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/geometry/rect_conversions.h"
  13
  14 namespace {
  15
  16 const int kNoLayer = -1;
  17
  18 bool ActsLikeClear(SkXfermode::Mode mode, unsigned src_alpha) {
  19   switch (mode) {
  20     case SkXfermode::kClear_Mode:
  21       return true;
  22     case SkXfermode::kSrc_Mode:
  23     case SkXfermode::kSrcIn_Mode:
  24     case SkXfermode::kDstIn_Mode:
  25     case SkXfermode::kSrcOut_Mode:
  26     case SkXfermode::kDstATop_Mode:
  27       return src_alpha == 0;
  28     case SkXfermode::kDstOut_Mode:
  29       return src_alpha == 0xFF;
  30     default:
  31       return false;
  32   }
  33 }
  34
  35 bool IsSolidColorPaint(const SkPaint& paint) {
  36   SkXfermode::Mode xfermode;
  37
  38   // getXfermode can return a NULL, but that is handled
  39   // gracefully by AsMode (NULL turns into kSrcOver mode).
  40   SkXfermode::AsMode(paint.getXfermode(), &xfermode);
  41
  42   // Paint is solid color if the following holds:
  43   // - Alpha is 1.0, style is fill, and there are no special effects
  44   // - Xfer mode is either kSrc or kSrcOver (kSrcOver is equivalent
  45   //   to kSrc if source alpha is 1.0, which is already checked).
  46   return (paint.getAlpha() == 255 &&
  47           !paint.getShader() &&
  48           !paint.getLooper() &&
  49           !paint.getMaskFilter() &&
  50           !paint.getColorFilter() &&
  51           !paint.getImageFilter() &&
  52           paint.getStyle() == SkPaint::kFill_Style &&
  53           (xfermode == SkXfermode::kSrc_Mode ||
  54            xfermode == SkXfermode::kSrcOver_Mode));
  55 }
  56
  57 // Returns true if the specified drawn_rect will cover the entire canvas, and
  58 // that the canvas is not clipped (i.e. it covers ALL of the canvas).
  59 bool IsFullQuad(SkCanvas* canvas, const SkRect& drawn_rect) {
  60   if (!canvas->isClipRect())
  61     return false;
  62
  63   SkIRect clip_irect;
  64   canvas->getClipDeviceBounds(&clip_irect);
  65   // if the clip is smaller than the canvas, we're partly clipped, so abort.
  66   if (!clip_irect.contains(SkIRect::MakeSize(canvas->getDeviceSize())))
  67     return false;
  68
  69   const SkMatrix& matrix = canvas->getTotalMatrix();
  70   // If the transform results in a non-axis aligned
  71   // rect, then be conservative and return false.
  72   if (!matrix.rectStaysRect())
  73     return false;
  74
  75   SkRect device_rect;
  76   matrix.mapRect(&device_rect, drawn_rect);
  77   SkRect clip_rect;
  78   clip_rect.set(clip_irect);
  79   return device_rect.contains(clip_rect);
  80 }
  81
  82 } // namespace
  83
  84 namespace skia {
  85
  86 void AnalysisCanvas::SetForceNotSolid(bool flag) {
  87   is_forced_not_solid_ = flag;
  88   if (is_forced_not_solid_)
  89     is_solid_color_ = false;
  90 }
  91
  92 void AnalysisCanvas::SetForceNotTransparent(bool flag) {
  93   is_forced_not_transparent_ = flag;
  94   if (is_forced_not_transparent_)
  95     is_transparent_ = false;
  96 }
  97
  98 void AnalysisCanvas::drawPaint(const SkPaint& paint) {
  99   SkRect rect;
 100   getClipBounds(&rect);
 101   drawRect(rect, paint);
 102 }
 103
 104 void AnalysisCanvas::drawPoints(SkCanvas::PointMode mode,
 105                                 size_t count,
 106                                 const SkPoint points[],
 107                                 const SkPaint& paint) {
 108   is_solid_color_ = false;
 109   is_transparent_ = false;
 110   ++draw_op_count_;
 111 }
 112
 113 void AnalysisCanvas::drawRect(const SkRect& rect, const SkPaint& paint) {
 114   // This recreates the early-exit logic in SkCanvas.cpp.
 115   SkRect scratch;
 116   if (paint.canComputeFastBounds() &&
 117       quickReject(paint.computeFastBounds(rect, &scratch))) {
 118     return;
 119   }
 120
 121   // An extra no-op check SkCanvas.cpp doesn't do.
 122   if (paint.nothingToDraw())
 123     return;
 124
 125   bool does_cover_canvas = IsFullQuad(this, rect);
 126
 127   SkXfermode::Mode xfermode;
 128   SkXfermode::AsMode(paint.getXfermode(), &xfermode);
 129
 130   // This canvas will become transparent if the following holds:
 131   // - The quad is a full tile quad
 132   // - We're not in "forced not transparent" mode
 133   // - Transfer mode is clear (0 color, 0 alpha)
 134   //
 135   // If the paint alpha is not 0, or if the transfrer mode is
 136   // not src, then this canvas will not be transparent.
 137   //
 138   // In all other cases, we keep the current transparent value
 139   if (does_cover_canvas &&
 140       !is_forced_not_transparent_ &&
 141       ActsLikeClear(xfermode, paint.getAlpha())) {
 142     is_transparent_ = true;
 143   } else if (paint.getAlpha() != 0 || xfermode != SkXfermode::kSrc_Mode) {
 144     is_transparent_ = false;
 145   }
 146
 147   // This bitmap is solid if and only if the following holds.
 148   // Note that this might be overly conservative:
 149   // - We're not in "forced not solid" mode
 150   // - Paint is solid color
 151   // - The quad is a full tile quad
 152   if (!is_forced_not_solid_ && IsSolidColorPaint(paint) && does_cover_canvas) {
 153     is_solid_color_ = true;
 154     color_ = paint.getColor();
 155   } else {
 156     is_solid_color_ = false;
 157   }
 158   ++draw_op_count_;
 159 }
 160
 161 void AnalysisCanvas::drawOval(const SkRect& oval, const SkPaint& paint) {
 162   is_solid_color_ = false;
 163   is_transparent_ = false;
 164   ++draw_op_count_;
 165 }
 166
 167 void AnalysisCanvas::drawRRect(const SkRRect& rr, const SkPaint& paint) {
 168   // This should add the SkRRect to an SkPath, and call
 169   // drawPath, but since drawPath ignores the SkPath, just
 170   // do the same work here.
 171   is_solid_color_ = false;
 172   is_transparent_ = false;
 173   ++draw_op_count_;
 174 }
 175
 176 void AnalysisCanvas::drawPath(const SkPath& path, const SkPaint& paint) {
 177   is_solid_color_ = false;
 178   is_transparent_ = false;
 179   ++draw_op_count_;
 180 }
 181
 182 void AnalysisCanvas::drawBitmap(const SkBitmap& bitmap,
 183                                 SkScalar left,
 184                                 SkScalar top,
 185                                 const SkPaint*) {
 186   is_solid_color_ = false;
 187   is_transparent_ = false;
 188   ++draw_op_count_;
 189 }
 190
 191 void AnalysisCanvas::drawBitmapRectToRect(const SkBitmap&,
 192                                           const SkRect* src,
 193                                           const SkRect& dst,
 194                                           const SkPaint* paint,
 195                                           DrawBitmapRectFlags flags) {
 196   // Call drawRect to determine transparency,
 197   // but reset solid color to false.
 198   SkPaint tmpPaint;
 199   if (!paint)
 200     paint = &tmpPaint;
 201   drawRect(dst, *paint);
 202   is_solid_color_ = false;
 203   ++draw_op_count_;
 204 }
 205
 206 void AnalysisCanvas::drawBitmapNine(const SkBitmap& bitmap,
 207                                     const SkIRect& center,
 208                                     const SkRect& dst,
 209                                     const SkPaint* paint) {
 210   is_solid_color_ = false;
 211   is_transparent_ = false;
 212   ++draw_op_count_;
 213 }
 214
 215 void AnalysisCanvas::drawSprite(const SkBitmap& bitmap,
 216                                 int left,
 217                                 int top,
 218                                 const SkPaint* paint) {
 219   is_solid_color_ = false;
 220   is_transparent_ = false;
 221   ++draw_op_count_;
 222 }
 223
 224 void AnalysisCanvas::onDrawText(const void* text,
 225                                 size_t len,
 226                                 SkScalar x,
 227                                 SkScalar y,
 228                                 const SkPaint& paint) {
 229   is_solid_color_ = false;
 230   is_transparent_ = false;
 231   ++draw_op_count_;
 232 }
 233
 234 void AnalysisCanvas::onDrawPosText(const void* text,
 235                                    size_t byteLength,
 236                                    const SkPoint pos[],
 237                                    const SkPaint& paint) {
 238   is_solid_color_ = false;
 239   is_transparent_ = false;
 240   ++draw_op_count_;
 241 }
 242
 243 void AnalysisCanvas::onDrawPosTextH(const void* text,
 244                                     size_t byteLength,
 245                                     const SkScalar xpos[],
 246                                     SkScalar constY,
 247                                     const SkPaint& paint) {
 248   is_solid_color_ = false;
 249   is_transparent_ = false;
 250   ++draw_op_count_;
 251 }
 252
 253 void AnalysisCanvas::onDrawTextOnPath(const void* text,
 254                                       size_t len,
 255                                       const SkPath& path,
 256                                       const SkMatrix* matrix,
 257                                       const SkPaint& paint) {
 258   is_solid_color_ = false;
 259   is_transparent_ = false;
 260   ++draw_op_count_;
 261 }
 262
 263 void AnalysisCanvas::onDrawTextBlob(const SkTextBlob* blob,
 264                                     SkScalar x,
 265                                     SkScalar y,
 266                                     const SkPaint &paint) {
 267   is_solid_color_ = false;
 268   is_transparent_ = false;
 269   ++draw_op_count_;
 270 }
 271
 272 void AnalysisCanvas::onDrawDRRect(const SkRRect& outer,
 273                                   const SkRRect& inner,
 274                                   const SkPaint& paint) {
 275   is_solid_color_ = false;
 276   is_transparent_ = false;
 277   ++draw_op_count_;
 278 }
 279
 280 void AnalysisCanvas::drawVertices(SkCanvas::VertexMode,
 281                                   int vertex_count,
 282                                   const SkPoint verts[],
 283                                   const SkPoint texs[],
 284                                   const SkColor colors[],
 285                                   SkXfermode* xmode,
 286                                   const uint16_t indices[],
 287                                   int index_count,
 288                                   const SkPaint& paint) {
 289   is_solid_color_ = false;
 290   is_transparent_ = false;
 291   ++draw_op_count_;
 292 }
 293
 294 // Needed for now, since SkCanvas requires a bitmap, even if it is not backed
 295 // by any pixels
 296 static SkBitmap MakeEmptyBitmap(int width, int height) {
 297   SkBitmap bitmap;
 298   bitmap.setInfo(SkImageInfo::MakeUnknown(width, height));
 299   return bitmap;
 300 }
 301
 302 AnalysisCanvas::AnalysisCanvas(int width, int height)
 303     : INHERITED(MakeEmptyBitmap(width, height)),
 304       saved_stack_size_(0),
 305       force_not_solid_stack_level_(kNoLayer),
 306       force_not_transparent_stack_level_(kNoLayer),
 307       is_forced_not_solid_(false),
 308       is_forced_not_transparent_(false),
 309       is_solid_color_(true),
 310       color_(SK_ColorTRANSPARENT),
 311       is_transparent_(true),
 312       draw_op_count_(0) {
 313 }
 314
 315 AnalysisCanvas::~AnalysisCanvas() {}
 316
 317 bool AnalysisCanvas::GetColorIfSolid(SkColor* color) const {
 318   if (is_transparent_) {
 319     *color = SK_ColorTRANSPARENT;
 320     return true;
 321   }
 322   if (is_solid_color_) {
 323     *color = color_;
 324     return true;
 325   }
 326   return false;
 327 }
 328
 329 bool AnalysisCanvas::abortDrawing() {
 330   // Early out as soon as we have more than one draw op.
 331   // TODO(vmpstr): Investigate if 1 is the correct metric here. We need to
 332   // balance the amount of time we spend analyzing vs how many tiles would be
 333   // solid if the number was higher.
 334   if (draw_op_count_ > 1) {
 335     // We have to reset solid/transparent state to false since we don't
 336     // know whether consequent operations will make this false.
 337     is_solid_color_ = false;
 338     is_transparent_ = false;
 339     return true;
 340   }
 341   return false;
 342 }
 343
 344 void AnalysisCanvas::OnComplexClip() {
 345   // complex clips can make our calls to IsFullQuad invalid (ie have false
 346   // positives). As a precaution, force the setting to be non-solid
 347   // and non-transparent until we pop this
 348   if (force_not_solid_stack_level_ == kNoLayer) {
 349     force_not_solid_stack_level_ = saved_stack_size_;
 350     SetForceNotSolid(true);
 351   }
 352   if (force_not_transparent_stack_level_ == kNoLayer) {
 353     force_not_transparent_stack_level_ = saved_stack_size_;
 354     SetForceNotTransparent(true);
 355   }
 356 }
 357
 358 void AnalysisCanvas::onClipRect(const SkRect& rect,
 359                                 SkRegion::Op op,
 360                                 ClipEdgeStyle edge_style) {
 361   INHERITED::onClipRect(rect, op, edge_style);
 362 }
 363
 364 void AnalysisCanvas::onClipPath(const SkPath& path,
 365                                 SkRegion::Op op,
 366                                 ClipEdgeStyle edge_style) {
 367   OnComplexClip();
 368   INHERITED::onClipRect(path.getBounds(), op, edge_style);
 369 }
 370
 371 void AnalysisCanvas::onClipRRect(const SkRRect& rrect,
 372                                  SkRegion::Op op,
 373                                  ClipEdgeStyle edge_style) {
 374   OnComplexClip();
 375   INHERITED::onClipRect(rrect.getBounds(), op, edge_style);
 376 }
 377
 378 void AnalysisCanvas::onClipRegion(const SkRegion& deviceRgn, SkRegion::Op op) {
 379   const ClipEdgeStyle edge_style = kHard_ClipEdgeStyle;
 380   if (deviceRgn.isRect()) {
 381     onClipRect(SkRect::MakeFromIRect(deviceRgn.getBounds()), op, edge_style);
 382     return;
 383   }
 384   OnComplexClip();
 385   INHERITED::onClipRect(
 386       SkRect::MakeFromIRect(deviceRgn.getBounds()), op, edge_style);
 387 }
 388
 389 void AnalysisCanvas::willSave() {
 390   ++saved_stack_size_;
 391   INHERITED::willSave();
 392 }
 393
 394 SkCanvas::SaveLayerStrategy AnalysisCanvas::willSaveLayer(
 395     const SkRect* bounds,
 396     const SkPaint* paint,
 397     SkCanvas::SaveFlags flags) {
 398
 399   ++saved_stack_size_;
 400
 401   SkIRect canvas_ibounds = SkIRect::MakeSize(this->getDeviceSize());
 402   SkRect canvas_bounds;
 403   canvas_bounds.set(canvas_ibounds);
 404
 405   // If after we draw to the saved layer, we have to blend with the current
 406   // layer, then we can conservatively say that the canvas will not be of
 407   // solid color.
 408   if ((paint && !IsSolidColorPaint(*paint)) ||
 409       (bounds && !bounds->contains(canvas_bounds))) {
 410     if (force_not_solid_stack_level_ == kNoLayer) {
 411       force_not_solid_stack_level_ = saved_stack_size_;
 412       SetForceNotSolid(true);
 413     }
 414   }
 415
 416   // If after we draw to the save layer, we have to blend with the current
 417   // layer using any part of the current layer's alpha, then we can
 418   // conservatively say that the canvas will not be transparent.
 419   SkXfermode::Mode xfermode = SkXfermode::kSrc_Mode;
 420   if (paint)
 421     SkXfermode::AsMode(paint->getXfermode(), &xfermode);
 422   if (xfermode != SkXfermode::kSrc_Mode) {
 423     if (force_not_transparent_stack_level_ == kNoLayer) {
 424       force_not_transparent_stack_level_ = saved_stack_size_;
 425       SetForceNotTransparent(true);
 426     }
 427   }
 428
 429   INHERITED::willSaveLayer(bounds, paint, flags);
 430   // Actually saving a layer here could cause a new bitmap to be created
 431   // and real rendering to occur.
 432   return kNoLayer_SaveLayerStrategy;
 433 }
 434
 435 void AnalysisCanvas::willRestore() {
 436   DCHECK(saved_stack_size_);
 437   if (saved_stack_size_) {
 438     --saved_stack_size_;
 439     if (saved_stack_size_ < force_not_solid_stack_level_) {
 440       SetForceNotSolid(false);
 441       force_not_solid_stack_level_ = kNoLayer;
 442     }
 443     if (saved_stack_size_ < force_not_transparent_stack_level_) {
 444       SetForceNotTransparent(false);
 445       force_not_transparent_stack_level_ = kNoLayer;
 446     }
 447   }
 448
 449   INHERITED::willRestore();
 450 }
 451
 452 }  // namespace skia
 453
 454