畫廊(Gallery), 實現OnItemSelectedListener把圖形顯示在圖像視圖(ImageView)上

延續上一篇文章畫廊(Gallery), 這次練習實現OnItemSelectedListener, 把正被選擇的圖形(即正中間那一個)顯示在佈局內的另一個圖像視圖(ImageView)上.



先創建一個文件夾/res/drawable, 並複製一些PNG圖形到/res/drawable內. 我使用的文件名為a01.png~a15.png.

修改main.xml, 在Gallery外多加一個圖像視圖(ImageView).

<?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"
  />
<ImageView
  android:id="@+id/imageview"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  />
</LinearLayout>

修改源碼.

package com.AndroidGallery;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.ImageView;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;


public class AndroidGallery extends Activity{

private ImageView myImageView;

/** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.main);
    
      myImageView = (ImageView)findViewById(R.id.imageview);
    
      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
   myImageView.setImageResource(mThumbIds[arg2]);
  }

  @Override
  public void onNothingSelected(AdapterView<?> arg0) {
   // TODO Auto-generated method stub
  
  }
  
  };

  private Integer[] mThumbIds = {
          R.drawable.a01,
          R.drawable.a02,
          R.drawable.a03,
          R.drawable.a04,
          R.drawable.a05,
          R.drawable.a06,
          R.drawable.a07,
          R.drawable.a08,
          R.drawable.a09,
          R.drawable.a10,
          R.drawable.a11,
          R.drawable.a12,
          R.drawable.a13,
          R.drawable.a14,
          R.drawable.a15,
        };

  public class ImageAdapter extends BaseAdapter{
   private Context context;
 
   public ImageAdapter(Context c){
    context = c;
   }
 
   @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;
   }
  }
}

參考另一篇: "畫廊(Gallery), 及有一點動畫效果的圖像切換器(ImageSwitcher)"