OpenTween/ImageListViewItem.cs

   1 // OpenTween - Client of Twitter
   2 // Copyright (c) 2007-2011 kiri_feather (@kiri_feather) <kiri.feather@gmail.com>
   3 //           (c) 2008-2011 Moz (@syo68k)
   4 //           (c) 2008-2011 takeshik (@takeshik) <http://www.takeshik.org/>
   5 //           (c) 2010-2011 anis774 (@anis774) <http://d.hatena.ne.jp/anis774/>
   6 //           (c) 2010-2011 fantasticswallow (@f_swallow) <http://twitter.com/f_swallow>
   7 //           (c) 2011      Egtra (@egtra) <http://dev.activebasic.com/egtra/>
   8 // All rights reserved.
   9 //
  10 // This file is part of OpenTween.
  11 //
  12 // This program is free software; you can redistribute it and/or modify it
  13 // under the terms of the GNU General Public License as published by the Free
  14 // Software Foundation; either version 3 of the License, or (at your option)
  15 // any later version.
  16 //
  17 // This program is distributed in the hope that it will be useful, but
  18 // WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  19 // or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  20 // for more details.
  21 //
  22 // You should have received a copy of the GNU General Public License along
  23 // with this program. If not, see <http://www.gnu.org/licenses/>, or write to
  24 // the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
  25 // Boston, MA 02110-1301, USA.
  26
  27 using System;
  28 using System.Net.Http;
  29 using System.Threading.Tasks;
  30 using System.Windows.Forms;
  31
  32 namespace OpenTween
  33 {
  34     public class ImageListViewItem : ListViewItem
  35     {
  36         protected readonly ImageCache imageCache;
  37         protected readonly string imageUrl;
  38
  39         /// <summary>
  40         /// 状態表示に使用するアイコンのインデックスを取得・設定する。
  41         /// </summary>
  42         /// <remarks>
  43         /// StateImageIndex は不必要な処理が挟まるため、使用しないようにする。
  44         /// </remarks>
  45         public int StateIndex { get; set; }
  46
  47         private WeakReference imageReference = new WeakReference(null);
  48         private Task imageTask = null;
  49
  50         public event EventHandler ImageDownloaded;
  51
  52         public ImageListViewItem(string[] items)
  53             : this(items, null, null)
  54         {
  55         }
  56
  57         public ImageListViewItem(string[] items, ImageCache imageCache, string imageUrl)
  58             : base(items)
  59         {
  60             this.imageCache = imageCache;
  61             this.imageUrl = imageUrl;
  62             this.StateIndex = -1;
  63
  64             var image = imageCache?.TryGetFromCache(imageUrl);
  65
  66             if (image != null)
  67                 this.imageReference.Target = image;
  68         }
  69
  70         public Task GetImageAsync(bool force = false)
  71         {
  72             if (this.imageTask == null || this.imageTask.IsCompleted)
  73             {
  74                 this.imageTask = this.GetImageAsyncInternal(force);
  75             }
  76
  77             return this.imageTask;
  78         }
  79
  80         private async Task GetImageAsyncInternal(bool force)
  81         {
  82             if (string.IsNullOrEmpty(this.imageUrl))
  83                 return;
  84
  85             if (!force && this.imageReference.Target != null)
  86                 return;
  87
  88             try
  89             {
  90                 var image = await this.imageCache.DownloadImageAsync(this.imageUrl, force);
  91
  92                 this.imageReference.Target = image;
  93
  94                 if (this.ListView == null || !this.ListView.Created || this.ListView.IsDisposed)
  95                     return;
  96
  97                 if (this.Index < this.ListView.VirtualListSize)
  98                 {
  99                     this.ListView.RedrawItems(this.Index, this.Index, true);
 100
 101                     this.ImageDownloaded?.Invoke(this, EventArgs.Empty);
 102                 }
 103             }
 104             catch (HttpRequestException) { }
 105             catch (InvalidImageException) { }
 106             catch (TaskCanceledException) { }
 107         }
 108
 109         public MemoryImage Image
 110         {
 111             get
 112             {
 113                 return (MemoryImage)this.imageReference.Target;
 114             }
 115         }
 116
 117         public Task RefreshImageAsync()
 118         {
 119             this.imageReference.Target = null;
 120             return this.GetImageAsync(true);
 121         }
 122     }
 123 }