Java：mouseDragged并在图形界面中移动

新手程序员在这里。

我正在制作一个程序，用于在笛卡尔坐标系中呈现用户输入的方程。 目前我遇到一些让用户在坐标中自由移动视图的问题。 目前使用mouseDragged，用户可以稍微拖动视图，但是一旦用户释放鼠标并尝试再次移动视图，原点就会快速回到鼠标光标的当前位置。 让用户自由移动的最佳方法是什么？ 提前致谢！

这是绘图区域的代码。

import java.awt.Color; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Point; import java.awt.Rectangle; import java.awt.event.MouseEvent; import java.awt.event.MouseListener; import java.awt.event.MouseMotionListener; import java.awt.geom.Line2D; import java.awt.geom.Point2D; import javax.swing.JPanel; public class DrawingArea extends JPanel implements MouseMotionListener { private final int x_panel = 350; // width of the panel private final int y_panel = 400; // height of the panel private int div_x; // width of one square private int div_y; // height of one square private int real_y; private int real_x; private Point origin; // the origin of the coordinate private Point temp; // temporary point private static int y = 0; private static int x = 0; DrawingArea() { setBackground(Color.WHITE); real_x = x_panel; real_y = y_panel; setDivisionDefault(); setOrigin(new Point((real_x / 2), (real_y / 2))); setSize(x_panel, y_panel); addMouseMotionListener(this); } DrawingArea(Point origin, Point destination) { this.origin = origin; this.destination = destination; panel = new JPanel(); panel.setSize(destination.x, destination.y); panel.setLocation(origin); this.panel.setBackground(Color.red); panel.setLayout(null); } @Override public void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D line = (Graphics2D) g; temp = new Point(origin.x, origin.y); line.setColor(Color.red); drawHelpLines(line); line.setColor(Color.blue); drawOrigin(line); line.setColor(Color.green); for (int i = 0; i < 100; i++) { // This is a test line //temp = this.suora(); temp.x++; temp.y++; line.drawLine(temp.x, temp.y, temp.x, temp.y); } } public void setOrigin(Point p) { origin = p; } public void drawOrigin(Graphics2D line) { line.drawLine(origin.x, 0, origin.x, y_panel); line.drawLine(0, origin.y, x_panel, origin.y); } public void drawHelpLines(Graphics2D line) { int xhelp= origin.x; int yhelp= origin.y; for (int i = 0; i < 20; i++) { xhelp+= div_x; line.drawLine(xhelp, 0, xhelp, y_panel); } xhelp= origin.x; for (int i = 0; i < 20; i++) { xhelp-= div_x; line.drawLine(xhelp, 0, xhelp, y_panel); } for (int i = 0; i < 20; i++) { yhelp-= div_y; line.drawLine(0, yhelp,x_panel, yhelp); } yhelp= origin.y; for (int i = 0; i < 20; i++) { yhelp+= div_y; line.drawLine(0, yhelp, x_panel, yhelp); } } public void setDivisionDefault() { div_x = 20; div_y = 20; } @Override public void mouseDragged(MouseEvent e) { //Point temp_point = new Point(mouse_x,mouse_y); Point coords = new Point(e.getX(), e.getY()); setOrigin(coords); repaint(); } @Override public void mouseMoved(MouseEvent e) { } } 

Answer 1

基于此示例 ，以下程序允许用户将轴的交点拖动到从面板中心开始的任意点origin 。

 import java.awt.Cursor; import java.awt.Dimension; import java.awt.EventQueue; import java.awt.Graphics; import java.awt.Point; import java.awt.event.MouseAdapter; import java.awt.event.MouseEvent; import java.awt.event.MouseMotionAdapter; import javax.swing.JFrame; import javax.swing.JPanel; /** * @see https://stackoverflow.com/a/15576413/230513 * @see https://stackoverflow.com/a/5312702/230513 */ public class MouseDragTest extends JPanel { private static final String TITLE = "Drag me!"; private static final int W = 640; private static final int H = 480; private Point origin = new Point(W / 2, H / 2); private Point mousePt; public MouseDragTest() { this.setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR)); this.addMouseListener(new MouseAdapter() { @Override public void mousePressed(MouseEvent e) { mousePt = e.getPoint(); repaint(); } }); this.addMouseMotionListener(new MouseMotionAdapter() { @Override public void mouseDragged(MouseEvent e) { int dx = e.getX() - mousePt.x; int dy = e.getY() - mousePt.y; origin.setLocation(origin.x + dx, origin.y + dy); mousePt = e.getPoint(); repaint(); } }); } @Override public Dimension getPreferredSize() { return new Dimension(W, H); } @Override public void paintComponent(Graphics g) { super.paintComponent(g); g.drawLine(0, origin.y, getWidth(), origin.y); g.drawLine(origin.x, 0, origin.x, getHeight()); } public static void main(String[] args) { EventQueue.invokeLater(new Runnable() { @Override public void run() { JFrame f = new JFrame(TITLE); f.add(new MouseDragTest()); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.pack(); f.setLocationRelativeTo(null); f.setVisible(true); } }); } }