Android API 实验记录 (三）

不知道大家做了HelloGallery试验没有。

兄弟本来Gallery试验早就做了，先开始是参照HelloViews文档做。貌似不行。主要问题是没有贴一个主题样式配置文件。

小抱怨一下Android SDK文档的更新不及时以及太概述，可能是Google有意要锻炼大家的学习主动性。

瞎话少叙，实例伺候。

 

Step1、布局及资源

 

main.xml

 

xml version ="1.0" encoding ="utf-8" ?>
< LinearLayout xmlns:android ="http://schemas.android.com/apk/res/android"
         android:orientation ="vertical"
         android:layout_width ="fill_parent"
         android:layout_height ="fill_parent"
         >
   < TextView    
         android:layout_width ="fill_parent"    
         android:layout_height ="wrap_content"    
         android:text ="@string/hello"
         />
   < Gallery
     android:layout_width ="fill_parent"
     android:layout_height ="wrap_content"
     android:id ="@+id/gallery" >
   Gallery >
        
LinearLayout >

 

string.xml

xml version ="1.0" encoding ="utf-8" ?>
< resources >
         < string name ="hello" >Hello World, HiGallery! string >
         < string name ="app_name" >HiGallery string >
         < string name ="gallery_text" >Gallery Context button test string >
resources >

 

如果你的HelloGallery抱怨，请把下面配置文件补上。

attrs.xml

xml version ="1.0" encoding ="utf-8" ?>

< resources >
        
        
         < declare-styleable name ="GalleryOne" >
                 < attr name ="android:galleryItemBackground" />
         declare-styleable >
        
resources >

 

Step2、Java代码

package com.penguin7.gallery;

import android.app.Activity;
import android.content.Context;
import android.content.res.TypedArray;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.view.ContextMenu.ContextMenuInfo;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.ImageView;
import android.widget.Toast;
import android.widget.AdapterView.AdapterContextMenuInfo;

public class HiGallery extends Activity {
         /** Called when the activity is first created. */
        @Override
         public void onCreate(Bundle savedInstanceState) {
                 super.onCreate(savedInstanceState);
                setContentView(R.layout.main);
                
                 // 引用Gallery视图
                Gallery g = (Gallery)findViewById(R.id.gallery);
                 // 设定适配Gallery对象为自定义图像适配器ImageAdapter
                g.setAdapter( new ImageAdapter( this));
                
                 // 新建AdapterView匿名对象设定事件监听，并使用Toast消息提示
                g.setOnItemClickListener( new AdapterView.OnItemClickListener() {
                  @Override
                         public void onItemClick(AdapterView parent, View v, int position, long id) {
                                Toast.makeText(HiGallery. this, "This is number " + position, Toast.LENGTH_SHORT).show();
                        }
                });
                
                 // 为Gallery对象注册背景上下文按钮
                registerForContextMenu(g);
        }

        @Override
         public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) {
                menu.add(R.string.gallery_text);
        }
        
        @Override
         public boolean onContextItemSelected(MenuItem item) {
                AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo();
                Toast.makeText( this, "Context Menu Longpress: " + info.position, Toast.LENGTH_SHORT).show();
                 return true;
        }

         public class ImageAdapter extends BaseAdapter {
                 int mGalleryItemBackground;
                
                 public ImageAdapter(Context c) {
                        mContext = c;
                         // 获取上下文主题风格信息 定义在res/values/attrs.xml中
                        TypedArray a = obtainStyledAttributes(R.styleable.GalleryOne);
                        mGalleryItemBackground = a.getResourceId(
                                        R.styleable.GalleryOne_android_galleryItemBackground, 0);
                        a.recycle();
                }

                 public int getCount() {
                         return mImageIds.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(mImageIds[position]);
                        i.setScaleType(ImageView.ScaleType.FIT_XY);
                        i.setLayoutParams( new Gallery.LayoutParams(136, 88));
                        
                         // The preferred Gallery item background
                        i.setBackgroundResource(mGalleryItemBackground);
                        
                         return i;
                }

                 private Context mContext;

                 private Integer[] mImageIds = {
                                R.drawable.gallery_photo_1,
                                R.drawable.gallery_photo_2,
                                R.drawable.gallery_photo_3,
                                R.drawable.gallery_photo_4,
                                R.drawable.gallery_photo_5,
                                R.drawable.gallery_photo_6,
                                R.drawable.gallery_photo_7,
                                R.drawable.gallery_photo_8
                };
        }

}

 

Step3、效果图