Read-only access to brush in Backgroundworker

Question

I have a list of objects which among other properties contain a Brush (property name "Color").

In a Backgroundworker I want to write the contents of these objects to a file. Everything works fine until I try to read the color of the brush property.

//this works fine
var brush = myObject.Color;

//this fails with InvalidOperationException
var c= ((SolidColorBrush)myObject.Color).Color;

It seems as if my code is somehow modifying the color but I don't see where/how. Is there a way to read-only access the color of the brush?

Regards,

tabina

are there any more clues inside the exception class – Dean Chalk Apr 25 '12 at 14:38 — Dean Chalk, Apr 25 '12 at 14:38

score 0 · Accepted Answer · answered Apr 25 '12 at 14:32

0

Do i sense that you're accessing UI objects on a thread that didn't create them. You cannot access UI objects from a BGW thread. That's the golden rule not to forget using BGW class

answered Apr 25 '12 at 14:32

this-Me

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How could I solve this? I thought read-only access would be fine. – tabina Apr 25 '12 at 14:40
1

It appears access is access. Pass the color not the UI object. – paparazzo Apr 25 '12 at 14:50

score 0 · Answer 2 · answered Apr 25 '12 at 14:56

If there is no need to modify the objects after they have been added to that list, you might try to Freeze them before they get accessed from a different thread.

Make sure that the Freeze call happens in the UI thread, where you created those objects. You might also check if freezing is possible at all by calling CanFreeze beforehand.

Read-only access to brush in Backgroundworker

2 Answers2