使用MouseDrag方法拖动图像

我正在尝试编写可以使用mouseDragged方法拖动图像的位置，但我似乎无法使用当前代码成功执行此操作。 我的目的是确保当我对applet中的每个图像进行拖动时，它会跟随光标。

/* Using drag mouseEvent, all objects in the app can be dragged... */ package finals_two; import java.applet.*; import java.awt.*; import java.awt.event.*; /* 10/16/2015 * @author michael.pabilona */ public class Finals_Two extends Applet implements MouseMotionListener { int hei, wid, xCoordinate, yCoordinate; Image leftReceiver1, leftReceiver2, leftReceiver3; Image rightReceiver1, rightReceiver2, rightReceiver3; Image leftSpiker, rightSpiker, center, setter; public void init() { hei = getSize().height; wid = getSize().width; xCoordinate = hei; yCoordinate = wid; addMouseMotionListener(this); } public void mouseDragged(MouseEvent e) { xCoordinate = e.getX(); yCoordinate = e.getY(); repaint(); } public void paint(Graphics gr) { setBackground(Color.white); gr.setColor(Color.black); //court bound top line gr.drawLine(400, 130, 1200, 130); //court bound bottom line gr.drawLine(200, 530, 1000, 530); //court bound left line gr.drawLine(400, 130, 200, 530); //court bound right line gr.drawLine(1000, 530, 1200, 130); //net gr.drawLine(800, 130, 600, 530); gr.drawLine(800, 130, 800, 0); gr.drawLine(600, 530, 600, 400); //net horizontal lines gr.drawLine(800, 0, 600, 400); gr.drawLine(800, 10, 600, 410); gr.drawLine(800, 20, 600, 420); gr.drawLine(800, 30, 600, 430); gr.drawLine(800, 40, 600, 440); gr.drawLine(800, 50, 600, 450); gr.drawLine(800, 60, 600, 460); gr.drawLine(800, 70, 600, 470); gr.drawLine(800, 80, 600, 480); //net vertical lines gr.drawLine(795, 5, 795, 90); gr.drawLine(790, 20, 790, 100); gr.drawLine(785, 30, 785, 110); gr.drawLine(780, 40, 780, 120); gr.drawLine(775, 50, 775, 130); gr.drawLine(770, 60, 770, 140); gr.drawLine(765, 70, 765, 150); gr.drawLine(760, 80, 760, 160); gr.drawLine(755, 90, 755, 170); gr.drawLine(750, 100, 750, 180); gr.drawLine(745, 110, 745, 190); gr.drawLine(740, 120, 740, 200); gr.drawLine(735, 130, 735, 210); gr.drawLine(730, 140, 730, 220); gr.drawLine(725, 150, 725, 230); gr.drawLine(720, 160, 720, 240); gr.drawLine(715, 170, 715, 250); gr.drawLine(710, 180, 710, 260); gr.drawLine(705, 190, 705, 270); gr.drawLine(700, 200, 700, 280); gr.drawLine(695, 210, 695, 290); gr.drawLine(690, 220, 690, 300); gr.drawLine(685, 230, 685, 310); gr.drawLine(680, 240, 680, 320); gr.drawLine(675, 250, 675, 330); gr.drawLine(670, 260, 670, 340); gr.drawLine(665, 270, 665, 350); gr.drawLine(660, 280, 660, 360); gr.drawLine(655, 290, 655, 370); gr.drawLine(650, 300, 650, 380); gr.drawLine(645, 310, 645, 390); gr.drawLine(640, 320, 640, 400); gr.drawLine(635, 330, 635, 410); gr.drawLine(630, 340, 630, 420); gr.drawLine(625, 350, 625, 430); gr.drawLine(620, 360, 620, 440); gr.drawLine(615, 370, 615, 450); gr.drawLine(610, 380, 610, 460); gr.drawLine(605, 390, 605, 470); gr.drawLine(600, 390, 600, 480); //left mid line gr.drawLine(625, 130, 425, 530); //right mid line gr.drawLine(975, 130, 775, 530); //left backend receivers leftReceiver1 = getImage(getDocumentBase(),"receiver.jpg"); gr.drawImage(leftReceiver1, 400, 100, 90, 90, this); leftReceiver2 = getImage(getDocumentBase(),"receiver.jpg"); gr.drawImage(leftReceiver2, 325, 250, 90, 90, this); leftReceiver3 = getImage(getDocumentBase(),"server1.jpg"); gr.drawImage(leftReceiver3, 75, 375, 150, 150, this); //right backend receivers rightReceiver1 = getImage(getDocumentBase(),"receiver1.jpg"); gr.drawImage(rightReceiver1, 1000, 100, 100, 100, this); rightReceiver2 = getImage(getDocumentBase(),"receiver1.jpg"); gr.drawImage(rightReceiver2, 950, 250, 100, 100, this); rightReceiver3 = getImage(getDocumentBase(),"receiver1.jpg"); gr.drawImage(rightReceiver3, 900, 400, 100, 100, this); //left front liners leftSpiker = getImage(getDocumentBase(),"spiker.jpg"); gr.drawImage(leftSpiker, 650, 30, 100, 100, this); center = getImage(getDocumentBase(),"spiker.jpg"); gr.drawImage(center,600,150,100,100,this); setter = getImage(getDocumentBase(),"setter.jpg"); gr.drawImage(setter, 500, 300, 150, 150, this); //right front liners rightSpiker = getImage(getDocumentBase(),"spiker1.jpg"); gr.drawImage(rightSpiker,650,350,130,130,this); center = getImage(getDocumentBase(),"server.jpg"); gr.drawImage(center,750,150,130,130,this); setter = getImage(getDocumentBase(),"defense1.jpg"); gr.drawImage(setter,850,90,110,110,this); } @Override public void mouseMoved(MouseEvent e) { throw new UnsupportedOperationException("Not supported yet."); //To change body of generated methods, choose Tools | Templates. } } 

这是我目前的代码。 有人能告诉我我错过了什么或我在这里做错了什么？

Answer 1

为了拖动任何东西，你需要知道一些事情。 你需要知道它们的位置和所占据的空间。

一旦你知道，你可以监视mouseDragged事件并更新它们的位置。

 import java.awt.Dimension; import java.awt.EventQueue; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Image; import java.awt.Point; import java.awt.Rectangle; import java.awt.event.MouseAdapter; import java.awt.event.MouseEvent; import java.io.IOException; import java.util.HashMap; import java.util.Map; import javax.imageio.ImageIO; import javax.swing.JFrame; import javax.swing.JPanel; import javax.swing.UIManager; import javax.swing.UnsupportedLookAndFeelException; public class DragMe { public static void main(String[] args) { new DragMe(); } public DragMe() { 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 TestPane()); frame.pack(); frame.setLocationRelativeTo(null); frame.setVisible(true); } }); } public class TestPane extends JPanel { private Map locations; public TestPane() { locations = new HashMap<>(25); try { locations.put(ImageIO.read(getClass().getResource("/Pony.png")), new Point(0, 0)); } catch (IOException ex) { ex.printStackTrace(); } MouseAdapter ma = new MouseAdapter() { private Image dragImage; private Point clickOffset; @Override public void mousePressed(MouseEvent e) { for (Map.Entry entry : locations.entrySet()) { Image image = entry.getKey(); Point point = entry.getValue(); Rectangle bounds = new Rectangle( point.x, point.y, image.getWidth(TestPane.this), image.getHeight(TestPane.this)); if (bounds.contains(e.getPoint())) { dragImage = image; clickOffset = new Point(point.x - e.getPoint().x, point.y - e.getPoint().y); break; } } } @Override public void mouseReleased(MouseEvent e) { dragImage = null; clickOffset = null; } @Override public void mouseDragged(MouseEvent e) { if (dragImage != null) { Point dragPoint = new Point(e.getPoint()); dragPoint.x += clickOffset.x; dragPoint.y += clickOffset.y; locations.put(dragImage, dragPoint); repaint(); } } }; addMouseListener(ma); addMouseMotionListener(ma); } @Override public Dimension getPreferredSize() { return new Dimension(400, 400); } protected void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D) g.create(); for (Map.Entry entry : locations.entrySet()) { Point point = entry.getValue(); g2d.drawImage(entry.getKey(), point.x, point.y, this); } g2d.dispose(); } } }