本示例为通过媒体内容提供器获取本机中的图片显示在Gallery中。
活动中简单的初始化代码
private void InitGallery()
{
Gallery gallery = FindViewById<Gallery> (Resource.Id.gallery);
gallery.Adapter = new ImageAdapter (this);
}
ImageAdapter 类为自己定义的适配器，继承BaseAdapter类，其中核心代码为GetView方法。
BaseAdapter为抽象类必须实现指定方法，右键BaseAdapter类，选择Implement Abstract Class，添加要实现的方法。
ImageAdapter 的代码实现
public class ImageAdapter:BaseAdapter
{
private Context context; public ImageAdapter(Context context)
{
this.context = context;
} #region implemented abstract members of BaseAdapter
public override Java.Lang.Object GetItem (int position)
{
ImageCursor.MoveToPosition (position);
return ImageCursor.GetString ();
}
public override long GetItemId (int position)
{
return position;
}
public override View GetView (int position, View convertView, ViewGroup parent)
{
//避免不断的销毁和创建新视图
if (convertView == null) {
ImageView imageView = new ImageView (context);
ImageCursor.MoveToPosition (position);
var imageUrl = ImageCursor.GetString ();
Console.WriteLine (imageUrl);
//根据输出判断 MediaStore.Images.Media.InterfaceConst.Data 查询结果为图片路径
//imageView.SetImageURI (Android.Net.Uri.WithAppendedPath(MediaStore.Images.Media.ExternalContentUri,imageID));
imageView.SetImageURI (Android.Net.Uri.Parse(imageUrl));
imageView.SetScaleType (ImageView.ScaleType.FitCenter);
return imageView;
} else {
return convertView as ImageView;
}
}
public override int Count {
get {
return ImageCursor.Count;
}
}
#endregion private Android.Database.ICursor imageCursor;
public Android.Database.ICursor ImageCursor {
get{
if (imageCursor==null) {
imageCursor = GetImageCursor ();
}
return imageCursor;
}
set{ imageCursor = value; }
} //查询本机图片
private Android.Database.ICursor GetImageCursor(){
return (context as Activity).ManagedQuery (MediaStore.Images.Media.ExternalContentUri,
new string[] {MediaStore.Images.Media.InterfaceConsts.Data},null,null,null);
}
}
注意：一定要保证本机或者模拟器中存在图片文件，不然会报出No entry for content的异常。
此外学的过程中了解到一个Xamarin组件，地址：http://components.xamarin.com/view/xamarin.mobile，不知道效果怎么要。