Android入门之Gallery+ImageSwitcher用法实例解析

继上一篇介绍了如何使用gallery控件之后，本文就来讲一下gallery 与imageswitcher的结合使用。本文所述实例代码将实现一个简单的浏览图片的功能。

先贴出程序运行截图如下：

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:

<?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>

java程序的源码如下:

package com.testimageview;
import java.lang.reflect.field;
import java.util.arraylist;
import android.app.activity;
import android.content.context;
import android.os.bundle;
import android.view.motionevent;
import android.view.view;
import android.view.view.ontouchlistener;
import android.view.viewgroup;
import android.view.animation.animationutils;
import android.widget.adapterview;
import android.widget.baseadapter;
import android.widget.gallery;
import android.widget.imageswitcher;
import android.widget.imageview;
import android.widget.adapterview.onitemselectedlistener;
import android.widget.gallery.layoutparams;
import android.widget.viewswitcher.viewfactory;
public class testimageview extends activity implements viewfactory {
 private imageswitcher is;
 private gallery gallery;
 private int downx,upx;
  private arraylist<integer> imglist=new arraylist<integer>();//图像id
  
 @override
 protected void oncreate(bundle savedinstancestate) {
 // todo auto-generated method stub
 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 (field field : fields)
   {
   if (!"icon".equals(field.getname()))//除了icon之外的图片
   { 
    int index = 0;
  try {
   index = field.getint(r.drawable.class);
  } catch (illegalargumentexception e) {
   // todo auto-generated catch block
   e.printstacktrace();
  } catch (illegalaccessexception e) {
   // todo auto-generated catch block
   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(new ontouchlistener(){
  /*
  * 在imageswitcher控件上滑动可以切换图片
  */
  @override
  public boolean ontouch(view v, motionevent event) {
  if(event.getaction()==motionevent.action_down)
  {
   downx=(int) event.getx();//取得按下时的坐标
   return true;
  }
  else if(event.getaction()==motionevent.action_up)
  {
   upx=(int) event.getx();//取得松开时的坐标
   int index=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;
   }
   else if(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);
   return true;
  }
  return false;
  }
  
 });
 
 //设置gallery控件
 gallery = (gallery) findviewbyid(r.id.gallery);
 gallery.setadapter(new imageadapter(this));
 gallery.setonitemselectedlistener(new onitemselectedlistener(){
  @override
  public void onitemselected(adapterview<?> arg0, view arg1,
   int position, long arg3) {
  is.setimageresource(imglist.get(position));
  }
  @override
  public void onnothingselected(adapterview<?> arg0) {
  // todo auto-generated method stub
  }
  
 });
 }
 //设置imgaeswitcher
 @override
 public view makeview() {
 imageview i = new imageview(this);
 i.setbackgroundcolor(0xff000000);
 i.setscaletype(imageview.scaletype.center);//居中
 i.setlayoutparams(new imageswitcher.layoutparams(//自适应图片大小
  layoutparams.fill_parent, layoutparams.fill_parent));
 return i;
 }
 public class imageadapter extends baseadapter {
 public imageadapter(context c) {
  mcontext = c;
 }
 public int getcount() {
  return imglist.size();
 }
 public object getitem(int position) {
  return position;
 }
 public long getitemid(int position) {
  return position;
 }
 public view getview(int position, view convertview, viewgroup parent) {
  imageview i = new imageview(mcontext);
  i.setimageresource(imglist.get(position));
  i.setadjustviewbounds(true);
  i.setlayoutparams(new gallery.layoutparams(
   layoutparams.wrap_content, layoutparams.wrap_content));
  return i;
 }
 private context mcontext;
 }
}