Android之ImageSwitcher控件概述
在win7中查看图片会有图片预览窗格效果，下面通过一个实例来说。
1.界面布局
在xml布局文件中，我们使用LinearLayout对整个界面进行水平布局。在界面的左端设置了一个GirdView控件，用来显示列表。在GridView控件的右面设置一个ImageSwitcher，a当点击GridView中的图片时，会在ImageView上显示出来。代码如下：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/layout" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="horizontal" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context="com.example.eg_win7viewphoto.MainActivity" > <GridView android:id="@+id/gridview" android:layout_width="418dp" android:layout_height="432dp" android:layout_marginTop="10px" android:layout_weight="0.65" android:horizontalSpacing="3px" android:numColumns="4" android:verticalSpacing="3px" > </GridView> <ImageSwitcher android:id="@+id/imageswitcher" android:layout_width="499dp" android:layout_height="match_parent" android:padding="20px" /> </LinearLayout>
2.程序运行主要界面如下：
3.ViewFactory接口
要将图片显示在ImageSwitcher控件中，必须为ImageSwitcher类设置一个ViewFactory，用来将显示的图片和父窗口区分开来。这可以通过如下方法来实现：
ImageSwitcher.setFactory();
此外，我们还需要实现ViewSwitcher.ViewFactory接口中的makeView()抽象方法，通过该方法可以返回一个ImageView对象，所有图片都将通过该ImageView对象来进行显示。具体实现方法如下：
imageswitcher.setFactory(new ViewFactory() {
ImageView imageview1;
@Override
public View makeView() {
// TODO Auto-generated method stub
imageview1=new ImageView(MainActivity.this);
imageview1.setScaleType(ImageView.ScaleType.FIT_CENTER);
imageview1.setLayoutParams(new ImageSwitcher.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT));
return imageview1;
}
});
4.获取图片资源
通过查看ImageSwitcher的API帮助文档
（http://developer.android.com/reference/android/widget/ImageSwitcher.html），我们可以看出向ImageSwitcher加载图片有以下三种方式：
（1）public void setImageDrawable(Drawable drawable);
（2）public void setImageResource(int resid);
（3）public void setImageURI(Uri uri);
其中，setImageDrawable()方法通过Drawable对象来获取图片资源；setImageResource()方法通过图片资源Id来获取图片资源；setImageURI()方法通过图片的Uri路径来获取图片资源。
在该实例中，我们选择使用setImageResource()方法来获取图片资源.
imageswitcher.setImageResource(imageId[((imageId.length)/2)]);
5.创建BaseAdapter对象，重写该对象的getView()方法设置显示图片的格式
BaseAdapter adapter=new BaseAdapter() {
ImageView imageview2;
@Override
public View getView(int position, View contentView, ViewGroup parent) {
// TODO Auto-generated method stub
if(contentView==null){
imageview2=new ImageView(MainActivity.this);
/*****设置图像高度与宽度******/
imageview2.setAdjustViewBounds(true);
imageview2.setMaxHeight(113);
imageview2.setMaxWidth(150);
/**********************/
imageview2.setPadding(5, 5, 5, 5);
}else{
imageview2=(ImageView)contentView;
}
imageview2.setImageResource(imageId[position]);
return imageview2;
}
/*
* 获得当前选项的ID(non-Javadoc)
* @see android.widget.Adapter#getItemId(int)
*/
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
/**
* 获得当前选项
*/
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return position;
}
/**
* 获得数量
*/
@Override
public int getCount() {
// TODO Auto-generated method stub
return imageId.length;
}
};
6.将GridVIew与适配器BaseAdapter对象关联，设置单击GridView对象监听器
gridView.setAdapter(adapter);//将适配器与GridView
gridView.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parant, View view, int position , long id) {
// TODO Auto-generated method stub
imageswitcher.setImageResource(imageId[position]);//显示选中的图片
}
});
附：Java全部代码
package com.example.eg_win7viewphoto;
import android.support.v7.app.ActionBarActivity;
import android.app.ActionBar.LayoutParams;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.AnimationUtils;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageSwitcher;
import android.widget.ImageView;
import android.widget.ViewSwitcher.ViewFactory;
public class MainActivity extends ActionBarActivity {
private int[] imageId=new int[]{
R.drawable.img01,R.drawable.img02,R.drawable.img03,R.drawable.img04,
R.drawable.img04,R.drawable.img05,R.drawable.img07,R.drawable.img08,
R.drawable.img09,R.drawable.img10,R.drawable.img11,R.drawable.img12
};
private ImageSwitcher imageswitcher;
private GridView gridView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
imageswitcher=(ImageSwitcher)findViewById(R.id.imageswitcher);
gridView=(GridView)findViewById(R.id.gridview);
imageswitcher.setInAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_in));
imageswitcher.setOutAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_out));
imageswitcher.setFactory(new ViewFactory() {
ImageView imageview1;
@Override
public View makeView() {
// TODO Auto-generated method stub
imageview1=new ImageView(MainActivity.this);
imageview1.setScaleType(ImageView.ScaleType.FIT_CENTER);
imageview1.setLayoutParams(new ImageSwitcher.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT));
return imageview1;
}
});
imageswitcher.setImageResource(imageId[((imageId.length)/2)]);
BaseAdapter adapter=new BaseAdapter() {
ImageView imageview2;
@Override
public View getView(int position, View contentView, ViewGroup parent) {
// TODO Auto-generated method stub
if(contentView==null){
imageview2=new ImageView(MainActivity.this);
/*****设置图像高度与宽度******/
imageview2.setAdjustViewBounds(true);
imageview2.setMaxHeight(113);
imageview2.setMaxWidth(150);
/**********************/
imageview2.setPadding(5, 5, 5, 5);
}else{
imageview2=(ImageView)contentView;
}
imageview2.setImageResource(imageId[position]);
return imageview2;
}
/*
* 获得当前选项的ID(non-Javadoc)
* @see android.widget.Adapter#getItemId(int)
*/
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
/**
* 获得当前选项
*/
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return position;
}
/**
* 获得数量
*/
@Override
public int getCount() {
// TODO Auto-generated method stub
return imageId.length;
}
};
gridView.setAdapter(adapter);//将适配器与GridView
gridView.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parant, View view, int position , long id) {
// TODO Auto-generated method stub
imageswitcher.setImageResource(imageId[position]);//显示选中的图片
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}