panelpic.java

详细介绍了Java图形编程的知识

package grapro;

import java.awt.*;
import javax.swing.JPanel;
import java.awt.event.*;
import java.awt.image.*;

public class PanelPic extends JPanel {
  int startx,starty,oldx,oldy,newx,newy;
  int action;
  public Color cl;
  public int mode;
  public boolean isempty;
  public Image ibuff;
  public Graphics buffgra;
  public boolean hasbuff;
  Image img;

  public PanelPic() {
    try {
      jbInit();
    }
    catch(Exception ex) {
      ex.printStackTrace();
    }
  }
  void jbInit() throws Exception {
    this.setBackground(Color.white);
    this.addMouseMotionListener(new java.awt.event.MouseMotionAdapter() {
      public void mouseDragged(MouseEvent e) {
        this_mouseDragged(e);
      }
    });
    this.addMouseListener(new java.awt.event.MouseAdapter() {
      public void mousePressed(MouseEvent e) {
        this_mousePressed(e);
      }
      public void mouseReleased(MouseEvent e) {
        this_mouseReleased(e);
      }
    });

    startx = -1;
    starty = -1;
    oldx = -1;
    oldy = -1;
    newx = -1;
    newy = -1;
    action = -1;
    mode = 1;
    hasbuff = false;
    isempty = true;
  }

  public void pdraw(Graphics gra) {
    gra.setColor(this.getForeground());
    if (mode == 4) {        //铅笔
      gra.setPaintMode();
      switch(action) {
        case 1:
          oldx = newx;
          oldy = newy;
          drawpic(gra,oldx,oldy,newx,newy);
          break;
        case 2:
          drawpic(gra,oldx,oldy,newx,newy);
          oldx = newx;
          oldy = newy;
         break;
        case 3:
          drawpic(gra,oldx,oldy,newx,newy);
          oldx = -1;
          oldy = -1;
          newx = -1;
          newy = -1;
          startx = -1;
          starty = -1;
         break;
        default: break;
      }
      repaint();
      return;
    }
    if (mode == 5) {        //橡皮
      gra.setPaintMode();
      gra.setColor(Color.white);
      switch(action) {
        case 1:
          drawpic(gra,oldx,oldy,newx,newy);
          break;
        case 2:
          drawpic(gra,oldx,oldy,newx,newy);
         break;
        case 3:
          drawpic(gra,oldx,oldy,newx,newy);
          oldx = -1;
          oldy = -1;
          newx = -1;
          newy = -1;
          startx = -1;
          starty = -1;
         break;
        default: break;
      }
      repaint();
      return;
    }
    if (mode == 4) {

      return;
    }
    switch(action) {
      case 1:
        oldx = newx;
        oldy = newy;
        if (mode != 3)
          drawpic(gra,startx,starty,newx,newy);
        break;
      case 2:
        gra.setXORMode(Color.white);
        drawpic(gra,startx,starty,oldx,oldy);
        drawpic(gra,startx,starty,newx,newy);
        oldx = newx;
        oldy = newy;
       break;
      case 3:
        gra.setXORMode(Color.white);
        drawpic(gra,startx,starty,oldx,oldy);
        gra.setPaintMode();
        drawpic(gra,startx,starty,newx,newy);
        if (!isempty) {
          fillpic(gra,startx,starty,newx,newy);
        }
        oldx = -1;
        oldy = -1;
        newx = -1;
        newy = -1;
        startx = -1;
        starty = -1;
       break;
      default: break;
    }
    repaint();
  }

  void this_mousePressed(MouseEvent e) {
    startx = e.getX();
    starty = e.getY();
    newx = startx;
    newy = starty;
    action = 1;//表明是确定第一个点
    if(ibuff == null)
      init_buff();
    pdraw(buffgra);
  }

  void this_mouseDragged(MouseEvent e) {
    newx = e.getX();
    newy = e.getY();
    action = 2;//表明是在拖动过程中
    if(ibuff == null)
      init_buff();
    pdraw(buffgra);
  }

  void this_mouseReleased(MouseEvent e) {
    newx = e.getX();
    newy = e.getY();
    action = 3;//表明已经放开按键，绘画结束
    if(ibuff == null)
      init_buff();
    pdraw(buffgra);
  }

  void drawpic(Graphics gra,int x1,int y1,int x2,int y2) {
    int tx,ty;
    switch (mode) {
      case 1://画线
        gra.drawLine(x1,y1,x2,y2);
        break;
      case 2://矩形
        if(x1>x2) {
          tx = x2;
          x2 = x1;
          x1 = tx;
        }
        if(y1>y2) {
          ty = y2;
          y2 = y1;
          y1 = ty;
        }
        gra.drawRect(x1,y1,x2-x1,y2-y1);
        break;
      case 3://椭圆
        if(x1>x2) {
          tx = x2;
          x2 = x1;
          x1 = tx;
        }
        if(y1>y2) {
          ty = y2;
          y2 = y1;
          y1 = ty;
        }
        gra.drawOval(x1,y1,x2-x1,y2-y1);
        break;
      case 4://铅笔
        gra.drawLine(x1,y1,x2,y2);
        break;
      case 5://橡皮
        gra.drawRect(x2-5,y2-5,10,10);
        gra.fillRect(x2-5,y2-5,10,10);
        break;
      case 7:
        break;
      case 8:
        break;
      default:
        break;
    }
  }

  public void fillpic(Graphics gra,int x1,int y1,int x2,int y2) {
    int tx,ty;
    switch (mode) {
      case 2://矩形
        if(x1>x2) {
          tx = x2;
          x2 = x1;
          x1 = tx;
        }
        if(y1>y2) {
          ty = y2;
          y2 = y1;
          y1 = ty;
        }
        gra.fillRect(x1,y1,x2-x1,y2-y1);
        break;
      case 3://椭圆
        if(x1>x2) {
          tx = x2;
          x2 = x1;
          x1 = tx;
        }
        if(y1>y2) {
          ty = y2;
          y2 = y1;
          y1 = ty;
        }
        gra.fillOval(x1,y1,x2-x1,y2-y1);
        break;
      default:
        break;
    }
    repaint();
  }

  public void paintComponent(Graphics gra) {
    super.paintComponent(gra);
    if (ibuff != null)
      gra.drawImage(ibuff,0,0,this);
  }

  public void init_buff() {
    ibuff = createImage(getWidth(),getHeight());
    buffgra = ibuff.getGraphics();
    buffgra.setColor(Color.white);
    buffgra.fillRect(0,0,getWidth(),getHeight());
    buffgra.setColor(Color.black);
  }

  public void  loadimage (String s) {
    img = Toolkit.getDefaultToolkit().getImage(s);
    if(ibuff == null)
      init_buff();
    buffgra.drawImage(img,0,0,getWidth(),getHeight(),this);
  }

  public boolean imageUpdate(Image img, int flags, int x, int y, int w, int h) {
    Color col;
    if (flags == ImageObserver.ALLBITS){
      col = buffgra.getColor();
      buffgra.setColor(Color.white);
      buffgra.fillRect(0,0,getWidth(),getHeight());
      buffgra.drawImage(img,0,0,getWidth(),getHeight(),this);
      buffgra.setColor(col);
      repaint();
      return false;
    }
    return true;
  }

  public void clearAll() {
    Color col = buffgra.getColor();
    buffgra.setColor(Color.white);
    buffgra.fillRect(0,0,getWidth(),getHeight());
    buffgra.setColor(col);
    repaint();
  }
}