Android入门第十三篇之Gallery + ImageSwitcher

本文来自http://blog.csdn.net/hellogv/，引用必须注明出处！

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:

 <?xmlversion="1.0"encoding="utf-8"?>
 <RelativeLayoutxmlns:android="http://schemas.android.com/apk/res/android"
 android:layout_width="match_parent"
 android:layout_height="match_parent">

 <ImageSwitcherandroid:id="@+id/switcher"
 android:layout_width="match_parent"android:layout_height="match_parent"/>

 <Galleryandroid: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:

 packagecom.testImageView;
 importjava.lang.reflect.Field;
 importjava.util.ArrayList;
 importandroid.app.Activity;
 importandroid.content.Context;
 importandroid.os.Bundle;
 importandroid.view.MotionEvent;
 importandroid.view.View;
 importandroid.view.View.OnTouchListener;
 importandroid.view.ViewGroup;
 importandroid.view.animation.AnimationUtils;
 importandroid.widget.AdapterView;
 importandroid.widget.BaseAdapter;
 importandroid.widget.Gallery;
 importandroid.widget.ImageSwitcher;
 importandroid.widget.ImageView;
 importandroid.widget.AdapterView.OnItemSelectedListener;
 importandroid.widget.Gallery.LayoutParams;
 importandroid.widget.ViewSwitcher.ViewFactory;
 publicclasstestImageViewextendsActivityimplementsViewFactory{
 privateImageSwitcheris;
 privateGallerygallery;
 privateintdownX,upX;
 privateArrayList<Integer>imgList=newArrayList<Integer>();//图像ID

 @Override
 protectedvoidonCreate(BundlesavedInstanceState){
 //TODOAuto-generatedmethodstub
 super.onCreate(savedInstanceState);
 setContentView(R.layout.main);
 //用反射机制来获取资源中的图片ID
 Field[]fields=R.drawable.class.getDeclaredFields();
 for(Fieldfield:fields)
 {
 if(!"icon".equals(field.getName()))//除了icon之外的图片
 {
 intindex=0;
 try{
 index=field.getInt(R.drawable.class);
 }catch(IllegalArgumentExceptione){
 //TODOAuto-generatedcatchblock
 e.printStackTrace();
 }catch(IllegalAccessExceptione){
 //TODOAuto-generatedcatchblock
 e.printStackTrace();
 }
 //保存图片ID
 imgList.add(index);
 }
 }

 //设置ImageSwitcher控件
 is=(ImageSwitcher)findViewById(R.id.switcher);
 is.setFactory(this);
 is.setInAnimation(AnimationUtils.loadAnimation(this,
 android.R.anim.fade_in));
 is.setOutAnimation(AnimationUtils.loadAnimation(this,
 android.R.anim.fade_out));
 is.setOnTouchListener(newOnTouchListener(){
 /*
 *在ImageSwitcher控件上滑动可以切换图片
 */
 @Override
 publicbooleanonTouch(Viewv,MotionEventevent){
 if(event.getAction()==MotionEvent.ACTION_DOWN)
 {
 downX=(int)event.getX();//取得按下时的坐标
 returntrue;
 }
 elseif(event.getAction()==MotionEvent.ACTION_UP)
 {
 upX=(int)event.getX();//取得松开时的坐标
 intindex=0;
 if(upX-downX>100)//从左拖到右，即看前一张
 {
 //如果是第一，则去到尾部
 if(gallery.getSelectedItemPosition()==0)
 index=gallery.getCount()-1;
 else
 index=gallery.getSelectedItemPosition()-1;
 }
 elseif(downX-upX>100)//从右拖到左，即看后一张
 {
 //如果是最后，则去到第一
 if(gallery.getSelectedItemPosition()==(gallery.getCount()-1))
 index=0;
 else
 index=gallery.getSelectedItemPosition()+1;
 }
 //改变gallery图片所选，自动触发ImageSwitcher的setOnItemSelectedListener
 gallery.setSelection(index,true);
 returntrue;
 }
 returnfalse;
 }

 });

 //设置gallery控件
 gallery=(Gallery)findViewById(R.id.gallery);
 gallery.setAdapter(newImageAdapter(this));
 gallery.setOnItemSelectedListener(newOnItemSelectedListener(){
 @Override
 publicvoidonItemSelected(AdapterView<?>arg0,Viewarg1,
 intposition,longarg3){
 is.setImageResource(imgList.get(position));
 }
 @Override
 publicvoidonNothingSelected(AdapterView<?>arg0){
 //TODOAuto-generatedmethodstub
 }

 });
 }
 //设置ImgaeSwitcher
 @Override
 publicViewmakeView(){
 ImageViewi=newImageView(this);
 i.setBackgroundColor(0xFF000000);
 i.setScaleType(ImageView.ScaleType.CENTER);//居中
 i.setLayoutParams(newImageSwitcher.LayoutParams(//自适应图片大小
 LayoutParams.FILL_PARENT,LayoutParams.FILL_PARENT));
 returni;
 }
 publicclassImageAdapterextendsBaseAdapter{
 publicImageAdapter(Contextc){
 mContext=c;
 }
 publicintgetCount(){
 returnimgList.size();
 }
 publicObjectgetItem(intposition){
 returnposition;
 }
 publiclonggetItemId(intposition){
 returnposition;
 }
 publicViewgetView(intposition,ViewconvertView,ViewGroupparent){
 ImageViewi=newImageView(mContext);
 i.setImageResource(imgList.get(position));
 i.setAdjustViewBounds(true);
 i.setLayoutParams(newGallery.LayoutParams(
 LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT));
 returni;
 }
 privateContextmContext;
 }

 }