C++ SkRandom::nextF方法代码示例

void PathText::Glyph::reset(SkRandom& rand, int w, int h) {
    int screensize = SkTMax(w, h);
    const SkRect& bounds = fPath.getBounds();
    SkScalar t;

    fPosition = {rand.nextF() * w, rand.nextF() * h};
    t = pow(rand.nextF(), 100);
    fZoom = ((1 - t) * screensize / 50 + t * screensize / 3) /
            SkTMax(bounds.width(), bounds.height());
    fSpin = rand.nextF() * 360;
    fMidpt = {bounds.centerX(), bounds.centerY()};
}

    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();
    }

    // SkMatrix44::setConcat() has a fast path for matrices that are at most scale+translate.
    SetConcatMatrix44Bench(bool fastPath)
        : INHERITED(fastPath ? "setconcat_fast" : "setconcat_general")
{
        if (fastPath) {
            const SkMScalar v = SkDoubleToMScalar(1.5);
            fM1.setScale(v,v,v);
            fM2.setTranslate(v,v,v);
        } else {
            SkRandom rand;
            for (int x = 0; x < 4; x++) {
            for (int y = 0; y < 4; y++) {
                fM1.setFloat(x,y, rand.nextF());
                fM2.setFloat(x,y, rand.nextF());
            }}
        }
    }

    void onDelayedSetup() override {
        SkScalar w = SkIntToScalar(fShapesSize.width());
        SkScalar h = SkIntToScalar(fShapesSize.height());

        fRect.setRect(SkRect::MakeXYWH(-w / 2, -h / 2, w, h));
        fOval.setOval(fRect.rect());
        fRRect.setNinePatch(fRect.rect(), w / 8, h / 13, w / 11, h / 7);

        if (kNone_ShapesType != fInnerShapesType) {
            fRect.inset(w / 7, h / 11, &fInnerRect);
            fInnerRect.offset(w / 28, h / 44);
            fInnerOval.setOval(fInnerRect.rect());
            fInnerRRect.setRectXY(fInnerRect.rect(), w / 13, w / 7);
        }

        SkRandom rand;
        fShapes.push_back_n(fNumShapes);
        for (int i = 0; i < fNumShapes; i++) {
            float pad = sqrtf(static_cast<float>(fShapesSize.width() * fShapesSize.width()) +
                              static_cast<float>(fShapesSize.height() * fShapesSize.height()));
            fShapes[i].fMatrix.setTranslate(0.5f * pad + rand.nextF() * (kBenchWidth - pad),
                                            0.5f * pad + rand.nextF() * (kBenchHeight - pad));
            fShapes[i].fMatrix.preRotate(rand.nextF() * 360.0f);
            if (fPerspective) {
                fShapes[i].fMatrix.setPerspX(0.00015f);
                fShapes[i].fMatrix.setPerspY(-0.00015f);
            }
            fShapes[i].fColor = rand.nextU() | 0xff808080;
        }
        for (int i = 0; i < fNumShapes; i++) {
            // Do this in a separate loop so mixed shapes get the same random numbers during
            // placement as non-mixed do.
            int shapeType = fShapesType;
            if (kMixed_ShapesType == shapeType) {
                shapeType = rand.nextRangeU(kRect_ShapesType, kRRect_ShapesType);
            }
            int innerShapeType = fInnerShapesType;
            if (kMixed_ShapesType == innerShapeType) {
                innerShapeType = rand.nextRangeU(kRect_ShapesType, kRRect_ShapesType);
            }
            if (kNone_ShapesType == innerShapeType) {
                switch (shapeType) {
                    using namespace std;
                    using namespace std::placeholders;
                    case kRect_ShapesType:
                        fShapes[i].fDraw = bind(&SkCanvas::drawRect, _1, cref(fRect.rect()), _2);
                        break;
                    case kOval_ShapesType:
                        fShapes[i].fDraw = bind(&SkCanvas::drawOval, _1, cref(fOval.rect()), _2);
                        break;
                    case kRRect_ShapesType:
                        fShapes[i].fDraw = bind(&SkCanvas::drawRRect, _1, cref(fRRect), _2);
                        break;
                }
            } else {
                const SkRRect* outer;
                switch (shapeType) {
                    case kRect_ShapesType: outer = &fRect; break;
                    case kOval_ShapesType: outer = &fOval; break;
                    case kRRect_ShapesType: outer = &fRRect; break;
                }
                const SkRRect* inner;
                switch (innerShapeType) {
                    case kRect_ShapesType: inner = &fInnerRect; break;
                    case kOval_ShapesType: inner = &fInnerOval; break;
                    case kRRect_ShapesType: inner = &fInnerRRect; break;
                }
                fShapes[i].fDraw = std::bind(&SkCanvas::drawDRRect, std::placeholders::_1,
                                             std::cref(*outer), std::cref(*inner),
                                             std::placeholders::_2);
            }
        }
    }