求SWT可拖动控件 例子

Question

想实现这样一个功能先把png图片加载到自定义控件上面   然后这个控件是可以拖动的就是你可以点击一个小的图片  然后拖动它到场景里面来求例子程序

Answer 1

自己找了一个 
import org.eclipse.swt.SWT;
import org.eclipse.swt.dnd.DND;
import org.eclipse.swt.dnd.DragSource;
import org.eclipse.swt.dnd.DragSourceAdapter;
import org.eclipse.swt.dnd.DragSourceEvent;
import org.eclipse.swt.dnd.DropTarget;
import org.eclipse.swt.dnd.DropTargetAdapter;
import org.eclipse.swt.dnd.DropTargetEvent;
import org.eclipse.swt.dnd.TextTransfer;
import org.eclipse.swt.dnd.Transfer;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Tree;
import org.eclipse.swt.widgets.TreeItem;public class SimpleDNDExample {  public static void main(String[] args) {
    Shell shell = new Shell();
    shell.setLayout(new FillLayout());    // Create the tree and some tree items
    final Tree tree = new Tree(shell, SWT.NONE);
    TreeItem item1 = new TreeItem(tree, SWT.NONE);
    item1.setText("Item 1");
    TreeItem item2 = new TreeItem(tree, SWT.NONE);
    item2.setText("Item 2");
    TreeItem item3 = new TreeItem(tree, SWT.NONE);
    item3.setText("Item 3");
    TreeItem item4 = new TreeItem(tree, SWT.NONE);
    item4.setText("Item 4");    // Create the drag source on the tree
    DragSource ds = new DragSource(tree, DND.DROP_MOVE);
    ds.setTransfer(new Transfer[] { TextTransfer.getInstance() });
    ds.addDragListener(new DragSourceAdapter() {
      public void dragSetData(DragSourceEvent event) {
        // Set the data to be the first selected item's text
        event.data = tree.getSelection()[0].getText();
      }
    });    // Create the button
    final Button button = new Button(shell, SWT.FLAT);
    button.setText("Button");
    button.setAlignment(SWT.CENTER);    // Create the drop target on the button
    DropTarget dt = new DropTarget(button, DND.DROP_MOVE);
    dt.setTransfer(new Transfer[] { TextTransfer.getInstance() });
    dt.addDropListener(new DropTargetAdapter() {
      public void drop(DropTargetEvent event) {
        // Set the buttons text to be the text being dropped
        button.setText((String) event.data);
      }
    });    shell.pack();
    shell.open();
    Display display = Display.getDefault();
    while (!shell.isDisposed())
      if (!display.readAndDispatch())
        display.sleep();
    display.dispose();
  }}

Answer 2

http://www.111cn.cn/jsp/49/81c2aa90a2e6a3608a766abb54d0f1c2.htm

Answer 3

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.GridLayout;
import java.awt.Image;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.io.IOException;import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.TransferHandler;public class PictureDnd { private JFrame mainFrame;
private JPanel mainPanel;
private PictureComponent[] pictures; public PictureDnd() {
mainFrame = new JFrame();
mainPanel = new JPanel(new GridLayout(2, 2)); pictures = new PictureComponent[4];
pictures[0] = new PictureComponent(new ImageIcon("C:\\Image\\1.jpeg").getImage());
pictures[1] = new PictureComponent(new ImageIcon("C:\\Image\\2.jpeg").getImage());
pictures[2] = new PictureComponent(null);
pictures[3] = new PictureComponent(null); mainPanel.add(pictures[0]);
mainPanel.add(pictures[1]);
mainPanel.add(pictures[2]);
mainPanel.add(pictures[3]);
mainPanel.setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20)); mainFrame.getContentPane().add(mainPanel);
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainFrame.setSize(350, 400);
mainFrame.setLocationRelativeTo(null);
mainFrame.setVisible(true);
} public static void main(String[] args) {
new PictureDnd();
} private class PictureComponent extends JComponent implements FocusListener,
MouseListener, MouseMotionListener { private static final long serialVersionUID = 861556623335710551L;
private Image image;

public PictureComponent(Image image){
this.image = image;
setPreferredSize(new Dimension(125, 125));
setFocusable(true);
setTransferHandler(new PictureTransferHandler());
addFocusListener(this);
addMouseListener(this);
addMouseMotionListener(this);
}

public Image getImage(){
return image;
}

public void setImage(Image image){
this.image = image;
repaint();
}

// 绘制我们的类，简单的在上面画一幅图
public void paintComponent(Graphics graphics){
Graphics g = graphics.create();
g.setColor(Color.green); // 将当前图形上下文的当前颜色设置成green
g.fillRect(0, 0, image != null ? image.getWidth(this) : 125, image != null ? image.getHeight(this) : 125); // 绘制矩形
if(image != null){
g.drawImage(image, 0, 0, this);
}
if(isFocusOwner()){
g.setColor(Color.red);
}else{
g.setColor(Color.black);
}
// 画边框，如果是焦点获得者，边框为红色，否则为黑色
g.drawRect(0, 0, image != null ? image.getWidth(this) : 125, image != null ? image.getHeight(this) : 125);
g.dispose(); // 释放此图形的上下文并释放它所使用的所有系统资源。
}

@Override
public void focusGained(FocusEvent e) {
repaint();
} @Override
public void focusLost(FocusEvent e) {
repaint();
} @Override
public void mouseClicked(MouseEvent e) {
requestFocusInWindow();
} @Override
public void mouseEntered(MouseEvent e) { } @Override
public void mouseExited(MouseEvent e) { } @Override
public void mousePressed(MouseEvent e) { } @Override
public void mouseReleased(MouseEvent e) { } @Override
public void mouseDragged(MouseEvent e) {
JComponent c = (JComponent)e.getSource();
TransferHandler handler = c.getTransferHandler();
// exportAsDrag
handler.exportAsDrag(c, e, TransferHandler.COPY);
} @Override
public void mouseMoved(MouseEvent e) { } }

// 一个用来包装数据的类, 此类只包含有图片类型的数据，
private class TransferablePicture implements Transferable{

/* DataFlavor.imageFlavor 是DataFlavor定义的一个DataFlavor类型
 因为图片常用，所以它自带有这种类型，不用我们自定义，以后再看如何定义*/
DataFlavor flavors[] = {DataFlavor.imageFlavor};
Image image;

public TransferablePicture(Image image){
this.image = image;
}

@Override
public Object getTransferData(DataFlavor flavor)
throws UnsupportedFlavorException, IOException {
// 根据参数返回数据
if(flavor.equals(DataFlavor.imageFlavor)){
return image;
}
return null;
} @Override
public DataFlavor[] getTransferDataFlavors() {
return flavors;// 返回Transferable包含哪些数据类型
} @Override
public boolean isDataFlavorSupported(DataFlavor flavor) {
for(DataFlavor f: flavors){
if(flavor.equals(f)){
return true;
}
}
return false;
// return flavor.equals(DataFlavor.imageFlavor);
}

}

@SuppressWarnings("serial")
private class PictureTransferHandler extends TransferHandler{
public Transferable createTransferable(JComponent c){
PictureComponent pc = (PictureComponent)c;
// 调用构造函数以包装数据，将我们要包装的数据以参数形式传入
return new TransferablePicture(pc.getImage());
}

// 判断是否可以导入数据
public boolean canImport(JComponent c, DataFlavor[] flavors){
for(DataFlavor flavor: flavors){
if(flavor.equals(DataFlavor.imageFlavor)){
return true;
}
}
return false;
}

// 导入数据
public boolean importData(JComponent c, Transferable t){
if(canImport(c, t.getTransferDataFlavors())){
PictureComponent pc = (PictureComponent)c;
try {
Image image = (Image) t.getTransferData(DataFlavor.imageFlavor);
pc.setImage(image);
return true;
} catch (UnsupportedFlavorException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
return false;
}

public void exportDone(JComponent c, Transferable data, int action){
// 传完数据以后要判断是移动还是复杂，然后再决定是否要删除拖放源的数据
PictureComponent picture = (PictureComponent) c;
if(action == MOVE){
picture.setImage(null);
}
}

public int getSourceActions(JComponent c){
return COPY_OR_MOVE;
}

}


}