Get/Set Pixels

GetPixels

boolean ZOOM = true;
void go()
{
  // 100x100
  int x = 30;
  int y = 30;
  int w = 10;
  int h = 10;
  // A 10x10 square with (12,30) the top left corner
  color[] c = new color[w*h];
  
  // Set Green
  c = FillColor(color(0,255,0), c);
  SetPixels(0,0,w,h,c);
  // Set Blue
  c = FillColor(color(0,0,255), c);
  SetPixels(10,0,w,h,c);
  // Put half of each somewhere else
  c = GetPixels(5,0,w,h);
  SetPixels(x,y,w,h,c);


  // Debug corners
  pixelCache[0] = color(255,0,0);
  pixelCache[49] = color(255,0,0);
}

color[] GetPixels(int x, int y, int w, int h)
{
  color[] c = new color[w*h];
  int s = x + (y * width);
  int z = 0;
  for (int i = s; i < s+w; i++)
    for (int j = 0; j < h; j++)
    {
      int loc = i + (j * width);
      c[z] = pixelCache[loc];
      z++;
    }
    return c;
}

void SetPixels(int x, int y, int w, int h, color[] p)
{
  int s = x + (y * width);
  int z = 0;
  for (int i = s; i < s+w; i++)
    for (int j = 0; j < h; j++)
    {
      int loc = i + (j * width);
      pixelCache[loc] = p[z];
      z++;
    }
}

color[] FillColor(color c, color[] a)
{
  for(int i = 0; i < a.length; i++)
    a[i] = c;
  return a;
}

// ---------------------------------------
//       DONT EDIT BELOW THIS LINE
// ---------------------------------------

PImage img;
int scaleWidth = 50;
int scaleHeight = 50;
color[] pixelCache;

// ---------------------------------------
void draw()
{
  begin();
  go();
  finish();
}
// ---------------------------------------
void setup() {
  size(200, 200);
  noSmooth();
  img = createImage(width, height, RGB);
  image(img, 0, 0);
}
// ---------------------------------------
void begin() {
 loadPixels();  
  pixelCache = pixels;
  for (int x = 0; x < width; x++) {
    for (int y = 0; y < height; y++) {
      int loc = x + y * width;
      if (x % 2 == 0) { // If we are an even column
        pixelCache[loc] = color(255);
      } else {          // If we are an odd column
        pixelCache[loc] = color(240);
      }
    }
  }
}
// ---------------------------------------
void finish() {
  pixels = pixelCache;
  updatePixels(); 
  img.pixels = pixels;
  img.updatePixels();
  if(ZOOM)
  copy(img, 0, 0, scaleWidth, scaleHeight, 0, 0, width, height);
}