图片拖拽练习

package graphicsDrag; import java.awt.AlphaComposite; import java.awt.Color; import java.awt.Dimension; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.Image; 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.util.LinkedList; import java.util.List; import javax.swing.ImageIcon; import javax.swing.JFrame; import javax.swing.JPanel; /** * 图片拖拽练习 * @author tiger * * 0,点中图片拖动可移动图片位置 * 1,拖动鼠标选中区域内图片 * 2,按住Ctrl键可连续选择图片，并拖动所有已选图片。 * 3,按下shift键，在拖动同时复制图片。 */ @SuppressWarnings({ "unchecked", "serial" }) public class MyPanel extends JPanel implements MouseListener, MouseMotionListener{ private int width = 600; private int height = 450; /** * 所有图片集合 */ private List list = new LinkedList(); /** * 当前所选图片集合 */ private List select_list = new LinkedList(); /** * 当前所选图片的复制品的集合 。。。用于按下Ctrl键时的拖动 */ private List copy_list = new LinkedList(); public MyPanel() { this.setPreferredSize(new Dimension(width,height)); this.setFocusable(true); ImageObject object = new ImageObject("g_2_1.png", 100, 200); list.add(object); object = new ImageObject("g_434.png", 50, 200); list.add(object); object = new ImageObject("g_461.png", 150, 300); list.add(object); object = new ImageObject("g_462.png", 400, 100); list.add(object); this.setFocusable(true); this.addMouseListener(this); this.addMouseMotionListener(this); } /** * 封装了图片的对象 * @author tiger * */ class ImageObject{ Image image ; int x, y; Rectangle rect; boolean isSelect; public ImageObject() { } public ImageObject(String imageName, int x, int y) { ImageIcon icon = new ImageIcon(getClass().getResource("/image/" + imageName)); image = icon.getImage(); this.x = x; this.y = y; rect = new Rectangle(x, y, image.getWidth(null), image.getHeight(null)); } public void paint(Graphics g) { g.drawImage(image, x, y, null); if(isSelect) { g.setColor(Color.BLACK); g.drawRect(x - 1, y - 1, image.getWidth(null) + 1, image.getHeight(null) + 1); } } public boolean contains (int x, int y) { return rect.contains(x, y); } public boolean contains (Point p) { return rect.contains(p.x, p.y); } public void move(int moveX, int moveY) { this.x += moveX; this.y += moveY; this.rect.x = this.x; this.rect.y = this.y; } public ImageObject clone() { ImageObject object = new ImageObject(); object.x = this.x; object.y = this.y; object.image = this.image; object.isSelect = this.isSelect; object.rect = new Rectangle(x, y, image.getWidth(null), image.getHeight(null)); return object; } } public void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2 = (Graphics2D) g; ImageObject object = null; for (int i = 0; i < list.size(); i++) { object = (ImageObject) list.get(i); object.paint(g2); } //半透明画复制图 g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.75f)); for (int i = 0; i < copy_list.size(); i++) { object = (ImageObject) copy_list.get(i); object.paint(g2); } //画选择框 g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 1)); if(selectRect != null) { g2.setColor(Color.green); g2.draw(selectRect); } g2.dispose(); } @Override public void mouseClicked(MouseEvent e) { } @Override public void mouseEntered(MouseEvent e) { } @Override public void mouseExited(MouseEvent e) { } /** * 上次点击的点 */ private Point prePoint ; /** * ctrl按下后可以连续选择图片 * shift按下后会复制所选择的图片 */ @Override public void mousePressed(MouseEvent e) { Point p = e.getPoint(); ImageObject object; if (e.isControlDown()) { System.out.println("ctrl is press down !!!"); }else{ for (int i = 0; i < select_list.size(); i++) { object = (ImageObject) select_list.get(i); object.isSelect = false; } select_list.clear(); } for (int i = 0; i < list.size(); i++) { object = (ImageObject) list.get(i); if(object.contains(p) && select_list.contains(object) == false) { select_list.add(object); object.isSelect = true; if(e.isShiftDown()) { copy_list.add(object.clone()); } break; } } prePoint = p; this.repaint(); } private Rectangle selectRect; @Override public void mouseDragged(MouseEvent e) { Point p = e.getPoint(); if(select_list.isEmpty()) { selectRect = new Rectangle(Math.min(p.x, prePoint.x), Math.min(p.y, prePoint.y), Math.abs(p.x - prePoint.x), Math.abs(p.y - prePoint.y)); this.repaint(); return; } //针对用选择框选择的图片，shift按下时copy_list还为空的情况 if(e.isShiftDown() && copy_list.isEmpty()) { for (int i = 0; i < select_list.size(); i++) { copy_list.add(((ImageObject) select_list.get(i)).clone()); } } int moveX = p.x - prePoint.x; int moveY = p.y - prePoint.y; ImageObject object; List list ; if(e.isShiftDown()) { list = copy_list; }else{ list = select_list; } for (int i = 0; i < list.size(); i++) { object = (ImageObject) list.get(i); object.move(moveX, moveY); } prePoint = p; this.repaint(); } @Override public void mouseReleased(MouseEvent e) { prePoint = null; if(selectRect != null) { ImageObject object; for (int i = 0; i < list.size(); i++) { object = (ImageObject) list.get(i); if(object.rect.intersects(selectRect)) { select_list.add(object); object.isSelect = true; } } selectRect = null; this.repaint(); return; } if(e.isShiftDown() || e.isControlDown()) { return; } ImageObject object; for (int i = 0; i < copy_list.size(); i++) { object = (ImageObject) copy_list.get(i); object.isSelect = false; list.add(object); } copy_list.clear(); this.repaint(); } @Override public void mouseMoved(MouseEvent e) { } public static void main(String[] args) { JFrame frame = new JFrame("图片拖动测试"); JPanel panel = new MyPanel(); frame.getContentPane().add(panel); frame.pack(); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.setLocationRelativeTo(null); frame.setVisible(true); } }