コード例 #1
0
ファイル: tilemodes.cpp プロジェクト: gw280/skia
 TilingGM()
         : fLooper(SkIntToScalar(1), SkIntToScalar(2), SkIntToScalar(2),
                   0x88000000) {
     for (size_t i = 0; i < SK_ARRAY_COUNT(gConfigs); i++) {
         makebm(&fTexture[i], gConfigs[i], gWidth, gHeight);
     }
 }
コード例 #2
0
 void onDelayedSetup() override {
     int w = 40;
     int h = 40;
     makebm(&fBmp, w, h);
     fBmShader = SkShader::CreateBitmapShader(fBmp,
                                              SkShader::kRepeat_TileMode,
                                              SkShader::kRepeat_TileMode);
     int offset = 2;
     int count = 0;
     for (int j = 0; j < NY; ++j) {
         for (int i = 0; i < NX; ++i) {
             int x = (w + offset) * i;
             int y = (h * offset) * j;
             if (kRect_DrawType == fDrawType) {
                 fRects[count].set(SkIntToScalar(x), SkIntToScalar(y),
                                   SkIntToScalar(x + w), SkIntToScalar(y + h));
             } else {
                 fPaths[count].moveTo(SkIntToScalar(x), SkIntToScalar(y));
                 fPaths[count].rLineTo(SkIntToScalar(w), 0);
                 fPaths[count].rLineTo(0, SkIntToScalar(h));
                 fPaths[count].rLineTo(SkIntToScalar(-w + 1), 0);
             }
             if (0 == count % 2) {
                 fColors[count]  = fPattern1.fColor;
                 fShaders[count] = fPattern1.fIsBitmap ? fBmShader : nullptr;
             } else {
                 fColors[count]  = fPattern2.fColor;
                 fShaders[count] = fPattern2.fIsBitmap ? fBmShader : nullptr;
             }
             ++count;
         }
     }
 }
コード例 #3
0
ファイル: SampleTiling.cpp プロジェクト: alexanderbill/skia
 TilingView()
         : fLooper(SkBlurDrawLooper::Create(0x88000000,
                                            SkBlurMask::ConvertRadiusToSigma(SkIntToScalar(1)),
                                            SkIntToScalar(2), SkIntToScalar(2))) {
     for (size_t i = 0; i < SK_ARRAY_COUNT(gColorTypes); i++) {
         makebm(&fTexture[i], gColorTypes[i], gWidth, gHeight);
     }
 }
コード例 #4
0
ファイル: SampleShaderText.cpp プロジェクト: Arternis/skia
static SkShader* MakeBitmapShader(SkShader::TileMode tx, SkShader::TileMode ty,
                           int w, int h) {
    static SkBitmap bmp;
    if (bmp.isNull()) {
        makebm(&bmp, w/2, h/4);
    }
    return SkShader::CreateBitmapShader(bmp, tx, ty);
}
コード例 #5
0
    void onDraw(SkCanvas* canvas) override {
        if (nullptr == fImage) {
            fImage = makebm(gSurfaceSize, gSurfaceSize);
        }

        const SkRect dstRect = { 0, 0, SkIntToScalar(64), SkIntToScalar(64)};
        const int kMaxSrcRectSize = 1 << (SkNextLog2(gSurfaceSize) + 2);

        constexpr int kPadX = 30;
        constexpr int kPadY = 40;

        int rowCount = 0;
        canvas->translate(SkIntToScalar(kPadX), SkIntToScalar(kPadY));
        canvas->save();
        SkRandom random;

        SkPaint paint;
        paint.setAntiAlias(fAA);
        for (int w = 1; w <= kMaxSrcRectSize; w *= 3) {
            for (int h = 1; h <= kMaxSrcRectSize; h *= 3) {

                const SkIRect srcRect =
                        SkIRect::MakeXYWH((gSurfaceSize - w) / 2, (gSurfaceSize - h) / 2, w, h);
                canvas->save();
                switch (random.nextU() % 3) {
                    case 0:
                        canvas->rotate(random.nextF() * 10.f);
                        break;
                    case 1:
                        canvas->rotate(-random.nextF() * 10.f);
                        break;
                    case 2:
                        // rect stays rect
                        break;
                }
                canvas->drawImageRect(fImage.get(), srcRect, dstRect, &paint,
                                      SkCanvas::kFast_SrcRectConstraint);
                canvas->restore();

                canvas->translate(dstRect.width() + SK_Scalar1 * kPadX, 0);
                ++rowCount;
                if ((dstRect.width() + 2 * kPadX) * rowCount > gSize) {
                    canvas->restore();
                    canvas->translate(0, dstRect.height() + SK_Scalar1 * kPadY);
                    canvas->save();
                    rowCount = 0;
                }
            }
        }
        canvas->restore();
    }
コード例 #6
0
 void onOnceBeforeDraw() override {
     fImage.reset(makebm(&fLargeBitmap, gBmpSize, gBmpSize));
 }
コード例 #7
0
    void onDraw(SkCanvas* canvas) override {
        static const char kText[] = "SKIA";
        static const int kTextLen = SK_ARRAY_COUNT(kText) - 1;
        static const int kPointSize = 55;

        SkTDArray<LabeledMatrix> matrices;
        matrices.append()->fMatrix.reset();
        matrices.top().fLabel = "Identity";
        matrices.append()->fMatrix.setScale(1.2f, 0.8f);
        matrices.top().fLabel = "Scale";
        matrices.append()->fMatrix.setRotate(10.f);
        matrices.top().fLabel = "Rotate";
        matrices.append()->fMatrix.reset();
        matrices.top().fMatrix.setPerspX(-0.0015f);
        matrices.top().fMatrix.setPerspY(+0.0015f);
        matrices.top().fLabel = "Persp";

        SkTDArray<LabeledMatrix> localMatrices;
        localMatrices.append()->fMatrix.reset();
        localMatrices.top().fLabel = "Identity";
        localMatrices.append()->fMatrix.setScale(2.5f, 0.2f);
        localMatrices.top().fLabel = "Scale";
        localMatrices.append()->fMatrix.setRotate(45.f);
        localMatrices.top().fLabel = "Rotate";
        localMatrices.append()->fMatrix.reset();
        localMatrices.top().fMatrix.setPerspX(-0.007f);
        localMatrices.top().fMatrix.setPerspY(+0.008f);
        localMatrices.top().fLabel = "Persp";

        static SkBitmap bmp;
        if (bmp.isNull()) {
            makebm(&bmp, kPointSize / 2, kPointSize / 2);
        }

        SkPaint fillPaint;
        fillPaint.setAntiAlias(true);
        sk_tool_utils::set_portable_typeface_always(&fillPaint);
        fillPaint.setTextSize(SkIntToScalar(kPointSize));
        fillPaint.setFilterQuality(kLow_SkFilterQuality);

        SkPaint outlinePaint;
        outlinePaint.setAntiAlias(true);
        sk_tool_utils::set_portable_typeface_always(&outlinePaint);
        outlinePaint.setTextSize(SkIntToScalar(kPointSize));
        outlinePaint.setStyle(SkPaint::kStroke_Style);
        outlinePaint.setStrokeWidth(0.f);

        SkScalar w = fillPaint.measureText(kText, kTextLen);
        static SkScalar kPadY = 0.5f * kPointSize;
        static SkScalar kPadX = 1.5f * kPointSize;

        SkPaint strokePaint(fillPaint);
        strokePaint.setStyle(SkPaint::kStroke_Style);
        strokePaint.setStrokeWidth(kPointSize * 0.1f);

        SkPaint labelPaint;
        labelPaint.setColor(0xff000000);
        labelPaint.setAntiAlias(true);
        sk_tool_utils::set_portable_typeface_always(&labelPaint);
        labelPaint.setTextSize(12.f);

        canvas->translate(15.f, 15.f);
        canvas->drawBitmap(bmp, 0, 0);
        canvas->translate(0, bmp.height() + labelPaint.getTextSize() + 15.f);

        static const char kLabelLabel[] = "localM / canvasM";
        canvas->drawText(kLabelLabel, strlen(kLabelLabel), 0, 0, labelPaint);
        canvas->translate(0, 15.f);

        canvas->save();
        SkScalar maxLabelW = 0;
        canvas->translate(0, kPadY / 2 + kPointSize);
        for (int lm = 0; lm < localMatrices.count(); ++lm) {
            canvas->drawText(matrices[lm].fLabel, strlen(matrices[lm].fLabel),
                             0, labelPaint.getTextSize() - 1, labelPaint);
            SkScalar labelW = labelPaint.measureText(matrices[lm].fLabel,
                              strlen(matrices[lm].fLabel));
            maxLabelW = SkMaxScalar(maxLabelW, labelW);
            canvas->translate(0.f, 2 * kPointSize + 2.5f * kPadY);
        }
        canvas->restore();

        canvas->translate(maxLabelW + kPadX / 2.f, 0.f);

        for (int s = 0; s < 2; ++s) {
            SkPaint& paint = s ? strokePaint : fillPaint;

            SkScalar columnH = 0;
            for (int m = 0; m < matrices.count(); ++m) {
                columnH = 0;
                canvas->save();
                canvas->drawText(matrices[m].fLabel, strlen(matrices[m].fLabel),
                                 0, labelPaint.getTextSize() - 1, labelPaint);
                canvas->translate(0, kPadY / 2 + kPointSize);
                columnH += kPadY / 2 + kPointSize;
                for (int lm = 0; lm < localMatrices.count(); ++lm) {
                    paint.setShader(
                        SkShader::CreateBitmapShader(bmp,
                                                     SkShader::kMirror_TileMode,
                                                     SkShader::kRepeat_TileMode,
                                                     &localMatrices[lm].fMatrix))->unref();

                    canvas->save();
                    canvas->concat(matrices[m].fMatrix);
                    canvas->drawText(kText, kTextLen, 0, 0, paint);
                    canvas->drawText(kText, kTextLen, 0, 0, outlinePaint);
                    canvas->restore();

                    SkPath path;
                    path.arcTo(SkRect::MakeXYWH(-0.1f * w, 0.f,
                                                1.2f * w, 2.f * kPointSize),
                               225.f, 359.f,
                               false);
                    path.close();

                    canvas->translate(0.f, kPointSize + kPadY);
                    columnH += kPointSize + kPadY;

                    canvas->save();
                    canvas->concat(matrices[m].fMatrix);
                    canvas->drawTextOnPath(kText, kTextLen, path, NULL, paint);
                    canvas->drawTextOnPath(kText, kTextLen, path, NULL, outlinePaint);
                    canvas->restore();
                    SkPaint stroke;
                    stroke.setStyle(SkPaint::kStroke_Style);
                    canvas->translate(0.f, kPointSize + kPadY);
                    columnH += kPointSize + kPadY;
                }
                canvas->restore();
                canvas->translate(w + kPadX, 0.f);
            }
            if (0 == s) {
                canvas->drawLine(0.f, -kPadY, 0.f, columnH + kPadY, outlinePaint);
                canvas->translate(kPadX / 2, 0.f);
                static const char kFillLabel[] = "Filled";
                static const char kStrokeLabel[] = "Stroked";
                SkScalar y = columnH + kPadY / 2;
                SkScalar fillX = -outlinePaint.measureText(kFillLabel, strlen(kFillLabel)) - kPadX;
                SkScalar strokeX = kPadX;
                canvas->drawText(kFillLabel, strlen(kFillLabel), fillX, y, labelPaint);
                canvas->drawText(kStrokeLabel, strlen(kStrokeLabel), strokeX, y, labelPaint);
            }
        }
    }
コード例 #8
0
ファイル: tilemodes_scaled.cpp プロジェクト: aseprite/skia
    void onDraw(SkCanvas* canvas) override {
        float scale = 32.f/kPOTSize;

        int size = fPowerOfTwoSize ? kPOTSize : kNPOTSize;

        SkRect r = { 0, 0, SkIntToScalar(size*2), SkIntToScalar(size*2) };

        const char* gColorTypeNames[] = { "8888" , "565", "4444" };

        constexpr SkFilterQuality gFilterQualitys[] =
            { kNone_SkFilterQuality,
              kLow_SkFilterQuality,
              kMedium_SkFilterQuality,
              kHigh_SkFilterQuality };
        const char* gFilterNames[] = { "None", "Low", "Medium", "High" };

        constexpr SkShader::TileMode gModes[] = {
            SkShader::kClamp_TileMode, SkShader::kRepeat_TileMode, SkShader::kMirror_TileMode };
        const char* gModeNames[] = { "C", "R", "M" };

        SkScalar y = SkIntToScalar(24);
        SkScalar x = SkIntToScalar(10)/scale;

        for (size_t kx = 0; kx < SK_ARRAY_COUNT(gModes); kx++) {
            for (size_t ky = 0; ky < SK_ARRAY_COUNT(gModes); ky++) {
                SkPaint p;
                SkString str;
                p.setAntiAlias(true);
                sk_tool_utils::set_portable_typeface(&p);
                str.printf("[%s,%s]", gModeNames[kx], gModeNames[ky]);

                p.setTextAlign(SkPaint::kCenter_Align);
                canvas->drawText(str.c_str(), str.size(), scale*(x + r.width()/2), y, p);

                x += r.width() * 4 / 3;
            }
        }

        y = SkIntToScalar(40) / scale;

        for (size_t i = 0; i < SK_ARRAY_COUNT(gColorTypes); i++) {
            for (size_t j = 0; j < SK_ARRAY_COUNT(gFilterQualitys); j++) {
                x = SkIntToScalar(10)/scale;
                for (size_t kx = 0; kx < SK_ARRAY_COUNT(gModes); kx++) {
                    for (size_t ky = 0; ky < SK_ARRAY_COUNT(gModes); ky++) {
                        SkPaint paint;
#if 1 // Temporary change to regen bitmap before each draw. This may help tracking down an issue
      // on SGX where resizing NPOT textures to POT textures exhibits a driver bug.
                        if (!fPowerOfTwoSize) {
                            makebm(&fTexture[i], gColorTypes[i], size, size);
                        }
#endif
                        setup(&paint, fTexture[i], gFilterQualitys[j], gModes[kx], gModes[ky]);
                        paint.setDither(true);

                        canvas->save();
                        canvas->scale(scale,scale);
                        canvas->translate(x, y);
                        canvas->drawRect(r, paint);
                        canvas->restore();

                        x += r.width() * 4 / 3;
                    }
                }
                {
                    SkPaint p;
                    SkString str;
                    p.setAntiAlias(true);
                    sk_tool_utils::set_portable_typeface(&p);
                    str.printf("%s, %s", gColorTypeNames[i], gFilterNames[j]);
                    canvas->drawText(str.c_str(), str.size(), scale*x, scale*(y + r.height() * 2 / 3), p);
                }

                y += r.height() * 4 / 3;
            }
        }
    }
コード例 #9
0
ファイル: tilemodes_scaled.cpp プロジェクト: aseprite/skia
 void onOnceBeforeDraw() override {
     int size = fPowerOfTwoSize ? kPOTSize : kNPOTSize;
     for (size_t i = 0; i < SK_ARRAY_COUNT(gColorTypes); i++) {
         makebm(&fTexture[i], gColorTypes[i], size, size);
     }
 }
コード例 #10
0
ファイル: tilemodes_scaled.cpp プロジェクト: aseprite/skia
static sk_sp<SkShader> make_bm(SkShader::TileMode tx, SkShader::TileMode ty) {
    SkBitmap bm;
    makebm(&bm, kN32_SkColorType, gWidth, gHeight);
    return SkShader::MakeBitmapShader(bm, tx, ty);
}
コード例 #11
0
ファイル: shadertext.cpp プロジェクト: 03050903/skia
    void onDraw(SkCanvas* canvas) override {
        const char text[] = "Shaded Text";
        const int textLen = SK_ARRAY_COUNT(text) - 1;
        const int pointSize = 36;

        const int w = pointSize * textLen;
        const int h = pointSize;

        SkPoint pts[2] = {
            { 0, 0 },
            { SkIntToScalar(w), SkIntToScalar(h) }
        };
        SkScalar textBase = SkIntToScalar(h/2);

        SkShader::TileMode tileModes[] = {
            SkShader::kClamp_TileMode,
            SkShader::kRepeat_TileMode,
            SkShader::kMirror_TileMode
        };

        static const int gradCount = SK_ARRAY_COUNT(gGradData) *
                                     SK_ARRAY_COUNT(gGradMakers);
        static const int bmpCount = SK_ARRAY_COUNT(tileModes) *
                                    SK_ARRAY_COUNT(tileModes);
        sk_sp<SkShader> shaders[gradCount + bmpCount];

        int shdIdx = 0;
        for (size_t d = 0; d < SK_ARRAY_COUNT(gGradData); ++d) {
            for (size_t m = 0; m < SK_ARRAY_COUNT(gGradMakers); ++m) {
                shaders[shdIdx++] = gGradMakers[m](pts,
                                                   gGradData[d],
                                                   SkShader::kClamp_TileMode);
            }
        }

        SkBitmap bm;
        makebm(&bm, w/16, h/4);
        for (size_t tx = 0; tx < SK_ARRAY_COUNT(tileModes); ++tx) {
            for (size_t ty = 0; ty < SK_ARRAY_COUNT(tileModes); ++ty) {
                shaders[shdIdx++] = SkShader::MakeBitmapShader(bm, tileModes[tx], tileModes[ty]);
            }
        }

        SkPaint paint;
        paint.setDither(true);
        paint.setAntiAlias(true);
        sk_tool_utils::set_portable_typeface(&paint);
        paint.setTextSize(SkIntToScalar(pointSize));

        canvas->save();
        canvas->translate(SkIntToScalar(20), SkIntToScalar(10));

        SkPath path;
        path.arcTo(SkRect::MakeXYWH(SkIntToScalar(-40), SkIntToScalar(15),
                                    SkIntToScalar(300), SkIntToScalar(90)),
                                    SkIntToScalar(225), SkIntToScalar(90),
                                    false);
        path.close();

        static const int testsPerCol = 8;
        static const int rowHeight = 60;
        static const int colWidth = 300;
        canvas->save();
        for (int s = 0; s < static_cast<int>(SK_ARRAY_COUNT(shaders)); s++) {
            canvas->save();
            int i = 2*s;
            canvas->translate(SkIntToScalar((i / testsPerCol) * colWidth),
                              SkIntToScalar((i % testsPerCol) * rowHeight));
            paint.setShader(shaders[s]);
            canvas->drawText(text, textLen, 0, textBase, paint);
            canvas->restore();
            canvas->save();
            ++i;
            canvas->translate(SkIntToScalar((i / testsPerCol) * colWidth),
                              SkIntToScalar((i % testsPerCol) * rowHeight));
            canvas->drawTextOnPath(text, textLen, path, nullptr, paint);
            canvas->restore();
        }
        canvas->restore();

    }
コード例 #12
0
ファイル: tilemodes.cpp プロジェクト: Jichao/skia
    void onDraw(SkCanvas* canvas) override {

        int size = fPowerOfTwoSize ? kPOTSize : kNPOTSize;

        SkRect r = { 0, 0, SkIntToScalar(size*2), SkIntToScalar(size*2) };

        static const char* gConfigNames[] = { "8888", "565", "4444" };

        static const bool           gFilters[] = { false, true };
        static const char*          gFilterNames[] = {     "point",                     "bilinear" };

        static const SkShader::TileMode gModes[] = { SkShader::kClamp_TileMode, SkShader::kRepeat_TileMode, SkShader::kMirror_TileMode };
        static const char*          gModeNames[] = {    "C",                    "R",                   "M" };

        SkScalar y = SkIntToScalar(24);
        SkScalar x = SkIntToScalar(10);

        for (size_t kx = 0; kx < SK_ARRAY_COUNT(gModes); kx++) {
            for (size_t ky = 0; ky < SK_ARRAY_COUNT(gModes); ky++) {
                SkPaint p;
                SkString str;
                p.setAntiAlias(true);
                sk_tool_utils::set_portable_typeface_always(&p);
                p.setDither(true);
                str.printf("[%s,%s]", gModeNames[kx], gModeNames[ky]);

                p.setTextAlign(SkPaint::kCenter_Align);
                canvas->drawText(str.c_str(), str.size(), x + r.width()/2, y, p);

                x += r.width() * 4 / 3;
            }
        }

        y += SkIntToScalar(16);

        for (size_t i = 0; i < SK_ARRAY_COUNT(gColorTypes); i++) {
            for (size_t j = 0; j < SK_ARRAY_COUNT(gFilters); j++) {
                x = SkIntToScalar(10);
                for (size_t kx = 0; kx < SK_ARRAY_COUNT(gModes); kx++) {
                    for (size_t ky = 0; ky < SK_ARRAY_COUNT(gModes); ky++) {
                        SkPaint paint;
#if 1 // Temporary change to regen bitmap before each draw. This may help tracking down an issue
                        // on SGX where resizing NPOT textures to POT textures exhibits a driver bug.
                        if (!fPowerOfTwoSize) {
                            makebm(&fTexture[i], gColorTypes[i], size, size);
                        }
#endif
                        setup(&paint, fTexture[i], gFilters[j], gModes[kx], gModes[ky]);
                        paint.setDither(true);

                        canvas->save();
                        canvas->translate(x, y);
                        canvas->drawRect(r, paint);
                        canvas->restore();

                        x += r.width() * 4 / 3;
                    }
                }
                {
                    SkPaint p;
                    SkString str;
                    p.setAntiAlias(true);
                    sk_tool_utils::set_portable_typeface_always(&p);
                    str.printf("%s, %s", gConfigNames[i], gFilterNames[j]);
                    canvas->drawText(str.c_str(), str.size(), x, y + r.height() * 2 / 3, p);
                }

                y += r.height() * 4 / 3;
            }
        }
    }
コード例 #13
0
ファイル: drawbitmaprect.cpp プロジェクト: eitanlevy97/skia
 void setupImage(SkCanvas* canvas) {
     fImage = makebm(canvas, &fLargeBitmap, gBmpSize, gBmpSize);
 }
コード例 #14
0
ファイル: drawbitmaprect.cpp プロジェクト: Jimmy0319/skia
    virtual void onDraw(SkCanvas* canvas) {
        static const int kBmpSize = 2048;
        if (fLargeBitmap.isNull()) {
            makebm(&fLargeBitmap, kBmpSize, kBmpSize);
        }
        SkRect dstRect = { 0, 0, SkIntToScalar(64), SkIntToScalar(64)};
        static const int kMaxSrcRectSize = 1 << (SkNextLog2(kBmpSize) + 2);

        static const int kPadX = 30;
        static const int kPadY = 40;
        SkPaint paint;
        paint.setAlpha(0x20);
        canvas->drawBitmapRect(fLargeBitmap, NULL,
                               SkRect::MakeWH(gSize * SK_Scalar1,
                                              gSize * SK_Scalar1),
                               &paint);
        canvas->translate(SK_Scalar1 * kPadX / 2,
                          SK_Scalar1 * kPadY / 2);
        SkPaint blackPaint;
        SkScalar titleHeight = SK_Scalar1 * 24;
        blackPaint.setColor(SK_ColorBLACK);
        blackPaint.setTextSize(titleHeight);
        blackPaint.setAntiAlias(true);
        SkString title;
        title.printf("Bitmap size: %d x %d", kBmpSize, kBmpSize);
        canvas->drawText(title.c_str(), title.size(), 0,
                         titleHeight, blackPaint);

        canvas->translate(0, SK_Scalar1 * kPadY / 2  + titleHeight);
        int rowCount = 0;
        canvas->save();
        for (int w = 1; w <= kMaxSrcRectSize; w *= 4) {
            for (int h = 1; h <= kMaxSrcRectSize; h *= 4) {

                SkIRect srcRect = SkIRect::MakeXYWH((kBmpSize - w) / 2,
                                                    (kBmpSize - h) / 2,
                                                    w, h);
                canvas->drawBitmapRect(fLargeBitmap, &srcRect, dstRect);

                SkString label;
                label.appendf("%d x %d", w, h);
                blackPaint.setAntiAlias(true);
                blackPaint.setStyle(SkPaint::kFill_Style);
                blackPaint.setTextSize(SK_Scalar1 * 10);
                SkScalar baseline = dstRect.height() +
                                    blackPaint.getTextSize() + SK_Scalar1 * 3;
                canvas->drawText(label.c_str(), label.size(),
                                    0, baseline,
                                    blackPaint);
                blackPaint.setStyle(SkPaint::kStroke_Style);
                blackPaint.setStrokeWidth(SK_Scalar1);
                blackPaint.setAntiAlias(false);
                canvas->drawRect(dstRect, blackPaint);

                canvas->translate(dstRect.width() + SK_Scalar1 * kPadX, 0);
                ++rowCount;
                if ((dstRect.width() + kPadX) * rowCount > gSize) {
                    canvas->restore();
                    canvas->translate(0, dstRect.height() + SK_Scalar1 * kPadY);
                    canvas->save();
                    rowCount = 0;
                }
            }
        }

        {
            // test the following code path:
            // SkGpuDevice::drawPath() -> SkGpuDevice::drawWithMaskFilter()
            SkIRect srcRect;
            SkPaint paint;
            SkBitmap bm;

            bm = make_chessbm(5, 5);
            paint.setFilterLevel(SkPaint::kLow_FilterLevel);

            srcRect.setXYWH(1, 1, 3, 3);
            SkMaskFilter* mf = SkBlurMaskFilter::Create(
                kNormal_SkBlurStyle,
                SkBlurMask::ConvertRadiusToSigma(SkIntToScalar(5)),
                SkBlurMaskFilter::kHighQuality_BlurFlag |
                SkBlurMaskFilter::kIgnoreTransform_BlurFlag);
            paint.setMaskFilter(mf)->unref();
            canvas->drawBitmapRect(bm, &srcRect, dstRect, &paint);
        }
    }