如何在不影响其他组件的情况下重新绘制组件

Question

I subclass JPanel to show animated images using a timer. Here's the timer's task.

private class AnimationTimerTask extends TimerTask {
    @Override
    public void run() {
        // Change the current image

        repaint();
    }
}

Besides, I override the paintComponent method to draw the current image.

I use this class to create an object as the background and there is a label on it. I use the "setComponentZOrder" method to make sure the label is on the background.

At first, the label is shown normal. But it was covered by the background after the background's image changed, which means the repaint method is called.

I guess the problem is caused by the repaint of the background object.

I replace the repaint() to getParent.repaint(), and the problem solved. But I don't think it's the right way.

Answer 1

I'm honestly not sure if this is the right or wrong answer, so I hope others can chime in on this. But there is something called the RepaintManager . That article says:

For most programs, the RepaintManager can be viewed as part of Swing's internal system and can virtually be ignored. However, its API provides programs the option of gaining finer control over certain aspects of painting.

It has methods like this:

public static RepaintManager currentManager(JComponent c)
public synchronized void addDirtyRegion(JComponent c, int x, int y, int w, int h) 
public Rectangle getDirtyRegion(JComponent aComponent)
public void markCompletelyDirty(JComponent aComponent) 

It's straight forward to use these methods to do what you want.