Android手势滑动GestureDetector和OnGestureListener(二)

main.xml如下:

<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>

MainActivity如下:

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;
		}
	}
}