Inserting Image to FlowDocument

Question

I'm working on a wpf application. I want to create a FlowDocument object and print it. As the creation step takes some seconds and freeze the UI, I move my code to new thread. The problem is that I need to set an Image in the FlowDocument and need to create Image UIElement, but UI Controls cannot be created in background threads ! I've also tried so many Dispather.Invoke() scenarios, but they catch exception about object owner thread.

I wonder is there any other methods to insert image into the FlowDocument? Or is it possible to create Image UIElement in background thread?

any suggestion would be appreciated.

P.S : Some Example Code =>

BitmapImage bitmapImage = SingletonSetting.GetInstance().Logo;
Image v = new Image() { Source = bitmapImage };
currnetrow.Cells.Add(new TableCell(new BlockUIContainer(v)));




Image v = ((App)Application.Current).Dispatcher.Invoke(new Func<Image>(() =>
{
    BitmapImage bitmapImage = SingletonSetting.GetInstance().Logo;
    return new Image() { Source = bitmapImage};
}));
currnetrow.Cells.Add(new TableCell(new BlockUIContainer(v)));

score 1 · Accepted Answer · edited May 23 '17 at 12:16

1

If you don't need to modify the BitmapImage, then you can freeze it and use it on the UI thread.

// Executing on non UI Thread
BitmapImage bitmapImage = SingletonSetting.GetInstance().Logo;
bitmapImage.Freeze(); // Has to be done on same thread it was created on - maybe freeze it in the Singleton instead?

Application.Current.Dispatcher.Invoke(() => {
    // Executing on UI Thread
    Image v = new Image() { Source = bitmapImage };
    currnetrow.Cells.Add(new TableCell(new BlockUIContainer(v)));
});

After chatting with you, what you really needed to do was run your task in a STA thread, since you were making UI controls on it. How to do that? See this answer:

Set ApartmentState on a Task

edited May 23 '17 at 12:16

Community

1
1

answered Sep 02 '16 at 14:27

J.H.

4,232
1
18
16

thanks for your answer, but it cause exception on the last line. It say "The calling thread cannot access this object because a different thread owns it" – Mohamad MohamadPoor Sep 02 '16 at 20:53
the currnetrow.Cells... line? What thread was currnetrow made on? – J.H. Sep 02 '16 at 20:54
yes, the background thread create it ! I suppose using currentrow in the UI thread is the problem ! – Mohamad MohamadPoor Sep 02 '16 at 20:56
Dispatcher.Invoke() run the code on the UI thread. Isn't It? I bring out the last line, but again same error, this time I suppose v cannot be accessed in the background thread. – Mohamad MohamadPoor Sep 02 '16 at 21:00
yes all the code is on non UI thread, except those two line on the dispatcher which is on UI thread. – Mohamad MohamadPoor Sep 02 '16 at 21:02
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/122548/discussion-between-j-h-and-evil). – J.H. Sep 02 '16 at 21:03

Inserting Image to FlowDocument

1 Answers1