我创建了一个具有放大和缩小功能的面板,但是滚动条不起作用,我的意思是当我放大时,我无法滚动看到整个面板。
这是我的代码:
import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JScrollPane;
import java.awt.Dimension;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
@SuppressWarnings("serial")
public class PanelWithZoom extends JPanel{
private JButton btnZoomIn;
private JButton btnZoomOut;
private double scale = 1;
private JPanel innerPanel;
private JPanel outerPanel;
public PanelWithZoom() {
setLayout(new BorderLayout(0, 0));
JPanel panel = new JPanel();
add(panel, BorderLayout.NORTH);
btnZoomIn = new JButton("zoom in");
btnZoomIn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent arg0) {
scale = scale + 0.1;
outerPanel.repaint();
outerPanel.revalidate();
}
});
panel.add(btnZoomIn);
btnZoomOut = new JButton("zoom out");
btnZoomOut.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
scale = scale - 0.1;
outerPanel.repaint();
outerPanel.revalidate();
}
});
panel.add(btnZoomOut);
JPanel panel_1 = new JPanel();
add(panel_1, BorderLayout.WEST);
JPanel panel_2 = new JPanel();
add(panel_2, BorderLayout.SOUTH);
JPanel panel_3 = new JPanel();
add(panel_3, BorderLayout.EAST);
outerPanel = new JPanel(){
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
int w = (int) getWidth();
int h = (int) getHeight();
// Translate used to make sure scale is centered
g2.translate(w/2, h/2);
g2.scale(scale, scale);
g2.translate(-w/2, -h/2);
}
};
JScrollPane scroll = new JScrollPane(outerPanel);
add(scroll, BorderLayout.CENTER);
innerPanel = new JPanel(){
@Override
protected void paintComponent(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
g2.setColor(Color.white);
g2.fillRect(0, 0, getWidth(), getHeight());
g2.setColor(Color.black);
g2.drawString("String for test", 10, 50);
g2.drawRect(0, 0, getWidth()-1, getHeight()-1);
setPreferredSize(new Dimension(595, 842));
}
};
outerPanel.add(innerPanel);
}
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setContentPane(new PanelWithZoom());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
frame.setVisible(true);
}
}
你可以测试一下来理解我的意思
重写组件的getPreferredSize
方法,根据scale
和组件的原始大小返回组件的大小
因为你想对子组件应用缩放,你可能想要覆盖paint
而不是paintComponent
outerPanel = new JPanel(){
@Override
public void paint(Graphics g) {
Graphics2D g2 = (Graphics2D) g.create();
g2.scale(scale, scale);
super.paint(g);
g2.dispose()
}
}
但是,Swing组件可以独立于它们的父容器进行绘制,这意味着在绘制子组件时可能不会调用paint
方法…
问题是,它不会缩放鼠标事件(或一堆其他属性)。
对于不断增加的问题列表,一个更好的解决方案是使用类似JXLayer的东西,如下所示
指出:
- 使用
Graphics#create
来复制Graphics
上下文和Graphics#dispose
的属性,在处理翻译/转换/渲染提示和其他属性时更安全,因为对副本的任何更改都不会影响原始 - 不要在任何油漆方法中调用任何方法,这可能直接或间接导致触发重画事件,你将结束在一个讨厌的永无止境的循环,最终将消耗你的CPU
图形#创建和#处置示例…
outerPanel = new JPanel(){
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g.create();
int w = (int) getWidth();
int h = (int) getHeight();
// Translate used to make sure scale is centered
g2.translate(w/2, h/2);
g2.scale(scale, scale);
g2.translate(-w/2, -h/2);
g2.dispose();
}
}