Reference for Processing version 1.2. If you have a previous version, use the reference included with your software. If you see any errors or have suggestions, please let us know. If you prefer a more technical reference, visit the Processing Javadoc.

// Move the mouse across the image
// to change its value

int value = 0;

void draw() {
  fill(value);
  rect(25, 25, 50, 50);
}

void mouseMoved() {
  value = value + 5;
  if (value > 255) {
    value = 0;
  }
}

void mouseMoved() {
  statements
}