高级组件之画廊视图

1.使用gallery组件创建画廊视图
android:animationduration  设置列表项切换时的动画持续时间
android:gravity 设置对齐方式
android:spacing 设置列表之间的间距
android:unselectedalpha 设置没有选中的列表透明度
布局代码：
<Gallery
        android:id="@+id/gallery1"
        android:spacing="10px"
        android:unselectedAlpha="0.5"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
2.在res/values目录中，创建一个名称为attr的文件
代码如下：
<declare-styleable name="Gallery">
        <attr name="android:galleryItemBackground"/>
    </declare-styleable>
3.创建一个保存图片ID的数组
final int[] imageid = new int[]{R.drawable.img7,R.drawable.img8,
R.drawable.img9,R.drawable.img10,R.drawable.img11,
R.drawable.img12,R.drawable.img13,R.drawable.img14,
R.drawable.img15,R.drawable.img16,R.drawable.img17,
R.drawable.img18,R.drawable.img19,R.drawable.img20,
R.drawable.img21,R.drawable.img22,R.drawable.img23,
R.drawable.img24};
4.创建baseadapter类的对象，并重写getview(),getitemid(),getitem(),getcount()方法
Gallery gallery = (Gallery) findViewById(R.id.gallery1);
BaseAdapter baseAdapter = new BaseAdapter() {

@Override
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView;
if (convertView==null) {
imageView = new ImageView(MainActivity.this);
imageView.setScaleType(ImageView.ScaleType.FIT_XY);
imageView.setLayoutParams(new Gallery.LayoutParams(180, 135));
TypedArray typedArray = obtainStyledAttributes(R.styleable.Gallery);
imageView.setBackgroundResource(typedArray.getResourceId
(R.styleable.Gallery_android_galleryItemBackground, 0));
imageView.setPadding(5, 0, 5, 0);
}else {
imageView = (ImageView)convertView;
}
imageView.setImageResource(imageid[position]);
return imageView;
}



@Override
public long getItemId(int position) {
return position;
}

@Override
public Object getItem(int position) {
return position;
}

@Override
public int getCount() {
return imageid.length;
}
};
5.将适配器与gallery关联，并为gallery添加事件监听器
gallery.setAdapter(baseAdapter);
gallery.setSelection(imageid.length/2);
gallery.setOnItemClickListener(new OnItemClickListener() {

@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
Toast.makeText(MainActivity.this, "你选择了"+String.valueOf(position)+"张照片", Toast.LENGTH_SHORT).show();
}
});