分辨率：24X24

最大圆

 代码:

#include <QApplication>
#include <QImage>
#include <QPainter>

int main(int argc, char *argv[])
{
    QImage image(QSize(24,24),QImage::Format_ARGB32);
    image.fill(QColor(0,0,0,0));
    QPainter paint(&image);
    QRectF rect = image.rect();

    paint.setPen(QColor(255,255,255,0));
    paint.setBrush(QColor(255,255,255,255));

    paint.drawEllipse(rect);
    image.save("sun.png");

    return 0;
}

效果：

半径减一半

#include <QApplication>
#include <QImage>
#include <QPainter>
#include <QRect>
int main()
{
    QImage image(QSize(24,24),QImage::Format_ARGB32);
    image.fill(QColor(0,0,0,0));
    QPainter paint(&image);
    QRectF rect = image.rect();

    paint.setPen(QColor(255,255,255,0));
    paint.setBrush(QColor(255,255,255,255));

    // paint.drawEllipse(rect);
    paint.drawEllipse(rect.center().toPoint(),6,6);
    image.save("sun.png");

    return 0;
}