R – .NET Compact Framework: how to ensure form is visible before running code

compact-frameworkperformanceuser interfacewinforms

We've got a Model-View-Presenter setup with our .NET Compact Framework app. A standard CF Form is implementing the view interface, and passed into the constructor of the presenter. the presenter tells the form to show itself by calling view.Run(); the view then does a Show() on itself, and the presenter takes over again, loading up data and populating it into the view.

Problem is that the view does not finishing showing itself before control is returned to the presenter. since the presenter code blocks for a few seconds while loading data, the effect is that the form is not visible for a few seconds. it's not until after the presenter finishes it's data load that the form becomes visible, even though the form called Show() on itself before the presenter started its data loading.

In a standard windows environment, i could use the .Shown event on the form… but compact framework doesn't have this, and I can't find an equivalent.

Does anyone know of an even, a pinvoke, or some other way to get my form to be fully visible before kicking off some code on the presenter? at this point, i'd be ok with the form calling to the presenter and telling the presenter to start it's data load.

FYI – we're trying to avoid multi-threading, to cut down on complexity and resource usage.

Best Answer

If your key problem is that the form won't paint before your presenter data loading methods are completed, and you have a call to this.Show() in your Form_Load, try putting Application.DoEvents() directly after this.Show() to force/allow the form to paint.

protected void Form_Load(blah blah blah)
{
   this.Show();
   Application.DoEvents();

   ... data loading methods ...
}

Related Solutions

C# – Cross-thread operation not valid: Control accessed from a thread other than the thread it was created on

As per Prerak K's update comment (since deleted):

I guess I have not presented the question properly.

Situation is this: I want to load data into a global variable based on the value of a control. I don't want to change the value of a control from the child thread. I'm not going to do it ever from a child thread.

So only accessing the value so that corresponding data can be fetched from the database.

The solution you want then should look like:

UserContrl1_LOadDataMethod()
{
    string name = "";
    if(textbox1.InvokeRequired)
    {
        textbox1.Invoke(new MethodInvoker(delegate { name = textbox1.text; }));
    }
    if(name == "MyName")
    {
        // do whatever
    }
}

Do your serious processing in the separate thread before you attempt to switch back to the control's thread. For example:

UserContrl1_LOadDataMethod()
{
    if(textbox1.text=="MyName") //<<======Now it wont give exception**
    {
        //Load data correspondin to "MyName"
        //Populate a globale variable List<string> which will be
        //bound to grid at some later stage
        if(InvokeRequired)
        {
            // after we've done all the processing, 
            this.Invoke(new MethodInvoker(delegate {
                // load the control with the appropriate data
            }));
            return;
        }
    }
}

R – Upgrading Compact Framework 1 app from VS 2003 to VS 2005 breaks form designer

Well some things changed while going from VS2003 to VS2005 one of those things is the way the form designer adds code to your Form class. It creates a separate .designer.cs class and creates a partial class with the same name as you main form class. All the designer generated code now goes in this background class. This is done so that the form designer generated code stays out of your hair.

Now its plausible that the VS2005 designer no longer recognizes the in-file designer code generated by the previous version. You can try to create a new WinForms project and see how it differs from your current project then make appropriate amends to your current project.

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