steps;
 602       bool can_hit_consider_rect = false;
 603       switch (direction_) {
 604         case UP:
 605           if (valid_column() && consider_bottom_ < index_y_)
 606             steps_to_take = index_y_ - consider_bottom_ - 1;
 607           can_hit_consider_rect |= consider_right_ >= index_x_;
 608           break;
 609         case LEFT:
 610           if (valid_row() && consider_right_ < index_x_)
 611             steps_to_take = index_x_ - consider_right_ - 1;
 612           can_hit_consider_rect |= consider_top_ <= index_y_;
 613           break;
 614         case DOWN:
 615           if (valid_column() && consider_top_ > index_y_)
 616             steps_to_take = consider_top_ - index_y_ - 1;
 617           can_hit_consider_rect |= consider_left_ <= index_x_;
 618           break;
 619         case RIGHT:
 620           if (valid_row() && consider_left_ > index_x_)
 621             steps_to_take = consider_left_ - index_x_ - 1;
 622           can_hit_consider_rect |= consider_bottom_ >= index_y_;
 623           break;
 624       }
 625       steps_to_take = std::min(steps_to_take, max_steps);
 626       DCHECK_GE(steps_to_take, 0);
 627
 628       index_x_ += steps_to_take * delta_x_;
 629       index_y_ += steps_to_take * delta_y_;
 630       current_step_ += steps_to_take;
 631
 632       if (can_hit_consider_rect)
 633         cannot_hit_consider_count = 0;
 634       else
 635         ++cannot_hit_consider_count;
 636     }
 637   }
 638
 639   if (cannot_hit_consider_count >= 4)
 640     done();
 641   return *this;
 642 }
 643
 644 bool TilingData::SpiralDifferenceIterator::needs_direction_switch() const {
 645   return current_step_ >= current_step_count();
 646 }
 647
 648 void TilingData::SpiralDifferenceIterator::switch_direction() {
 649   // Note that delta_x_ and delta_y_ always remain between -1 and 1.
 650   int new_delta_x_ = delta_y_;
 651   delta_y_ = -delta_x_;
 652   delta_x_ = new_delta_x_;
 653
 654   current_step_ = 0;
 655   direction_ = static_cast<Direction>((direction_ + 1) % 4);
 656
 657   if (direction_ == RIGHT || direction_ == LEFT) {
 658     ++vertical_step_count_;
 659     ++horizontal_step_count_;
 660   }
 661 }
 662
 663 TilingData::ReverseSpiralDifferenceIterator::ReverseSpiralDifferenceIterator() {
 664   done();
 665 }
 666
 667 TilingData::ReverseSpiralDifferenceIterator::ReverseSpiralDifferenceIterator(
 668     const TilingData* tiling_data,
 669     const gfx::Rect& consider_rect,
 670     const gfx::Rect& ignore_rect,
 671     const gfx::Rect& center_rect)
 672     : consider_left_(-1),
 673       consider_top_(-1),
 674       consider_right_(-1),
 675       consider_bottom_(-1),
 676       around_left_(-1),
 677       around_top_(-1),
 678       around_right_(-1),
 679       around_bottom_(-1),
 680       ignore_left_(-1),
 681       ignore_top_(-1),
 682       ignore_right_(-1),
 683       ignore_bottom_(-1),
 684       direction_(LEFT),
 685       delta_x_(-1),
 686       delta_y_(0),
 687       current_step_(0),
 688       horizontal_step_count_(0),
 689       vertical_step_count_(0) {
 690   if (tiling_data->num_tiles_x() <= 0 || tiling_data->num_tiles_y() <= 0) {
 691     done();
 692     return;
 693   }
 694
 695   gfx::Rect tiling_bounds_rect(tiling_data->tiling_size());
 696   gfx::Rect consider(consider_rect);
 697   gfx::Rect ignore(ignore_rect);
 698   gfx::Rect center(center_rect);
 699   consider.Intersect(tiling_bounds_rect);
 700   ignore.Intersect(tiling_bounds_rect);
 701   if (consider.IsEmpty()) {
 702     done();
 703     return;
 704   }
 705
 706   consider_left_ = tiling_data->TileXIndexFromSrcCoord(consider.x());
 707   consider_top_ = tiling_data->TileYIndexFromSrcCoord(consider.y());
 708   consider_right_ = tiling_data->TileXIndexFromSrcCoord(consider.right() - 1);
 709   consider_bottom_ = tiling_data->TileYIndexFromSrcCoord(consider.bottom() - 1);
 710
 711   if (!ignore.IsEmpty()) {
 712     ignore_left_ = tiling_data->TileXIndexFromSrcCoord(ignore.x());
 713     ignore_top_ = tiling_data->TileYIndexFromSrcCoord(ignore.y());
 714     ignore_right_ = tiling_data->TileXIndexFromSrcCoord(ignore.right() - 1);
 715     ignore_bottom_ = tiling_data->TileYIndexFromSrcCoord(ignore.bottom() - 1);
 716
 717     // Clamp ignore indices to consider indices.
 718     ignore_left_ = std::max(ignore_left_, consider_left_);
 719     ignore_top_ = std::max(ignore_top_, consider_top_);
 720     ignore_right_ = std::min(ignore_right_, consider_right_);
 721     ignore_bottom_ = std::min(ignore_bottom_, consider_bottom_);
 722   }
 723
 724   if (ignore_left_ == consider_left_ && ignore_right_ == consider_right_ &&
 725       ignore_top_ == consider_top_ && ignore_bottom_ == consider_bottom_) {
 726     done();
 727     return;
 728   }
 729
 730   // Determine around left, such that it is between -1 and num_tiles_x.
 731   if (center.x() < 0 || center.IsEmpty())
 732     around_left_ = -1;
 733   else if (center.x() >= tiling_data->tiling_size().width())
 734     around_left_ = tiling_data->num_tiles_x();
 735   else
 736     around_left_ = tiling_data->TileXIndexFromSrcCoord(center.x());
 737
 738   // Determine around top, such that it is between -1 and num_tiles_y.
 739   if (center.y() < 0 || center.IsEmpty())
 740     around_top_ = -1;
 741   else if (center.y() >= tiling_data->tiling_size().height())
 742     around_top_ = tiling_data->num_tiles_y();
 743   else
 744     around_top_ = tiling_data->TileYIndexFromSrcCoord(center.y());
 745
 746   // Determine around right, such that it is between -1 and num_tiles_x.
 747   int right_src_coord = center.right() - 1;
 748   if (right_src_coord < 0 || center.IsEmpty()) {
 749     around_right_ = -1;
 750   } else if (right_src_coord >= tiling_data->tiling_size().width()) {
 751     around_right_ = tiling_data->num_tiles_x();
 752   } else {
 753     around_right_ = tiling_data->TileXIndexFromSrcCoord(right_src_coord);
 754   }
 755
 756   // Determine around bottom, such that it is between -1 and num_tiles_y.
 757   int bottom_src_coord = center.bottom() - 1;
 758   if (bottom_src_coord < 0 || center.IsEmpty()) {
 759     around_bottom_ = -1;
 760   } else if (bottom_src_coord >= tiling_data->tiling_size().height()) {
 761     around_bottom_ = tiling_data->num_tiles_y();
 762   } else {
 763     around_bottom_ = tiling_data->TileYIndexFromSrcCoord(bottom_src_coord);
 764   }
 765
 766   // Figure out the maximum distance from the around edge to consider edge.
 767   int max_distance = 0;
 768   max_distance = std::max(max_distance, around_top_ - consider_top_);
 769   max_distance = std::max(max_distance, around_left_ - consider_left_);
 770   max_distance = std::max(max_distance, consider_bottom_ - around_bottom_);
 771   max_distance = std::max(max_distance, consider_right_ - around_right_);
 772
 773   // The step count is the length of the edge (around_right_ - around_left_ + 1)
 774   // plus twice the max distance to pad (to the right and to the left). This way
 775   // the initial rect is the size proportional to the center, but big enough
 776   // to cover the consider rect.
 777   //
 778   // C = consider rect
 779   // A = around rect
 780   // . = area of the padded around rect
 781   // md = max distance (note in the picture below, there's md written vertically
 782   //      as well).
 783   // I = initial starting position
 784   //
 785   //       |md|  |md|
 786   //
 787   //     - ..........
 788   //     m ..........
 789   //     d ..........
 790   //     - CCCCCCC...
 791   //       CCCCAAC...
 792   //       CCCCAAC...
 793   //     - ..........
 794   //     m ..........
 795   //     d ..........
 796   //     - ..........I
 797   vertical_step_count_ = around_bottom_ - around_top_ + 1 + 2 * max_distance;
 798   horizontal_step_count_ = around_right_ - around_left_ + 1 + 2 * max_distance;
 799
 800   // Start with one to the right of the padded around rect.
 801   index_x_ = around_right_ + max_distance + 1;
 802   index_y_ = around_bottom_ + max_distance;
 803
 804   // The current index is outside a valid tile, so advance immediately.
 805   ++(*this);
 806 }
 807
 808 TilingData::ReverseSpiralDifferenceIterator&
 809     TilingData::ReverseSpiralDifferenceIterator::
 810     operator++() {
 811   while (!in_around_rect()) {
 812     if (needs_direction_switch())
 813       switch_direction();
 814
 815     index_x_ += delta_x_;
 816     index_y_ += delta_y_;
 817     ++current_step_;
 818
 819     if (in_around_rect()) {
 820       break;
 821     } else if (in_consider_rect()) {
 822       // If the tile is in the consider rect but not in ignore rect, then it's a
 823       // valid tile to visit.
 824       if (!in_ignore_rect())
 825         break;
 826
 827       // Steps needed to reach the very edge of the ignore rect, while remaining
 828       // inside it (so that the continue would take us outside).
 829       int steps_to_edge = 0;
 830       switch (direction_) {
 831         case UP:
 832           steps_to_edge = index_y_ - ignore_top_;
 833           break;
 834         case LEFT:
 835           steps_to_edge = index_x_ - ignore_left_;
 836           break;
 837         case DOWN:
 838           steps_to_edge = ignore_bottom_ - index_y_;
 839           break;
 840         case RIGHT:
 841           steps_to_edge = ignore_right_ - index_x_;
 842           break;
 843       }
 844
 845       // We need to switch directions in |max_steps|.
 846       int max_steps = current_step_count() - current_step_;
 847
 848       int steps_to_take = std::min(steps_to_edge, max_steps);
 849       DCHECK_GE(steps_to_take, 0);
 850
 851       index_x_ += steps_to_take * delta_x_;
 852       index_y_ += steps_to_take * delta_y_;
 853       current_step_ += steps_to_take;
 854     } else {
 855       // We're not in the consider rect.
 856
 857       int max_steps = current_step_count() - current_step_;
 858       int steps_to_take = max_steps;
 859
 860       // We might hit the consider rect before needing to switch directions:
 861       // update steps to take.
 862       switch (direction_) {
 863         case UP:
 864           if (valid_column() && consider_bottom_ < index_y_)
 865             steps_to_take = index_y_ - consider_bottom_ - 1;
 866           break;
 867         case LEFT:
 868           if (valid_row() && consider_right_ < index_x_)
 869             steps_to_take = index_x_ - consider_right_ - 1;
 870           break;
 871         case DOWN:
 872           if (valid_column() && consider_top_ > index_y_)
 873             steps_to_take = consider_top_ - index_y_ - 1;
 874           break;
 875         case RIGHT:
 876           if (valid_row() && consider_left_ > index_x_)
 877             steps_to_take = consider_left_ - index_x_ - 1;
 878           break;
 879       }
 880       steps_to_take = std::min(steps_to_take, max_steps);
 881       DCHECK_GE(steps_to_take, 0);
 882
 883       index_x_ += steps_to_take * delta_x_;
 884       index_y_ += steps_to_take * delta_y_;
 885       current_step_ += steps_to_take;
 886     }
 887   }
 888
 889   // Once we enter the around rect, we're done.
 890   if (in_around_rect())
 891     done();
 892   return *this;
 893 }
 894
 895 bool TilingData::ReverseSpiralDifferenceIterator::needs_direction_switch()
 896     const {
 897   return current_step_ >= current_step_count();
 898 }
 899
 900 void TilingData::ReverseSpiralDifferenceIterator::switch_direction() {
 901   // Note that delta_x_ and delta_y_ always remain between -1 and 1.
 902   int new_delta_y_ = delta_x_;
 903   delta_x_ = -delta_y_;
 904   delta_y_ = new_delta_y_;
 905
 906   current_step_ = 0;
 907   direction_ = static_cast<Direction>((direction_ + 1) % 4);
 908
 909   if (direction_ == UP || direction_ == DOWN) {
 910     --vertical_step_count_;
 911     --horizontal_step_count_;
 912
 913     // We should always end up in an around rect at some point.
 914     // Since the direction is now vertical, we have to ensure that we will
 915     // advance.
 916     DCHECK_GE(horizontal_step_count_, 1);
 917     DCHECK_GE(vertical_step_count_, 1);
 918   }
 919 }
 920
 921 }  // namespace cc