text: 
  /*
   * Copyright 2011 Google Inc.
   *
   * Use of this source code is governed by a BSD-style license that can be
   * found in the LICENSE file.
   */
  #include "gm.h"
  #include "SkBitmap.h"
  #include "SkShader.h"
  #include "SkXfermode.h"
  
  namespace skiagm {
  
  static void make_bitmaps(int w, int h, SkBitmap* src, SkBitmap* dst,
                           SkBitmap* transparent) {
      src->allocN32Pixels(w, h);
      src->eraseColor(SK_ColorTRANSPARENT);
  
      SkPaint p;
      p.setAntiAlias(true);
  
      SkRect r;
      SkScalar ww = SkIntToScalar(w);
      SkScalar hh = SkIntToScalar(h);
  
      {
          SkCanvas c(*src);
          p.setColor(0xFFFFCC44);
          r.set(0, 0, ww*3/4, hh*3/4);
          c.drawOval(r, p);
      }
  
      dst->allocN32Pixels(w, h);
      dst->eraseColor(SK_ColorTRANSPARENT);
  
      {
          SkCanvas c(*dst);
          p.setColor(0xFF66AAFF);
          r.set(ww/3, hh/3, ww*19/20, hh*19/20);
          c.drawRect(r, p);
      }
  
      transparent->allocN32Pixels(w, h);
      transparent->eraseColor(SK_ColorTRANSPARENT);
  }
  
  static uint16_t gData[] = { 0xFFFF, 0xCCCF, 0xCCCF, 0xFFFF };
  
  class XfermodesGM : public GM {
      enum SrcType {
       //! A WxH image with a rectangle in the lower right.
       kRectangleImage_SrcType               = 0x01,
       //! kRectangleImage_SrcType with an alpha of 34.5%.
       kRectangleImageWithAlpha_SrcType      = 0x02,
       //! kRectnagleImageWithAlpha_SrcType scaled down by half.
       kSmallRectangleImageWithAlpha_SrcType = 0x04,
       //! kRectangleImage_SrcType drawn directly instead in an image.
       kRectangle_SrcType                    = 0x08,
       //! Two rectangles, first on the right half, second on the bottom half.
       kQuarterClear_SrcType                 = 0x10,
       //! kQuarterClear_SrcType in a layer.
       kQuarterClearInLayer_SrcType          = 0x20,
       //! A W/2xH/2 transparent image.
       kSmallTransparentImage_SrcType        = 0x40,
       //! kRectangleImage_SrcType drawn directly with a mask.
       kRectangleWithMask_SrcType            = 0x80,
  
       kAll_SrcType                          = 0xFF, //!< All the source types.
       kBasic_SrcType                        = 0x03, //!< Just basic source types.
      };
  
      SkBitmap    fBG;
      SkBitmap    fSrcB, fDstB, fTransparent;
  
      /* The srcType argument indicates what to draw for the source part. Skia
       * uses the implied shape of the drawing command and these modes
       * demonstrate that.
       */
      void draw_mode(SkCanvas* canvas, SkXfermode* mode, SrcType srcType,
                     SkScalar x, SkScalar y) {
          SkPaint p;
          SkMatrix m;
          bool restoreNeeded = false;
          m.setTranslate(x, y);
  
          canvas->drawBitmap(fSrcB, x, y, &p);
          p.setXfermode(mode);
          switch (srcType) {
              case kSmallTransparentImage_SrcType: {
                  m.postScale(SK_ScalarHalf, SK_ScalarHalf, x, y);
  
                  SkAutoCanvasRestore acr(canvas, true);
                  canvas->concat(m);
                  canvas->drawBitmap(fTransparent, 0, 0, &p);
                  break;
              }
              case kQuarterClearInLayer_SrcType: {
                  SkRect bounds = SkRect::MakeXYWH(x, y, SkIntToScalar(W),
                                                   SkIntToScalar(H));
                  canvas->saveLayer(&bounds, &p);
                  restoreNeeded = true;
                  p.setXfermodeMode(SkXfermode::kSrcOver_Mode);
                  // Fall through.
              }
              case kQuarterClear_SrcType: {
                  SkScalar halfW = SkIntToScalar(W) / 2;
                  SkScalar halfH = SkIntToScalar(H) / 2;
                  p.setColor(0xFF66AAFF);
                  SkRect r = SkRect::MakeXYWH(x + halfW, y, halfW,
                                              SkIntToScalar(H));
                  canvas->drawRect(r, p);
                  p.setColor(0xFFAA66FF);
                  r = SkRect::MakeXYWH(x, y + halfH, SkIntToScalar(W), halfH);
                  canvas->drawRect(r, p);
                  break;
              }
              case kRectangleWithMask_SrcType: {
                  canvas->save();
                  restoreNeeded = true;
                  SkScalar w = SkIntToScalar(W);
                  SkScalar h = SkIntToScalar(H);
                  SkRect r = SkRect::MakeXYWH(x, y + h / 4, w, h * 23 / 60);
                  canvas->clipRect(r);
                  // Fall through.
              }
              case kRectangle_SrcType: {
                  SkScalar w = SkIntToScalar(W);
                  SkScalar h = SkIntToScalar(H);
                  SkRect r = SkRect::MakeXYWH(x + w / 3, y + h / 3,
                                              w * 37 / 60, h * 37 / 60);
                  p.setColor(0xFF66AAFF);
                  canvas->drawRect(r, p);
                  break;
              }
              case kSmallRectangleImageWithAlpha_SrcType:
                  m.postScale(SK_ScalarHalf, SK_ScalarHalf, x, y);
                  // Fall through.
              case kRectangleImageWithAlpha_SrcType:
                  p.setAlpha(0x88);
                  // Fall through.
              case kRectangleImage_SrcType: {
                  SkAutoCanvasRestore acr(canvas, true);
                  canvas->concat(m);
                  canvas->drawBitmap(fDstB, 0, 0, &p);
                  break;
              }
              default:
                  break;
          }
  
          if (restoreNeeded) {
              canvas->restore();
          }
      }
  
      void onOnceBeforeDraw() SK_OVERRIDE {
          fBG.installPixels(SkImageInfo::Make(2, 2, kARGB_4444_SkColorType,
                                              kOpaque_SkAlphaType),
                            gData, 4);
  
          make_bitmaps(W, H, &fSrcB, &fDstB, &fTransparent);
      }
  
  public:
      const static int W = 64;
      const static int H = 64;
      XfermodesGM() {}
  
  protected:
      SkString onShortName() SK_OVERRIDE {
          return SkString("xfermodes");
      }
  
      SkISize onISize() SK_OVERRIDE {
          return SkISize::Make(1990, 640);
      }
  
      void onDraw(SkCanvas* canvas) SK_OVERRIDE {
          canvas->translate(SkIntToScalar(10), SkIntToScalar(20));
  
          const struct {
              SkXfermode::Mode  fMode;
              const char*       fLabel;
              int               fSourceTypeMask;  // The source types to use this
                                                  // mode with. See draw_mode for
                                                  // an explanation of each type.
                                                  // PDF has to play some tricks
                                                  // to support the base modes,
                                                  // test those more extensively.
          } gModes[] = {
              { SkXfermode::kClear_Mode,        "Clear",        kAll_SrcType   },
              { SkXfermode::kSrc_Mode,          "Src",          kAll_SrcType   },
              { SkXfermode::kDst_Mode,          "Dst",          kAll_SrcType   },
              { SkXfermode::kSrcOver_Mode,      "SrcOver",      kAll_SrcType   },
              { SkXfermode::kDstOver_Mode,      "DstOver",      kAll_SrcType   },
              { SkXfermode::kSrcIn_Mode,        "SrcIn",        kAll_SrcType   },
              { SkXfermode::kDstIn_Mode,        "DstIn",        kAll_SrcType   },
              { SkXfermode::kSrcOut_Mode,       "SrcOut",       kAll_SrcType   },
              { SkXfermode::kDstOut_Mode,       "DstOut",       kAll_SrcType   },
              { SkXfermode::kSrcATop_Mode,      "SrcATop",      kAll_SrcType   },
              { SkXfermode::kDstATop_Mode,      "DstATop",      kAll_SrcType   },
  
              { SkXfermode::kXor_Mode,          "Xor",          kBasic_SrcType },
              { SkXfermode::kPlus_Mode,         "Plus",         kBasic_SrcType },
              { SkXfermode::kModulate_Mode,     "Modulate",     kAll_SrcType   },
              { SkXfermode::kScreen_Mode,       "Screen",       kBasic_SrcType },
              { SkXfermode::kOverlay_Mode,      "Overlay",      kBasic_SrcType },
              { SkXfermode::kDarken_Mode,       "Darken",       kBasic_SrcType },
              { SkXfermode::kLighten_Mode,      "Lighten",      kBasic_SrcType },
              { SkXfermode::kColorDodge_Mode,   "ColorDodge",   kBasic_SrcType },
              { SkXfermode::kColorBurn_Mode,    "ColorBurn",    kBasic_SrcType },
              { SkXfermode::kHardLight_Mode,    "HardLight",    kBasic_SrcType },
              { SkXfermode::kSoftLight_Mode,    "SoftLight",    kBasic_SrcType },
              { SkXfermode::kDifference_Mode,   "Difference",   kBasic_SrcType },
              { SkXfermode::kExclusion_Mode,    "Exclusion",    kBasic_SrcType },
              { SkXfermode::kMultiply_Mode,     "Multiply",     kAll_SrcType   },
              { SkXfermode::kHue_Mode,          "Hue",          kBasic_SrcType },
              { SkXfermode::kSaturation_Mode,   "Saturation",   kBasic_SrcType },
              { SkXfermode::kColor_Mode,        "Color",        kBasic_SrcType },
              { SkXfermode::kLuminosity_Mode,   "Luminosity",   kBasic_SrcType },
          };
  
          const SkScalar w = SkIntToScalar(W);
          const SkScalar h = SkIntToScalar(H);
          SkMatrix m;
          m.setScale(SkIntToScalar(6), SkIntToScalar(6));
          SkShader* s = SkShader::CreateBitmapShader(fBG,
                                                     SkShader::kRepeat_TileMode,
                                                     SkShader::kRepeat_TileMode,
                                                     &m);
  
          SkPaint labelP;
          labelP.setAntiAlias(true);
          sk_tool_utils::set_portable_typeface(&labelP);
          labelP.setTextAlign(SkPaint::kCenter_Align);
  
          const int W = 5;
  
          SkScalar x0 = 0;
          SkScalar y0 = 0;
          for (int sourceType = 1; sourceType & kAll_SrcType; sourceType <<= 1) {
              SkScalar x = x0, y = y0;
              for (size_t i = 0; i < SK_ARRAY_COUNT(gModes); i++) {
                  if ((gModes[i].fSourceTypeMask & sourceType) == 0) {
                      continue;
                  }
                  SkXfermode* mode = SkXfermode::Create(gModes[i].fMode);
                  SkAutoUnref aur(mode);
                  SkRect r;
                  r.set(x, y, x+w, y+h);
  
                  SkPaint p;
                  p.setStyle(SkPaint::kFill_Style);
                  p.setShader(s);
                  canvas->drawRect(r, p);
  
                  canvas->saveLayer(&r, NULL);
                  draw_mode(canvas, mode, static_cast<SrcType>(sourceType),
                            r.fLeft, r.fTop);
                  canvas->restore();
  
                  r.inset(-SK_ScalarHalf, -SK_ScalarHalf);
                  p.setStyle(SkPaint::kStroke_Style);
                  p.setShader(NULL);
                  canvas->drawRect(r, p);
  
  #if 1
                  canvas->drawText(gModes[i].fLabel, strlen(gModes[i].fLabel),
                                   x + w/2, y - labelP.getTextSize()/2, labelP);
  #endif
                  x += w + SkIntToScalar(10);
                  if ((i % W) == W - 1) {
                      x = x0;
                      y += h + SkIntToScalar(30);
                  }
              }
              if (y < 320) {
                  if (x > x0) {
                      y += h + SkIntToScalar(30);
                  }
                  y0 = y;
              } else {
                  x0 += SkIntToScalar(400);
                  y0 = 0;
              }
          }
          s->unref();
      }
  
  private:
      typedef GM INHERITED;
  };
  
  //////////////////////////////////////////////////////////////////////////////
  
  static GM* MyFactory(void*) { return new XfermodesGM; }
  static GMRegistry reg(MyFactory);
  
  }
  