在JButton上绘制图形 [英] Drawing graphics on top of a JButton

问题描述

我有一种情况，在GridLayout上有一堆JButton。我需要每个JButton都有：

1. 一个背景图片（但是如果需要，仍然保留默认按钮的样子） li>
   
2. 由其他类顶部绘制的自定义图形
   

我对背景图像没有任何问题，因为我正在使用setIcon（），但我在绘制背景顶部的东西时遇到问题。有一次，我能够在按钮的顶部绘图，但点击按钮后，图纸消失了。

基本上，我需要一种让我的JButton拥有公共方法的方法，它允许另一个类在其上绘制任何东西，比如：

  public void drawSomething（）{
 Graphics g = this.getGraphics（）; 
 g.drawOval（3,2,2,2）; 
 repaint（）; 
} 
  

或

  public Graphics getGraphics（）{
 return this.getGraphics（）; 
} 
  

然后另一个类可以这样做：

  button.getGraphics（）。drawSomething（）; 
  

后者更符合我的要求，但第一个同样有用。

有什么办法可以解决这个问题吗？此外，覆盖父类方法paintComponent（）并不会帮助，因为我需要每个按钮都具有不同的图形。 解析方案

可以继承JButton并覆盖paintComponent（）。
您可以通过为子类提供外部画家来处理每个具有不同图形的按钮。

  public class MyButton扩展了JButton {
私人画家画家; 
 
 public void paintComponent（Graphics g）{
 super.paintComponent（g）; 
 painter.paint（g）; 
 
 
 
 public interface Painter {
 public void paint（Graphics g）; 
} 
  

你不能随意绘制按钮，因为绘画会得到当按钮下次重新粉刷时丢失。

I have a situation wherein I have a bunch of JButtons on a GridLayout. I need each of the JButtons to have:

1. a background image (but retain the ability to keep the default button look if needed)
2. custom graphics drawn on top by other classes

I have no trouble with the background image, since I am using setIcon() but I am having problems drawing things on top of the background. At one point I was able to draw on top of the button, but after the button was clicked, the drawings disappeared. How can make the button keep this drawing state?

Basically, I need a way for my JButtons to have public methods that would allow another class to draw anything on it such as:

public void drawSomething() {
  Graphics g = this.getGraphics();
  g.drawOval(3,2,2,2);
  repaint();
}

or

public Graphics getGraphics() {
  return this.getGraphics();
}

then another class could do this:

button.getGraphics().drawSomething();

The latter is more what I am looking for but the first is equally useful.

Is there any way to go about this? Also, overriding the parent class method paintComponent() doesn't help since I need each button to have different graphics.

解决方案

you can subclass JButton and override paintComponent(). you can handle each button having a different graphic by providing an external 'painter' to the subclass. Or just have a different subclass for each different graphic.

public class MyButton extends JButton {
    private Painter painter;

    public void paintComponent(Graphics g) {
       super.paintComponent(g);
       painter.paint(g);
    }
}

public interface Painter {
    public void paint(Graphics g);
}

you cannot just paint on the button as you are doing as the painting will get lost when the button is next repainted.

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