Detect TouchEvent on custom View to free draw path dynamically

Override onTouchEvent() method of custom View, to create path dynamically.

Create a new class MyView extends View, MyView.java.

package com.AndroidMyCanvas;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

public class MyView extends View {
 
 boolean freeTouched = false;
 Path freePath;

 public MyView(Context context) {
  super(context);
 }

 public MyView(Context context, AttributeSet attrs) {
  super(context, attrs);
 }

 public MyView(Context context, AttributeSet attrs, int defStyle) {
  super(context, attrs, defStyle);
 }

 @Override
 protected void onDraw(Canvas canvas) {
  // TODO Auto-generated method stub
  super.onDraw(canvas);
  Paint paint = new Paint();
  paint.setStyle(Paint.Style.STROKE);
  paint.setColor(Color.WHITE);
  paint.setStrokeWidth(3);
  
  if(freeTouched){
   canvas.drawPath(freePath, paint);
  }

 }

 @Override
 public boolean onTouchEvent(MotionEvent event) {
  
  switch(event.getAction()){
  case MotionEvent.ACTION_UP:
   freeTouched = false;
   break;
  case MotionEvent.ACTION_DOWN:
   freeTouched = true;
   freePath = new Path();
   freePath.moveTo(event.getX(), event.getY());
   break;
  case MotionEvent.ACTION_MOVE:
   freePath.lineTo(event.getX(), event.getY());
   invalidate();
   break;
  }
  
  return true;
 }

}

Modify main Java activity to setContentView() using our custom View, MyView.

package com.AndroidMyCanvas;

import android.app.Activity;
import android.os.Bundle;

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