Method updateShader

snap_drawing/src/snap_drawing/cpp/Drawing/LinearGradient.cpp:47–111

}

void LinearGradient::updateShader(const Rect& bounds) {
    if (isEmpty()) {
        _shader = nullptr;
    } else {
        auto halfWidth = bounds.x() + (bounds.width() / 2);
        auto halfHeight = bounds.y() + (bounds.height() / 2);

        Point points[2];

        switch (_orientation) {
            case LinearGradientOrientationTopBottom:
                points[0] = Point::make(halfWidth, bounds.top);
                points[1] = Point::make(halfWidth, bounds.bottom);
                break;
            case LinearGradientOrientationTopRightBottomLeft:
                points[0] = Point::make(bounds.right, bounds.top);
                points[1] = Point::make(bounds.left, bounds.bottom);
                break;
            case LinearGradientOrientationRightLeft:
                points[0] = Point::make(bounds.right, halfHeight);
                points[1] = Point::make(bounds.left, halfHeight);
                break;
            case LinearGradientOrientationBottomRightTopLeft:
                points[0] = Point::make(bounds.right, bounds.bottom);
                points[1] = Point::make(bounds.left, bounds.top);
                break;
            case LinearGradientOrientationBottomTop:
                points[0] = Point::make(halfWidth, bounds.bottom);
                points[1] = Point::make(halfWidth, bounds.top);
                break;
            case LinearGradientOrientationBottomLeftTopRight:
                points[0] = Point::make(bounds.left, bounds.bottom);
                points[1] = Point::make(bounds.right, bounds.top);
                break;
            case LinearGradientOrientationLeftRight:
                points[0] = Point::make(bounds.left, halfHeight);
                points[1] = Point::make(bounds.right, halfHeight);
                break;
            case LinearGradientOrientationTopLeftBottomRight:
                points[0] = Point::make(bounds.left, bounds.top);
                points[1] = Point::make(bounds.right, bounds.bottom);
                break;
            default:
                points[0] = Point::make(halfWidth, bounds.top);
                points[1] = Point::make(halfWidth, bounds.bottom);
        }

        const auto* colorsData = reinterpret_cast<const SkColor*>(_colors.data());

        sk_sp<SkShader> shader;
        if (_colors.size() == _locations.size()) {
            // User provided color distribution

            _shader = SkGradientShader::MakeLinear(&points[0].getSkValue(),
                                                   colorsData,
                                                   _locations.data(),
                                                   static_cast<int>(_colors.size()),
                                                   SkTileMode::kClamp);