C++ SkRandom::nextSScalar1方法代码示例

    DrawAtlasDrawable(DrawAtlasProc proc, const SkRect& r)
        : fProc(proc), fBounds(r), fUseColors(false)
    {
        SkRandom rand;
        fAtlas = make_atlas(kAtlasSize, kCellSize);
        const SkScalar kMaxSpeed = 5;
        const SkScalar cell = SkIntToScalar(kCellSize);
        int i = 0;
        for (int y = 0; y < kAtlasSize; y += kCellSize) {
            for (int x = 0; x < kAtlasSize; x += kCellSize) {
                const SkScalar sx = SkIntToScalar(x);
                const SkScalar sy = SkIntToScalar(y);
                fTex[i].setXYWH(sx, sy, cell, cell);

                fRec[i].fCenter.set(sx + cell/2, sy + 3*cell/4);
                fRec[i].fVelocity.fX = rand.nextSScalar1() * kMaxSpeed;
                fRec[i].fVelocity.fY = rand.nextSScalar1() * kMaxSpeed;
                fRec[i].fScale = 1;
                fRec[i].fDScale = rand.nextSScalar1() / 16;
                fRec[i].fRadian = 0;
                fRec[i].fDRadian = rand.nextSScalar1() / 8;
                fRec[i].fAlpha = rand.nextUScalar1();
                fRec[i].fDAlpha = rand.nextSScalar1() / 10;
                i += 1;
            }
        }
    }

static void show_stroke(SkCanvas* canvas, bool doAA, SkScalar strokeWidth, int n) {
    SkRandom rand;
    SkPaint paint;
    paint.setAntiAlias(doAA);
    paint.setStyle(SkPaint::kStroke_Style);
    paint.setStrokeWidth(strokeWidth);
    
    for (int i = 0; i < n; ++i) {
        SkRect r;
        SkPath p;
        
        r.setXYWH(rand.nextSScalar1() * W, rand.nextSScalar1() * H,
                  rand.nextUScalar1() * W, rand.nextUScalar1() * H);
        paint.setColor(rand.nextU());
        canvas->drawRect(r, paint);
        
        r.setXYWH(rand.nextSScalar1() * W, rand.nextSScalar1() * H,
                  rand.nextUScalar1() * W, rand.nextUScalar1() * H);
        paint.setColor(rand.nextU());
        p.addOval(r);
        canvas->drawPath(p, paint);

        const SkScalar minx = -SkIntToScalar(W)/4;
        const SkScalar maxx = 5*SkIntToScalar(W)/4;
        const SkScalar miny = -SkIntToScalar(H)/4;
        const SkScalar maxy = 5*SkIntToScalar(H)/4;
        paint.setColor(rand.nextU());
        canvas->drawLine(randRange(rand, minx, maxx), randRange(rand, miny, maxy),
                         randRange(rand, minx, maxx), randRange(rand, miny, maxy),
                         paint);
    }
}

static void show_text(SkCanvas* canvas, bool doAA) {
    SkRandom rand;
    SkPaint paint;
    paint.setAntiAlias(doAA);
    paint.setLCDRenderText(true);
    paint.setTextSize(SkIntToScalar(20));
    
    for (int i = 0; i < 200; ++i) {
        paint.setColor((SK_A32_MASK << SK_A32_SHIFT) | rand.nextU());
        canvas->drawText("Hamburgefons", 12,
                         rand.nextSScalar1() * W, rand.nextSScalar1() * H + 20,
                         paint);
    }
}

    void onDraw(int loops, SkCanvas*) override {
        SkRandom r;
        enum {
            kMaxObjects = 4 * (1 << 10),
        };
        A* objects[kMaxObjects];

        // We delete if a random number [-1, 1] is < the thresh. Otherwise,
        // we allocate. We start allocate-biased and ping-pong to delete-biased
        SkScalar delThresh = -SK_ScalarHalf;
        const int kSwitchThreshPeriod = loops / (2 * kMaxObjects);
        int s = 0;

        int count = 0;
        for (int i = 0; i < loops; i++, ++s) {
            if (kSwitchThreshPeriod == s) {
                delThresh = -delThresh;
                s = 0;
            }
            SkScalar del = r.nextSScalar1();
            if (count &&
                    (kMaxObjects == count || del < delThresh)) {
                delete objects[count-1];
                --count;
            } else {
                objects[count] = new A;
                ++count;
            }
        }
        for (int i = 0; i < count; ++i) {
            delete objects[i];
        }
    }

    MathBench(const char name[])  {
        fName.printf("math_%s", name);

        SkRandom rand;
        for (int i = 0; i < kBuffer; ++i) {
            fSrc[i] = rand.nextSScalar1();
        }
    }

    MathBench(void* param, const char name[]) : INHERITED(param) {
        fName.printf("math_%s", name);

        SkRandom rand;
        for (int i = 0; i < kBuffer; ++i) {
            fSrc[i] = rand.nextSScalar1();
        }
    }

static int rand_pts(SkRandom& rand, SkPoint pts[4]) {
    int n = rand.nextU() & 3;
    n += 1;

    for (int i = 0; i < n; ++i) {
        pts[i].fX = rand.nextSScalar1();
        pts[i].fY = rand.nextSScalar1();
    }
    return n;
}

static void test_conic(skiatest::Reporter* reporter) {
    SkRandom rand;
    for (int i = 0; i < 1000; ++i) {
        SkPoint pts[3];
        for (int j = 0; j < 3; ++j) {
            pts[j].set(rand.nextSScalar1() * 100, rand.nextSScalar1() * 100);
        }
        for (int k = 0; k < 10; ++k) {
            SkScalar w = rand.nextUScalar1() * 2;
            SkConic conic(pts, w);

            const SkScalar dt = SK_Scalar1 / 128;
            SkScalar t = dt;
            for (int j = 1; j < 128; ++j) {
                test_conic_eval_pos(reporter, conic, t);
                test_conic_eval_tan(reporter, conic, t);
                t += dt;
            }
        }
    }
}

static void show_fill(SkCanvas* canvas, bool doAA) {
    SkRandom rand;
    SkPaint paint;
    paint.setAntiAlias(doAA);
    
    for (int i = 0; i < 50; ++i) {
        SkRect r;
        SkPath p;
        
        r.setXYWH(rand.nextSScalar1() * W, rand.nextSScalar1() * H,
                  rand.nextUScalar1() * W, rand.nextUScalar1() * H);
        paint.setColor(rand.nextU());
        canvas->drawRect(r, paint);
        
        r.setXYWH(rand.nextSScalar1() * W, rand.nextSScalar1() * H,
                  rand.nextUScalar1() * W, rand.nextUScalar1() * H);
        paint.setColor(rand.nextU());
        p.addOval(r);
        canvas->drawPath(p, paint);
    }
}

static void test_evalquadat(skiatest::Reporter* reporter) {
    SkRandom rand;
    for (int i = 0; i < 1000; ++i) {
        SkPoint pts[3];
        for (int j = 0; j < 3; ++j) {
            pts[j].set(rand.nextSScalar1() * 100, rand.nextSScalar1() * 100);
        }
        const SkScalar dt = SK_Scalar1 / 128;
        SkScalar t = dt;
        for (int j = 1; j < 128; ++j) {
            SkPoint r0;
            SkEvalQuadAt(pts, t, &r0);
            SkPoint r1 = SkEvalQuadAt(pts, t);
            check_pairs(reporter, i, t, "quad-pos", r0.fX, r0.fY, r1.fX, r1.fY);
            
            SkVector v0;
            SkEvalQuadAt(pts, t, nullptr, &v0);
            SkVector v1 = SkEvalQuadTangentAt(pts, t);
            check_pairs(reporter, i, t, "quad-tan", v0.fX, v0.fY, v1.fX, v1.fY);

            t += dt;
        }
    }
}

    virtual void onDraw(SkCanvas* canvas) {
        // explicitly add spaces, to test a prev. bug
        const char* text = "Ham bur ge fons";
        int len = SkToInt(strlen(text));
        SkPath path;

        SkPaint paint;
        paint.setAntiAlias(true);
        sk_tool_utils::set_portable_typeface(&paint);
        paint.setTextSize(SkIntToScalar(48));

        canvas->translate(SkIntToScalar(10), SkIntToScalar(64));

        canvas->drawText(text, len, 0, 0, paint);
        paint.getTextPath(text, len, 0, 0, &path);
        strokePath(canvas, path);
        path.reset();

        SkAutoTArray<SkPoint>  pos(len);
        SkAutoTArray<SkScalar> widths(len);
        paint.getTextWidths(text, len, &widths[0]);

        SkRandom rand;
        SkScalar x = SkIntToScalar(20);
        SkScalar y = SkIntToScalar(100);
        for (int i = 0; i < len; ++i) {
            pos[i].set(x, y + rand.nextSScalar1() * 24);
            x += widths[i];
        }

        canvas->translate(0, SkIntToScalar(64));

        canvas->drawPosText(text, len, &pos[0], paint);
        paint.getPosTextPath(text, len, &pos[0], &path);
        strokePath(canvas, path);
    }

//.........这里部分代码省略.........

    SkMatrix rotate;
    rotate.setRotate(128 * SK_Scalar1);
    REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SK_Scalar1, rotate.getMinScale(), SK_ScalarNearlyZero));
    REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SK_Scalar1, rotate.getMaxScale(), SK_ScalarNearlyZero));
    success = rotate.getMinMaxScales(scales);
    REPORTER_ASSERT(reporter, success);
    REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SK_Scalar1, scales[0], SK_ScalarNearlyZero));
    REPORTER_ASSERT(reporter, SkScalarNearlyEqual(SK_Scalar1, scales[1], SK_ScalarNearlyZero));

    SkMatrix translate;
    translate.setTranslate(10 * SK_Scalar1, -5 * SK_Scalar1);
    REPORTER_ASSERT(reporter, SK_Scalar1 == translate.getMinScale());
    REPORTER_ASSERT(reporter, SK_Scalar1 == translate.getMaxScale());
    success = translate.getMinMaxScales(scales);
    REPORTER_ASSERT(reporter, success && SK_Scalar1 == scales[0] && SK_Scalar1 == scales[1]);

    SkMatrix perspX;
    perspX.reset();
    perspX.setPerspX(SkScalarToPersp(SK_Scalar1 / 1000));
    REPORTER_ASSERT(reporter, -SK_Scalar1 == perspX.getMinScale());
    REPORTER_ASSERT(reporter, -SK_Scalar1 == perspX.getMaxScale());
    // Verify that getMinMaxScales() doesn't update the scales array on failure.
    scales[0] = -5;
    scales[1] = -5;
    success = perspX.getMinMaxScales(scales);
    REPORTER_ASSERT(reporter, !success && -5 * SK_Scalar1 == scales[0] && -5 * SK_Scalar1  == scales[1]);

    SkMatrix perspY;
    perspY.reset();
    perspY.setPerspY(SkScalarToPersp(-SK_Scalar1 / 500));
    REPORTER_ASSERT(reporter, -SK_Scalar1 == perspY.getMinScale());
    REPORTER_ASSERT(reporter, -SK_Scalar1 == perspY.getMaxScale());
    scales[0] = -5;
    scales[1] = -5;
    success = perspY.getMinMaxScales(scales);
    REPORTER_ASSERT(reporter, !success && -5 * SK_Scalar1 == scales[0] && -5 * SK_Scalar1  == scales[1]);

    SkMatrix baseMats[] = {scale, rot90Scale, rotate,
                           translate, perspX, perspY};
    SkMatrix mats[2*SK_ARRAY_COUNT(baseMats)];
    for (size_t i = 0; i < SK_ARRAY_COUNT(baseMats); ++i) {
        mats[i] = baseMats[i];
        bool invertable = mats[i].invert(&mats[i + SK_ARRAY_COUNT(baseMats)]);
        REPORTER_ASSERT(reporter, invertable);
    }
    SkRandom rand;
    for (int m = 0; m < 1000; ++m) {
        SkMatrix mat;
        mat.reset();
        for (int i = 0; i < 4; ++i) {
            int x = rand.nextU() % SK_ARRAY_COUNT(mats);
            mat.postConcat(mats[x]);
        }

        SkScalar minScale = mat.getMinScale();
        SkScalar maxScale = mat.getMaxScale();
        REPORTER_ASSERT(reporter, (minScale < 0) == (maxScale < 0));
        REPORTER_ASSERT(reporter, (maxScale < 0) == mat.hasPerspective());

        SkScalar scales[2];
        bool success = mat.getMinMaxScales(scales);
        REPORTER_ASSERT(reporter, success == !mat.hasPerspective());
        REPORTER_ASSERT(reporter, !success || (scales[0] == minScale && scales[1] == maxScale));

        if (mat.hasPerspective()) {
            m -= 1; // try another non-persp matrix
            continue;
        }

        // test a bunch of vectors. All should be scaled by between minScale and maxScale
        // (modulo some error) and we should find a vector that is scaled by almost each.
        static const SkScalar gVectorScaleTol = (105 * SK_Scalar1) / 100;
        static const SkScalar gCloseScaleTol = (97 * SK_Scalar1) / 100;
        SkScalar max = 0, min = SK_ScalarMax;
        SkVector vectors[1000];
        for (size_t i = 0; i < SK_ARRAY_COUNT(vectors); ++i) {
            vectors[i].fX = rand.nextSScalar1();
            vectors[i].fY = rand.nextSScalar1();
            if (!vectors[i].normalize()) {
                i -= 1;
                continue;
            }
        }
        mat.mapVectors(vectors, SK_ARRAY_COUNT(vectors));
        for (size_t i = 0; i < SK_ARRAY_COUNT(vectors); ++i) {
            SkScalar d = vectors[i].length();
            REPORTER_ASSERT(reporter, SkScalarDiv(d, maxScale) < gVectorScaleTol);
            REPORTER_ASSERT(reporter, SkScalarDiv(minScale, d) < gVectorScaleTol);
            if (max < d) {
                max = d;
            }
            if (min > d) {
                min = d;
            }
        }
        REPORTER_ASSERT(reporter, SkScalarDiv(max, maxScale) >= gCloseScaleTol);
        REPORTER_ASSERT(reporter, SkScalarDiv(minScale, min) >= gCloseScaleTol);
    }
}

 void onDelayedSetup() override  {
     SkRandom rand;
     for (int i = 0; i < N; ++i) {
         fFloats[i] = 300.0f * (rand.nextSScalar1() + 0.5f);
     }
 }

// having unknown values in our arrays can throw off the timing a lot, perhaps
// handling NaN values is a lot slower. Anyway, this guy is just meant to put
// reasonable values in our arrays.
template <typename T> void init9(T array[9]) {
    SkRandom rand;
    for (int i = 0; i < 9; i++) {
        array[i] = rand.nextSScalar1();
    }
}

void test_matrix_max_stretch(skiatest::Reporter* reporter) {
    SkMatrix identity;
    identity.reset();
    REPORTER_ASSERT(reporter, SK_Scalar1 == identity.getMaxStretch());

    SkMatrix scale;
    scale.setScale(SK_Scalar1 * 2, SK_Scalar1 * 4);
    REPORTER_ASSERT(reporter, SK_Scalar1 * 4 == scale.getMaxStretch());

    SkMatrix rot90Scale;
    rot90Scale.setRotate(90 * SK_Scalar1);
    rot90Scale.postScale(SK_Scalar1 / 4, SK_Scalar1 / 2);
    REPORTER_ASSERT(reporter, SK_Scalar1 / 2 == rot90Scale.getMaxStretch());

    SkMatrix rotate;
    rotate.setRotate(128 * SK_Scalar1);
    REPORTER_ASSERT(reporter, SkScalarAbs(SK_Scalar1 - rotate.getMaxStretch()) <= SK_ScalarNearlyZero);

    SkMatrix translate;
    translate.setTranslate(10 * SK_Scalar1, -5 * SK_Scalar1);
    REPORTER_ASSERT(reporter, SK_Scalar1 == translate.getMaxStretch());

    SkMatrix perspX;
    perspX.reset();
    perspX.setPerspX(SkScalarToPersp(SK_Scalar1 / 1000));
    REPORTER_ASSERT(reporter, -SK_Scalar1 == perspX.getMaxStretch());

    SkMatrix perspY;
    perspY.reset();
    perspY.setPerspX(SkScalarToPersp(-SK_Scalar1 / 500));
    REPORTER_ASSERT(reporter, -SK_Scalar1 == perspY.getMaxStretch());

    SkMatrix baseMats[] = {scale, rot90Scale, rotate,
                           translate, perspX, perspY};
    SkMatrix mats[2*SK_ARRAY_COUNT(baseMats)];
    for (size_t i = 0; i < SK_ARRAY_COUNT(baseMats); ++i) {
        mats[i] = baseMats[i];
        bool invertable = mats[i].invert(&mats[i + SK_ARRAY_COUNT(baseMats)]);
        REPORTER_ASSERT(reporter, invertable);
    }
    SkRandom rand;
    for (int m = 0; m < 1000; ++m) {
        SkMatrix mat;
        mat.reset();
        for (int i = 0; i < 4; ++i) {
            int x = rand.nextU() % SK_ARRAY_COUNT(mats);
            mat.postConcat(mats[x]);
        }
        SkScalar stretch = mat.getMaxStretch();
        
        if ((stretch < 0) != mat.hasPerspective()) {
            stretch = mat.getMaxStretch();
        }

        REPORTER_ASSERT(reporter, (stretch < 0) == mat.hasPerspective());

        if (mat.hasPerspective()) {
            m -= 1; // try another non-persp matrix
            continue;
        }

        // test a bunch of vectors. None should be scaled by more than stretch
        // (modulo some error) and we should find a vector that is scaled by
        // almost stretch.
        static const SkScalar gStretchTol = (105 * SK_Scalar1) / 100;
        static const SkScalar gMaxStretchTol = (97 * SK_Scalar1) / 100;
        SkScalar max = 0;
        SkVector vectors[1000];
        for (size_t i = 0; i < SK_ARRAY_COUNT(vectors); ++i) {
            vectors[i].fX = rand.nextSScalar1();
            vectors[i].fY = rand.nextSScalar1();
            if (!vectors[i].normalize()) {
                i -= 1;
                continue;
            }
        }
        mat.mapVectors(vectors, SK_ARRAY_COUNT(vectors));
        for (size_t i = 0; i < SK_ARRAY_COUNT(vectors); ++i) {
            SkScalar d = vectors[i].length();
            REPORTER_ASSERT(reporter, SkScalarDiv(d, stretch) < gStretchTol);
            if (max < d) {
                max = d;
            }
        }
        REPORTER_ASSERT(reporter, SkScalarDiv(max, stretch) >= gMaxStretchTol);
    }
}