/** BufferTest
 * @author Tim Stefanini
 * @version 1.0
 */
 
package SlidingBuffer;

import java.awt.*;
import java.applet.*;
import java.util.Date;
public class BufferTest extends java.applet.Applet{
      Image       offscreenImage=null;
      Graphics    offscreenGraphics=null;
      public void init ()
      { try
        {   setupBuffer ();
                offscreenGraphics.setColor (Color.blue);
                drawGrid ();
        }//end try
        catch (Exception e)//reall bad
        {   System.exit(1);
        }//end catch
      }//end init ()
            
      private void setupBuffer ()
      { try
        {   //set up image for double buffering
            offscreenImage = createImage ( this.miBuffersize ,this.miBuffersize);
            offscreenGraphics = offscreenImage.getGraphics ();
        }//end try
        catch (Exception e)
        { e.printStackTrace ();
                                                     
        }//end catch
  }//end setupBuffer()
       
        private void drawGrid ()
        {  int iXpos =0;
           int iYpos =0;
           offscreenGraphics.setFont(new Font("TimesRoman", Font.PLAIN,8));
           for (int x=0; x <= 2000; x+= 150)
               for (int y=0; y<=2000; y+= 150)
               {  iXpos = x + miBufferShiftX +25 ;
                  iYpos = y + miBufferShiftY +25;
                  offscreenGraphics.drawRect(iXpos, iYpos, 50, 50);
                  offscreenGraphics.drawString(x+ "," +y, iXpos +5, iYpos +20);
               }
        }//end drawGrid ()
        
        private void ClearBuffer ()
        { offscreenGraphics.setColor (Color.white);
          //erase old draw
          offscreenGraphics.fillRect(0,0, miBuffersize, miBuffersize);
          offscreenGraphics.setColor (Color.blue);
        }//end ClearBuffer ()
        
        private void SlideBuffer ()
        { Date myd = new Date();
          long start =  myd.getTime();
          // offscreenGraphics.setColor (Color.white); 
          //erase old draw
          // drawGrid ();
          ClearBuffer ();      
          miBufferShiftX += miXpan;
          miBufferShiftY += miYpan;
          miXpan = miYpan =0;
          mfDragInit = false;
          // offscreenGraphics.setColor (Color.blue);
          drawGrid ();
          repaint ();
          Date date2 = new Date();
          long finish =  date2.getTime();
          System.out.println("slid buffer in " + (int)(finish - start) + "secs");
        }
        
        public boolean mouseUp(Event evt, int x, int y)
        { SlideBuffer ();
          return true;
        }//emd mouseUp(.,.,.)
                 
        public boolean mouseDown(Event evt, int x, int y)
        {   mfDragInit = false;
            return true;
        }
                      
        public boolean mouseDrag (Event evt, int x, int y)   
        {  if (mfDragInit)
           {  miXpan = ( x - miOldx);
              miYpan = (y - miOldy);
              repaint();
           }//end if
           else
           {  miOldy = y;
              miOldx = x;
              mfDragInit = true;
           }//end else
           //Add 100 pixel mouse drag interval to do a buffer slide
           int miMouseDragInterval = 100;
           if ( (miXpan >= miMouseInterval)
             ||(miXpan <= - miMouseInterval)
             ||(miYpan >= miDragInterval)
             ||(miYpan <=- miDragInterval) )
             SlideBuffer ();
             return true;
        } //end mouseDrag
        
   
        public void paint (Graphics g)
        {
           g.drawImage (offscreenImage, miXpan, miYpan, this);
        }//end paint
                
        //private variables
        private Canvas mDrawingObject;
        private int miXpan = 0;
        private int miYpan = 0;
        private int miOldx = 0;  
        private int miOldy = 0;
        private int miBufferShiftX = 0;
        private int miBufferShiftY =0;
        private boolean mfDragInit = true;
        private final int miBuffersize = 600;
        
       //make this at least size of window
       //{{DECLARE_CONTROLS
       //}}
}//end class BufferTest