双缓冲绘制无闪烁

1、public class BufferedDraw extends JPanel implements MouseListener, MouseMotionListener Rectangle rect = new Rectangle(0, 0, 100, 50); BufferedImage bi = new BufferedImage(5, 5, BufferedImage.TYPE_INT_RGB); Graphics2D big; int last_x, last_y; boolean firstTime = true; Rectangle area; boolean pressOut

2、 = false; public BufferedDraw() setBackground(Color.white); addMouseMotionListener(this); addMouseListener(this); / Handles the event of the user pressing down the mouse button. public void mousePressed(MouseEvent e) last_x = rect.x - e.getX(); last_y = rect.y - e.getY(); / Checks whether or not the

3、 cursor is inside of the rectangle while the / user is pressing themouse. if (rect.contains(e.getX(), e.getY() updateLocation(e); else pressOut = true; / Handles the event of a user dragging the mouse while holding down the / mouse button. public void mouseDragged(MouseEvent e) if (!pressOut) update

4、Location(e); / Handles the event of a user releasing the mouse button. public void mouseReleased(MouseEvent e) if (rect.contains(e.getX(), e.getY() updateLocation(e); public void mouseMoved(MouseEvent e) public void mouseClicked(MouseEvent e) public void mouseExited(MouseEvent e) public void mouseEn

5、tered(MouseEvent e) public void updateLocation(MouseEvent e) rect.setLocation(last_x + e.getX(), last_y + e.getY(); repaint(); public void paint(Graphics g) update(g); public void update(Graphics g) Graphics2D g2 = (Graphics2D) g; if (firstTime) Dimension dim = getSize(); int w = dim.width; int h =

6、dim.height; area = new Rectangle(dim); bi = (BufferedImage) createImage(w, h); big = bi.createGraphics(); rect.setLocation(w / 2 - 50, h / 2 - 25); big.setStroke(new BasicStroke(8.0f); firstTime = false; big.setColor(Color.white); big.clearRect(0, 0, area.width, area.height); big.setPaint(Color.red)

7、; big.draw(rect); big.setPaint(Color.blue); big.fill(rect); g2.drawImage(bi, 0, 0, this); private boolean checkRect() if (area = null) return false; if (area.contains(rect.x, rect.y, 100, 50) return true; int new_x = rect.x; int new_y = rect.y; if (rect.x + 100) > area.width) new_x = area.width -

8、 99; if (rect.x < 0) new_x = -1; if (rect.y + 50) > area.height) new_y = area.height - 49; if (rect.y < 0) new_y = -1; rect.setLocation(new_x, new_y); return false; public static void main(String s) JFrame f = new JFrame("BufferedShapeMover"); f.addWindowListener(new WindowAdapter() public void windowClosing(WindowEvent e) System.exit(0); ); f.getContentPane().setLayout(new Bord