第四课 Gallery的使用

直接上代码

1.Layout——Main.axml

<?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"

    android:minWidth="25px"

    android:minHeight="25px">

    <TextView

        android:text="@string/Welcome"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:id="@+id/textView1" />

    <Gallery

        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:id="@+id/gallery1" />

</LinearLayout>

2.Activity1.cs

using System;

using Android.App;

using Android.Content;

using Android.Runtime;

using Android.Views;

using Android.Widget;

using Android.OS;

using Android.Database;

using Android.Provider;

namespace GalleryViewDemo

    [Activity(Label = "Gallery View Sample", MainLauncher = true, Icon = "@drawable/icon")]

    public class GalleryViewSample : Activity

        protected override void OnCreate(Bundle bundle)

            base.OnCreate(bundle);

            // Set our view from the "main" layout resource

            SetContentView(Resource.Layout.Main);

            CreateGallery();

        private void CreateGallery()

            Gallery g = this.FindViewById<Gallery>(Resource.Id.gallery1);

            g.Adapter = new ImageAdapter(this);

3.ImageAdapter.cs

using System;using System.Collections.Generic;using System.Linq;using System.Text;using Android;using Android.App;using Android.Content;using Android.OS;using Android.Runtime;using Android.Views;using Android.Widget;using Android.Database;using Android.Provider;namespace GalleryViewDemo{    public class ImageAdapter : BaseAdapter    {        Context _Context;        ICursor _ImageCursor;        protected ICursor ImageCursor        {            get            {                if (_ImageCursor == null)                {                    _ImageCursor = GetImageCursor();                }                return _ImageCursor;            }            set            {                _ImageCursor = value;            }        }        public ImageAdapter(Context c)        {            _Context = c;        }        private ICursor GetImageCursor()        {            string[] Projection = { MediaStore.Images.Thumbnails.ImageId };            var ImageCursor = ((Activity)_Context).ManagedQuery(MediaStore.Images.Thumbnails.ExternalContentUri,                Projection, null, null, null);            return ImageCursor;        }        public override int Count        {            get { return ImageCursor.Count; }        }        public override Java.Lang.Object GetItem(int position)        {            return position;        }        public override long GetItemId(int position)        {            ImageCursor.MoveToPosition(position);            var ImageId = ImageCursor.GetString(0);            return position;        }        public override View GetView(int position, View convertView, ViewGroup parent)        {            if (convertView == null)            {                ImageView ReturnView = new ImageView(_Context);                ImageCursor.MoveToPosition(position);                var ImageId = ImageCursor.GetString(0);                ReturnView.SetImageURI(Android.Net.Uri.WithAppendedPath(MediaStore.Images.Thumbnails.ExternalContentUri, ImageId));                ReturnView.SetScaleType(ImageView.ScaleType.CenterCrop);                return ReturnView;            }            else            {                return(ImageView) convertView;            }        }    }}

在模拟器中,先下载了两幅图片,运行成功。

在手机上运行失败，尚不知道原因，求解。

1.Layout——Main.axml

2.Activity1.cs

3.ImageAdapter.cs

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