仅在一个方向上的鼠标运动侦听器 [英] mouse motion listener only in one direction

问题描述

我一直在研究 Java 中的鼠标运动侦听器，但无法完全解决它，因为我希望对象朝着鼠标在屏幕上指向的方向移动，但不幸的是，当鼠标位于小程序窗口内时，物体只向一个方向移动.下面是我的代码..

i have been working on mouse motion listener in Java couldn't sort it out completely because i want the object to move towards the direction where ever on the screen the mouse is pointed at but unforunately when the mouse is inside the applet window, the object moves only towards a single direction. Here is my code below..

import java.awt.*;
import java.awt.geom.*;
import java.util.*;
import java.applet.*;
import java.awt.event.*;
import javax.swing.*;

public class MouseOver extends Applet implements KeyListener, MouseListener,
      MouseMotionListener {
   private int[] Xpoints = { 0, -5, 5 };
   private int[] Ypoints = { -10, -2, -2 };
   private double xpos, ypos;
   private Polygon poly;
   int polyrot = 0;
   private int width; // !! added
   private int height; // !! added

   public void init() {
      poly = new Polygon(Xpoints, Ypoints, Xpoints.length);
      addKeyListener(this);
      addMouseListener(this);
      addMouseMotionListener(this);
   }

   public void paint(Graphics g) {
      Graphics2D g2d = (Graphics2D) g;
      AffineTransform id = new AffineTransform();
      width = getSize().width;
      height = getSize().height;
      g2d.setColor(Color.BLACK);
      g2d.fillRect(0, 0, width, height);
      g2d.setColor(Color.RED);
      g2d.draw(poly);
      g2d.translate(width / 2, height / 2);
      g2d.rotate(Math.toRadians(polyrot));
      g2d.scale(5, 5);
   }

   public void keyReleased(KeyEvent k) {
   }

   public void keyTyped(KeyEvent k) {
   }

   public void keyPressed(KeyEvent k) {
      switch (k.getKeyCode()) {
      case KeyEvent.VK_LEFT:
         if (polyrot < 0) {
            polyrot = 359;
            polyrot++;
         }
         repaint();
         break;
      case KeyEvent.VK_RIGHT:
         if (polyrot > 360) {
            polyrot = 0;
            polyrot--;
         }
         repaint();
         break;
      }
   }

   public void mouseEntered(MouseEvent m) {
   }

   public void mouseExited(MouseEvent m) {
   }

   public void mouseReleased(MouseEvent m) {
   }

   public void mouseClicked(MouseEvent m) {
   }

   public void mousePressed(MouseEvent m) {
      switch (m.getButton()) {
      case MouseEvent.BUTTON1:
         if (polyrot < 0) {
            polyrot = 359;
            polyrot--;
         }
         repaint();
         break;
      case MouseEvent.BUTTON2:
         if (polyrot > 360) {
            polyrot = 0;
            polyrot++;
         }
         repaint();
         break;
      }
   }

   public void mouseMoved(MouseEvent e) {
      xpos = getX();
      if (xpos < 0) {
         polyrot--;
      } else if (xpos > 0) {
         polyrot++;
      }
      repaint();
      // !! break; // Doesn't belong here
   }

   @Override
   public void mouseDragged(MouseEvent e) {
      // You forgot this method
   }
}

推荐答案

您的问题在于这一行:

public void mouseMoved(MouseEvent e){
 xpos=getX(); // ******
 if(xpos<0){polyrot--;}
 else if(xpos>0){polyrot++;}
 repaint();
 break;
}

返回小程序的 x 位置不是鼠标光标.您需要使用 MouseEvent 对象 e 来获取鼠标的位置.改为:

That returns the x position of the applet not the mouse cursor. You need to use your MouseEvent object, e and instead get the mouse's position. Change it to:

xpos = e.getX();

请不要忽略我对您的问题所做的评论.请记住，我们是在空闲时间提供帮助的志愿者.请不要让它变得比帮助您更困难.

Please don't ignore the comment that I made to your question. Please remember that we're volunteers who help on our free time. Please don't make it any more difficult than it has to be to help you.

我已尝试编辑您的代码以使其能够编译，但现在已缩进.考虑创建 Swing 应用程序，而不是 AWT 应用程序，因为 Swing 应用程序更加灵活、强大和健壮.

I've tried to edit your code so that it compiles, and now is indented. Consider creating a Swing application, not an AWT application, since Swing apps are more flexible, powerful and robust.

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