/* 
	assignment4.java
	Date: 			12/13/00
	Title:			assignment4 - final project
	Author:			Ruth West 
	Description:	Applet displays an image that is an interactive painting. 
					You can change the colors of the painting when you move the mouse 
*/


import java.applet.*;
import java.awt.*;
import java.awt.image.*;

public class assignment4 extends Applet {

		

		int mouseX = 200;  //original x value for mouse position, used to calculate mouse movement differences
		int mouseY = 200;  //original y value for mouse position, used to calculate mouse movement differences
		int mouseDiffx;    //original mouse x minus new mouse x --- done in mouse method 
		int mouseDiffy;    //original mouse y minus new mouse y --- done in mouse method 

		int width;     //width of my image
		int height;    //height of my image
    	int[] pixels;  //array to hold the pixels of my image
    	int[] pixelscopy; //array to save the original pixels
    	Image myImage; //the image to work with
    	
    

    //get my image and display it on the applet "screen" 
    public void init(){
        
     

		myImage = getImage(getDocumentBase(), "img04lg.jpg");
	 	getThePixels(myImage);
     	myImage = showImage();
   

	}// end init

    //get the pixels of the image so that they can be processed
    public void getThePixels(Image picture){

         waitToOpenImage(picture);

         width  = picture.getWidth(this);
         height = picture.getHeight(this);
         
         pixels = new int[width*height];
         PixelGrabber pg = new PixelGrabber(picture,0,0,width,height,pixels,0,width);

        try
        {
            pg.grabPixels();
        } catch (InterruptedException e){
            System.out.println("Cannot open Pixels");
        }//end exception



		//make an array to copy the original pixels into - without this array to save the original pixels into the image gets progressively destroyed as I change the color of the pixels
		pixelscopy = new int[width*height];
		for(int index=0; index<width*height; index++){
			int c = pixels[index];//read in from original
			pixelscopy[index] = c;
		}//end loop

    }// end getThePixels



	//make sure the image is loaded before begin processing
	void waitToOpenImage(Image picture){
		MediaTracker tracker=new MediaTracker(this);
		tracker.addImage(picture,0);
		try
		{
			tracker.waitForID(0);
		} catch (InterruptedException e){
			System.out.println("Cannot wait for picture");
		}
	}//end waitToOpenImage


    //shift the color of the entire image when you drag the mouse along the horizontal
    public void shift(){
  
   		for(int index=0; index<width*height; index++){
   		
   			int c=pixelscopy[index]; // read in from original pixel array
   			int r=(c&0xff0000)>>16;
   			int g=(c&0xff00)>>8;
   			int b=(c&0xff);
   		

			r = (int)(r * Math.abs(mouseDiffx)/100.0);//shift the r pixel color
			//g = (int)(g * Math.abs(mouseDiffy)/50.0);//shift the g pixel color - when I use this it goes to black to quickly
			//b = (int)(b * Math.abs(mouseDiffy)/100.0);//looks more interesting with r as the source for this change than when I used b
			b = (int)(r * Math.abs(mouseDiffy)/100.0);//looks better this way!
			
   			pixels[index] = (c&0xff000000) + ((r&0xff0000)<<16) + ((c&0xff00)<<8) + (b&0xff);
   		
   		}//end shift loop
     }//end shift method
 
 
  
    //allow new/modified image to be displayed onto screen
	public Image showImage(){
		return createImage(new MemoryImageSource(width,height,pixels,0,width));
	}//end show image




    //paint the image on the applet 
    public void paint(Graphics g){

    g.drawImage(myImage, 0, 0, this);
    System.out.println("paint");

	}//end paint


	//override paint to reduce flicker
    public void update(Graphics g){
	paint(g);
	}



	//use mouse move to generate values for x and y   
	public boolean mouseMove(Event e, int x, int y){
		
		mouseDiffx = x - mouseX;//difference of current mouse x to original mouse x --- to be used in modifying image colors
		mouseDiffy = y - mouseY;//difference of current mouse y to original mouse y --- to be used in modifying image colors
		
		
		shift();// shift the colors
		myImage = showImage();//display the changed image on the screen
		
		repaint();
		
		return true;
		
	}//end mouseMove
	


}//end applet