Detect Multi-Touch Event, test on Custom View

package com.TestMultiTouch;

import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;

public class TestMultiTouch extends Activity {
 
 public class MultiTouchView extends View{
  
  //In this test, handle maximum of 2 pointer
  final int MAX_POINT_CNT = 2;
  
  private Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
  float[] x = new float[MAX_POINT_CNT];
  float[] y = new float[MAX_POINT_CNT];
  boolean[] isTouch = new boolean[MAX_POINT_CNT];

  public MultiTouchView(Context context) {
   super(context);
   // TODO Auto-generated constructor stub
  }

  @Override
  protected void onDraw(Canvas canvas) {
   // TODO Auto-generated method stub
   if(isTouch[0]){
       paint.setStyle(Paint.Style.STROKE);
       paint.setStrokeWidth(1);
       paint.setColor(Color.RED);
       canvas.drawCircle(x[0], y[0], 50f, paint);
   }
   if(isTouch[1]){
       paint.setStyle(Paint.Style.STROKE);
       paint.setStrokeWidth(1);
       paint.setColor(Color.BLUE);
       canvas.drawCircle(x[1], y[1], 50f, paint);
   }
  }

  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
   // TODO Auto-generated method stub
   setMeasuredDimension(MeasureSpec.getSize(widthMeasureSpec),
            MeasureSpec.getSize(heightMeasureSpec));
  }

  @Override
  public boolean onTouchEvent(MotionEvent motionEvent) {
   // TODO Auto-generated method stub
   
   int pointerIndex = ((motionEvent.getAction() & MotionEvent.ACTION_POINTER_ID_MASK) 
     >> MotionEvent.ACTION_POINTER_ID_SHIFT);
   int pointerId = motionEvent.getPointerId(pointerIndex);
   int action = (motionEvent.getAction() & MotionEvent.ACTION_MASK);
   int pointCnt = motionEvent.getPointerCount();
   
   if (pointCnt <= MAX_POINT_CNT){
    if (pointerIndex <= MAX_POINT_CNT - 1){

     for (int i = 0; i < pointCnt; i++) {
      int id = motionEvent.getPointerId(i);
      x[id] = (int)motionEvent.getX(i);
      y[id] = (int)motionEvent.getY(i);
      }
     
     switch (action){
     case MotionEvent.ACTION_DOWN:
      isTouch[pointerId] = true;
      break;
     case MotionEvent.ACTION_POINTER_DOWN:
      isTouch[pointerId] = true;
      break;
     case MotionEvent.ACTION_MOVE:
      isTouch[pointerId] = true;
      break;
     case MotionEvent.ACTION_UP:
      isTouch[pointerId] = false;
      break;
     case MotionEvent.ACTION_POINTER_UP:
      isTouch[pointerId] = false;
      break;
     case MotionEvent.ACTION_CANCEL:
      isTouch[pointerId] = false;
      break;
     default:
      isTouch[pointerId] = false;
     }
    }
   }
   
   invalidate();
   return true;
  }
  
 }

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new MultiTouchView(this));
    }
}

Related Post:
- Detect Touch Event
- Detect Touch Event, test on Custom View
- Detect Multi-Touch Event

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