Android实战简易教程-第十二枪（ViewFlipper实现幻灯效果）

ViewFlipper 在实际项目中用到的不是很多了，但是作为初学者的我们还是有必要了解一下它的主要用法。本实例结合手势类（GestureDetector），实现图片的浏览功能。

直接看代码

1.MainActivity.java:

package org.yayun.demo;

import android.app.Activity;
import android.os.Bundle;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.ViewGroup.LayoutParams;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.ImageView;
import android.widget.ViewFlipper;

public class MainActivity extends Activity implements
    android.view.GestureDetector.OnGestureListener {

  private int[] imgs = { R.drawable.img1, R.drawable.img2, R.drawable.img3 };
  private GestureDetector gestureDetector;
  private ViewFlipper viewFlipper;
  private Activity mActivity;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    mActivity = this;
    viewFlipper = (ViewFlipper) findViewById(R.id.viewflipper);

    gestureDetector = new GestureDetector(this);//手势监听

    for (int i = 0; i < imgs.length; i++) { // 添加图片源
      ImageView iv = new ImageView(this);
      iv.setImageResource(imgs[i]);
      iv.setScaleType(ImageView.ScaleType.FIT_XY);
      viewFlipper.addView(iv, new LayoutParams(LayoutParams.FILL_PARENT,
          LayoutParams.FILL_PARENT));
    }

    viewFlipper.setAutoStart(true); // 设置自动播放功能（点击事件，前自动播放）
    viewFlipper.setFlipInterval(3000);//间隔3秒
    if (viewFlipper.isAutoStart() && !viewFlipper.isFlipping()) {
      viewFlipper.startFlipping();
    }
  }

  @Override
  public boolean onTouchEvent(MotionEvent event) {
    // TODO Auto-generated method stub
    viewFlipper.stopFlipping(); // 点击事件后，停止自动播放
    viewFlipper.setAutoStart(false);
    return gestureDetector.onTouchEvent(event); // 注册手势事件
  }

  public boolean onDown(MotionEvent arg0) {
    // TODO Auto-generated method stub
    return false;
  }

  public boolean onFling(MotionEvent e1, MotionEvent e2, float arg2,
      float arg3) {
    if (e2.getX() - e1.getX() > 120) { // 从左向右滑动（左进右出）
      Animation rInAnim = AnimationUtils.loadAnimation(mActivity,
        R.layout.push_right_in); // 向右滑动左侧进入的渐变效果（alpha 0.1 -> 1.0）
      Animation rOutAnim = AnimationUtils.loadAnimation(mActivity,
          R.layout.push_right_out); // 向右滑动右侧滑出的渐变效果（alpha 1.0 -> 0.1）

      viewFlipper.setInAnimation(rInAnim);
      viewFlipper.setOutAnimation(rOutAnim);
      viewFlipper.showPrevious();
      return true;
    } else if (e2.getX() - e1.getX() < -120) { // 从右向左滑动（右进左出）
      Animation lInAnim = AnimationUtils.loadAnimation(mActivity,
          R.layout.push_left_in); // 向左滑动左侧进入的渐变效果（alpha 0.1 -> 1.0）
      Animation lOutAnim = AnimationUtils.loadAnimation(mActivity,
          R.layout.push_left_out); // 向左滑动右侧滑出的渐变效果（alpha 1.0 -> 0.1）

      viewFlipper.setInAnimation(lInAnim);
      viewFlipper.setOutAnimation(lOutAnim);
      viewFlipper.showNext();
      return true;
    }
    return true;
  }

  public void onLongPress(MotionEvent arg0) {
    // TODO Auto-generated method stub

  }

  public boolean onScroll(MotionEvent arg0, MotionEvent arg1, float arg2,
      float arg3) {
    // TODO Auto-generated method stub
    return false;
  }

  public void onShowPress(MotionEvent arg0) {
    // TODO Auto-generated method stub

  }

  public boolean onSingleTapUp(MotionEvent arg0) {
    // TODO Auto-generated method stub
    return false;
  }

}

上面的代码主要注意GestureDetector类的使用。

2.active_main.xml:

<?xml version="1.0" encoding="utf-8"?>  
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:layout_width="fill_parent"  
    android:layout_height="fill_parent"  
    android:orientation="vertical" >  
  
    <ViewFlipper  
        android:id="@+id/viewflipper"  
        android:layout_width="fill_parent"  
        android:layout_height="fill_parent"/>  
  
</LinearLayout>

下面看四个动画文件，很简单.

1.push_left_in.xml

<?xml version="1.0" encoding="utf-8"?>    
<set xmlns:android="http://schemas.android.com/apk/res/android" >    
    <translate    
        android:duration="1500"    
        android:fromXDelta="100%p"    
        android:toXDelta="0" />  <!-- 位移   -->
    
    <alpha    
        android:duration="1500"    
        android:fromAlpha="0.1"    
        android:toAlpha="1.0" /> <!-- 渐变    -->
</set>

2.push_left_out.xml

<?xml version="1.0" encoding="utf-8"?>    
<set xmlns:android="http://schemas.android.com/apk/res/android" >    
    <translate    
        android:duration="1500"    
        android:fromXDelta="0"    
        android:toXDelta="-100%p" />    
    
    <alpha    
        android:duration="1500"    
        android:fromAlpha="1.0"    
        android:toAlpha="0.1" />    
</set>

3.push_right_in.xml

<?xml version="1.0" encoding="utf-8"?>    
<set xmlns:android="http://schemas.android.com/apk/res/android" >    
    <translate    
        android:duration="1500"    
        android:fromXDelta="-100%p"    
        android:toXDelta="0" />    
    
    <alpha    
        android:duration="1500"    
        android:fromAlpha="0.1"    
        android:toAlpha="1.0" />    
</set>

4.push_right_out.xml

<?xml version="1.0" encoding="utf-8"?>    
<set xmlns:android="http://schemas.android.com/apk/res/android" >    
    <translate    
        android:duration="1500"    
        android:fromXDelta="0"    
        android:toXDelta="100%p" />    
    
    <alpha    
        android:duration="1500"    
        android:fromAlpha="1.0"    
        android:toAlpha="0.1" />    
</set>

运行实例如下：

求关注，谢谢