java 绘制、重绘、paintComponent
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Paint, repaint , paintComponent
提问by The Answer
excuse me i search a lot to find how those 3 functions (paint, repaint, paintComponent) interact between them but i have no idea. Can you explain me exactly when they are called ( because sometimes java call it without me asking him) what they do exactly and what is the difference between them. Thank you
对不起，我搜索了很多以找到这 3 个函数（paint、repaint、paintComponent）如何在它们之间交互，但我不知道。你能准确地解释我什么时候被调用（因为有时java会在我不问他的情况下调用它）他们究竟做了什么，他们之间有什么区别。谢谢
回答by scottysseus
I am not sure about "paint", but I can explain the relationship between repaint() and paintComponent().
我不确定“paint”，但我可以解释 repaint() 和paintComponent() 之间的关系。
In my limited experience with java, the paintComponent() method is a method in the JPanel class and is a member of "swing".
在我有限的java经验中，paintComponent()方法是JPanel类中的一个方法，是“swing”的成员。
The paintComponent() method handles all of the "painting". Essentially, it draws whatever you want into the JPanel usings a Graphic object.
PaintComponent() 方法处理所有的“绘画”。本质上，它使用 Graphic 对象将您想要的任何内容绘制到 JPanel 中。
repaint() is an inherited instance method for all JPanel objects. Calling [your_JPanel_object].repaint() calls the paintComponent() method.
repaint() 是所有 JPanel 对象的继承实例方法。调用 [your_JPanel_object].repaint() 调用paintComponent() 方法。
Every time you wish to change the appearance of your JPanel, you must call repaint().
每次您希望更改 JPanel 的外观时，都必须调用 repaint()。
Certain actions automatically call the repaint() method:
某些操作会自动调用 repaint() 方法：
- Re-sizing your window
- Minimizing and maximizing your window
- 重新调整窗口大小
- 最小化和最大化你的窗口
to name a few.
仅举几例。
IN SHORT paintComponent() is a method defined in JPanel or your own custom class that extends JPanel. repaint() is a method called in another class (such as JFrame) that eventually calls paintComponent().
简而言之，paintComponent() 是在 JPanel 或您自己的扩展 JPanel 的自定义类中定义的方法。repaint() 是在另一个类（如 JFrame）中调用的方法，它最终调用了paintComponent()。
here is an example:
这是一个例子：
public class MyPanel extends JPanel{
public void paintComponent(Graphics g){
super.paintComponent(g);
g.draw([whatever you want]);
...
...
}
}
public class MyFrame extends JFrame{
public MyFrame(){
MyPanel myPanel = new MyPanel();
myPanel.repaint();
}
}
