Re: Invoking a form that was created on a separate thread

Probably about 15 seconds all told, they are surveys that have to be carried
out by engineers on site so they contain quite a lot of stuff.
The only other way I thought about it was using the splash screen example
thats about that runs on a separate thread and instead of it being a
splashscreen it would be the pogress bar.

Dan

"Daniel Moth" <dmoth74@xxxxxxxxxxx> wrote in message
news:%23MSrJemQFHA.3560@xxxxxxxxxxxxxxxxxxxxxxx
> OK it wasn't clear that you are parsing an XML file to create a form
> (XAML-style). I thought you were parsing an XML file for other more
> conventional purposes and just needed to report progress to the UI.
>
> I think you are on a loser there. You are going to have to bear the
> performance hit for choosing such an approach. Do the form loading/xaml
> parsing on the UI thread and stick an hour glass up or some progress bar
> to inform the user that they are in for a wait. Basically, trying to do
> anything with UI elements on other threads is not supported (unless you
> come up with some wacky ideas and I don't have any). How long does it take
> to load the form if you just let it run and wait?
>
> Cheers
> Daniel
> --
> http://www.danielmoth.com/Blog/
>
>
> "Dannyboy" <daniel@xxxxxxxxxxxxxxxxxxxxxxx> wrote in message
> news:e9wlPVmQFHA.3144@xxxxxxxxxxxxxxxxxxxxxxx
>> Hi Daniel
>>
>> The my problem occurs in that the new form and all its controls only get
>> created by the parsing routine, its a bit like xaml so all the form
>> definition is in the xml file that is parsed, So I need to be able to
>> parse these files which can take a while on the XDA's but still give
>> progress back and be able to interact with the code behind (the class
>> that instantiated the parsing) once the form is created and showed.
>>
>> Sorry if I'm not quite getting this.
>> Thanks
>> Dan
>>
>> "Daniel Moth" <dmoth74@xxxxxxxxxxx> wrote in message
>> news:%23ifZhDmQFHA.2788@xxxxxxxxxxxxxxxxxxxxxxx
>>> Don't return a form from a background thread. The form should be on the
>>> main form. It is the progress info (percentage and possibly status text)
>>> that you return to the main thread/form from the background thread. With
>>> backgroundWorker you don't need to explicitly invoke anything. Keep your
>>> parsing on the background thread if you have calculated that it takes
>>> too long and hence would block the UI.
>>>
>>> Whether you are using the BW from my site (VB version) or from opennetcf
>>> (C# version), the sample here should help:
>>> http://www.danielmoth.com/Blog/2004/12/backgroundworker-sample.html
>>>
>>> Cheers
>>> Daniel
>>> --
>>> http://www.danielmoth.com/Blog/
>>>
>>>
>>> "Dannyboy" <daniel@xxxxxxxxxxxxxxxxxxxxxxx> wrote in message
>>> news:uH18yffQFHA.3988@xxxxxxxxxxxxxxxxxxxxxxx
>>>> Hi Daniel thanks for that I shall go through your background worker
>>>> code, I do currently have a background process implemenation that is
>>>> based on an article written by Rocky Lhotka on msdn
>>>> http://msdn.microsoft.com/vbasic/using/columns/adventures/default.aspx?pull=/library/en-us/dnadvnet/html/vbnet09272002.asp
>>>> the trouble is the blasted form that is returned from that background
>>>> process throws an exception everytime I try and invoke its show method.
>>>>
>>>> Should I be changing the implementation so that I don't do the parsing
>>>> on the background thread?
>>>>
>>>> Dan
>>>>
>>>> "Daniel Moth" <dmoth74@xxxxxxxxxxx> wrote in message
>>>> news:enGb7SfQFHA.508@xxxxxxxxxxxxxxxxxxxxxxx
>>>>> Check out the BackgroundWorker or do it yourself (parsing on thread
>>>>> and updating the form with control invoke)
>>>>>
>>>>> Cheers
>>>>> Daniel
>>>>> --
>>>>> http://www.danielmoth.com/Blog/
>>>>>
>>>>>
>>>>> "Dannyboy" <daniel@xxxxxxxxxxxxxxxxxxxxxxx> wrote in message
>>>>> news:%23bFkZNfQFHA.248@xxxxxxxxxxxxxxxxxxxxxxx
>>>>>> Hi Chris your right its not good all, the the thing is the xml files
>>>>>> that are being parsed are pretty big and they take quite a bit of
>>>>>> time, so I need to put a progress bar on, I did try creating that on
>>>>>> the main the and then updating that from a separate thread.
>>>>>>
>>>>>> If there is a better way to do this I'm open to all suggestions cos
>>>>>> this is p#@*ing me off
>>>>>>
>>>>>> Thanks
>>>>>> Dan
>>>>>> "Chris Tacke, eMVP" <ctacke@xxxxxxxxxxxxxxxxxxxxxx> wrote in message
>>>>>> news:u9%23zJ0dQFHA.1528@xxxxxxxxxxxxxxxxxxxxxxx
>>>>>>> The first question has to be why are you creating a Form on another
>>>>>>> thread? It's a very bad idea, a bad design, and bad practice.
>>>>>>>
>>>>>>>
>>>>>>> --
>>>>>>> Chris Tacke
>>>>>>> Co-founder
>>>>>>> OpenNETCF.org
>>>>>>> Has OpenNETCF helped you? Consider donating to support us!
>>>>>>> http://www.opennetcf.org/donate
>>>>>>>
>>>>>>>
>>>>>>> "Dan" <daniel@xxxxxxxxxxxxxxxxxxxxxxx> wrote in message
>>>>>>> news:e5x$vrdQFHA.3628@xxxxxxxxxxxxxxxxxxxxxxx
>>>>>>>> Hi everyone
>>>>>>>>
>>>>>>>> I have a class which parses an xml file and creates a form and its
>>>>>>>> controls from it, and I have recenlty moved this so that it happens
>>>>>>>> on its own thread, I know about controls that are created on a
>>>>>>>> different thread to the UI can not just have its methods called
>>>>>>>> without using invoke so with this I have tried several different
>>>>>>>> ways to get the form to show but I'm having problems.
>>>>>>>>
>>>>>>>> The ways I have have tried are:
>>>>>>>>
>>>>>>>> 1. With the form that is returned from the parsing class I have
>>>>>>>> tried
>>>>>>>> me.invoke(new delegateSub(addressof newform.show))
>>>>>>>> This throws the error "Cannot call Invoke or InvokeAsync on a
>>>>>>>> control until the window handle has been created."
>>>>>>>>
>>>>>>>> 2. Add a controller class that is also created on the separate
>>>>>>>> thread which shows the form when the parsing is complete, this does
>>>>>>>> show the form briefly but it then disappears.
>>>>>>>>
>>>>>>>> 3. With the same controller class I use
>>>>>>>> Application.Run(parsedform). This works beautifully apart from one
>>>>>>>> small snag, the class which starts the parsing is passed a
>>>>>>>> reference to the parser and acts as the code behind for the the
>>>>>>>> controls that are created in the parsed form e.g. the click event
>>>>>>>> of a button in the parsed form is handled by a method in the class
>>>>>>>> that is sent to the parser. This is where this method seems to
>>>>>>>> fall down because the reference no longer works.
>>>>>>>>
>>>>>>>> Am I fighting a loosing battle with this or can anyone offer some
>>>>>>>> code of wisdom.
>>>>>>>> Any help will be much appreciated.
>>>>>>>>
>>>>>>>> Many Thanks
>>>>>>>> Dan
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>
>>>>
>>>
>>
>>
>


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