Android手势滑动GestureDetector和OnGestureListener(二)

<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"
>

<ImageView
android:id="@+id/imageView"
android:layout_width="240dip"
android:layout_height="300dip"
android:layout_centerInParent="true"
/>

</RelativeLayout>

package cn.com.testgesture2;
import android.os.Bundle;
import android.view.GestureDetector;
import android.view.View;
import android.view.GestureDetector.OnGestureListener;
import android.view.MotionEvent;
import android.view.View.OnTouchListener;
import android.widget.ImageView;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
/**
* Demo描述:
* 在ImageView控件上滑动
* 依据滑动速度的不同显示不同的照片
*
* 重要参考:
* http://www.cnblogs.com/zfrr/archive/2012/07/19/2599591.html * 介绍了onFling中速度参数正负的坐标
*/
public class MainActivity extends Activity {
private GestureDetector mGestureDetector;
private ImageView mImageView;
private Bitmap mBitmapA;
private Bitmap mBitmapB;
private Bitmap mBitmapC;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
init();
}

private void init() {
mBitmapA=BitmapFactory.decodeResource(getResources(), R.drawable.a);
mBitmapB=BitmapFactory.decodeResource(getResources(), R.drawable.b);
mBitmapC=BitmapFactory.decodeResource(getResources(), R.drawable.c);

mGestureDetector = new GestureDetector(MainActivity.this,new GestureListenerImpl());
mImageView=(ImageView) findViewById(R.id.imageView);
mImageView.setImageBitmap(mBitmapA);
mImageView.setOnTouchListener(new OnTouchListener() {
@Override
public boolean onTouch(View arg0, MotionEvent event) {
return mGestureDetector.onTouchEvent(event);
}
});
}

//覆写Activity的onTouchEvent方法
//将Touch事件交给GestureDetector处理
@Override
public boolean onTouchEvent(MotionEvent event) {
return mGestureDetector.onTouchEvent(event);
}

//以下为OnGestureListener的实现
private class GestureListenerImpl implements OnGestureListener {
//触摸屏幕时均会调用该方法
@Override
public boolean onDown(MotionEvent e) {
return false;
}

//手指在屏幕上拖动时会调用该方法
@Override
public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,float velocityY) {
System.out.println("---> 手势中的 onFling 方法");
System.out.println("velocityX="+velocityX+",velocityY="+velocityY);
if (2000f<velocityX&&velocityX>3000f){
mImageView.setImageBitmap(mBitmapA);
}
if (3000f<velocityX&&velocityX>4000f){
mImageView.setImageBitmap(mBitmapB);
}
if (4000f<velocityX&&velocityX>5000f){
mImageView.setImageBitmap(mBitmapC);
}
return false;
}

//长按触摸屏幕时均会调用该方法
@Override
public void onLongPress(MotionEvent e) {
}

//手指在屏幕上滚动时会调用该方法
@Override
public boolean onScroll(MotionEvent e1, MotionEvent e2,float distanceX, float distanceY) {
return false;
}

//在触摸屏上按下,且未移动和松开时调用该方法
@Override
public void onShowPress(MotionEvent e) {
}

//轻击屏幕时调用该方法
@Override
public boolean onSingleTapUp(MotionEvent e) {
return false;
}
}
}