用参数repaint（）调用paintComponent（） [英] Calling paintComponent() with parameters using repaint()
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问题描述
paintComponent（）方法，以便它知道在哪里绘制形状。 public void mouseClicked（MouseEvent e）{
System.out.println（Adding Shape）;
repaint（）;
}
class CanvasDrawArea extends JPanel {
//程序第一次启动时应该运行
@Override
public void paintComponent（Graphics g）{
super.paintComponent（g）;
canvas.setBackground（CANVAS_COLOR）;
}
//这里的问题是
public void paintComponent（Graphics g，int x，int y）{
super.paintComponent（g）;
g.fillRect（x，y，RECTANGLE_WIDTH，RECTANGLE_HEIGHT）;
$ / code> 基本上我试图通过让paintComponent重载在程序开始时通过调用 repaint（） / pack（）方法来运行，另一个将运行当我给它的X和Y坐标。然而，我不确定我是如何去传递x和y参数的，因为没有办法在 repaint（）方法中传递它们。
解决方案
- 你永远不需要调用
paintComponent或paint 直接由repaint管理器在需要时自动调用它们... - 创建
java .util.List并存储每个鼠标点击的Point，调用repaint从mouseClicked方法完成此操作。 - 在
paintComponent（Graphics）方法，遍历点的List并绘制所需的形状。
举个简单的例子...
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Dotty {
public static void main（String [] args）{
new Dotty（）;
$ b public Dotty（）{
EventQueue.invokeLater（new Runnable（）{
@Override
public void run（）{
尝试{
UIManager.setLookAndFeel（UIManager.getSystemLookAndFeelClassName（））;
} catch（ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex）{
ex.printStackTrace（）;
}
JFrame frame = new JFrame（Testing）;
frame.setDefaultCloseOperation（JFrame.EXIT_ON_CLOSE）;
frame.add（new DottyPane（））;
frame.pack（）;
frame.setLocationRelativeTo（null）;
frame.setVisible（true）;
}
}）;
}
public class DottyPane extends JPanel {
private List< Point>点;
public DottyPane（）{
points = new ArrayList<>（25）;
addMouseListener（new MouseAdapter（）{
@Override
public void mouseClicked（MouseEvent e）{
points.add（e.getPoint（））;
repaint（）;
}
}）;
}
@Override
public Dimension getPreferredSize（）{
return new Dimension（200，200）;
@Override
protected void paintComponent（Graphics g）{
super.paintComponent（g）;
Graphics2D g2d =（Graphics2D）g.create（）;
g2d.setColor（Color.RED）;
for（Point p：points）{
g2d.fillOval（p.x - 5，p.y - 5，10，10）;
}
g2d.dispose（）;
}
}
}
I am very new to graphics with Java, so just ask if any additional information is needed :)
I am trying to paint shapes based on where the mouse clicks on the screen. Because of this, I need to pass the x and y coordinates of where I clicked to the paintComponent() method so that it will know where to paint the shape.
public void mouseClicked(MouseEvent e) {
System.out.println("Adding Shape");
repaint();
}
class CanvasDrawArea extends JPanel{
//this should run when the program first starts
@Override
public void paintComponent(Graphics g){
super.paintComponent(g);
canvas.setBackground(CANVAS_COLOR);
}
//here is where the question is
public void paintComponent(Graphics g, int x, int y){
super.paintComponent(g);
g.fillRect(x, y, RECTANGLE_WIDTH, RECTANGLE_HEIGHT);
}
}
basically I am trying to overload the paintComponent by having one that runs right when the program starts by calling the repaint() / pack() method, and one that will run when I give it the x and y coordinates. I am unsure, however, how I am supposed to go about passing the x and y parameters, as there is no way to pass them in the repaint() method.
解决方案
- You should never have the need to call
paintComponentorpaintdirectly these are called automatically by the repaint manager when required... - Create
java.util.Listand store thePointof each mouse click in it, callrepaintfrom themouseClickedmethod after you have done this. - In your
paintComponent(Graphics)method, iterate over theListof points and paint the shape you need.
As a simple example...
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Dotty {
public static void main(String[] args) {
new Dotty();
}
public Dotty() {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new DottyPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class DottyPane extends JPanel {
private List<Point> points;
public DottyPane() {
points = new ArrayList<>(25);
addMouseListener(new MouseAdapter() {
@Override
public void mouseClicked(MouseEvent e) {
points.add(e.getPoint());
repaint();
}
});
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
@Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setColor(Color.RED);
for (Point p : points) {
g2d.fillOval(p.x - 5, p.y - 5, 10, 10);
}
g2d.dispose();
}
}
}
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