This reference is for Processing 2.0+. 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.

Name | ### mouseButton
Examples |
    // Click within the image and press
    // the left and right mouse buttons to
    // change the value of the rectangle
    void draw() {
      if (mousePressed && (mouseButton == LEFT)) {
        fill(0);
      } else if (mousePressed && (mouseButton == RIGHT)) {
        fill(255);
      } else {
        fill(126);
      }
      rect(25, 25, 50, 50);
    }
    // Click within the image and press
    // the left and right mouse buttons to
    // change the value of the rectangle
    void draw() {
      rect(25, 25, 50, 50);
    }

    void mousePressed() {
      if (mouseButton == LEFT) {
        fill(0);
      } else if (mouseButton == RIGHT) {
        fill(255);
      } else {
        fill(126);
      }
    }
Description | When a mouse button is pressed, the value of the system variable mouseButton is set to either LEFT, RIGHT, or CENTER, depending on which button is pressed. (If no button is pressed, mouseButton may be reset to 0. For that reason, it's best to use mousePressed first to test if any button is being pressed, and only then test the value of mouseButton, as shown in the examples above.)
Related | mouseX mouseY pmouseX pmouseY mousePressed mousePressed() mouseReleased() mouseClicked() mouseMoved() mouseDragged() mouseWheel()

Updated on May 19, 2014 05:30:02pm PDT