java – 重写JApplet中的paint方法

我正在开发一个项目,使JApplet的内容自动缩放到html中指定的大小.我意识到这是布局管理器所做的事情,但由于我不允许重写整个applet结构,我决定尝试覆盖paint并简单地将Graphics对象的AffineTransform设置为适当缩放的版本,然后在顶部容器中捕获鼠标事件,并使用适当的缩放变换将其缩小.我现在卡在绘图部分.在Web浏览器中查看时,它会正确呈现缩放版本一次,然后将图像缩小回原始大小.此外,似乎JApplet中的paint方法只被调用一次.这是我的代码的裁剪版本,专注于问题.任何帮助,将不胜感激.提前致谢.

import javax.swing.JApplet;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;

public class Test extends JApplet
{
        public static final int ORIGINAL_APPLET_WIDTH = 1024;
        public static final int ORIGINAL_APPLET_HEIGHT = 800;
        private AffineTransform scalingTransform;
        private AffineTransform inverseScalingTransform;
 @Override
 public void init()
 {
            double xFactor = ((double)(this.getWidth()))/((double)(Test.ORIGINAL_APPLET_WIDTH));
            double yFactor = ((double)(this.getHeight()))/((double)(Test.ORIGINAL_APPLET_HEIGHT));
            this.scalingTransform = new AffineTransform();
            this.inverseScalingTransform = new AffineTransform();
            this.scalingTransform.scale(xFactor,yFactor);
            this.inverseScalingTransform.scale(1D/xFactor,1D/yFactor);
 }
    @Override
    public void paint(Graphics g)
    {
        ((Graphics2D)g).setTransform(Test.this.scalingTransform);
        super.paint(g);
    }
}

解决方法

经过大量研究,我发现问题在于JApplet的绘制方法不经常被调用.相反,内容窗格有自己的绘图表面,所以我只需要替换内容窗格以使其上传.继承人我这样做的方式：

@Override
    public void init()
    {
            double xFactor = ((double)(this.getWidth()))/((double)(qt.ORIGINAL_APPLET_WIDTH));
            double yFactor = ((double)(this.getHeight()))/((double)(qt.ORIGINAL_APPLET_HEIGHT));
            this.scalingTransform = new AffineTransform();
            this.inverseScalingTransform = new AffineTransform();
            this.scalingTransform.scale(xFactor,1D/yFactor);
            JPanel drawScale = new JPanel()
            {
                @Override
                public void paint(Graphics g)
                {
                    ((Graphics2D)g).setTransform(Test.this.scalingTransform);
                    super.paint(g);
                }
                @Override
                public void paintAll(Graphics g)
                {
                    ((Graphics2D)g).setTransform(Test.this.scalingTransform);
                    super.paintAll(g);
                }
                @Override
                public void paintComponents(Graphics g)
                {
                    ((Graphics2D)g).setTransform(Test.this.scalingTransform);
                    super.paintComponents(g);
                }
                @Override
                public void paintComponent(Graphics g)
                {
                    ((Graphics2D)g).setTransform(Test.this.scalingTransform);
                    super.paintComponents(g);
                }
            };
            Container oldPane = this.getContentPane();
            drawScale.setLayout(oldPane.getLayout());

            this.setContentPane(drawScale);
}

当然,除了applet中的那些之外,这些绘制方法也是如此.