Processing code: implement button

The example implement two rect as button, and fill the circle with corresponding color.

implement button in Processing

int buttonA_x = 300;
int buttonA_y = 50;
int buttonA_width = 50;
int buttonA_height = 50;
int buttonA_colorR = 0xff;
int buttonA_colorG = 0x00;
int buttonA_colorB = 0x00;

int buttonB_x = 300;
int buttonB_y = 150;
int buttonB_width = 50;
int buttonB_height = 50;
int buttonB_r = 10;
int buttonB_color = 200;

int defaultColor = 150;

boolean buttonA_clicked = false;
boolean buttonB_clicked = false;

void setup() {  // setup() runs once
  size(400, 300);
  background(255);
}
 
void draw() {
  
  if(buttonA_clicked){
    fill(buttonA_colorR, buttonA_colorG, buttonA_colorB);
  }else if(buttonB_clicked){
    fill(buttonB_color);
  }else{
    fill(defaultColor);
  }
  ellipse(width/2, height/2, 100, 100);

  fill(buttonA_colorR, buttonA_colorG, buttonA_colorB);
  rect(buttonA_x, buttonA_y, buttonA_width, buttonA_height);
  
  fill(buttonB_color);
  rect(buttonB_x, buttonB_y, buttonB_width, buttonB_height, buttonB_r);
}

/* The mouseClicked() function is called once after a mouse button 
 * has been pressed and then released.
 */
void mouseClicked(){
  // mouseX = x of mouse click position
  // mouseY = y of mouse click position
  
  if (mouseX >= buttonA_x && mouseX <= buttonA_x + buttonA_width && 
      mouseY >= buttonA_y && mouseY <= buttonA_y + buttonA_height) {
     buttonA_clicked = true;
   } else {
     buttonA_clicked = false;
   }
   
   if (mouseX >= buttonB_x && mouseX <= buttonB_x + buttonB_width && 
       mouseY >= buttonB_y && mouseY <= buttonB_y + buttonB_height) {
     buttonB_clicked = true;
   } else {
     buttonB_clicked = false;
   }
}