java 是否可以将 JPanel 叠加在另一个之上？
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Is it possible to overlay a JPanel on top of another?
提问by sdasdadas
I am attempting to overlay a smaller panel (sub) over a larger panel (parent). The dimensions of sub are smaller than that of parent.
我试图将较小的面板 ( sub) 覆盖在较大的面板 ( parent) 上。sub 的尺寸小于 parent 的尺寸。
JPanel sub = new JPanel();
JPanel parent = new CustomPanel();
I would like to override parent's paintComponentmethod to draw sub in the top left hand corner with an offset of 5 pixels from the top and left sides. It would look something like this:
我想覆盖父的paintComponent方法，在左上角绘制子，从顶部和左侧偏移 5 个像素。它看起来像这样：
class CustomPanel extends JPanel() {
JPanel sub = null;
public CustomPanel(JPanel sub) {
this.sub = sub;
}
@Override
public void paintComponent(Graphics g) {
this.paintComponent(g);
// TODO: Here is where I would call something like sub.paint();
// However, I want sub to "start its paint" 5 pixels inside of
// parent's dimensions. How do I specify this?
Is it possible to tell sub to paint itself at a specific location? Terrible idea?
是否可以告诉 sub 在特定位置绘制自己？可怕的想法？
回答by Eugene Ryzhikov
Why don't you just setLayout(null)on the parent panel and then, before adding the sub panel to parent , set it's position and dimensions using it's setBoundsmethod. This way there is no need to use paintComponentfor positioning the sub panel.
为什么不只是setLayout(null)在父面板上，然后在将子面板添加到 parent 之前，使用它的setBounds方法设置它的位置和尺寸。这样就不需要paintComponent用于定位子面板。
Is case you parent panel should have specific layout with other components and sub should overlay all that, look into JLayer(Java 7) / JXLayer(Java 6).
如果您的父面板应该与其他组件具有特定的布局，而子面板应该覆盖所有这些，请查看JLayer(Java 7) / JXLayer(Java 6)。
Third solution can be using JLayeredPane.
第三个解决方案可以使用JLayeredPane。
