设置窗口

Question

的内部区域的大小我有一个简单的函数，生成一个包含图像的JFrame：

//The window 
JFrame frame = new JFrame(); 
//Topmost component of the window 
Container main = frame.getContentPane(); 
//Turns out this is probably the simplest way to render image on screen 
//with guaranteed 1:1 aspect ratio 
JPanel panel = new JPanel() { 
    @Override 
    protected void paintComponent(Graphics g) { 
     super.paintComponent(g); 
     g.drawImage(image, 0, 0, null); 
    } 
}; 
//Put the image drawer in the topmost window component 
main.add(panel); 
//Set window size to the image size plus some padding dimensions 
frame.setSize(image.getWidth(null)+1, image.getHeight(null)+15); 

frame.setVisible(true); 

结果：

我认为出现这种情况，因为窗口尺寸包括顶栏和窗口边框的大小。

我也试着设置大小为JPanel和JFrame中调用pack()：

//Set the size to the panel and let JFrame size itself properly 
panel.setSize(image.getWidth(null), image.getHeight(null)); 
frame.pack(); 

结果更糟糕：

所以，我怎么能准确地指定内部窗口尺寸像素？

Here's the full function code.

Answer 1

通过重写的JPanel的getPreferredSize方法和使其可见

JPanel panel = new JPanel() { 
    @Override 
    protected void paintComponent(Graphics g) { 
     super.paintComponent(g); 
     g.drawImage(image, 0, 0, null); 
    } 
    @Override 
    public Dimension getPreferredSize(){ 
     return new Dimension(image.getWidth(), image.getHeight()); 
    } 
}; 

查看其回答Use of overriding getPreferredSize() instead of using setPreferredSize() for fixed size Components之前呼吁JFramepack()指定面板的优选大小关于这种技术的使用和效果，或者方法的使用和效果