CODEWITHSUNDEEP
wpfmultithreadingbackgroundworker
mjk6026
mjk6026

Reputation: 1484

WPF : Is it impossible to UI load in background thread?

I've making a some application which build a huge-sized FlowDocument. The elapsed time of building FlowDocument was about 3~4 seconds.

So I like to building FlowDocument in BackgroundWorker, not UI thread. but BackgroundWorker can't return WPF UI object. (It occured InvalidOperationException exception.)

how can i solve this problem?

Upvotes: 6

Views: 3730

Answers (1)

Ed Bayiates
Ed Bayiates

Reputation: 11210

If you want to build a FlowDocument in another thread, it has to be a second UI-type thread, not a BackgroundWorker. In spite of what the documentation says, you CAN build more than one UI-type thread. However, you cannot create UI objects in one thread, and use them in another. You could save your FlowDocument to disk and then reload it in the foreground UI thread, though.

This article has a good example with two UI threads, and in fact I have used this code to process XPS files in a background thread, very similar to what you are doing. Make sure your second UI thread is set to STA apartment state, and as I said, do not try to use any UI objects created in one thread, in a different thread. It won't work.

Upvotes: 7

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