Android入门（53）——第八章 使用GestureDetector进行手势识别

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >

<ImageView
android:id="@+id/img"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="190dp"
android:src="@drawable/ic_launcher" />

</RelativeLayout>

package com.example.gesturedetectodemo;

import android.os.Bundle;
import android.app.Activity;
import android.view.GestureDetector;
import android.view.GestureDetector.SimpleOnGestureListener;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.ImageView;
import android.widget.Toast;

public class MainActivity extends Activity {

ImageView img;
GestureDetector myGestureDetector;

class myGestureListener extends SimpleOnGestureListener {
@Override
// 滑动过程中，e1是开始事件，e2是结束事件
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
float velocityY) {
// TODO Auto-generated method stub
if (e1.getX() - e2.getX() > 1) {
Toast.makeText(MainActivity.this, "从右往左滑动", 2000).show();
} else if (e2.getX() - e1.getX() > 1) {
Toast.makeText(MainActivity.this, "从左往右滑动", 2000).show();
}
return super.onFling(e1, e2, velocityX, velocityY);
}
}

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

img = (ImageView) findViewById(R.id.img);
myGestureDetector = new GestureDetector(MainActivity.this, new myGestureListener());
//	myGestureDetector = new GestureDetector(new myGestureListener());

img.setOnTouchListener(new OnTouchListener() {
// 触屏一刹那，触发MotionEvent事件：
// 它可以捕获触摸屏幕发生的Event事件：
@Override
public boolean onTouch(View v, MotionEvent event) {
// GestureDetector转发MotionEvent对象至OnGestureListener
myGestureDetector.onTouchEvent(event);
return false;
}
});
}
}