用Itemtemplate或IValueConverter的LongListSelector的严重错误

我即将把我的头发脱落，但在我这样做之前，我会试着请你们帮忙…也许有人有同样的问题，可以帮助我。

所以这里是交易。我有一个名为SourceZoneselect的LongListSelector定义如下：

<phone:LongListSelector x:Name="SourceZoneselect" Grid.Row="2" LayoutMode="Grid" GridCellSize="160,160" BorderThickness="0" HorizontalContentAlignment="Stretch" VerticalContentAlignment="Stretch" Background="White" Width="480" Foreground="Black" ItemTemplate="{StaticResource DataTemplateContentZone}" {StaticResource LongListSelectorStyleContentZone}" ScrollViewer.VerticalScrollBarVisibility="Visible" Margin="-2,0"/>

ItemTemplate是一个DataTemplateSelector，如下所示：

还有2个值转换器：

in .xaml file <phone:PhoneApplicationPage.Resources> <local:PhotoSelectedConverter x:Name="PhotoSelectedConverter"/> <local:VideoSelectedConverter x:Name="VideoSelectedConverter"/> in .cs file public class PhotoSelectedConverter : IValueConverter { public object Convert(object value,Type typeName,object parameter,CultureInfo language) { bool selected = (bool)value; if (!selected) { return "Collapsed"; } else { return "Visible"; } } public object ConvertBack(object value,CultureInfo language) { return DependencyProperty.UnsetValue; } } public class VideoSelectedConverter : IValueConverter { public object Convert(object value,CultureInfo language) { double selected = (double)value; if (selected == 0.0) { return "Collapsed"; } else { return "Visible"; } } public object ConvertBack(object value,CultureInfo language) { return DependencyProperty.UnsetValue; } }

这是直接制作在数据模板上定义的名为GridSelected的Grid的代码，就好像item绑定 – > selected属性为false，GridSelected应该是Collapsed，如果它是true，那么它应该是Visible …

这里是代码：

... List<StayClassLibrary.Media> medias = await Media.GetMediasByAlbum(albmLst,App.Current.AppUser,App.Current.WSConfig); if (selectedSourceZone.Count > 0) { selectedSourceZone.Clear(); } selectedSourceZone = null; selectedSourceZone = new ObservableCollection<Idisposable>(); SourceZoneselect.ClearValue(LongListSelector.DataContextProperty); SourceZoneselect.ClearValue(LongListSelector.ItemsSourceProperty); SourceZoneselect.UpdateLayout(); popupsourceZone_Select.UpdateLayout(); GridSourceZoneselect.UpdateLayout(); if (medias.Count == 0) { NoImagesFound.Visibility = System.Windows.Visibility.Visible; } else { NoImagesFound.Visibility = System.Windows.Visibility.Collapsed; //Todo criar PictureItems foreach (StayClassLibrary.Media item in medias) { BitmapImage b = new BitmapImage(); b.UriSource = new Uri(item.thumbnail,UriKind.RelativeOrAbsolute); b.ImageFailed += b_ImageFailed; bool found = false; foreach (var media in selectedContentZone) { if(media.GetType() == typeof(PictureItemWeb)) { if(((PictureItemWeb)media).idMedia == item.idMidia) { if (!selectedSourceMedias.Contains(item.idMidia.ToString())) { found = true; } break; } } else if(media.GetType() == typeof(VideoItem)) { if (((VideoItem)media).idMedia == item.idMidia) { if (!selectedSourceMedias.Contains(item.idMidia.ToString())) { found = true; } break; } } } if (item.type == "image") { selectedSourceZone.Insert(0,new PictureItemWeb { Thumb = b,Pic = new BitmapImage(new Uri(item.source,UriKind.RelativeOrAbsolute)),dateBinary = DateTime.Now.ToBinary(),idAlbum = item.idAlbum,idMedia = item.idMidia,imgurl = item.source,ThumbUrl = item.thumbnail,selected = false,selectable = true,added = found,cancellationToken = new CancellationTokenSource() }); } else if (item.type == "video") { selectedSourceZone.Insert(0,new VideoItem { Thumb = b,VideoUrl = item.source,VideoThumbUrl = item.thumbnail,Selected = 0.0,cancellationToken = new CancellationTokenSource() }); } b = null; } if (selectedSourceZone.Count > 0) { Storyboard sb = new Storyboard(); DoubleAnimation fadein = new DoubleAnimation(); fadein.From = 0.0; fadein.To = 1.0; fadein.Duration = new Duration(TimeSpan.FromSeconds(0.35)); Storyboard.SetTarget(fadein,SourceZoneselect); Storyboard.SetTargetProperty(fadein,new PropertyPath("Opacity")); sb.Children.Add(fadein); sb.Begin(); SourceZoneselect.ItemsSource = null; SourceZoneselect.ClearValue(LongListSelector.DataContextProperty); SourceZoneselect.ClearValue(LongListSelector.ItemsSourceProperty); SourceZoneselect.ItemsSource = selectedSourceZone; // *1 foreach (var item in selectedSourceZone) { if(item.GetType() == typeof(PictureItemWeb)) { if(selectedSourceMedias.Contains(((PictureItemWeb)item).idMedia.ToString())) { ((PictureItemWeb)item).selected = true; } } else if (item.GetType() == typeof(VideoItem)) { if (selectedSourceMedias.Contains(((VideoItem)item).idMedia.ToString())) { ((VideoItem)item).Selected = 1.0; } } UpdateSelectedState(SourceZoneselect,item); // *2 } } else { NoImagesFound.Visibility = System.Windows.Visibility.Visible; Storyboard sb = new Storyboard(); DoubleAnimation fadein = new DoubleAnimation(); fadein.From = 0.0; fadein.To = 1.0; fadein.Duration = new Duration(TimeSpan.FromSeconds(0.35)); Storyboard.SetTarget(fadein,NoImagesFound); Storyboard.SetTargetProperty(fadein,new PropertyPath("Opacity")); sb.Children.Add(fadein); sb.Begin(); } }

* 1在这里，当我设置SourceZoneselect.ItemsSource = selectedSourceZone; 它应该激活IValueConverter它不…我有一个断点在那里，它永远不会经过那里。

* 2这个函数UpdateSelectedState（）我创build了试图手动修复和更新每个媒体的GridSelected可见性

private void UpdateSelectedState(DependencyObject targetElement,object item) { var count = VisualTreeHelper.GetChildrenCount(targetElement); if (count == 0) return; for (int i = 0; i < count; i++) { var child = VisualTreeHelper.GetChild(targetElement,i); if (child is Button) { Button targetItem = (Button)child; if (item.GetType() == typeof(PictureItemWeb)) { if (((PictureItemWeb)targetItem.DataContext).idMedia == ((PictureItemWeb)item).idMedia) { var g = targetItem.FindName("GridSelected"); if (((Guid)((Grid)g).Tag) == ((PictureItemWeb)item).idMedia) { if (((PictureItemWeb)item).selected) { ((Grid)g).Visibility = System.Windows.Visibility.Visible; } else { ((Grid)g).Visibility = System.Windows.Visibility.Collapsed; } } return; } } else if (item.GetType() == typeof(VideoItem)) { if (((VideoItem)targetItem.DataContext).idMedia == ((VideoItem)item).idMedia) { var g = targetItem.FindName("GridSelected"); if (((VideoItem)item).Selected == 1.0) { ((Grid)g).Visibility = System.Windows.Visibility.Visible; } else { ((Grid)g).Visibility = System.Windows.Visibility.Collapsed; } return; } return; } } else { UpdateSelectedState(child,item); } } }

这是我点击图片时的代码。（它所做的就是将所选属性更改为true / false，并显示/隐藏所选项目的GridSelected：

private void Button_SourceZone_Select_Click(object sender,RoutedEventArgs e) { var media = ((Button)sender).DataContext; if (media.GetType() == typeof(PictureItemWeb)) { int index = selectedSourceZone.IndexOf(((PictureItemWeb)((Button)sender).DataContext)); if (index != -1) { ((PictureItemWeb)selectedSourceZone.ElementAt(index)).selected = !((PictureItemWeb)selectedSourceZone.ElementAt(index)).selected; } var g = ((Button)sender).FindName("GridSelected"); if (((PictureItemWeb)selectedSourceZone.ElementAt(index)).selected) { ((Grid)g).Visibility = System.Windows.Visibility.Visible; } else { ((Grid)g).Visibility = System.Windows.Visibility.Collapsed; } } else if (media.GetType() == typeof(VideoItem)) { int index = selectedSourceZone.IndexOf(((VideoItem)((Button)sender).DataContext)); if (index != -1) { ((VideoItem)selectedSourceZone.ElementAt(index)).Selected = (((VideoItem)selectedSourceZone.ElementAt(index)).Selected == 0.0) ? 1.0 : 0.0; } var g = ((Button)sender).FindName("GridSelected"); if (((VideoItem)selectedSourceZone.ElementAt(index)).Selected == 1.0) { ((Grid)g).Visibility = System.Windows.Visibility.Visible; } else { ((Grid)g).Visibility = System.Windows.Visibility.Collapsed; } } }

好吧，所有的代码现在在这里。

我没有发布的唯一的事情是当我点击确认select时的function..它所做的就是将媒体的ID添加到列表中，如：

selectedSourceMedias.Add(((PictureItemWeb)item).idMedia.ToString());

然后closurespopup窗口并将longlistselector设置为null。

所以当我点击一个button来再次显示列表。它重新创build了整个列表！如我发布的第一个代码所示（它请求媒体，将longlistselector再次设置为null，并重新创buildlonglist项目（哪一个PictureWeb和VideoItem都是Idisposable）。

最后！这是让我发疯的原因。我已经debugging过，它应该是完美的工作！但是情况是这样的：

我第一次发现，所有媒体都没有选中。那很好。（ValueConverter首次在这里激活）

然后，如果我closures并再次打开，它们将被重新创build，并且仍然全部被取消选中（GridSelected全部被折叠）（但是现在，ValueConverter未被激活）

现在我select前3个媒体，我点击的3 UI元素的GridSelected被更改为可见，然后我确认select。（我debugging，正确的ID保存在selectedSourceMedias）

然后我点击再次打开列表。（所有东西都被重新创build，并在// * 1之前将ItemsSource设置为新创build的selectedSourceZone，并且不调用ValueConverted）

在// * 1之后，我手动将所选的和UpdateSelectedStatus（）设置为每一个（debugging时也select了正确的介质（第一到第三个））（（Grid）g）.Visibility = System .Windows.Visibility.Visible;以及在selectedSourceMedias ID列表上的所有其他选项都通过折叠行…

现在，当所有的代码运行，并返回到模拟器的顶部的3张照片（应该有GridSelected可见的那些是折叠和3张照片吃完列表的末尾显示为选定!!!是让我疯狂的错误）

还有更多！如果我点击另一个button，加载completelly新的媒体（ValueConverted被激活，所有通过折叠（这是很好））通过它显示模拟器和前3名的照片显示为选定的！

所以我认为有一个内部的错误，使数据模板具有相同的名称（“GridSelected”）

我知道这可能会让你头疼，但是请尽量帮助我！

让我知道你是否有类似的问题，以及你如何解决这个问题。

谢谢大家！！！

好吧，我找到了解决我的问题…如果你有任何人发现自己的这个问题…请注意，有一个错误，在某些地方没有清理它的缓存或什么…解决方案是我只是在设置SourceZoneselect.ItemsSource之前添加这些行：

SourceZoneselect.ClearValue(LongListSelector.ItemTemplateProperty); SourceZoneselect.ItemTemplate = null; SourceZoneselect.ItemTemplate = this.Resources["DataTemplateContentZone"] as DataTemplate;

所以如果你想每次运行转换器，都需要手动清除模板并重新应用

用Itemtemplate或IValueConverter的LongListSelector的严重错误

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