Android Multi Touch, drawLine example

안드로이드에서 멀티터치를 이용하여 터치된 지점을 연결하는 선 그리기 예

res/layout/main.xml

 <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <com.example.androidapp.MyMultiTouchView 
        android:id="@+id/multitouchview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</LinearLayout>

TestActivity.java

 package com.example.androidapp;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.MotionEvent;
import android.widget.TextView;

public class TestActivity extends Activity {
	
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
	}
}

MyMultiTouchView.java

 package com.example.androidapp;

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

public class MyMultiTouchView extends View {
	
	Paint paint = new Paint();
	float[]pts = new float[4];
	boolean isMultiTouch;
	
	public MyMultiTouchView(Context context) {
		super(context);
		init();
	}

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

	private void init(){
		paint.setColor(Color.RED);
		paint.setStrokeWidth(5);
		paint.setStrokeCap(Paint.Cap.BUTT);
	}
	@Override
	public boolean onTouchEvent(MotionEvent event) {
		int action = event.getAction();
		switch(action & MotionEvent.ACTION_MASK) {
		case MotionEvent.ACTION_POINTER_DOWN:
		{
			isMultiTouch = true;
			int cnt = event.getPointerCount();
			int tmp = 0;
			for(int i=0;i<cnt;i++){
				int idx = event.findPointerIndex(i);
				pts[tmp++] = (int) event.getX(idx);
				pts[tmp++] = (int) event.getY(idx);
			}
		}
		break;
		case MotionEvent.ACTION_POINTER_UP:
			pts[0]=pts[1]=pts[2]=pts[3]=0;
			isMultiTouch = false;
		break;
		case MotionEvent.ACTION_MOVE:
		{
			if(isMultiTouch) {
				int cnt = event.getPointerCount();
				int tmp = 0;
				for(int i=0;i<cnt;i++){
					int idx = event.findPointerIndex(i);
					pts[tmp++] = (int) event.getX(idx);
					pts[tmp++] = (int) event.getY(idx);
				}
			}
		}
		break;
		}
		invalidate();
		return true;
	}
	
	@Override
	protected void onDraw(Canvas canvas) {
		super.onDraw(canvas);
		canvas.drawColor(Color.WHITE);
		canvas.drawLines(pts, paint);
	}
}