Ran*_*dom 6 c# wpf multithreading image
我正在一个标记为STA的不同线程中创建一个Window,这个窗口有一些控件和图像.
我去关闭这个窗口并打开主UI空间中的另一个窗口我有一个打印对话框并使用以下代码来获取FixedDocumentSequence:
var tempFileName = System.IO.Path.GetTempFileName();
File.Delete(tempFileName);
using (var xpsDocument = new XpsDocument(tempFileName, FileAccess.ReadWrite, CompressionOption.NotCompressed))
{
var writer = XpsDocument.CreateXpsDocumentWriter(xpsDocument);
writer.Write(this.DocumentPaginator);
}
using (var xpsDocument = new XpsDocument(tempFileName, FileAccess.Read, CompressionOption.NotCompressed))
{
var xpsDoc = xpsDocument.GetFixedDocumentSequence();
return xpsDoc;
}
在线上:
writer.Write(this.DocumentPaginator);
我从内部调用VerifyAccess获取InvalidOperationException,这是StackTrace:
bei System.Windows.Threading.Dispatcher.VerifyAccess()
bei System.Windows.Threading.DispatcherObject.VerifyAccess()
bei System.Windows.Media.Imaging.BitmapDecoder.get_IsDownloading()
bei System.Windows.Media.Imaging.BitmapFrameDecode.get_IsDownloading()
bei System.Windows.Media.Imaging.BitmapSource.FreezeCore(Boolean isChecking)
bei System.Windows.Freezable.Freeze(Boolean isChecking)
bei System.Windows.PropertyMetadata.DefaultFreezeValueCallback(DependencyObject d, DependencyProperty dp, EntryIndex entryIndex, PropertyMetadata metadata, Boolean isChecking)
bei System.Windows.Freezable.FreezeCore(Boolean isChecking)
bei System.Windows.Media.Animation.Animatable.FreezeCore(Boolean isChecking)
bei System.Windows.Freezable.Freeze()
bei System.Windows.Media.DrawingDrawingContext.DrawImage(ImageSource imageSource, Rect rectangle, AnimationClock rectangleAnimations)
bei System.Windows.Media.DrawingDrawingContext.DrawImage(ImageSource imageSource, Rect rectangle)
bei System.Windows.Media.DrawingContextDrawingContextWalker.DrawImage(ImageSource imageSource, Rect rectangle)
bei System.Windows.Media.RenderData.BaseValueDrawingContextWalk(DrawingContextWalker ctx)
bei System.Windows.Media.DrawingServices.DrawingGroupFromRenderData(RenderData renderData)
bei System.Windows.UIElement.GetDrawing()
bei System.Windows.Media.VisualTreeHelper.GetDrawing(Visual reference)
bei System.Windows.Xps.Serialization.VisualTreeFlattener.StartVisual(Visual visual)
bei System.Windows.Xps.Serialization.ReachVisualSerializer.SerializeTree(Visual visual, XmlWriter resWriter, XmlWriter bodyWriter)
bei System.Windows.Xps.Serialization.ReachVisualSerializer.SerializeObject(Object serializedObject)
bei System.Windows.Xps.Serialization.DocumentPageSerializer.SerializeChild(Visual child, SerializableObjectContext parentContext)
bei System.Windows.Xps.Serialization.DocumentPageSerializer.PersistObjectData(SerializableObjectContext serializableObjectContext)
bei System.Windows.Xps.Serialization.ReachSerializer.SerializeObject(Object serializedObject)
bei System.Windows.Xps.Serialization.DocumentPageSerializer.SerializeObject(Object serializedObject)
bei System.Windows.Xps.Serialization.DocumentPaginatorSerializer.PersistObjectData(SerializableObjectContext serializableObjectContext)
bei System.Windows.Xps.Serialization.DocumentPaginatorSerializer.SerializeObject(Object serializedObject)
bei System.Windows.Xps.Serialization.XpsSerializationManager.SaveAsXaml(Object serializedObject)
bei System.Windows.Xps.XpsDocumentWriter.SaveAsXaml(Object serializedObject, Boolean isSync)
bei System.Windows.Xps.XpsDocumentWriter.Write(DocumentPaginator documentPaginator)
由于StackTrace做了一些调用BitmapSource/BitmapDecoder,我想到尝试删除图像并将原位Image控件的Source设置为null
<Image Source={x:Null} />
在我使用我的所有图像执行此操作后,我的代码运行顺利,并且没有更多异常被触发.
我尝试使用以下方法制作自定义图像以解决此问题:
public class CustomImage : Image
{
public CustomImage()
{
this.Loaded += CustomImage_Loaded;
this.SourceUpdated += CustomImage_SourceUpdated;
}
private void CustomImage_SourceUpdated(object sender, System.Windows.Data.DataTransferEventArgs e)
{
FreezeSource();
}
private void CustomImage_Loaded(object sender, System.Windows.RoutedEventArgs e)
{
FreezeSource();
}
private void FreezeSource()
{
if (this.Source == null)
return;
var freeze = this.Source as Freezable;
if (freeze != null && freeze.CanFreeze && !freeze.IsFrozen)
freeze.Freeze();
}
}
但我仍然得到错误.我更喜欢寻找适用于我的WPF应用程序中所有图像的解决方案.
希望我清楚自己,因为用2个线程解释并且在某个时刻有一个随机的异常是很奇怪的.
编辑: 经过一些进一步的测试后,我现在能够向您展示一个可重现的应用程序,并且希望它更清楚.
你需要3个窗口,1个文件夹和1个图像.在我的例子中,它的MainWindow.xaml Window1.xaml Window2.xaml
图像是文件夹的名称,并且有一个名为"plus.png"的图像.
MainWindow.xaml:
<StackPanel Orientation="Vertical">
<StackPanel.Resources>
<Style TargetType="{x:Type Button}">
<Setter Property="Margin"
Value="0,0,0,5"></Setter>
</Style>
</StackPanel.Resources>
<Button Content="Open Window 1" Click="OpenWindowInNewThread" />
<Button Content="Open Window 2" Click="OpenWindowInSameThread" />
</StackPanel>
MainWindow.xaml.cs:
private void OpenWindowInNewThread(object sender, RoutedEventArgs e)
{
var th = new Thread(() =>
{
SynchronizationContext.SetSynchronizationContext(new DispatcherSynchronizationContext(Dispatcher.CurrentDispatcher));
var x = new Window1();
x.Closed += (s, ec) => Dispatcher.CurrentDispatcher.BeginInvokeShutdown(DispatcherPriority.Background);
x.Show();
System.Windows.Threading.Dispatcher.Run();
});
th.SetApartmentState(ApartmentState.STA);
th.IsBackground = true;
th.Start();
}
private void OpenWindowInSameThread(object sender, RoutedEventArgs e)
{
var x = new Window2();
x.Show();
}
Window1.xaml:
<StackPanel Orientation="Horizontal">
<ToggleButton Template="{StaticResource PlusToggleButton}" />
</StackPanel>
Window1.xaml.cs: 那里只有构造函数没有代码......
Window2.xaml:
<StackPanel Orientation="Horizontal">
<ToggleButton Template="{StaticResource PlusToggleButton}" />
<Button Content="Print Me" Click="Print"></Button>
</StackPanel>
Window2.xaml.cs:
public void Print(object sender, RoutedEventArgs e)
{
PrintDialog pd = new PrintDialog();
pd.PrintVisual(this, "HelloWorld");
}
App.xaml中:
<ControlTemplate x:Key="PlusToggleButton"
TargetType="{x:Type ToggleButton}">
<Image Name="Image"
Source="/WpfApplication1;component/Images/plus.png"
Stretch="None" />
</ControlTemplate>
重现步骤:
希望它现在更容易帮助我.
EDIT2:
添加了缺少的代码部分,抱歉这个错误.
可能有助于解决问题的另一个信息是,当您按相反的顺序单击按钮 - 第一个窗口2而不是窗口1 - 而不是去尝试打印没有异常会触发,所以我仍然相信它的一些图像缓存问题,当图像首次加载到主UI-Thread打印时,如果不是,它将失败.
Window1您正在使用由on创建的 UI 对象Window2。
本质上，部分内容ControlTemplate在线程之间共享，这是不应该发生的（即BitmapImage，正如我从您的调用堆栈中读到的那样）。
您可以明确告知不共享：
<ControlTemplate x:Key="PlusToggleButton"
TargetType="{x:Type ToggleButton}"
x:Shared="False">