android初体验-HelloGallery实例详解

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="Gallery">
        <attr name="android:galleryItemBackground">
        </attr>
    </declare-styleable>
</resources>

    public ImageAdapter(Context c) {
        mContext = c;
        TypedArray a = obtainStyledAttributes(android.R.styleable.Theme);
        mGalleryItemBackground = a.getResourceId(
                android.R.styleable.Theme_galleryItemBackground, 0);
        a.recycle();
    }

    public ImageAdapter(Context c) {
        mContext = c;
        TypedArray a = c.obtainStyledAttributes(R.styleable.Gallery);
        mGalleryItemBackground = a.getResourceId(
                R.styleable.Gallery_galleryItemBackground, 0);
        a.recycle();
    }

<?xml version="1.0" encoding="utf-8"?>
<AbsoluteLayout
    android:id="@+id/widget_absolutelayout"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    xmlns:android="http://schemas.android.com/apk/res/android"
 >
	<Gallery
		android:id="@+id/gallery"
	    android:layout_width="fill_parent"
	    android:layout_height="wrap_content"
 
	/>
	<!-- Gallery 屏幕上方显示一排图片，滚动显示 -->
	<ImageView
		android:id="@+id/view_photo"
		android:layout_width="fill_parent"
		android:layout_height="wrap_content"
		android:layout_y="100px"
	/>
	<!-- ImageView 屏幕下方显示选中的那张图片的大图 -->
</AbsoluteLayout>

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="Gallery">
        <attr name="android:galleryItemBackground">
        </attr>
    </declare-styleable>
</resources>

public class HelloGallery extends Activity {
 
	private ImageView imageView;
	private ImageAdapter imageAdapter;
 
	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);
		imageAdapter = new ImageAdapter(this);
		imageView = (ImageView) findViewById(R.id.view_photo);
		Gallery g = (Gallery) findViewById(R.id.gallery);
		g.setAdapter(new ImageAdapter(this));
		g.setOnItemClickListener(new OnItemClickListener() {
			public void onItemClick(AdapterView parent, View v, int position,
					long id) {
				Toast.makeText(
						HelloGallery.this,
						"" + imageAdapter.mImageIds[position] + "this is "
								+ position + " photo", Toast.LENGTH_SHORT)
						.show();
 
				imageView.setBackgroundResource
(imageAdapter.mImageIds[position]);
			}
		});
	}
}

public class ImageAdapter extends BaseAdapter {
 
	int mGalleryItemBackground;
	private Context mContext;
 
	public Integer[] mImageIds = { R.drawable.budala, R.drawable.cloud,
			R.drawable.cloud_2, R.drawable.green, R.drawable.greenwater,
			R.drawable.hill, R.drawable.hillsunning, R.drawable.mountain,
			R.drawable.tibet, R.drawable.tree_water, R.drawable.water };
 
	public ImageAdapter(Context c) {
		mContext = c;
		TypedArray a = c.obtainStyledAttributes(R.styleable.Gallery);
		// obtainStyledAtrributes is a method of Context class,so add the c.
		// before this method
		mGalleryItemBackground = a.getResourceId(
				R.styleable.Gallery_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.setLayoutParams(new Gallery.LayoutParams(150, 100));
		i.setScaleType(ImageView.ScaleType.FIT_XY);
		i.setBackgroundResource(mGalleryItemBackground);
 
		return i;
	}
}