ui/gfx/canvas.cc

   1 // Copyright (c) 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 "ui/gfx/canvas.h"
   6
   7 #include <cmath>
   8 #include <limits>
   9
  10 #include "base/i18n/rtl.h"
  11 #include "base/logging.h"
  12 #include "third_party/skia/include/core/SkBitmap.h"
  13 #include "third_party/skia/include/effects/SkGradientShader.h"
  14 #include "ui/gfx/font_list.h"
  15 #include "ui/gfx/geometry/rect.h"
  16 #include "ui/gfx/geometry/rect_conversions.h"
  17 #include "ui/gfx/geometry/safe_integer_conversions.h"
  18 #include "ui/gfx/geometry/size_conversions.h"
  19 #include "ui/gfx/scoped_canvas.h"
  20 #include "ui/gfx/skia_util.h"
  21 #include "ui/gfx/transform.h"
  22
  23 #if defined(OS_WIN)
  24 #include "ui/gfx/canvas_skia_paint.h"
  25 #endif
  26
  27 namespace gfx {
  28
  29 Canvas::Canvas(const Size& size, float image_scale, bool is_opaque)
  30     : image_scale_(image_scale),
  31       canvas_(NULL) {
  32   Size pixel_size = ToCeiledSize(ScaleSize(size, image_scale));
  33   owned_canvas_ = skia::AdoptRef(skia::CreatePlatformCanvas(pixel_size.width(),
  34                                                             pixel_size.height(),
  35                                                             is_opaque));
  36   canvas_ = owned_canvas_.get();
  37 #if defined(OS_WIN) || defined(OS_MACOSX)
  38   // skia::PlatformCanvas instances are initialized to 0 by Cairo on Linux, but
  39   // uninitialized on Win and Mac.
  40   if (!is_opaque)
  41     owned_canvas_->clear(SkColorSetARGB(0, 0, 0, 0));
  42 #endif
  43
  44   SkScalar scale_scalar = SkFloatToScalar(image_scale);
  45   canvas_->scale(scale_scalar, scale_scalar);
  46 }
  47
  48 Canvas::Canvas(const ImageSkiaRep& image_rep, bool is_opaque)
  49     : image_scale_(image_rep.scale()),
  50       owned_canvas_(skia::AdoptRef(
  51           skia::CreatePlatformCanvas(image_rep.pixel_width(),
  52                                      image_rep.pixel_height(),
  53                                      is_opaque))),
  54       canvas_(owned_canvas_.get()) {
  55   SkScalar scale_scalar = SkFloatToScalar(image_scale_);
  56   canvas_->scale(scale_scalar, scale_scalar);
  57   DrawImageInt(ImageSkia(image_rep), 0, 0);
  58 }
  59
  60 Canvas::Canvas()
  61     : image_scale_(1.0),
  62       owned_canvas_(skia::AdoptRef(skia::CreatePlatformCanvas(0, 0, false))),
  63       canvas_(owned_canvas_.get()) {
  64 }
  65
  66 Canvas::~Canvas() {
  67 }
  68
  69 // static
  70 Canvas* Canvas::CreateCanvasWithoutScaling(SkCanvas* canvas,
  71                                            float image_scale) {
  72   return new Canvas(canvas, image_scale);
  73 }
  74
  75 void Canvas::RecreateBackingCanvas(const Size& size,
  76                                    float image_scale,
  77                                    bool is_opaque) {
  78   image_scale_ = image_scale;
  79   Size pixel_size = ToFlooredSize(ScaleSize(size, image_scale));
  80   owned_canvas_ = skia::AdoptRef(skia::CreatePlatformCanvas(pixel_size.width(),
  81                                                             pixel_size.height(),
  82                                                             is_opaque));
  83   canvas_ = owned_canvas_.get();
  84   SkScalar scale_scalar = SkFloatToScalar(image_scale);
  85   canvas_->scale(scale_scalar, scale_scalar);
  86 }
  87
  88 // static
  89 void Canvas::SizeStringInt(const base::string16& text,
  90                            const FontList& font_list,
  91                            int* width,
  92                            int* height,
  93                            int line_height,
  94                            int flags) {
  95   float fractional_width = static_cast<float>(*width);
  96   float factional_height = static_cast<float>(*height);
  97   SizeStringFloat(text, font_list, &fractional_width,
  98                   &factional_height, line_height, flags);
  99   *width = ToCeiledInt(fractional_width);
 100   *height = ToCeiledInt(factional_height);
 101 }
 102
 103 // static
 104 int Canvas::GetStringWidth(const base::string16& text,
 105                            const FontList& font_list) {
 106   int width = 0, height = 0;
 107   SizeStringInt(text, font_list, &width, &height, 0, NO_ELLIPSIS);
 108   return width;
 109 }
 110
 111 // static
 112 float Canvas::GetStringWidthF(const base::string16& text,
 113                               const FontList& font_list) {
 114   float width = 0, height = 0;
 115   SizeStringFloat(text, font_list, &width, &height, 0, NO_ELLIPSIS);
 116   return width;
 117 }
 118
 119 // static
 120 int Canvas::DefaultCanvasTextAlignment() {
 121   return base::i18n::IsRTL() ? TEXT_ALIGN_RIGHT : TEXT_ALIGN_LEFT;
 122 }
 123
 124 ImageSkiaRep Canvas::ExtractImageRep() const {
 125   // Make a bitmap to return, and a canvas to draw into it. We don't just want
 126   // to call extractSubset or the copy constructor, since we want an actual copy
 127   // of the bitmap.
 128   const SkISize size = canvas_->getDeviceSize();
 129   SkBitmap result;
 130   result.allocN32Pixels(size.width(), size.height());
 131
 132   canvas_->readPixels(&result, 0, 0);
 133   return ImageSkiaRep(result, image_scale_);
 134 }
 135
 136 void Canvas::DrawDashedRect(const Rect& rect, SkColor color) {
 137   if (rect.IsEmpty())
 138     return;
 139   // Create a 2D bitmap containing alternating on/off pixels - we do this
 140   // so that you never get two pixels of the same color around the edges
 141   // of the focus rect (this may mean that opposing edges of the rect may
 142   // have a dot pattern out of phase to each other).
 143   static SkColor last_color;
 144   static SkBitmap* dots = NULL;
 145   if (!dots || last_color != color) {
 146     int col_pixels = 32;
 147     int row_pixels = 32;
 148
 149     delete dots;
 150     last_color = color;
 151     dots = new SkBitmap;
 152     dots->allocN32Pixels(col_pixels, row_pixels);
 153     dots->eraseARGB(0, 0, 0, 0);
 154
 155     uint32_t* dot = dots->getAddr32(0, 0);
 156     for (int i = 0; i < row_pixels; i++) {
 157       for (int u = 0; u < col_pixels; u++) {
 158         if ((u % 2 + i % 2) % 2 != 0) {
 159           dot[i * row_pixels + u] = color;
 160         }
 161       }
 162     }
 163   }
 164
 165   // Make a shader for the bitmap with an origin of the box we'll draw. This
 166   // shader is refcounted and will have an initial refcount of 1.
 167   skia::RefPtr<SkShader> shader = skia::AdoptRef(
 168       SkShader::CreateBitmapShader(
 169           *dots, SkShader::kRepeat_TileMode, SkShader::kRepeat_TileMode));
 170   // Assign the shader to the paint & release our reference. The paint will
 171   // now own the shader and the shader will be destroyed when the paint goes
 172   // out of scope.
 173   SkPaint paint;
 174   paint.setShader(shader.get());
 175
 176   DrawRect(Rect(rect.x(), rect.y(), rect.width(), 1), paint);
 177   DrawRect(Rect(rect.x(), rect.y() + rect.height() - 1, rect.width(), 1),
 178            paint);
 179   DrawRect(Rect(rect.x(), rect.y(), 1, rect.height()), paint);
 180   DrawRect(Rect(rect.x() + rect.width() - 1, rect.y(), 1, rect.height()),
 181            paint);
 182 }
 183
 184 void Canvas::Save() {
 185   canvas_->save();
 186 }
 187
 188 void Canvas::SaveLayerAlpha(uint8 alpha) {
 189   canvas_->saveLayerAlpha(NULL, alpha);
 190 }
 191
 192 void Canvas::SaveLayerAlpha(uint8 alpha, const Rect& layer_bounds) {
 193   SkRect bounds(RectToSkRect(layer_bounds));
 194   canvas_->saveLayerAlpha(&bounds, alpha);
 195 }
 196
 197 void Canvas::Restore() {
 198   canvas_->restore();
 199 }
 200
 201 void Canvas::ClipRect(const Rect& rect) {
 202   canvas_->clipRect(RectToSkRect(rect));
 203 }
 204
 205 void Canvas::ClipPath(const SkPath& path, bool do_anti_alias) {
 206   canvas_->clipPath(path, SkRegion::kIntersect_Op, do_anti_alias);
 207 }
 208
 209 bool Canvas::IsClipEmpty() const {
 210   return canvas_->isClipEmpty();
 211 }
 212
 213 bool Canvas::GetClipBounds(Rect* bounds) {
 214   SkRect out;
 215   if (canvas_->getClipBounds(&out)) {
 216     *bounds = ToEnclosingRect(SkRectToRectF(out));
 217     return true;
 218   }
 219   *bounds = gfx::Rect();
 220   return false;
 221 }
 222
 223 void Canvas::Translate(const Vector2d& offset) {
 224   canvas_->translate(SkIntToScalar(offset.x()), SkIntToScalar(offset.y()));
 225 }
 226
 227 void Canvas::Scale(int x_scale, int y_scale) {
 228   canvas_->scale(SkIntToScalar(x_scale), SkIntToScalar(y_scale));
 229 }
 230
 231 void Canvas::DrawColor(SkColor color) {
 232   DrawColor(color, SkXfermode::kSrcOver_Mode);
 233 }
 234
 235 void Canvas::DrawColor(SkColor color, SkXfermode::Mode mode) {
 236   canvas_->drawColor(color, mode);
 237 }
 238
 239 void Canvas::FillRect(const Rect& rect, SkColor color) {
 240   FillRect(rect, color, SkXfermode::kSrcOver_Mode);
 241 }
 242
 243 void Canvas::FillRect(const Rect& rect,
 244                       SkColor color,
 245                       SkXfermode::Mode mode) {
 246   SkPaint paint;
 247   paint.setColor(color);
 248   paint.setStyle(SkPaint::kFill_Style);
 249   paint.setXfermodeMode(mode);
 250   DrawRect(rect, paint);
 251 }
 252
 253 void Canvas::DrawRect(const Rect& rect, SkColor color) {
 254   DrawRect(rect, color, SkXfermode::kSrcOver_Mode);
 255 }
 256
 257 void Canvas::DrawRect(const Rect& rect,
 258                       SkColor color,
 259                       SkXfermode::Mode mode) {
 260   SkPaint paint;
 261   paint.setColor(color);
 262   paint.setStyle(SkPaint::kStroke_Style);
 263   // Set a stroke width of 0, which will put us down the stroke rect path.  If
 264   // we set a stroke width of 1, for example, this will internally create a
 265   // path and fill it, which causes problems near the edge of the canvas.
 266   paint.setStrokeWidth(SkIntToScalar(0));
 267   paint.setXfermodeMode(mode);
 268
 269   DrawRect(rect, paint);
 270 }
 271
 272 void Canvas::DrawRect(const Rect& rect, const SkPaint& paint) {
 273   canvas_->drawIRect(RectToSkIRect(rect), paint);
 274 }
 275
 276 void Canvas::DrawPoint(const Point& p1, const SkPaint& paint) {
 277   canvas_->drawPoint(SkIntToScalar(p1.x()), SkIntToScalar(p1.y()), paint);
 278 }
 279
 280 void Canvas::DrawLine(const Point& p1, const Point& p2, SkColor color) {
 281   SkPaint paint;
 282   paint.setColor(color);
 283   paint.setStrokeWidth(SkIntToScalar(1));
 284   DrawLine(p1, p2, paint);
 285 }
 286
 287 void Canvas::DrawLine(const Point& p1, const Point& p2, const SkPaint& paint) {
 288   canvas_->drawLine(SkIntToScalar(p1.x()), SkIntToScalar(p1.y()),
 289                     SkIntToScalar(p2.x()), SkIntToScalar(p2.y()), paint);
 290 }
 291
 292 void Canvas::DrawCircle(const Point& center_point,
 293                         int radius,
 294                         const SkPaint& paint) {
 295   canvas_->drawCircle(SkIntToScalar(center_point.x()),
 296       SkIntToScalar(center_point.y()), SkIntToScalar(radius), paint);
 297 }
 298
 299 void Canvas::DrawRoundRect(const Rect& rect,
 300                            int radius,
 301                            const SkPaint& paint) {
 302   canvas_->drawRoundRect(RectToSkRect(rect), SkIntToScalar(radius),
 303                          SkIntToScalar(radius), paint);
 304 }
 305
 306 void Canvas::DrawPath(const SkPath& path, const SkPaint& paint) {
 307   canvas_->drawPath(path, paint);
 308 }
 309
 310 void Canvas::DrawFocusRect(const Rect& rect) {
 311   DrawDashedRect(rect, SK_ColorGRAY);
 312 }
 313
 314 void Canvas::DrawSolidFocusRect(const Rect& rect, SkColor color) {
 315   SkPaint paint;
 316   paint.setColor(color);
 317   paint.setStrokeWidth(SkIntToScalar(1));
 318   // Note: We cannot use DrawRect since it would create a path and fill it which
 319   // would cause problems near the edge of the canvas.
 320   int x1 = std::min(rect.x(), rect.right());
 321   int x2 = std::max(rect.x(), rect.right());
 322   int y1 = std::min(rect.y(), rect.bottom());
 323   int y2 = std::max(rect.y(), rect.bottom());
 324   DrawLine(Point(x1, y1), Point(x2, y1), paint);
 325   DrawLine(Point(x1, y2), Point(x2, y2), paint);
 326   DrawLine(Point(x1, y1), Point(x1, y2), paint);
 327   DrawLine(Point(x2, y1), Point(x2, y2 + 1), paint);
 328 }
 329
 330 void Canvas::DrawImageInt(const ImageSkia& image, int x, int y) {
 331   SkPaint paint;
 332   DrawImageInt(image, x, y, paint);
 333 }
 334
 335 void Canvas::DrawImageInt(const ImageSkia& image, int x, int y, uint8 a) {
 336   SkPaint paint;
 337   paint.setAlpha(a);
 338   DrawImageInt(image, x, y, paint);
 339 }
 340
 341 void Canvas::DrawImageInt(const ImageSkia& image,
 342                           int x,
 343                           int y,
 344                           const SkPaint& paint) {
 345   const ImageSkiaRep& image_rep = image.GetRepresentation(image_scale_);
 346   if (image_rep.is_null())
 347     return;
 348   const SkBitmap& bitmap = image_rep.sk_bitmap();
 349   float bitmap_scale = image_rep.scale();
 350
 351   ScopedCanvas scoper(this);
 352   canvas_->scale(SkFloatToScalar(1.0f / bitmap_scale),
 353                  SkFloatToScalar(1.0f / bitmap_scale));
 354   canvas_->drawBitmap(bitmap,
 355                       SkFloatToScalar(x * bitmap_scale),
 356                       SkFloatToScalar(y * bitmap_scale),
 357                       &paint);
 358 }
 359
 360 void Canvas::DrawImageInt(const ImageSkia& image,
 361                           int src_x,
 362                           int src_y,
 363                           int src_w,
 364                           int src_h,
 365                           int dest_x,
 366                           int dest_y,
 367                           int dest_w,
 368                           int dest_h,
 369                           bool filter) {
 370   SkPaint p;
 371   DrawImageInt(image, src_x, src_y, src_w, src_h, dest_x, dest_y,
 372                dest_w, dest_h, filter, p);
 373 }
 374
 375 void Canvas::DrawImageInt(const ImageSkia& image,
 376                           int src_x,
 377                           int src_y,
 378                           int src_w,
 379                           int src_h,
 380                           int dest_x,
 381                           int dest_y,
 382                           int dest_w,
 383                           int dest_h,
 384                           bool filter,
 385                           const SkPaint& paint) {
 386   DrawImageIntHelper(image, src_x, src_y, src_w, src_h, dest_x, dest_y, dest_w,
 387                      dest_h, filter, paint, image_scale_, false);
 388 }
 389
 390 void Canvas::DrawImageIntInPixel(const ImageSkia& image,
 391                                  int src_x,
 392                                  int src_y,
 393                                  int src_w,
 394                                  int src_h,
 395                                  int dest_x,
 396                                  int dest_y,
 397                                  int dest_w,
 398                                  int dest_h,
 399                                  bool filter,
 400                                  const SkPaint& paint) {
 401   // All values passed into this function are in pixels, i.e. no scaling needs
 402   // be done.
 403   // Logic as below:-
 404   // 1. Get the matrix transform from the canvas.
 405   // 2. Set the scale in the matrix to 1.0 while honoring the direction of the
 406   //    the scale (x/y). Example RTL layouts.
 407   // 3. Round off the X and Y translation components in the matrix. This is to
 408   //    reduce floating point errors during rect transformation. This is needed
 409   //    for fractional scale factors like 1.25/1.5, etc.
 410   // 4. Save the current state of the canvas and restore the state when going
 411   //    out of scope with ScopedCanvas.
 412   // 5. Set the modified matrix in the canvas. This ensures that no scaling
 413   //    will be done for draw operations on the canvas.
 414   // 6. Draw the image.
 415   SkMatrix matrix = canvas_->getTotalMatrix();
 416
 417   // Ensure that the direction of the x and y scales is preserved. This is
 418   // important for RTL layouts.
 419   matrix.setScaleX(matrix.getScaleX() > 0 ? 1.0f : -1.0f);
 420   matrix.setScaleY(matrix.getScaleY() > 0 ? 1.0f : -1.0f);
 421
 422   // Floor so that we get consistent rounding.
 423   matrix.setTranslateX(SkScalarFloorToScalar(matrix.getTranslateX()));
 424   matrix.setTranslateY(SkScalarFloorToScalar(matrix.getTranslateY()));
 425
 426   ScopedCanvas scoper(this);
 427
 428   canvas_->setMatrix(matrix);
 429
 430   DrawImageIntHelper(image,
 431                      src_x,
 432                      src_y,
 433                      src_w,
 434                      src_h,
 435                      dest_x,
 436                      dest_y,
 437                      dest_w,
 438                      dest_h,
 439                      filter,
 440                      paint,
 441                      image_scale_,
 442                      true);
 443 }
 444
 445 void Canvas::DrawImageInPath(const ImageSkia& image,
 446                              int x,
 447                              int y,
 448                              const SkPath& path,
 449                              const SkPaint& paint) {
 450   const ImageSkiaRep& image_rep = image.GetRepresentation(image_scale_);
 451   if (image_rep.is_null())
 452     return;
 453
 454   SkMatrix matrix;
 455   matrix.setTranslate(SkIntToScalar(x), SkIntToScalar(y));
 456   skia::RefPtr<SkShader> shader = CreateImageRepShader(
 457       image_rep,
 458       SkShader::kRepeat_TileMode,
 459       matrix);
 460
 461   SkPaint p(paint);
 462   p.setShader(shader.get());
 463   canvas_->drawPath(path, p);
 464 }
 465
 466 void Canvas::DrawStringRect(const base::string16& text,
 467                             const FontList& font_list,
 468                             SkColor color,
 469                             const Rect& display_rect) {
 470   DrawStringRectWithFlags(text, font_list, color, display_rect,
 471                           DefaultCanvasTextAlignment());
 472 }
 473
 474 void Canvas::DrawStringRectWithFlags(const base::string16& text,
 475                                      const FontList& font_list,
 476                                      SkColor color,
 477                                      const Rect& display_rect,
 478                                      int flags) {
 479   DrawStringRectWithShadows(text, font_list, color, display_rect, 0, flags,
 480                             ShadowValues());
 481 }
 482
 483 void Canvas::TileImageInt(const ImageSkia& image,
 484                           int x,
 485                           int y,
 486                           int w,
 487                           int h) {
 488   TileImageInt(image, 0, 0, x, y, w, h);
 489 }
 490
 491 void Canvas::TileImageInt(const ImageSkia& image,
 492                           int src_x,
 493                           int src_y,
 494                           int dest_x,
 495                           int dest_y,
 496                           int w,
 497                           int h) {
 498   TileImageInt(image, src_x, src_y, 1.0f, 1.0f, dest_x, dest_y, w, h);
 499 }
 500
 501 void Canvas::TileImageInt(const ImageSkia& image,
 502                           int src_x,
 503                           int src_y,
 504                           float tile_scale_x,
 505                           float tile_scale_y,
 506                           int dest_x,
 507                           int dest_y,
 508                           int w,
 509                           int h) {
 510   if (!IntersectsClipRectInt(dest_x, dest_y, w, h))
 511     return;
 512
 513   const ImageSkiaRep& image_rep = image.GetRepresentation(image_scale_);
 514   if (image_rep.is_null())
 515     return;
 516
 517   SkMatrix shader_scale;
 518   shader_scale.setScale(SkFloatToScalar(tile_scale_x),
 519                         SkFloatToScalar(tile_scale_y));
 520   shader_scale.preTranslate(SkIntToScalar(-src_x), SkIntToScalar(-src_y));
 521   shader_scale.postTranslate(SkIntToScalar(dest_x), SkIntToScalar(dest_y));
 522
 523   skia::RefPtr<SkShader> shader = CreateImageRepShader(
 524       image_rep,
 525       SkShader::kRepeat_TileMode,
 526       shader_scale);
 527
 528   SkPaint paint;
 529   paint.setShader(shader.get());
 530   paint.setXfermodeMode(SkXfermode::kSrcOver_Mode);
 531
 532   SkRect dest_rect = { SkIntToScalar(dest_x),
 533                        SkIntToScalar(dest_y),
 534                        SkIntToScalar(dest_x + w),
 535                        SkIntToScalar(dest_y + h) };
 536   canvas_->drawRect(dest_rect, paint);
 537 }
 538
 539 NativeDrawingContext Canvas::BeginPlatformPaint() {
 540   return skia::BeginPlatformPaint(canvas_);
 541 }
 542
 543 void Canvas::EndPlatformPaint() {
 544   skia::EndPlatformPaint(canvas_);
 545 }
 546
 547 void Canvas::Transform(const gfx::Transform& transform) {
 548   canvas_->concat(transform.matrix());
 549 }
 550
 551 Canvas::Canvas(SkCanvas* canvas, float image_scale)
 552     : image_scale_(image_scale),
 553       owned_canvas_(),
 554       canvas_(canvas) {
 555   DCHECK(canvas);
 556 }
 557
 558 bool Canvas::IntersectsClipRectInt(int x, int y, int w, int h) {
 559   SkRect clip;
 560   return canvas_->getClipBounds(&clip) &&
 561       clip.intersect(SkIntToScalar(x), SkIntToScalar(y), SkIntToScalar(x + w),
 562                      SkIntToScalar(y + h));
 563 }
 564
 565 bool Canvas::IntersectsClipRect(const Rect& rect) {
 566   return IntersectsClipRectInt(rect.x(), rect.y(),
 567                                rect.width(), rect.height());
 568 }
 569
 570 void Canvas::DrawImageIntHelper(const ImageSkia& image,
 571                                 int src_x,
 572                                 int src_y,
 573                                 int src_w,
 574                                 int src_h,
 575                                 int dest_x,
 576                                 int dest_y,
 577                                 int dest_w,
 578                                 int dest_h,
 579                                 bool filter,
 580                                 const SkPaint& paint,
 581                                 float image_scale,
 582                                 bool pixel) {
 583   DLOG_ASSERT(src_x + src_w < std::numeric_limits<int16_t>::max() &&
 584               src_y + src_h < std::numeric_limits<int16_t>::max());
 585   if (src_w <= 0 || src_h <= 0) {
 586     NOTREACHED() << "Attempting to draw bitmap from an empty rect!";
 587     return;
 588   }
 589
 590   if (!IntersectsClipRectInt(dest_x, dest_y, dest_w, dest_h))
 591     return;
 592
 593   float user_scale_x = static_cast<float>(dest_w) / src_w;
 594   float user_scale_y = static_cast<float>(dest_h) / src_h;
 595
 596   const ImageSkiaRep& image_rep = image.GetRepresentation(image_scale);
 597   if (image_rep.is_null())
 598     return;
 599
 600   SkRect dest_rect = { SkIntToScalar(dest_x),
 601                        SkIntToScalar(dest_y),
 602                        SkIntToScalar(dest_x + dest_w),
 603                        SkIntToScalar(dest_y + dest_h) };
 604
 605   if (src_w == dest_w && src_h == dest_h &&
 606       user_scale_x == 1.0f && user_scale_y == 1.0f &&
 607       image_rep.scale() == 1.0f && !pixel) {
 608     // Workaround for apparent bug in Skia that causes image to occasionally
 609     // shift.
 610     SkIRect src_rect = { src_x, src_y, src_x + src_w, src_y + src_h };
 611     const SkBitmap& bitmap = image_rep.sk_bitmap();
 612     canvas_->drawBitmapRect(bitmap, &src_rect, dest_rect, &paint);
 613     return;
 614   }
 615
 616   // Make a bitmap shader that contains the bitmap we want to draw. This is
 617   // basically what SkCanvas.drawBitmap does internally, but it gives us
 618   // more control over quality and will use the mipmap in the source image if
 619   // it has one, whereas drawBitmap won't.
 620   SkMatrix shader_scale;
 621   shader_scale.setScale(SkFloatToScalar(user_scale_x),
 622                         SkFloatToScalar(user_scale_y));
 623   shader_scale.preTranslate(SkIntToScalar(-src_x), SkIntToScalar(-src_y));
 624   shader_scale.postTranslate(SkIntToScalar(dest_x), SkIntToScalar(dest_y));
 625
 626   skia::RefPtr<SkShader> shader = CreateImageRepShaderForScale(
 627       image_rep,
 628       SkShader::kRepeat_TileMode,
 629       shader_scale,
 630       pixel ? 1.0f : image_rep.scale());
 631
 632   // Set up our paint to use the shader & release our reference (now just owned
 633   // by the paint).
 634   SkPaint p(paint);
 635   p.setFilterQuality(filter ? kLow_SkFilterQuality : kNone_SkFilterQuality);
 636   p.setShader(shader.get());
 637
 638   // The rect will be filled by the bitmap.
 639   canvas_->drawRect(dest_rect, p);
 640 }
 641
 642 }  // namespace gfx