Update diagram from background thread - Diagramming Components

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Update diagram from background thread (Read 2583 times)

jcaron YaBB Newbies Offline I Love MindFusion! Posts: 7 Joined: Jul 23^rd, 2019	Update diagram from background thread Jul 24^th, 2019 at 1:45pm	Print Post
	Hi, Is it possible to update a Diagram object in a separate thread? I have an operation where multiple nodes will be added/removed/updated on a user action and would like to push those actions to a separate thread to improve the user experience. If this is not possible, maybe I'll create a duplicate diagram to apply the changes and then replace the diagram object in the DiagramView. Thanks! Jean


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Slavcho YaBB Moderator Offline tech.support Posts: 3435 Joined: Oct 19^th, 2005	Re: Update diagram from background thread Reply #1 - Jul 24^th, 2019 at 2:08pm	Print Post
	Hi, If it's graph layout classes taking most of the time for you, try their ArrangeAsync methods. The Diagram class is definitely not thread-safe, but if you disable modifications on the DiagramView by setting Behavior = DoNothing, it might get safe enough to add items from a thread. Do let us know if it works Otherwise working with an offscreen copy and assigning it to DiagramView when the thread ends should be safe enough I guess. Regards, Slavcho Mindfusion


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Slavcho YaBB Moderator Offline tech.support Posts: 3435 Joined: Oct 19^th, 2005	Re: Update diagram from background thread Reply #2 - Jul 24^th, 2019 at 2:20pm	Print Post
	Setting Behavior will probably still be unsafe, because the worker thread could try modifying Diagram.Items while it's being iterated by drawing code in UI thread, and .NET throws exceptions for that. You can probably work around it by overriding DiagramView.OnPaint and synchronizing with the worker thread before calling base. Regards, Slavcho


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jcaron YaBB Newbies Offline I Love MindFusion! Posts: 7 Joined: Jul 23^rd, 2019	Re: Update diagram from background thread Reply #3 - Jul 24^th, 2019 at 2:43pm	Print Post
	Thanks Slavcho for yor quick answer. The Diagram object does not allow changes from a separate thread (generate CrossThread exception), even with the Behaviour set to DoNothing and the DiagramView in a tab that is not displayed (so no paint event). I used DoEvents to improve the responsiveness of the application and used the layout.ArrangeAsync. This is OK for small graph, but I will have to test how it behave when I reach a 1000 nodes. Thanks for your support! Jean


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