imagedisplay1.java

地图显示实例

import java.applet.*;
import java.awt.*;
import java.util.Vector;


public class ImageDisplay extends Canvas{
  Image currentImage; /* the last current selected image */
  String currentName; /* the name of the current selected symbol */
  int grids, unit;
  int imageNum, maxImageNum;
  Image[] images;
  String[] names;
  boolean[] selected;
  public Vector selectedList; /* use this Vector to get the selected images*/
  MediaTracker tracker;
  Color bg1 = Color.white, bg2 = Color.magenta;
  int row = 0;    /* current row number, for scrolling */

  public ImageDisplay(int gridnum, int u, int n) {
    grids = gridnum;
    unit = u;
    maxImageNum = n;
    imageNum = 0;
    images = new Image[ maxImageNum ];
    names = new String[ maxImageNum ];
    selected = new boolean[ maxImageNum ];
    selectedList = new Vector(maxImageNum);
    tracker = new MediaTracker(this);
    setBackground(bg1);
  }

  public void addImage(String name, Image new_image) {
    if (imageNum < maxImageNum) {
      imageNum++;
      images[ imageNum - 1 ] = new_image;
      names[ imageNum - 1 ] = name;
      selected[ imageNum - 1 ] = false;

      /* wait till image is loaded */
      tracker.addImage(images[ imageNum - 1 ], imageNum - 1);
      try {tracker.waitForID(imageNum - 1);  }
      catch (InterruptedException e) {} ;
      if (tracker.isErrorID(imageNum - 1)) 
	System.out.println("Error loading image " + (imageNum - 1));
    }
    else System.out.println("Error:ImageDisplay Overflow");
  }
  
  /* Warning:the stuff in draw() causes this.repaint() being called */
  public void paint(Graphics g) {
    draw();
  }

  public void scroll(int r) {
    row = r;
    repaint();
  }

  public void draw() {
    Graphics g = getGraphics();
    int count = row * grids;
    int x = 0, y = 0;  /* the grid x , y */
    int imageWidth, imageHeight, spacex = 5, spacey = 5; 
    g.clearRect(0, 0, size().width, size().height);

    while (count < imageNum) {

      /* compute the space padding */
      imageWidth = images[ count ].getWidth(this);
      imageHeight = images[ count ].getHeight(this);
      if (imageWidth < unit) spacex = (unit - imageWidth) / 2;
      if (imageHeight < unit) spacey = (unit - imageHeight) / 2;

      /* this causes the hightlight effect */
      if (selected[ count ]) g.setXORMode(bg2);
      else g.setPaintMode();

      g.drawImage(images[ count ], x * unit + spacex, y * unit + spacey, this);
      g.setFont(new Font("Courier", Font.BOLD, 12));
      int i = names[ count ].indexOf("_"); 
      /* draw in two lines if the string is two long */
      if (i < 0) g.drawString(names[ count ], x * unit + spacex, y * unit + unit);
      else {
	g.drawString(names[count].substring(0, i + 1), x * unit + spacex, y * unit + unit - 10);
	g.drawString(names[count].substring(i + 1), x * unit + spacex, y * unit + unit);
      }
      count++;
      if ((++x) >= grids) { y++; x = 0; }
    }
  }

  public boolean mouseUp(Event evt, int mousex, int mousey) { 
    int x = mousex / unit, y = mousey / unit;
    int n = y * grids + x  + row * grids;

    /* if ctrl key is not pressed,  unselect all */
    if ((evt.modifiers & Event.CTRL_MASK) == 0) unselectAll(); 

    if (x < grids && n < imageNum) {
      selected[ n ] =! selected[ n ];
      currentImage = images[ n ];
      currentName = names[ n ];
      if (selected[ n ]) selectedList.addElement(names[ n ]);
      else selectedList.removeElement(names[ n ]);
      draw();
    }
    draw();
    return false;
  }

  public void unselectAll() {
    for (int i = 0; i < imageNum; i++) selected[ i ] = false;
    selectedList.removeAllElements();
    currentImage = null;
    currentName = null;
  }
}



/*

class ReverseFilter extends RGBImageFilter {
  public ReverseFilter() {
    // this means the filter is position independent 
    canFilterIndexColorModel = true;
  }

  public int filterRGB(int x, int y, int rgb) {
    return (rgb ^ 0xFFFFFF);  // bitwise xor, has the effect of complement 
  }
}
*/