6

我正在创建一个 Java 应用程序，它允许用户查看图像并使用鼠标平移图像。为了实现图像的平移，我使用了JViewportsmouseClicked和事件的组合。mouseDragged大部分代码在 mouseDragged 方法中

public void mouseDragged(MouseEvent e, WindowWrapper w) {
    final JViewport vp = someFieldViewPort;

    //Getting the point that the mouse is dragged to to
    Point cp = e.getPoint();
    final Point vPoint = vp.getViewPosition();

    //I found the image went off the content to show the white border so I included this 
    // Here pp is a field that I sent when the mouse is clicked in a separate method

    if(vPoint.getX()+pp.x-cp.x>=0 & vPoint.getY()+pp.y-cp.y>=0)
        vPoint.translate(pp.x-cp.x, pp.y-cp.y);
    else if(vPoint.getX()+pp.x-cp.x>=0 & vPoint.getY()+pp.y-cp.y<0)
        vPoint.translate(pp.x-cp.x, (int) -vPoint.getY());
    else if(vPoint.getX()+pp.x-cp.x<0 & vPoint.getY()+pp.y-cp.y>=0)
        vPoint.translate((int) -vPoint.getX(), pp.y-cp.y);

    //finally set the position of the viewport
    vp.setViewPosition(vPoint);
    vp.repaint();
}

虽然这可行，但我觉得必须有一种更简单的方法来完成所有这些工作。如果不是全部，是否可以替换防止视口离开图像到周围边框的代码？

4

3 回答 3

9

尝试使用scrollRectToVisible(...)方法而不是JViewport#setViewPosition(...)：

import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import javax.swing.*;
public class HandScrollDemo {
  static class HandScrollListener extends MouseAdapter {
    private final Point pp = new Point();
    @Override public void mouseDragged(MouseEvent e) {
      JViewport vport = (JViewport)e.getSource();
      JComponent label = (JComponent)vport.getView();
      Point cp = e.getPoint();
      Point vp = vport.getViewPosition();
      vp.translate(pp.x-cp.x, pp.y-cp.y);
      label.scrollRectToVisible(new Rectangle(vp, vport.getSize()));
      //vport.setViewPosition(vp);
      pp.setLocation(cp);
    }
    @Override public void mousePressed(MouseEvent e) {
      pp.setLocation(e.getPoint());
    }
  }
  public JComponent makeUI() {
    JLabel label = new JLabel(new Icon() {
      TexturePaint TEXTURE = makeCheckerTexture();
      @Override public void paintIcon(Component c, Graphics g, int x, int y) {
        Graphics2D g2 = (Graphics2D)g.create();
        g2.setPaint(TEXTURE);
        g2.fillRect(x,y,c.getWidth(),c.getHeight());
        g2.dispose();
      }
      @Override public int getIconWidth()  { return 2000; }
      @Override public int getIconHeight() { return 2000; }
    });
    label.setBorder(BorderFactory.createLineBorder(Color.RED, 20));
    JScrollPane scroll = new JScrollPane(label);
    JViewport vport = scroll.getViewport();
    MouseAdapter ma = new HandScrollListener();
    vport.addMouseMotionListener(ma);
    vport.addMouseListener(ma);
    return scroll;
  }
  private static TexturePaint makeCheckerTexture() {
    int cs = 20;
    int sz = cs*cs;
    BufferedImage img = new BufferedImage(sz,sz,BufferedImage.TYPE_INT_ARGB);
    Graphics2D g2 = img.createGraphics();
    g2.setPaint(Color.GRAY);
    for(int i=0; i*cs<sz; i++) { for(int j=0; j*cs<sz; j++) {
      if((i+j)%2==0) { g2.fillRect(i*cs, j*cs, cs, cs); }
    }}
    g2.dispose();
    return new TexturePaint(img, new Rectangle(0,0,sz,sz));
  }
  public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
      @Override public void run() { createAndShowGUI(); }
    });
  }
  public static void createAndShowGUI() {
    JFrame f = new JFrame();
    f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
    f.getContentPane().add(new HandScrollDemo().makeUI());
    f.setSize(320, 320);
    f.setLocationRelativeTo(null);
    f.setVisible(true);
  }
}
于 2012-11-12T13:11:12.487 回答
3

我会以不同的方式来做。我可能会定义一个名为Image或类似的对象。它将定义一个BufferedImage和两个int值：x和y。

该Image对象还将有一个draw()方法，该方法只知道如何将图像绘制到该位置的Graphics2D对象。x, y

在鼠标事件上，我会修改对象内部和我要调用的组件的x和y值。Imagepaintimage.draw(g2)

于 2012-11-12T10:22:50.667 回答
3

+1 @Dans 回答。

这是我制作的一个示例，基本上使用带有添加MouseAdapter和覆盖mousePressed()和mouseDragged()方法的 JPanel。mouseDragged()方法将相应地增加图像的坐标x和y坐标，并通过paintComponent(...)ofJPanel和绘制Graphics2D#drawImage(Image img,int x,int y,ImageObserver io)。

在点击和拖动鼠标之前：

在此处输入图像描述

单击并拖动鼠标后：

在此处输入图像描述

//necessary imports
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import java.awt.image.BufferedImage;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

    /**
     * Default constructor
     */
    public Test() {
        initComponents();
    }

    /**
     * Initialize GUI and components (including ActionListeners etc)
     */
    private void initComponents() {
        JFrame frame = new JFrame("Test");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setResizable(false);

        PanPanel pp = null;
        try {
            pp = new PanPanel(ImageIO.read(new URL("http://www.sellcar.co.za/wp-content/uploads/2011/01/Porsche_911_Turbo.jpg")));
        } catch (Exception ex) {
            ex.printStackTrace();
        }

        frame.add(pp);
        //pack frame (size JFrame to match preferred sizes of added components and set visible
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {

        /**
         * Create GUI and components on Event-Dispatch-Thread
         */
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    //set nimbus look and feel
                    for (UIManager.LookAndFeelInfo info : UIManager.getInstalledLookAndFeels()) {
                        if ("Nimbus".equals(info.getName())) {
                            UIManager.setLookAndFeel(info.getClassName());
                            break;
                        }
                    }
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException e) {
                    e.printStackTrace();
                }
                //create GUI instance
                Test test = new Test();
            }
        });
    }
}

class PanPanel extends JPanel {

    private int x, y;
    private int width = 400, height = 400;
    BufferedImage img;
    private final static RenderingHints textRenderHints = new RenderingHints(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
    private final static RenderingHints imageRenderHints = new RenderingHints(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
    private final static RenderingHints renderHints = new RenderingHints(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
    static int startX, startY;

    public PanPanel(BufferedImage img) {
        x = 0;
        y = 0;
        this.img = img;

        addMouseListener(new MouseAdapter() {
            @Override
            public void mousePressed(MouseEvent me) {
                super.mousePressed(me);
                startX = me.getX();
                startY = me.getY();
            }
        });

        addMouseMotionListener(new MouseMotionAdapter() {
            @Override
            public void mouseDragged(MouseEvent me) {
                super.mouseDragged(me);

                if (me.getX() < startX) {//moving image to right
                    x -= 2;
                } else if (me.getX() > startX) {//moving image to left
                    x += 2;
                }

                if (me.getY() < startY) {//moving image up
                    y -= 2;
                } else if (me.getY() > startY) {//moving image to down
                    y += 2;
                }
                repaint();
            }
        });
    }

    @Override
    protected void paintComponent(Graphics grphcs) {
        super.paintComponent(grphcs);
        Graphics2D g2d = (Graphics2D) grphcs;

        //turn on some nice effects
        applyRenderHints(g2d);

        g2d.drawImage(img, x, y, null);
    }

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(width, height);
    }

    public static void applyRenderHints(Graphics2D g2d) {
        g2d.setRenderingHints(textRenderHints);
        g2d.setRenderingHints(imageRenderHints);
        g2d.setRenderingHints(renderHints);
    }
}
于 2012-11-12T13:48:46.683 回答