Android的圖片瀏覽源碼解讀

Android手機作業系統的應用方式靈活，簡單，深受廣大編程愛好者的喜愛。尤其是它的開原始碼，使得我們能夠方便的得到自己想要的功能需求。今天我們就為大家帶來了有關Android圖片瀏覽的相關方法。
本文來自：安卓航班網www.apkway.com
原文連結處：
http://www.apkway.com/forum.php?mod=viewthread&tid=697&extra=
首先是Android圖片瀏覽中layout xml:

java代碼：
Java代碼 
[font=宋體]< ?xml version="1.0" encoding="utf-8"?> 
    < RelativeLayout xmlns:android="Android.com/apk/res/Android">http://schemas.Android.com/apk/res/Android" Android:layout_width="fill_parent" 
    Android:layout_height="fill_parent"> 
    < ImageSwitcher 
    Android:id="@+id/switcher" 
    Android:layout_width="fill_parent" 
    Android:layout_height="fill_parent" 
    Android:layout_alignParentTop="true" 
    Android:layout_alignParentLeft="true" /> 
    < Gallery 
    Android:id="@+id/gallery" 
    Android:background="#55000000" 
    Android:layout_width="fill_parent" 
    Android:layout_height="60dp" 
    Android:layout_alignParentBottom="true" 
    Android:layout_alignParentLeft="true" 
    Android:gravity="center_vertical" 
    Android:spacing="16dp" /> 
    < /RelativeLayout> [/font] 

layout裡面用到了前面所說的兩個控制項，ImageSwitcher用啦顯示全圖，Gallery用來顯示縮圖。著重看看ImageSwitcher,在ImageSwitcher1中需要實現ViewSwitcher.ViewFactory這個介面，這個介面裡有個方法makeView，這樣就產生了用來顯示圖片的view. ImageSwitcher調用過程是這樣的，首先要有一個Factory為它提供一個View，然後ImageSwitcher就可以初始化各種資源了。注意在使用一個ImageSwitcher之前，一定要調用setFactory方法，要不setImageResource這個方法會報null 指標異常。

       下面是Android圖片瀏覽代碼：

java代碼：
Java代碼 
[font=宋體]package com.zx.imageswitcher; 
 
    import Android.app.Activity; 
    import Android.content.Context; 
    import Android.os.Bundle; 
    import Android.view.View; 
    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.ViewSwitcher; 
    import Android.widget.Gallery.LayoutParams; 
 
    public class ImageSwitcherTest extends Activity implements AdapterView.OnItemSelectedListener, ViewSwitcher.ViewFactory{ 
    private ImageSwitcher mSwitcher; 
    private Integer[] mThumbIds = { 
    R.drawable.sample_thumb_0, R.drawable.sample_thumb_1, R.drawable.sample_thumb_2, R.drawable.sample_thumb_3, R.drawable.sample_thumb_4, R.drawable.sample_thumb_5, R.drawable.sample_thumb_6, R.drawable.sample_thumb_7}; 
    private Integer[] mImageIds = { 
    R.drawable.sample_0, R.drawable.sample_1, R.drawable.sample_2, R.drawable.sample_3, R.drawable.sample_4, R.drawable.sample_5, R.drawable.sample_6, R.drawable.sample_7}; 
    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.main); 
    mSwitcher = (ImageSwitcher) findViewById(R.id.switcher); 
    mSwitcher.setFactory(this); 
    mSwitcher.setInAnimation(AnimationUtils.loadAnimation(this, Android.R.anim.fade_in)); mSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this, Android.R.anim.fade_out)); 
    Gallery g = (Gallery) findViewById(R.id.gallery); 
    g.setAdapter(new ImageAdapter(this)); 
    g.setOnItemSelectedListener(this); 
    } 
    /* * override for ViewSwitcher.ViewFactory#makeView() */ 
    public View makeView() { 
    ImageView i = new ImageView(this); 
    i.setBackgroundColor(0xFF000000); 
    i.setScaleType(ImageView.ScaleType.FIT_CENTER); 
    i.setLayoutParams(new ImageSwitcher.LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT)); 
    return i; 
    } 
    /*
    * override for
    * AdapterView.OnItemSelectedListener#onItemSelected()
    */ 
    public void onItemSelected(AdapterView parent, View v, int position, long id) { mSwitcher.setImageResource(mImageIds[position]); 
    } 
    /*
    * override for AdapterView.OnItemSelectedListener#onNothingSelected()
    */ 
    public void onNothingSelected(AdapterView< ?> arg0) { 
    // TODO Auto-generated method stub 
    } 
    public class ImageAdapter extends BaseAdapter { 
    public ImageAdapter(Context c) { 
    mContext = c; 
    } 
    public int getCount() { 
    return mThumbIds.length; 
    } 
    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(mThumbIds[position]); 
    i.setAdjustViewBounds(true); 
    i.setLayoutParams(new Gallery.LayoutParams( LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT)); 
    i.setBackgroundResource(R.drawable.picture_frame); 
    return i; 
    } 
    private Context mContext; 
    } 
 
    } [/font]