android.R.drawable

Android提供一些自帶的drawable資源, 由17301504至17301655; 可以通過android.R.drawable存取.

這篇文章修改上一個練習"畫廊(Gallery), 及有一點動畫效果的圖像切換器(ImageSwitcher)", 演示Android的drawable資源.



修改main.xml添加一個TextView, 顯示drawable資源的ID.

<?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"
    >
<Gallery
 android:id="@+id/gallery"
 android:layout_width="fill_parent"
 android:layout_height="100dp"
 android:spacing="10dp"
    />
<TextView
 android:layout_width="fill_parent"
 android:layout_height="wrap_content"
 android:id="@+id/resourceid"
 />
<ImageSwitcher
 android:id="@+id/imageswitcher"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
 />
</LinearLayout>

修改主程序, 主要在ImageAdapter的構造方法, 和OnItemSelectedListener的onItemSelected方法:

package com.AndroidGallery;

import android.app.Activity;
import android.content.Context;
import android.content.res.Resources;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.view.animation.AnimationUtils;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.ImageSwitcher;
import android.widget.ImageView;
import android.widget.AdapterView;
import android.widget.TextView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ViewSwitcher.ViewFactory;


public class AndroidGallery extends Activity implements ViewFactory{

 final int resourceStart = 17301504;
 final int resourceEnd = 17301655;
 final int ResourceLength = resourceEnd - resourceStart + 1; 
 
 private ImageSwitcher myImageSwitcher;
 private TextView resourceID;

 /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        resourceID = (TextView)findViewById(R.id.resourceid);
        
        myImageSwitcher = (ImageSwitcher)findViewById(R.id.imageswitcher);
        myImageSwitcher.setFactory(this);
        myImageSwitcher.setInAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_in));
        myImageSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_out));
        
        Gallery myGallery = (Gallery)findViewById(R.id.gallery);
        myGallery.setAdapter(new ImageAdapter(this));
        myGallery.setOnItemSelectedListener(myGalleryOnItemSelectedListener);
    }
    
    private OnItemSelectedListener myGalleryOnItemSelectedListener
     = new OnItemSelectedListener(){

   @Override
   public void onItemSelected(AdapterView<?> arg0, View arg1,
     int arg2, long arg3) {
    // TODO Auto-generated method stub
    myImageSwitcher.setImageResource(mThumbIds[arg2]);
    
    String strResource =
         arg0.getAdapter().getItem(arg2).toString() +
         " " +
         Resources.getSystem().getResourceName(arg2+resourceStart);
    resourceID.setText(strResource);
   }

   @Override
   public void onNothingSelected(AdapterView<?> arg0) {
    // TODO Auto-generated method stub
    
   }
     
    };
    
    private int[] mThumbIds = new int[ResourceLength];
    
    public class ImageAdapter extends BaseAdapter{
     private Context context;
     
     public ImageAdapter(Context c){
      context = c;
      for ( int i = 0; i < ResourceLength; i++)
      {
       mThumbIds[i] = i + resourceStart;
      }
     }
     
     @Override
     public int getCount() {
      // TODO Auto-generated method stub
      return mThumbIds.length;
     }

     @Override
     public Object getItem(int position) {
      // TODO Auto-generated method stub
      return mThumbIds[position];
     }

     @Override
     public long getItemId(int position) {
      // TODO Auto-generated method stub
      return position;
     }

     @Override
     public View getView(int position, View convertView, ViewGroup parent) {
      // TODO Auto-generated method stub
      ImageView imageView;
      if (convertView == null) {
       // if it's not recycled, initialize some attributes
       imageView = new ImageView(context);
       imageView.setLayoutParams(new Gallery.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
       imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
       imageView.setPadding(8, 8, 8, 8);
      } else {
             imageView = (ImageView) convertView;
      }
      imageView.setImageResource(mThumbIds[position]);
      return imageView;
     }
    }

 @Override
 public View makeView() {
  // TODO Auto-generated method stub
  ImageView i = new ImageView(this);
        i.setScaleType(ImageView.ScaleType.FIT_CENTER);
        i.setLayoutParams(new ImageSwitcher.LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
        return i;
 }
}