简单画心形

#define M_PI 3.14159265358979323846 // pi

void Heart::paintEvent(QPaintEvent *)
{
    QPainter painter(this);
    painter.translate(width()/2, height()/2);
    painter.setRenderHint(QPainter::Antialiasing);
    painter.setRenderHint(QPainter::TextAntialiasing);
    painter.setRenderHint(QPainter::SmoothPixmapTransform);

    painter.setPen(Qt::NoPen);
    painter.setBrush(QBrush(Qt::red));

    QVector<QPointF> lines;
    int a = 10;
    for (float t = 0; t < 2 * M_PI; t += 0.001) {
        float x = 16 * pow(sinf(t), 3);
        float y = 13 * cosf(t) - 5 * cosf(2 *t) - 2 * cosf(3 * t) - cosf(4 * t);
        lines.append(QPointF(x*a, -y*a));
    }

    painter.drawPolygon(lines);
}