Menggunakan Multi Touch

Untuk multitouch, Android API memiliki sejumlah class yang terkait dengan penanganan touch event, yang disebut MotionEvent. Di sisi Processing, kita hanya perlu meng-implementasikan method surfaceTouchEvent, yang akan dipanggil ketika ter-deteksi pergerakan (sentuhan).

Berikut adalah sebuah contoh yang sudah penulis coba, yang dikutip dari sebuah sumber:

import android.view.MotionEvent; 

float sw, sh, touchX, touchY;
int pointerCount;
ArrayList points;
PFont f;

void setup() {  
  //size doesn't really matter in an Android app
  size(displayWidth, displayHeight);  
  println(displayWidth);  
  println(displayHeight);  
  sw = displayWidth;  
  sh = displayHeight;  
  points = new ArrayList();  
  f = createFont("Arial", 16);  
} 

void draw() {  
  background(0);  
  smooth();    
  noFill();  
  stroke(255,0,0);  
  strokeWeight(2);  
  textFont(f);
  PVector tempPoint;
  for(int i=0; i<points.size(); i++) {
    tempPoint = (PVector) points.get(i);
    ellipse(tempPoint.x, tempPoint.y, 50, 50);
    text(tempPoint.x+", "+tempPoint.y, tempPoint.x+10, tempPoint.y-10);
  }
} 

public boolean surfaceTouchEvent(MotionEvent event) {
  pointerCount = event.getPointerCount();
  println("Number of pointers: "+pointerCount);
  points.clear();
  for(int i=1; i<=pointerCount; i++) {
    points.add(new PVector(event.getX(i-1), event.getY(i-1)));
  }

  //if the event is a pressed gesture finishing, 
  // it means the lifting the last touch point
  if(event.getActionMasked() == MotionEvent.ACTION_UP) points.clear();

  // if you want the variables for motionX/motionY, mouseX/mouseY etc.
  // to work properly, you'll need to call super.surfaceTouchEvent().
  return super.surfaceTouchEvent(event);

}

/* if single touch is all you need, this would work just fine
void mouseDragged() {  
  touchX = mouseX;  
  touchY = mouseY;
}
*/