[Android实例] android多点触摸demo

MultiTouchActivity

package com.zhaokai.multitouch;
import android.app.Activity;
import android.os.Bundle;
import android.view.Window;
import android.view.WindowManager;

public class MultiTouchActivity extends Activity {
    /** Called when the activity is first created. */
     /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      //隐藏标题栏
      requestWindowFeature(Window.FEATURE_NO_TITLE);
      //设置成全屏
      getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
      //设置为上面的MTView
      setContentView(new MySurfaceView(this));
    }
}

SurfaceView类： 

package com.zhaokai.multitouch;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceHolder.Callback;
import android.view.SurfaceView;
public class MySurfaceView extends SurfaceView implements Callback{
private static final int MAX_TOUCHPOINTS = 10;
private static final String START_TEXT = "请随便触摸屏幕进行测试";
private Paint textPaint = new Paint();
private Paint touchPaints[] = new Paint[MAX_TOUCHPOINTS];
private int colors[] = new int[MAX_TOUCHPOINTS];
private int width, height;
private float scale = 1.0f;

public MySurfaceView(Context context) {
  super(context);
  SurfaceHolder holder = getHolder();
  holder.addCallback(this);
  setFocusable(true); // 确保我们的View能获得输入焦点
  setFocusableInTouchMode(true); // 确保能接收到触屏事件
  init();
}
public void init(){
  // 初始化10个不同颜色的画笔
  textPaint.setColor(Color.WHITE);
  colors[0] = Color.BLUE;
  colors[1] = Color.RED;
  colors[2] = Color.GREEN;
  colors[3] = Color.YELLOW;
  colors[4] = Color.CYAN;
  colors[5] = Color.MAGENTA;
  colors[6] = Color.DKGRAY;
  colors[7] = Color.WHITE;
  colors[8] = Color.LTGRAY;
  colors[9] = Color.GRAY;
  for(int i=0;i
   touchPaints[i]=new Paint();
   touchPaints[i].setColor(colors[i]);
  }
}

@Override
public boolean onTouchEvent(MotionEvent event) {
  int pointerCount=event.getPointerCount();
  if(pointerCount>MAX_TOUCHPOINTS){
   pointerCount=MAX_TOUCHPOINTS;
  }
  Canvas c=getHolder().lockCanvas();
  if(c!=null){
   c.drawColor(Color.BLACK);
   if(event.getAction()==MotionEvent.ACTION_UP){
    // 当手离开屏幕时，清屏
    c.drawColor(Color.BLACK);
   }else{
     // 先在屏幕上画一个十字，然后画一个圆
    for(int i=0;i
     //获取一个触点的坐标，然后开始绘制
     int id=event.getPointerId(i);
     int x=(int)event.getX(i);
     int y=(int)event.getY(i);
     drawCrosshairsAndText(x, y, touchPaints[id], i, id, c);
    }
    for(int i=0;i
     int id=event.getPointerId(i);
     int x=(int)event.getX(i);
     int y=(int)event.getY(i);
     drawCircle(x, y, touchPaints[id],c);
    }
   }
   getHolder().unlockCanvasAndPost(c);
  }
  return true;
}

private void drawCrosshairsAndText(int x, int y, Paint paint, int ptr,int id, Canvas c) {
  c.drawLine(0, y, width, y, paint);
  c.drawLine(x, 0, x, height, paint);
  int textY = (int) ((15 + 20 * ptr) * scale);
  c.drawText("x" + ptr + "=" + x, 10 * scale, textY, textPaint);
  c.drawText("y" + ptr + "=" + y, 70 * scale, textY, textPaint);
  c.drawText("id" + ptr + "=" + id, width - 55 * scale, textY, textPaint);
}

private void drawCircle(int x, int y, Paint paint, Canvas c) {
  c.drawCircle(x, y, 40 * scale, paint);
}

@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
   int height) {
   this.width = width;
   this.height = height;
   if (width > height){
    this.scale = width / 480f;
   } else {
   this.scale = height / 480f;
   }
   textPaint.setTextSize(14 * scale);
   Canvas c = getHolder().lockCanvas();
   if (c != null) {              // 背景黑色
    c.drawColor(Color.BLACK);
    float tWidth = textPaint.measureText(START_TEXT);
    c.drawText(START_TEXT, width / 2 - tWidth / 2, height / 2,textPaint);
    getHolder().unlockCanvasAndPost(c);
  }
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
  // TODO Auto-generated method stub

}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
  // TODO Auto-generated method stub

}

}