android 手势识别（一）

一、使用GestureDetector 实现简单的屏幕左划右划事件

public class MainActivity extends Activity {
private ImageView img;
private GestureDetector mygestureDetector;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        img=(ImageView) findViewById(R.id.img);
        mygestureDetector=new GestureDetector(new myGestureListener());
        img.setOnTouchListener(new OnTouchListener() {

            @Override//捕获到搓摩屏幕发生的Event 事件
            public boolean onTouch(View v, MotionEvent event) {

                mygestureDetector.onTouchEvent(event);//转发给SimpleOnGestureListener类

                return true;
            }
        });
    }

    class myGestureListener extends SimpleOnGestureListener{

        @Override //滑动e1 为第一个事件  e2为第二个事件
        public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
                float velocityY) {
            if(e1.getX()-e2.getX()>50){
            Toast.makeText(MainActivity.this, "从右往左滑动", Toast.LENGTH_SHORT).show();
            }else if(e2.getX()-e1.getX()>50){
                Toast.makeText(MainActivity.this, "从左往右滑动", Toast.LENGTH_SHORT).show();             
            }
            return super.onFling(e1, e2, velocityX, velocityY);
        }
    }

}