Touch Screen Processing Sketch

float offset = 2.23;
float rot = 0.0;
import processing.serial.*;
int yPos =0;
int xPos = 0;

boolean colorRed = false;
boolean colorGreen = false;
boolean colorBlue = false;


 Serial myPort;        // The serial port


void setup() {
  smooth();
  size(1200,900);
  background(255);
   println(Serial.list());
   myPort = new Serial(this, Serial.list()[0], 115200);
    myPort.bufferUntil('\n');
}


void draw() {


}
void serialEvent (Serial myPort) {

   String inString = myPort.readStringUntil('\n');
    if (inString != null) {
       // trim off any whitespace:
       inString = trim(inString);
       int xCharPos = inString.indexOf("X");
       int yCharPos = inString.indexOf("Y");
       int pCharPos = inString.indexOf("P");

       String xString = inString.substring(xCharPos + 1, yCharPos);
       String yString = inString.substring(yCharPos + 1, pCharPos);
       String pString = inString.substring(pCharPos + 1, inString.length());

      println(xString + "\t" + yString + "\t" + pString);

      xPos = int(map((Integer.parseInt(xString)), 90, 950, 0, width));
      yPos = int(map((Integer.parseInt(yString)), 920, 120, 0, height));
      int ellipseSize = max(int(map((Integer.parseInt(pString)), 300, 150, 1, 200)),1) ;
      noStroke();
      fill(40,40,40,20);
      if (colorRed)
        fill(255, 0, 0, 20);
      if (colorGreen)
        fill(0,255,0,20);
      if (colorBlue)
        fill(0,0,255,20);
       ellipse(xPos, yPos, ellipseSize, ellipseSize);
     }
}

void keyPressed() {
  if (key == 'r' || key == 'R') {
    colorRed =! colorRed;
    colorGreen = false;
    colorBlue = false;
  }
    if (key == 'g' || key == 'G') {
    colorGreen =! colorGreen;
    colorRed = false;
    colorBlue = false;
  }
    if (key == 'b' || key == 'B') {
    colorBlue =! colorBlue;
    colorGreen = false;
    colorRed = false;
  }
}