// Get a picture from the location given and return
// a 2D arry of RGB pixel colors
color [][] getPicture(String location)
{
  PImage p;
  int i;
  color pix[][];

  p = loadImage(location);

  pix = new color [p.width][p.height];
  i = 0;
  for (int y=0; y<p.height; y=y+1) {
    for (int x=0; x<p.width; x=x+1) {
      pix[x][y] = p.pixels[i];
      i=i+1;
    }
  }

  return pix;
}



// Draw the picture given in the 2D pixel array
void drawPicture(color pix[][])
{
  int w, h;

  background(0);

  w = pix.length;
  h = pix[0].length;
  for (int y=0; y<h; y=y+1) {
    for (int x=0; x<w; x=x+1) {
      color c;

      noStroke();
      c = pix[x][y];
      fill(red(c), green(c), blue(c));
      rect(x, y, 1, 1);
    }
  }
  println("printed picture: ", w, "x", h);
}


// Return a 2D array of random pixel colors that fills the window
color [][] randomPicture()
{
  color pix[][];

  pix = new color [width][height];
  for (int y=0; y<height; y=y+1) {
    for (int x=0; x<width; x=x+1) {
      pix[x][y] = color(int(random(256)), 
        int(random(256)), 
        int(random(256)));
    }
  }
  return pix;
}


// Merge the two given pictures using xor and display 
// the results!
void mergePicture(color pixA[][], color pixB[][])
{
  int w;
  int h;

  background(0);

  // only display a picture that is the minimum dimension of
  // the two pictures input!
  w = min(pixA.length, pixB.length);
  h = min(pixA[0].length, pixB[0].length);
  for (int y=0; y<h; y=y+1) {
    for (int x=0; x<w; x=x+1) {
      noStroke();
      fill(magic(pixA[x][y], pixB[x][y]));
      rect(x, y, 1, 1);
    }
  }
}

// This xor's two colors together using the magic xor operator 
// that takes two bit strings and xor's them together.  
color magic(color a, color b)
{
  // xor each color channel and put them back together as a color!
  return color(
    int(red(a))^int(red(b)), 
    int(green(a))^int(green(b)), 
    int(blue(a))^int(blue(b))
    );
}


void setup()
{
  size(600, 400);  // size of picture you want to create!
  colorMode(RGB);  // required that you use RGB because png does!
  background(0);

  color p[][], q[][];

  // PUT YOUR CODE HERE!
}