滚动时,图像在滑块视图和列表视图中消失
本文关键字:视图 列表 消失 图像 滚动 | 更新日期: 2023-09-27 17:57:05
我有一个SliderView(AppStudio.Uwp.Controls)。图像在我加载页面后立即出现,但在滚动列表时消失。我也用列表视图对此进行了测试。同样的事情也在那里发生。
<controls:SliderView x:Name="sliderView" ItemsSource="{x:Bind listForOtherPicturesThumbnails}" ItemTemplate="{StaticResource Hero}"
RelativePanel.Below="mainImage"
RelativePanel.AlignLeftWithPanel="True"
RelativePanel.AlignRightWithPanel="True"
ArrowsVisibility="Visible"
/>
使用的项模板如下-
<DataTemplate x:Key="Hero" x:DataType="local:StorageItemThumbnailClass">
<Grid Margin="6" Padding="12" Background="White" BorderThickness="1" BorderBrush="LightGray">
<Image Source="{x:Bind Thumbnail, Converter={StaticResource ThumbnailtoImageConverter}}" Stretch="UniformToFill" HorizontalAlignment="Center" VerticalAlignment="Center" />
</Grid>
</DataTemplate>
缩略图在OnNavigated函数中生成如下-
protected async override void OnNavigatedTo(NavigationEventArgs e)
{
otherPicturesPathList = ((PictureWithList)e.Parameter).pathList;
await PopulateListOfOtherPicturesThumbnailsAsync();
Bindings.Update();
}
private async Task PopulateListOfOtherPicturesThumbnailsAsync()
{
if (otherPicturesPathList != null)
{
List<Task<StorageItemThumbnail>> thumbnailOperations = new List<Task<StorageItemThumbnail>>();
foreach (var path in otherPicturesPathList)
{
var storageFile = await StorageFile.GetFileFromPathAsync(path);
thumbnailOperations.Add(storageFile.GetThumbnailAsync(Windows.Storage.FileProperties.ThumbnailMode.PicturesView, 100).AsTask());
}
await Task.WhenAll(thumbnailOperations);
for (int k = 0; k < thumbnailOperations.Count; k++)
{
var task = thumbnailOperations[k];
listForOtherPicturesThumbnails.Add(new StorageItemThumbnailClass { Thumbnail = task.Result });
}
}
}
缩略图到图像转换器-
public object Convert(object value, Type targetType, object parameter, string language)
{
BitmapImage image = null;
if (value != null)
{
if (value.GetType() != typeof(StorageItemThumbnail))
{
throw new ArgumentException("Expected a thumbnail");
}
StorageItemThumbnail thumbnail = (StorageItemThumbnail)value;
image = new BitmapImage();
image.SetSource(thumbnail);
}
return (image);
}
存储项缩略图类-
public class StorageItemThumbnailClass : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
private StorageItemThumbnail _thumbnail;
private string _name;
public StorageItemThumbnail Thumbnail
{
get { return _thumbnail; }
set
{
_thumbnail = value;
// Call OnPropertyChanged whenever the property is updated
OnPropertyChanged("Thumbnail");
}
}
// Create the OnPropertyChanged method to raise the event
protected void OnPropertyChanged(string name)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(name));
}
public String Name
{
get { return _name; }
set
{
_name = value;
// Call OnPropertyChanged whenever the property is updated
OnPropertyChanged("Name");
}
}
}
如何解决此问题,以便图像保持首次加载页面时看到的样子?
我偶然发现了完全相同的问题。
解决方案是在ThumbnailtoImageConverter
中添加thumbnail.Seek(0);
。
//...
StorageItemThumbnail thumbnail = (StorageItemThumbnail)value;
thumbnail.Seek(0);
image = new BitmapImage();
image.SetSource(thumbnail);
引用链接:滚动时图像在滑块视图和列表视图中消失
我无法测试您的代码,但有两个建议:
- 您是否尝试过在转换器中设置断点?
- 看看Visual Studio的"输出"面板,也许你可以得到一些关于你的问题的信息
- 将您的代码替换为以下内容:
thumbnailOperations.Add(await storageFile.GetThumbnailAsync(Windows.Storage.FileProperties.ThumbnailMode.PicturesView, 100));
恕我直言,异步/等待模式有问题。