将多个graphic2d组件绘制到JPanel中 [英] Drawing multiple graphic2d components into JPanel
问题描述
我已经阅读了很多有关绘制Graphics2D组件并将其添加到JPanel/JFrame的教程，但是我找不到如何简单地将多个这些组件添加到一个JPanel中的教程.我下面的代码仅添加了1个组件(行)，而我找不到为什么无法添加更多组件的原因.
I've read a lot of tutorials on drawing Graphics2D components and adding to JPanel/JFrame but I can't find how to add multiple these components into one JPanel simply. My code below adds only 1 component (line) and I can't find why it isn't possible to add more.
我在做什么错了?
期望的行为:应该有3条红线.
我的整个代码:
package Examples;
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.BorderFactory;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Example1 extends JFrame {
private final JPanel panel;
public Example1() {
// jpanel with graphics
panel = new JPanel();
panel.setPreferredSize(new Dimension(200, 200));
panel.setBorder(BorderFactory.createLineBorder(Color.BLACK));
panel.setBackground(Color.WHITE);
add(panel);
// adding lines to jpanel
AddMyLine(); // 1st: this works well
AddMyLine(); // 2nd: this doesn't work
AddMyLine(); // 3rd: this doesn't work
setLayout(new FlowLayout(FlowLayout.LEFT));
setSize(250, 250);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
setLocationRelativeTo(null);
}
// add new line to jpanel
private void AddMyLine() {
MyLine c = new MyLine();
System.out.println(c);
panel.add(c);
}
// line component
private class MyLine extends JComponent {
public MyLine() {
setPreferredSize(new Dimension(200, 200));
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D)g;
g2d.setColor(Color.red);
g2d.setStroke(new BasicStroke(1));
int x1 = (int)Math.round(Math.random()*200);
int y1 = (int)Math.round(Math.random()*200);
int x2 = (int)Math.round(Math.random()*200);
int y2 = (int)Math.round(Math.random()*200);
g2d.drawLine(x1,y1,x2,y2);
}
}
public static void main(String args[]) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
new Example1();
}
});
}
}
推荐答案
您的MyLine类不应是Swing组件，因此不应扩展JComponent.相反，它应该是一个逻辑实体，并且实际上可以是实现Shape的对象(例如Line2D)，也可以是您自己的完整类，但是应该知道如何绘制自身，即，如果它不实现Shape，那么它应该具有其他类可以调用的某种draw(Graphics2D g)方法类型.我认为相反，您应该扩展面板的JPanel类，以便覆盖它的paintComponent方法，为它提供一个集合来容纳添加到其中的任何MyLine项，并在paintComponent内绘制MyLine项.
Your MyLine class should not be a Swing component and thus should not extend JComponent. Rather it should be a logical entity, and in fact can be something that implements Shape such as a Line2D, or could be your own complete class, but should know how to draw itself, i.e., if it does not implement Shape, then it should have some type of draw(Graphics2D g) method that other classes can call. I think instead you should work on extending your panel's JPanel class, such that you override its paintComponent method, give it a collection to hold any MyLine items added to it, and draw the MyLine items within the paintComponent.
其他选项包括直接绘制到BufferedImage上，然后在JPanel的paintComponent方法中显示该BufferedImage.这对于静态图片非常有用，但对于需要更改或移动的图片则不好.
Other options include drawing directly on to a BufferedImage, and then displaying that BufferedImage in your JPanel's paintComponent method. This is great for static images, but not good for images that need to change or move.
例如
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Line2D;
import java.util.ArrayList;
import java.util.List;
import javax.swing.*;
public class DrawChit extends JPanel {
private static final int PREF_W = 500;
private static final int PREF_H = PREF_W;
private List<Shape> shapes = new ArrayList<>();
public DrawChit() {
setBackground(Color.white);
}
public void addShape(Shape shape) {
shapes.add(shape);
repaint();
}
@Override // make it bigger
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
}
return new Dimension(PREF_W, PREF_H);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
for (Shape shape : shapes) {
g2.draw(shape);
}
}
private static void createAndShowGui() {
DrawChit drawChit = new DrawChit();
drawChit.addShape(new Line2D.Double(10, 10, 100, 100));
drawChit.addShape(new Ellipse2D.Double(120, 120, 200, 200));
JFrame frame = new JFrame("DrawChit");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(drawChit);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
或者使用我自己的MyDrawable类的示例，该类生成一个如下所示的GUI:
Or an example using my own MyDrawable class, which produces a GUI that looks like this:
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.Stroke;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Line2D;
import java.awt.geom.Rectangle2D;
import java.awt.geom.RoundRectangle2D;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
@SuppressWarnings("serial")
public class DrawChit extends JPanel {
private static final int PREF_W = 600;
private static final int PREF_H = PREF_W;
private List<MyDrawable> drawables = new ArrayList<>();
public DrawChit() {
setBackground(Color.white);
}
public void addMyDrawable(MyDrawable myDrawable) {
drawables.add(myDrawable);
repaint();
}
@Override
// make it bigger
public Dimension getPreferredSize() {
if (isPreferredSizeSet()) {
return super.getPreferredSize();
}
return new Dimension(PREF_W, PREF_H);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
for (MyDrawable myDrawable : drawables) {
myDrawable.draw(g2);
}
}
public void clearAll() {
drawables.clear();
repaint();
}
private static void createAndShowGui() {
final List<MyDrawable> myDrawables = new ArrayList<>();
myDrawables.add(new MyDrawable(new Line2D.Double(100, 40, 400, 400),
Color.red, new BasicStroke(40)));
myDrawables.add(new MyDrawable(new Ellipse2D.Double(50, 10, 400, 400),
Color.blue, new BasicStroke(18)));
myDrawables.add(new MyDrawable(new Rectangle2D.Double(40, 200, 300, 300),
Color.cyan, new BasicStroke(25)));
myDrawables.add(new MyDrawable(new RoundRectangle2D.Double(75, 75, 490, 450, 40, 40),
Color.green, new BasicStroke(12)));
final DrawChit drawChit = new DrawChit();
JFrame frame = new JFrame("DrawChit");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(drawChit);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
int timerDelay = 1000;
new Timer(timerDelay, new ActionListener() {
private int drawCount = 0;
@Override
public void actionPerformed(ActionEvent e) {
if (drawCount >= myDrawables.size()) {
drawCount = 0;
drawChit.clearAll();
} else {
drawChit.addMyDrawable(myDrawables.get(drawCount));
drawCount++;
}
}
}).start();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
class MyDrawable {
private Shape shape;
private Color color;
private Stroke stroke;
public MyDrawable(Shape shape, Color color, Stroke stroke) {
this.shape = shape;
this.color = color;
this.stroke = stroke;
}
public Shape getShape() {
return shape;
}
public Color getColor() {
return color;
}
public Stroke getStroke() {
return stroke;
}
public void draw(Graphics2D g2) {
Color oldColor = g2.getColor();
Stroke oldStroke = g2.getStroke();
g2.setColor(color);
g2.setStroke(stroke);
g2.draw(shape);
g2.setColor(oldColor);
g2.setStroke(oldStroke);
}
public void fill(Graphics2D g2) {
Color oldColor = g2.getColor();
Stroke oldStroke = g2.getStroke();
g2.setColor(color);
g2.setStroke(stroke);
g2.fill(shape);
g2.setColor(oldColor);
g2.setStroke(oldStroke);
}
}
这篇关于将多个graphic2d组件绘制到JPanel中的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
