I have a problem setting a Property
on the main thread
from another thread
.
This is what i do at the moment:
XAML:
<TabControl Name="tab"/>
Code Behind:
TabItem tabItem = new TabItem();
Binding myBinding = new Binding("ReportView") { Source = ViewModel, Mode = BindingMode.TwoWay, UpdateSourceTrigger = UpdateSourceTrigger.PropertyChanged };
BindingOperations.SetBinding(tabItem, TabItem.ContentProperty, myBinding);
tab.Items.Add(tabItem);
Thread t = new Thread(DoWork);
t.SetApartmentState(ApartmentState.STA);
t.Priority = ThreadPriority.Normal;
t.Start();
DoWork Method:
When i create the ReportPreviewView
inside the body of the Dispatcher.BeginInvoke
, i don't get an exception
:
public void DoWork(object sender)
{
//I create the relavant ViewModel
ReportViewModel reportViewModel = new ReportViewModel(SessionContext, Mediator, Parent.ReportRequest, false);
Dispatcher.BeginInvoke((Action)(() =>
{
//Create the relevant View
ReportPreviewView reportPreviewView = new ReportPreviewView(reportViewModel) { ReportName = Parent.ReportRequest.Report.ReportName };
ViewModel.ReportView = reportPreviewView;
}));
}
But this is not correct. It freezes up my UI thread
. The creation of the ReportPre开发者_开发问答viewView
takes quit a long time.
So then i move the creation of the ReportPreviewView
outside the Dispatcher.BeginInvoke
:
public void DoWork(object sender)
{
ReportViewModel reportViewModel = new ReportViewModel(SessionContext, Mediator, Parent.ReportRequest, false);
ReportPreviewView reportPreviewView = new ReportPreviewView(reportViewModel) { ReportName = Parent.ReportRequest.Report.ReportName };
Dispatcher.BeginInvoke((Action)(() =>
{
reportLoaderViewModel.ReportView = reportPreviewView;
}));
}
As soon as PropertyChanged
fires i get the following exception:
The calling thread cannot access this object because a different thread owns it
Any idea how i can get around this?
You have to create UI elements on UI dispatcher thread. There is no escape. So when you say
The creation of the ReportPreviewView takes quit a long time.
Did you anaylyse why is that? Does it have drawings, animations, heavy styles, non-virtualized panels (such as canvas)? Does it have some code in its constructor that takes time to complete?
If so, please reconsider your UI design.
In WPF the UI always freezes for heavy views. Even if you deserialize views using XAMLReader/Writer, the creation and hosting of the view object has to take place on UI thread.
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