Android入门第十三篇之Gallery + ImageSwitcher

上次讲了如何使用Gallery控件，这次就讲Gallery 与ImageSwitcher的结合使用，本文实现一个简单的浏览图片的功能。先贴出程序运行截图：

除了Gallery可以拖拉切换图片，我在ImageSwitcher控件加入了setOnTouchListener事件实现，使得ImageSwitcher也可以在拖拉中切换图片。本例子依然使用JAVA的反射机制来自动读取资源中的图片。

 

main.xml的源码如下:

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1. <? xml   version = "1.0"   encoding = "utf-8" ?>   
2. < RelativeLayout   xmlns:android = "http://schemas.android.com/apk/res/android"    
3.     android:layout_width = "match_parent"    
4.     android:layout_height = "match_parent" >    
5.       
6.     < ImageSwitcher   android:id = "@+id/switcher"   
7.         android:layout_width = "match_parent"   android:layout_height = "match_parent" />   
8.       
9.     < Gallery   android:id = "@+id/gallery"   
10.         android:background = "#55000000"   
11.         android:layout_width = "match_parent"   
12.         android:layout_alignParentBottom = "true"   
13.         android:layout_alignParentLeft = "true"   
14.           
15.         android:gravity = "center_vertical"   
16.         android:spacing = "16dp"   android:layout_height = "100dp" />   
17. </ RelativeLayout >   
18.      

<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent"> <ImageSwitcher android:id="@+id/switcher" android:layout_width="match_parent" android:layout_height="match_parent"/> <Gallery android:id="@+id/gallery" android:background="#55000000" android:layout_width="match_parent" android:layout_alignParentBottom="true" android:layout_alignParentLeft="true" android:gravity="center_vertical" android:spacing="16dp" android:layout_height="100dp"/> </RelativeLayout>

 

程序的源码如下:

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1. package  com.testImageView;  
2. import  java.lang.reflect.Field;  
3. import  java.util.ArrayList;  
4. import  android.app.Activity;  
5. import  android.content.Context;  
6. import  android.os.Bundle;  
7. import  android.view.MotionEvent;  
8. import  android.view.View;  
9. import  android.view.View.OnTouchListener;  
10. import  android.view.ViewGroup;  
11. import  android.view.animation.AnimationUtils;  
12. import  android.widget.AdapterView;  
13. import  android.widget.BaseAdapter;  
14. import  android.widget.Gallery;  
15. import  android.widget.ImageSwitcher;  
16. import  android.widget.ImageView;  
17. import  android.widget.AdapterView.OnItemSelectedListener;  
18. import  android.widget.Gallery.LayoutParams;  
19. import  android.widget.ViewSwitcher.ViewFactory;  
20. public   class  testImageView  extends  Activity  implements  ViewFactory {  
21.     private  ImageSwitcher is;  
22.     private  Gallery gallery;  
23.     private   int  downX,upX;  
24.     private  ArrayList<Integer> imgList= new  ArrayList<Integer>(); //图像ID   
25.       
26.     @Override   
27.     protected   void  onCreate(Bundle savedInstanceState) {  
28.         // TODO Auto-generated method stub   
29.         super .onCreate(savedInstanceState);  
30.         setContentView(R.layout.main);  
31.         //用反射机制来获取资源中的图片ID   
32.         Field[] fields = R.drawable.class .getDeclaredFields();  
33.         for  (Field field : fields)  
34.         {  
35.             if  (! "icon" .equals(field.getName())) //除了icon之外的图片   
36.             {     
37.                 int  index =  0 ;  
38.                 try  {  
39.                     index = field.getInt(R.drawable.class );  
40.                 } catch  (IllegalArgumentException e) {  
41.                     // TODO Auto-generated catch block   
42.                     e.printStackTrace();  
43.                 } catch  (IllegalAccessException e) {  
44.                     // TODO Auto-generated catch block   
45.                     e.printStackTrace();  
46.                 }  
47.                 //保存图片ID   
48.                 imgList.add(index);  
49.             }  
50.         }  
51.           
52.         //设置ImageSwitcher控件   
53.         is = (ImageSwitcher) findViewById(R.id.switcher);  
54.         is.setFactory(this );  
55.         is.setInAnimation(AnimationUtils.loadAnimation(this ,  
56.                 android.R.anim.fade_in));  
57.         is.setOutAnimation(AnimationUtils.loadAnimation(this ,  
58.                 android.R.anim.fade_out));  
59.         is.setOnTouchListener(new  OnTouchListener(){  
60.             /*  
61.              * 在ImageSwitcher控件上滑动可以切换图片  
62.              */   
63.             @Override   
64.             public   boolean  onTouch(View v, MotionEvent event) {  
65.                 if (event.getAction()==MotionEvent.ACTION_DOWN)  
66.                 {  
67.                     downX=(int ) event.getX(); //取得按下时的坐标   
68.                     return   true ;  
69.                 }  
70.                 else   if (event.getAction()==MotionEvent.ACTION_UP)  
71.                 {  
72.                     upX=(int ) event.getX(); //取得松开时的坐标   
73.                     int  index= 0 ;  
74.                     if (upX-downX> 100 ) //从左拖到右，即看前一张   
75.                     {  
76.                         //如果是第一，则去到尾部   
77.                         if (gallery.getSelectedItemPosition()== 0 )  
78.                            index=gallery.getCount()-1 ;  
79.                         else   
80.                             index=gallery.getSelectedItemPosition()-1 ;  
81.                     }  
82.                     else   if (downX-upX> 100 ) //从右拖到左，即看后一张   
83.                     {  
84.                         //如果是最后，则去到第一   
85.                         if (gallery.getSelectedItemPosition()==(gallery.getCount()- 1 ))  
86.                             index=0 ;  
87.                         else   
88.                             index=gallery.getSelectedItemPosition()+1 ;  
89.                     }  
90.                     //改变gallery图片所选，自动触发ImageSwitcher的setOnItemSelectedListener   
91.                     gallery.setSelection(index, true );  
92.                     return   true ;  
93.                 }  
94.                 return   false ;  
95.             }  
96.               
97.         });  
98.           
99.         //设置gallery控件   
100.         gallery = (Gallery) findViewById(R.id.gallery);  
101.         gallery.setAdapter(new  ImageAdapter( this ));  
102.         gallery.setOnItemSelectedListener(new  OnItemSelectedListener(){  
103.             @Override   
104.             public   void  onItemSelected(AdapterView<?> arg0, View arg1,  
105.                     int  position,  long  arg3) {  
106.                 is.setImageResource(imgList.get(position));  
107.             }  
108.             @Override   
109.             public   void  onNothingSelected(AdapterView<?> arg0) {  
110.                 // TODO Auto-generated method stub   
111.             }  
112.               
113.         });  
114.     }  
115.     //设置ImgaeSwitcher   
116.     @Override   
117.     public  View makeView() {  
118.         ImageView i = new  ImageView( this );  
119.         i.setBackgroundColor(0xFF000000 );  
120.         i.setScaleType(ImageView.ScaleType.CENTER);//居中   
121.         i.setLayoutParams(new  ImageSwitcher.LayoutParams( //自适应图片大小   
122.                 LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));  
123.         return  i;  
124.     }  
125.     public   class  ImageAdapter  extends  BaseAdapter {  
126.         public  ImageAdapter(Context c) {  
127.             mContext = c;  
128.         }  
129.         public   int  getCount() {  
130.             return  imgList.size();  
131.         }  
132.         public  Object getItem( int  position) {  
133.             return  position;  
134.         }  
135.         public   long  getItemId( int  position) {  
136.             return  position;  
137.         }  
138.         public  View getView( int  position, View convertView, ViewGroup parent) {  
139.             ImageView i = new  ImageView(mContext);  
140.             i.setImageResource(imgList.get(position));  
141.             i.setAdjustViewBounds(true );  
142.             i.setLayoutParams(new  Gallery.LayoutParams(  
143.                     LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));  
144.             return  i;  
145.         }  
146.         private  Context mContext;  
147.     }  
148.   
149. }