void draw(SkCanvas* canvas) {

    // This fiddle draws 4 instances of a LinearGradient, demonstrating

    // how the local matrix affects the gradient as well as the flag

    // which controls unpremul vs premul color interpolation.

​

    SkPaint strokePaint;

    strokePaint.setStyle(SkPaint::kStroke_Style);

    strokePaint.setColor(SK_ColorBLACK);

​

    SkPaint p;

    p.setStyle(SkPaint::kFill_Style);

​

    SkColor transparentGreen = SkColorSetARGB(0, 0, 255, 255);

    SkColor colors[] = { transparentGreen, SK_ColorBLUE, SK_ColorRED };

    SkScalar positions[] = { 0.0, 0.65, 1.0 };

​

    for (int i = 0; i < 4; i++) {

        SkScalar blockX = (i % 2) * 100;

        SkScalar blockY = (i / 2) * 100;

        SkPoint pts[] = { {blockX, blockY}, {blockX + 50, blockY + 100} };

​

        int flags = 0; // interpolate colors in unpremul

        if (i % 2 == 1) {

            // right column will have premul

            flags = SkGradientShader::Flags::kInterpolateColorsInPremul_Flag;

        }

​

        SkMatrix matr = SkMatrix::I();

        if (i / 2 == 1) {

            // bottom row will be rotated 45 degrees.

            matr.setRotate(45, blockX, blockY);

        }

​

        auto lgs = SkGradientShader::MakeLinear(

            pts, colors, positions, 3, SkTileMode::kMirror,

            flags, &matr);

​

        p.setShader(lgs);

        auto r = SkRect::MakeLTRB(blockX, blockY, blockX + 100, blockY + 100);

        canvas->drawRect(r, p);

        canvas->drawRect(r, strokePaint);

    }

}