如何使自定义框架正确重绘？

Question

I am trying to create my own custom GUI toolkit based on swing as a bit of a side project. My problem is this: I have created a frame with exit and minimize buttons however when I use the minimize button and maximise again, the window is not in the correct format. Here is my code for the frame class.

package com.SMS.GUI;

import java.awt.Color;
import java.awt.Frame;
import javax.swing.*;
import java.awt.event.MouseEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseListener;


/**
 *
 * @author Marc
 */
final class SMSFrame extends JFrame implements MouseListener{

GUIButton minimizeButton, exitButton;
JPanel titleBar;

SMSFrame(int width, int height){
    setResizable(false);
    setUndecorated(true);
    setSize(width,height);
    getContentPane().setBackground(Color.decode("#8e44ad"));
    setVisible(true);

    minimizeButton = new GUIButton((width-100),0,50,50,"#1abc9c");
    exitButton = new GUIButton((width-50), 0, 50, 50, "#d35400");
    titleBar = new JPanel();

    titleBar.setBackground(Color.decode("#2c3e50"));
    titleBar.setBounds(0, 0, width, 50);


    minimizeButton.addMouseListener(this);
    exitButton.addMouseListener(this);


    add(titleBar);
    titleBar.add(exitButton);
    titleBar.add(minimizeButton);

}


@Override
public void mouseClicked(MouseEvent e) {
}

@Override
public void mousePressed(MouseEvent e) {
    if(e.getSource() == exitButton){
        exitButton.setBackground(Color.decode("#c0392b"));
    }

    if(e.getSource() == minimizeButton){
        minimizeButton.setBackground(Color.decode("#2ecc71"));
    }
}

@Override
public void mouseReleased(MouseEvent e) {
    if(e.getSource() == exitButton){
        System.exit(0);
    }

    if(e.getSource() == minimizeButton){
        super.setState(JFrame.ICONIFIED);
    }
}

@Override
public void mouseEntered(MouseEvent e) {
    if(e.getSource() == exitButton){
        exitButton.setBackground(Color.decode("#e74c3c"));
    }

    if(e.getSource() == minimizeButton){
        minimizeButton.setBackground(Color.decode("#16a085"));
    }
}

@Override
public void mouseExited(MouseEvent e) {
    if(e.getSource() == exitButton){
        exitButton.setBackground(Color.decode("#d35400"));
    }

    if(e.getSource() == minimizeButton){
        minimizeButton.setBackground(Color.decode("#1abc9c"));
    }
}
}

Here is the code for the custom buttons(I used JPanels). package com.SMS.GUI;

import java.awt.Color;
import javax.swing.JPanel;


final class GUIButton extends JPanel{
        GUIButton(int x, int y, int width, int height, String hexidecimal_colour){
        setBackground(Color.decode(hexidecimal_colour));
        setBounds(x, y, width, height);
    }

        GUIButton(int width, int height, String hexidecimal_colour){
        setBackground(Color.decode(hexidecimal_colour));
        setSize(width, height);
    }
}

This is how the frame looks before minimizing:

This is how it looks after:

Answer 1

however when I use the minimize button and maximise again, the window is not in the correct format.

You really need to understand how Swing works if you want to customize a component. Swing was designed to be used with layout managers . The default layout manager for the content pane of a JFrame is a BorderLayout . The default layout manager for a JPanel is a FlowLayout .

The setSize() and/or setBounds() methods only work until the frame is "revalidated". When the frame is restored to is size the layout managers for each component are invoked and all the components are displayed at their preferred size.

titleBar = new JPanel();

So, the buttons on the "titleBar" get resized to their preferred size since they default FlowLayout is used. And the FlowLayout will then position the buttons in the center of the panel.

To fix this problem you need to override the getPreferredSize() method of the GuiButton class. Also, get rid of all the location related code. It is up to the layout manager to set the location/size.

Since you want the buttons aligned to the right of the panel, you will need to change the layout manager to use a right aligned FlowLayout . Read the FlowLayout API for the proper constructor to use when creating the layout manager.

add(titleBar);

This adds the "titleBar" to the CENTER of the BorderLayout , so when the frame is revalidated, this panel will now cover the entire frame based on the rules of the BorderLayout .

To fix this you can use:

add(titleBar, BorderLayout.PAGE_START);

Now the titlebar will only appear at the top for the frame.

So you need to read the Swing tutorial on Layout Managers to understand these changes. The tutorial has working examples of both the BorderLayout and the FlowLayout .

I also suggest you read the section on How to Make Frames for simple frame basics, including a better structure for you code. The example code shows the order of statement execution such that the setVisible() is the last statement.

Answer 2

You could try to repaint or revalidate when you are Deiconifying you window. To do this, implements WindowListener and use this method :

@Override
public void windowDeiconified(WindowEvent e) {
    //back to normal you could use this.setState(JFrame.NORMAL);
    //do stuff here.
}

don't forget the this.addWindowListener(this);

Also you extends JFrame so you could call this.setState(JFrame.ICONIFIED); instead of super method. It's not a complete solution but it's definitly a problem of component painting.