skia/ext/analysis_canvas.cc

   1 // Copyright (c) 2013 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 "base/debug/trace_event.h"
   6 #include "base/logging.h"
   7 #include "skia/ext/analysis_canvas.h"
   8 #include "third_party/skia/include/core/SkDraw.h"
   9 #include "third_party/skia/include/core/SkRRect.h"
  10 #include "third_party/skia/include/core/SkShader.h"
  11 #include "third_party/skia/src/core/SkRasterClip.h"
  12 #include "ui/gfx/rect_conversions.h"
  13
  14 namespace {
  15
  16 const int kNoLayer = -1;
  17
  18 bool IsSolidColorPaint(const SkPaint& paint) {
  19   SkXfermode::Mode xfermode;
  20
  21   // getXfermode can return a NULL, but that is handled
  22   // gracefully by AsMode (NULL turns into kSrcOver mode).
  23   SkXfermode::AsMode(paint.getXfermode(), &xfermode);
  24
  25   // Paint is solid color if the following holds:
  26   // - Alpha is 1.0, style is fill, and there are no special effects
  27   // - Xfer mode is either kSrc or kSrcOver (kSrcOver is equivalent
  28   //   to kSrc if source alpha is 1.0, which is already checked).
  29   return (paint.getAlpha() == 255 &&
  30           !paint.getShader() &&
  31           !paint.getLooper() &&
  32           !paint.getMaskFilter() &&
  33           !paint.getColorFilter() &&
  34           !paint.getImageFilter() &&
  35           paint.getStyle() == SkPaint::kFill_Style &&
  36           (xfermode == SkXfermode::kSrc_Mode ||
  37            xfermode == SkXfermode::kSrcOver_Mode));
  38 }
  39
  40 // Returns true if the specified drawn_rect will cover the entire canvas, and
  41 // that the canvas is not clipped (i.e. it covers ALL of the canvas).
  42 bool IsFullQuad(SkCanvas* canvas, const SkRect& drawn_rect) {
  43   if (!canvas->isClipRect())
  44     return false;
  45
  46   SkIRect clip_irect;
  47   canvas->getClipDeviceBounds(&clip_irect);
  48   // if the clip is smaller than the canvas, we're partly clipped, so abort.
  49   if (!clip_irect.contains(SkIRect::MakeSize(canvas->getDeviceSize())))
  50     return false;
  51
  52   const SkMatrix& matrix = canvas->getTotalMatrix();
  53   // If the transform results in a non-axis aligned
  54   // rect, then be conservative and return false.
  55   if (!matrix.rectStaysRect())
  56     return false;
  57
  58   SkRect device_rect;
  59   matrix.mapRect(&device_rect, drawn_rect);
  60   SkRect clip_rect;
  61   clip_rect.set(clip_irect);
  62   return device_rect.contains(clip_rect);
  63 }
  64
  65 } // namespace
  66
  67 namespace skia {
  68
  69 void AnalysisCanvas::SetForceNotSolid(bool flag) {
  70   is_forced_not_solid_ = flag;
  71   if (is_forced_not_solid_)
  72     is_solid_color_ = false;
  73 }
  74
  75 void AnalysisCanvas::SetForceNotTransparent(bool flag) {
  76   is_forced_not_transparent_ = flag;
  77   if (is_forced_not_transparent_)
  78     is_transparent_ = false;
  79 }
  80
  81 void AnalysisCanvas::clear(SkColor color) {
  82   is_transparent_ = (!is_forced_not_transparent_ && SkColorGetA(color) == 0);
  83   has_text_ = false;
  84
  85   if (!is_forced_not_solid_ && SkColorGetA(color) == 255) {
  86     is_solid_color_ = true;
  87     color_ = color;
  88   } else {
  89     is_solid_color_ = false;
  90   }
  91 }
  92
  93 void AnalysisCanvas::drawPaint(const SkPaint& paint) {
  94   // This check is in SkCanvas::drawPaint(), and some of our unittests rely on
  95   // on this, so we reproduce it here.
  96   if (isClipEmpty())
  97     return;
  98
  99   is_solid_color_ = false;
 100   is_transparent_ = false;
 101 }
 102
 103 void AnalysisCanvas::drawPoints(SkCanvas::PointMode mode,
 104                                 size_t count,
 105                                 const SkPoint points[],
 106                                 const SkPaint& paint) {
 107   is_solid_color_ = false;
 108   is_transparent_ = false;
 109 }
 110
 111 void AnalysisCanvas::drawRect(const SkRect& rect, const SkPaint& paint) {
 112   // This recreates the early-exit logic in SkCanvas.cpp, which aborts early
 113   // if the paint will "draw nothing".
 114   if (paint.nothingToDraw())
 115     return;
 116
 117   bool does_cover_canvas = IsFullQuad(this, rect);
 118
 119   SkXfermode::Mode xfermode;
 120   SkXfermode::AsMode(paint.getXfermode(), &xfermode);
 121
 122   // This canvas will become transparent if the following holds:
 123   // - The quad is a full tile quad
 124   // - We're not in "forced not transparent" mode
 125   // - Transfer mode is clear (0 color, 0 alpha)
 126   //
 127   // If the paint alpha is not 0, or if the transfrer mode is
 128   // not src, then this canvas will not be transparent.
 129   //
 130   // In all other cases, we keep the current transparent value
 131   if (does_cover_canvas &&
 132       !is_forced_not_transparent_ &&
 133       xfermode == SkXfermode::kClear_Mode) {
 134     is_transparent_ = true;
 135     has_text_ = false;
 136   } else if (paint.getAlpha() != 0 || xfermode != SkXfermode::kSrc_Mode) {
 137     is_transparent_ = false;
 138   }
 139
 140   // This bitmap is solid if and only if the following holds.
 141   // Note that this might be overly conservative:
 142   // - We're not in "forced not solid" mode
 143   // - Paint is solid color
 144   // - The quad is a full tile quad
 145   if (!is_forced_not_solid_ && IsSolidColorPaint(paint) && does_cover_canvas) {
 146     is_solid_color_ = true;
 147     color_ = paint.getColor();
 148     has_text_ = false;
 149   } else {
 150     is_solid_color_ = false;
 151   }
 152 }
 153
 154 void AnalysisCanvas::drawOval(const SkRect& oval, const SkPaint& paint) {
 155   is_solid_color_ = false;
 156   is_transparent_ = false;
 157 }
 158
 159 void AnalysisCanvas::drawRRect(const SkRRect& rr, const SkPaint& paint) {
 160   // This should add the SkRRect to an SkPath, and call
 161   // drawPath, but since drawPath ignores the SkPath, just
 162   // do the same work here.
 163   is_solid_color_ = false;
 164   is_transparent_ = false;
 165 }
 166
 167 void AnalysisCanvas::drawPath(const SkPath& path, const SkPaint& paint) {
 168   is_solid_color_ = false;
 169   is_transparent_ = false;
 170 }
 171
 172 void AnalysisCanvas::drawBitmap(const SkBitmap& bitmap,
 173                                 SkScalar left,
 174                                 SkScalar top,
 175                                 const SkPaint*) {
 176   is_solid_color_ = false;
 177   is_transparent_ = false;
 178 }
 179
 180 void AnalysisCanvas::drawBitmapRectToRect(const SkBitmap&,
 181                                           const SkRect* src,
 182                                           const SkRect& dst,
 183                                           const SkPaint* paint,
 184                                           DrawBitmapRectFlags flags) {
 185   // Call drawRect to determine transparency,
 186   // but reset solid color to false.
 187   SkPaint tmpPaint;
 188   if (!paint)
 189     paint = &tmpPaint;
 190   drawRect(dst, *paint);
 191   is_solid_color_ = false;
 192 }
 193
 194 void AnalysisCanvas::drawBitmapMatrix(const SkBitmap& bitmap,
 195                                       const SkMatrix& matrix,
 196                                       const SkPaint* paint) {
 197   is_solid_color_ = false;
 198   is_transparent_ = false;
 199 }
 200
 201 void AnalysisCanvas::drawBitmapNine(const SkBitmap& bitmap,
 202                                     const SkIRect& center,
 203                                     const SkRect& dst,
 204                                     const SkPaint* paint) {
 205   is_solid_color_ = false;
 206   is_transparent_ = false;
 207 }
 208
 209 void AnalysisCanvas::drawSprite(const SkBitmap& bitmap,
 210                                 int left,
 211                                 int top,
 212                                 const SkPaint* paint) {
 213   is_solid_color_ = false;
 214   is_transparent_ = false;
 215 }
 216
 217 void AnalysisCanvas::onDrawText(const void* text,
 218                                 size_t len,
 219                                 SkScalar x,
 220                                 SkScalar y,
 221                                 const SkPaint& paint) {
 222   is_solid_color_ = false;
 223   is_transparent_ = false;
 224   has_text_ = true;
 225 }
 226
 227 void AnalysisCanvas::onDrawPosText(const void* text,
 228                                    size_t byteLength,
 229                                    const SkPoint pos[],
 230                                    const SkPaint& paint) {
 231   is_solid_color_ = false;
 232   is_transparent_ = false;
 233   has_text_ = true;
 234 }
 235
 236 void AnalysisCanvas::onDrawPosTextH(const void* text,
 237                                     size_t byteLength,
 238                                     const SkScalar xpos[],
 239                                     SkScalar constY,
 240                                     const SkPaint& paint) {
 241   is_solid_color_ = false;
 242   is_transparent_ = false;
 243   has_text_ = true;
 244 }
 245
 246 void AnalysisCanvas::onDrawTextOnPath(const void* text,
 247                                       size_t len,
 248                                       const SkPath& path,
 249                                       const SkMatrix* matrix,
 250                                       const SkPaint& paint) {
 251   is_solid_color_ = false;
 252   is_transparent_ = false;
 253   has_text_ = true;
 254 }
 255
 256 void AnalysisCanvas::drawVertices(SkCanvas::VertexMode,
 257                                   int vertex_count,
 258                                   const SkPoint verts[],
 259                                   const SkPoint texs[],
 260                                   const SkColor colors[],
 261                                   SkXfermode* xmode,
 262                                   const uint16_t indices[],
 263                                   int index_count,
 264                                   const SkPaint& paint) {
 265   is_solid_color_ = false;
 266   is_transparent_ = false;
 267 }
 268
 269 // Needed for now, since SkCanvas requires a bitmap, even if it is not backed
 270 // by any pixels
 271 static SkBitmap MakeEmptyBitmap(int width, int height) {
 272   SkBitmap bitmap;
 273   bitmap.setConfig(SkBitmap::kNo_Config, width, height);
 274   return bitmap;
 275 }
 276
 277 AnalysisCanvas::AnalysisCanvas(int width, int height)
 278     : INHERITED(MakeEmptyBitmap(width, height)),
 279       saved_stack_size_(0),
 280       force_not_solid_stack_level_(kNoLayer),
 281       force_not_transparent_stack_level_(kNoLayer),
 282       is_forced_not_solid_(false),
 283       is_forced_not_transparent_(false),
 284       is_solid_color_(true),
 285       is_transparent_(true),
 286       has_text_(false) {}
 287
 288 AnalysisCanvas::~AnalysisCanvas() {}
 289
 290 bool AnalysisCanvas::GetColorIfSolid(SkColor* color) const {
 291   if (is_transparent_) {
 292     *color = SK_ColorTRANSPARENT;
 293     return true;
 294   }
 295   if (is_solid_color_) {
 296     *color = color_;
 297     return true;
 298   }
 299   return false;
 300 }
 301
 302 bool AnalysisCanvas::HasText() const { return has_text_; }
 303
 304 bool AnalysisCanvas::abortDrawing() {
 305   // Early out as soon as we have detected that the tile has text.
 306   return HasText();
 307 }
 308
 309 void AnalysisCanvas::onClipRect(const SkRect& rect, SkRegion::Op op,
 310                                 ClipEdgeStyle edge_style) {
 311
 312   INHERITED::onClipRect(rect, op, edge_style);
 313 }
 314
 315 void AnalysisCanvas::onClipPath(const SkPath& path, SkRegion::Op op,
 316                                 ClipEdgeStyle edge_style) {
 317   // clipPaths can make our calls to IsFullQuad invalid (ie have false
 318   // positives). As a precaution, force the setting to be non-solid
 319   // and non-transparent until we pop this
 320   if (force_not_solid_stack_level_ == kNoLayer) {
 321     force_not_solid_stack_level_ = saved_stack_size_;
 322     SetForceNotSolid(true);
 323   }
 324   if (force_not_transparent_stack_level_ == kNoLayer) {
 325     force_not_transparent_stack_level_ = saved_stack_size_;
 326     SetForceNotTransparent(true);
 327   }
 328
 329   INHERITED::onClipRect(path.getBounds(), op, edge_style);
 330 }
 331
 332 void AnalysisCanvas::onClipRRect(const SkRRect& rrect,
 333                                  SkRegion::Op op,
 334                                  ClipEdgeStyle edge_style) {
 335   // clipRRect can make our calls to IsFullQuad invalid (ie have false
 336   // positives). As a precaution, force the setting to be non-solid
 337   // and non-transparent until we pop this
 338   if (force_not_solid_stack_level_ == kNoLayer) {
 339     force_not_solid_stack_level_ = saved_stack_size_;
 340     SetForceNotSolid(true);
 341   }
 342   if (force_not_transparent_stack_level_ == kNoLayer) {
 343     force_not_transparent_stack_level_ = saved_stack_size_;
 344     SetForceNotTransparent(true);
 345   }
 346
 347   INHERITED::onClipRect(rrect.getBounds(), op, edge_style);
 348 }
 349
 350 void AnalysisCanvas::willSave(SkCanvas::SaveFlags flags) {
 351   ++saved_stack_size_;
 352   INHERITED::willSave(flags);
 353 }
 354
 355 SkCanvas::SaveLayerStrategy AnalysisCanvas::willSaveLayer(
 356     const SkRect* bounds,
 357     const SkPaint* paint,
 358     SkCanvas::SaveFlags flags) {
 359
 360   ++saved_stack_size_;
 361
 362   SkIRect canvas_ibounds = SkIRect::MakeSize(this->getDeviceSize());
 363   SkRect canvas_bounds;
 364   canvas_bounds.set(canvas_ibounds);
 365
 366   // If after we draw to the saved layer, we have to blend with the current
 367   // layer, then we can conservatively say that the canvas will not be of
 368   // solid color.
 369   if ((paint && !IsSolidColorPaint(*paint)) ||
 370       (bounds && !bounds->contains(canvas_bounds))) {
 371     if (force_not_solid_stack_level_ == kNoLayer) {
 372       force_not_solid_stack_level_ = saved_stack_size_;
 373       SetForceNotSolid(true);
 374     }
 375   }
 376
 377   // If after we draw to the save layer, we have to blend with the current
 378   // layer using any part of the current layer's alpha, then we can
 379   // conservatively say that the canvas will not be transparent.
 380   SkXfermode::Mode xfermode = SkXfermode::kSrc_Mode;
 381   if (paint)
 382     SkXfermode::AsMode(paint->getXfermode(), &xfermode);
 383   if (xfermode != SkXfermode::kSrc_Mode) {
 384     if (force_not_transparent_stack_level_ == kNoLayer) {
 385       force_not_transparent_stack_level_ = saved_stack_size_;
 386       SetForceNotTransparent(true);
 387     }
 388   }
 389
 390   INHERITED::willSaveLayer(bounds, paint, flags);
 391   // Actually saving a layer here could cause a new bitmap to be created
 392   // and real rendering to occur.
 393   return kNoLayer_SaveLayerStrategy;
 394 }
 395
 396 void AnalysisCanvas::willRestore() {
 397   DCHECK(saved_stack_size_);
 398   if (saved_stack_size_) {
 399     --saved_stack_size_;
 400     if (saved_stack_size_ < force_not_solid_stack_level_) {
 401       SetForceNotSolid(false);
 402       force_not_solid_stack_level_ = kNoLayer;
 403     }
 404     if (saved_stack_size_ < force_not_transparent_stack_level_) {
 405       SetForceNotTransparent(false);
 406       force_not_transparent_stack_level_ = kNoLayer;
 407     }
 408   }
 409
 410   INHERITED::willRestore();
 411 }
 412
 413 }  // namespace skia
 414
 415