e669. 绘制缓冲图像

To draw on a buffered image, create a graphics context on the buffered image.

    // Create a graphics context on the buffered image
    Graphics2D g2d = bimage.createGraphics();

    // Draw on the image
    g2d.setColor(Color.red);
    g2d.fill(new Ellipse2D.Float(0, 0, 200, 100));
    g2d.dispose();

If the buffered image supports transparency, (see e661 确定图像中是否有透明像素), pixels can be made transparent:

    g2d = bimage.createGraphics();

    // Make all filled pixels transparent
    Color transparent = new Color(0, 0, 0, 0);
    g2d.setColor(transparent);
    g2d.setComposite(AlphaComposite.Src);
    g2d.fill(new Rectangle2D.Float(20, 20, 100, 20));
    g2d.dispose();

原文地址：https://www.cnblogs.com/borter/p/9575510.html