JPanel 图形清除和重绘?

问题描述

我有一个带有 paintComponent() 函数的 JPanel.我将调用它一次，然后当用户单击不同的 JButton 时，我将设置一些标志并希望再次调用此函数，因为在设置标志后它会做一些略有不同的事情.

I have a JPanel with a paintComponent() function. I'll call it once, then when the user clicks a different JButton, I'll set some flag and want to call this function again as it will do something slightly different after the flag is set.

所以这就是我想知道的:如何清除 paintComponent 中的现有内容?要重绘，我是否只需再次调用 paintComponent ?

So here's what I'm wondering: how do I clear the existing stuff from paintComponent? And to redraw, do I just call paintComponent again?

目前我正在尝试以下方法:

Currently I'm trying the following:

flag2 = true;
repaint(); //I expect (want) paintComponent to be called again

在绘制组件中，我做的事情是:

In paint component, I do stuff like:

if (flag2==true) {
    g.drawRect(...);
} else {
    g.drawLine(...);
}

但是通过测试，我所做的似乎有问题.

But through testing it seems like there is something wrong with what I'm doing.

感谢您的帮助.

推荐答案

当你改变面板的属性时，你需要调用:

When you change a property of the panel then you need to invoke:

panel.repaint();

导致组件被重新绘制.

那么paintComponent()方法中的第一条语句应该是:

Then the first statement in the paintComponent() method should be:

super.paintComponent(g);

这将绘制背景，以便您现在可以进行自定义绘制.

This will paint the background so you can now do your custom painting.

如果您需要更多帮助，请发布说明问题的 SSCCE.

If you need more help then post your SSCCE that demonstrates the problem.

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