This should be easy
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Unfortunately it has proven otherwise. I have a simple C# form with a label control(prompt), an OK button, and a Cancel button. When the form loads, the OK button is disabled and the form spawns a worker thread that does some work (runs a pin-pad in this case) and calls a callback function when it is done. In the callback function I re-enable the OK button, and I want to set the focus to the OK button but I can't seem to do it. I used the Focus() method and it fails even though the CanFocus property is true. I also set the ActiveControl property of the form but this failed also. Does anyone have any sage advice for me? Neil Van Eps "Sweet liquor eases the pain" - Lionel Hutz from the Simpsons
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Unfortunately it has proven otherwise. I have a simple C# form with a label control(prompt), an OK button, and a Cancel button. When the form loads, the OK button is disabled and the form spawns a worker thread that does some work (runs a pin-pad in this case) and calls a callback function when it is done. In the callback function I re-enable the OK button, and I want to set the focus to the OK button but I can't seem to do it. I used the Focus() method and it fails even though the CanFocus property is true. I also set the ActiveControl property of the form but this failed also. Does anyone have any sage advice for me? Neil Van Eps "Sweet liquor eases the pain" - Lionel Hutz from the Simpsons
You will need to Invoke everything coming from the other thread.
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Unfortunately it has proven otherwise. I have a simple C# form with a label control(prompt), an OK button, and a Cancel button. When the form loads, the OK button is disabled and the form spawns a worker thread that does some work (runs a pin-pad in this case) and calls a callback function when it is done. In the callback function I re-enable the OK button, and I want to set the focus to the OK button but I can't seem to do it. I used the Focus() method and it fails even though the CanFocus property is true. I also set the ActiveControl property of the form but this failed also. Does anyone have any sage advice for me? Neil Van Eps "Sweet liquor eases the pain" - Lionel Hutz from the Simpsons
When getting/setting properties or calling methods on a control from another thread, you need to use
Control.Invoke. If you're not sure if you need to invoke the method (properties are just getter and setter methods), you can useControl.InvokeRequired. More information and examples can be found in the .NET Framework SDK regarding these members.Microsoft MVP, Visual C# My Articles
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When getting/setting properties or calling methods on a control from another thread, you need to use
Control.Invoke. If you're not sure if you need to invoke the method (properties are just getter and setter methods), you can useControl.InvokeRequired. More information and examples can be found in the .NET Framework SDK regarding these members.Microsoft MVP, Visual C# My Articles
So just because you declare a callback function doesn't mean it runs in the parent thread. Got it - thanks. Neil Van Eps "Sweet liquor eases the pain" - Lionel Hutz from the Simpsons
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So just because you declare a callback function doesn't mean it runs in the parent thread. Got it - thanks. Neil Van Eps "Sweet liquor eases the pain" - Lionel Hutz from the Simpsons
It runs in the thread context in which it was invoked.
Microsoft MVP, Visual C# My Articles