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[英]Calling repaint() in paintComponent() is using too much CPU
[英]Calling paintComponent() with parameters using repaint()
我对使用Java图形非常陌生,因此只需询问是否需要其他信息即可:)
我试图根据鼠标在屏幕上的单击位置绘制形状。 因此,我需要将单击位置的x和y坐标传递给paintComponent()
方法,以便它知道在何处绘制形状。
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);
}
}
基本上,我试图通过使一个在程序启动时通过调用repaint()
/ pack()
方法正确运行的方法正确运行,而在我给它提供x和y坐标时运行的方法正确地重载paintComponent。 但是,我不确定如何传递x和y参数,因为无法在repaint()
方法中传递它们。
paintComponent
或直接paint
,这些在需要时由重新绘制管理器自动调用... java.util.List
并将每个鼠标单击的Point
存储在其中,完成此操作后,从mouseClicked
方法调用repaint
。 paintComponent(Graphics)
方法中,遍历点List
并绘制所需的形状。 作为一个简单的例子...
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();
}
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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