Re: Why Won't My MainForm Focus/Activate? [modified] - C# Discussion Boards

18-Jun-08 0:30

Hi,

This is embarassing to ask, but I just can't figure it out. Why is it that when I run my application by double-clicking the .exe from windows explorer, it will load but it will stay behind the windows explorer window?

I think the problem lies on the splash screen which I call from the Main Form's constructor. I am calling it here because the splash screen displays the progress of the application start-up ("Initializing components...", "Loading user settings...", etc.) at the bottom of the splash screen.

After this closes, I then do a this.Activate() or this.Focus() in the Main Form's constructor.

What is wrong? :-s

Rafferty

Simon P Stevens18-Jun-08 0:47

18-Jun-08 0:47

Post some more code.

How are your loading, showing and closing your splash screen?

What does the apps entry point look like? (The "static void Main()" bit in Program.cs. There should be a line that says something like "Application.Run(new YourForm());")

Simon

ajtunbridge18-Jun-08 3:43

ajtunbridge

18-Jun-08 3:43

This is going to sound sarcastic but it's not meant to Smile | :)

Have you tried the BringToFront method for the form?

Karthik Kalyanasundaram18-Jun-08 4:21

Karthik Kalyanasundaram

18-Jun-08 4:21

Can you try with

this.WindowState = FormWindowState.Normal

Software - Bundle of bugs covered with features.

Rafferty Uy18-Jun-08 15:21

18-Jun-08 15:21

Hi all,

Thanks to everyone who replied. I tried calling this.BringToFront() in the MainForm's constructor and Load event but it still didn't work.
Here are some code:

Program.cs

/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main()
{
  Application.EnableVisualStyles();
  Application.SetCompatibleTextRenderingDefault(false);
  Application.Run(new MainForm());
}

MainForm.cs

/// <summary>
/// Initializes a new instance of the <see cref="MainForm" /> class.
/// </summary>
public MainForm()
{
  Splasher.Show(typeof (ProgressSplashForm));
            
  Splasher.Status = "Initializing components...";
  InitializeComponent();

  Splasher.ProgressValue = 80;
  ApplicationSession.Instance.PercentHoursBeforeAlert =
    Properties.Settings.Default.PercentHoursBeforeAlert;
  ApplicationSession.Instance.PercentHoursBeforeHighAlert =
    Properties.Settings.Default.PercentHoursBeforeHighAlert;

  Splasher.ProgressValue = 85;
  ApplicationSession.Instance.DbManager = new MsAccessDbManager(Application.StartupPath);
  RefreshAvailableFunctions(false);
            
  Splasher.Status = "Initialization completed.";
  Splasher.ProgressValue = 100;
  Splasher.Close();

  this.BringToFront();
  this.Activate();
}

/// <summary>
/// Handles the Load event of the MainForm control.
/// </summary>
/// <param name="sender">The source of the event.</param>
/// <param name="e">The <see cref="System.EventArgs" /> instance containing the event data.</param>
private void MainForm_Load(object sender, EventArgs e)
{
  this.BringToFront();
  this.Activate();
}

I also noticed that the this.IsHandleCreated and this.CanFocus properties are false in both the constructor and the load event.

*Note: The Splasher class is inspired by cncx's article[^] about splash screens. Sufficed to say, the Splasher.Show() method displays the splash screen by running a new application (Application.Run(_splashForm)).

Any ideas?

Rafferty

Rafferty Uy18-Jun-08 15:45

Re: Why Won't My MainForm Focus/Activate? [modified]

18-Jun-08 15:45

I forgot, this is the sequence of events:
1. (Window explorer on top) Double-clicks the app.exe file.
2. Splash screen displays on top of windows explorer
3. Splash screen closes
4. Windows explorer activates ?!
5. Main form loads BEHIND the windows explorer, Main form does not activate (the focus is still on windows explorer).

Rafferty

Simon P Stevens18-Jun-08 22:16

18-Jun-08 22:16

There doesn't seem to be anything unusual in your code. There are some odd bits in that splasher article though.

1) In the close method the code just totally swallows up all exceptions. This is very bad. something maybe going wrong and you won't know about it. Put some code in here to do something. (At the very very least, write to a log file so you know something went wrong. Ideally, Display an error message and shutdown the application)

2) The article uses Application.Run to start a new message pump from inside a separate thread. Seems a bit weird, not sure what impact this will have. .ShowDialog may have been a better way of doing it. This creates a nested message pump. (Maybe there is no difference, I'm not sure about this)

3) It uses reflection to manage the splash screen. Again, bit weird, he knows it's a form, why not just use a form object. Don't think this has any real problems though, it's just a bit of an odd way of doing things.

Let me try the Splasher stuff out and I'll get back to you in a bit.

[Edit: Yes, I get exactly the same issue with that splasher article code...Hang on...]

[Edit 2: Think you just need to abandon this article's method. The problem is something to do with having two message pumps running. When the first closes, the focus returns to the explorer window, even if you ensure the main form is fully loaded and displayed before letting the first message pump stop. I played around with it a bit, but it always causes exactly the same issue.

The reason that all those active/bring to front methods don't work is because they all rely on an api call that was changed with windows XP. It was decided that applications should not be allowed to steal focus because it annoys the user if they are working on something else.

I would suggest reading this[^] article. It describes a technique of using a ApplicationContext object to load two forms. Ignore all the stuff in there about reading/writing the window state to disk. Just use the appcontext to show your splash screen, do your initialising, show your main form and close your splash screen.]

Simon

modified on Thursday, June 19, 2008 4:56 AM

Rafferty Uy19-Jun-08 0:52

19-Jun-08 0:52

Hi Simon,

Thank you for the effort that you put into this. At least now I know why, I'll really have to fix this, but in the meantime I stopped showing the splash screen altogether Smile | :)

Rafferty

Simon P Stevens19-Jun-08 1:47

AppDomain for unloading an assembly

19-Jun-08 1:47

No prob.

It wasn't entirely selfless. One of our apps uses a similar technique for showing a message pumping splash screen, and has a similar issue. We'd never noticed it before because the app auto runs at start up, fullscreen and on a dedicated PC that is only used via a touch screen (no keyboard/mouse), but at some point we are going to convert it to a desktop user version so things like that will start to cause problems then.

Simon

elektrowolf18-Jun-08 0:21

elektrowolf

18-Jun-08 0:21

Hi!

this[^] MSDN page told me, I couldn't unload assemblies except I load them into an extra AppDomain and then unload the whole AppDomain. But how to do this? Can someone might give me a little example?

EDIT: I want to load the assembly from a file.

Thanks in advance, Eric

Simon P Stevens18-Jun-08 0:29

18-Jun-08 0:29

http://msdn.microsoft.com/en-us/library/yb506139.aspx[^]

See the links on "How to Create...", "How to unload..." and "How to load assemblies into..."

Simon

elektrowolf18-Jun-08 0:31

elektrowolf

18-Jun-08 0:31

In "How to load assemblies into..." I can only read how to load assemblies into the current AppDomain, which isn't very helpful.. Sniff | :^)

Simon P Stevens18-Jun-08 0:38

18-Jun-08 0:38

It's not very obvious I'll admit:

"Methods such as CreateInstance and CreateInstanceAndUnwrap of the AppDomain class can load assemblies into an application domain."

Simon

Simon P Stevens18-Jun-08 0:43

18-Jun-08 0:43

If you look in the method details for CreateInstanceAndUnwrap it includes an example for running code in a different appdomain.

(You should note that the assembly that contains the object you create with CreateInstanceAndUnwrap will be loaded into both appdomains, but you can use the object to load further assembiles only into the domain the code is running in. See the CreateInstanceAndUnwrap[^] page)

Simon

Generic type should accept only delegate types

elektrowolf18-Jun-08 2:04

elektrowolf

18-Jun-08 2:04

Great! Works now... Thx Smile | :)

N a v a n e e t h17-Jun-08 23:39

N a v a n e e t h

17-Jun-08 23:39

public class DownloadQueue<TCallBack>
{
}

In the above code, I need to allow only delegate types for TCallBack. I am not able find System.Delegate in the "where" condition. I tried this

public class DownloadQueue<TCallBack> where TCallBack : System.Delegate
{
}

But it's not allowing to write so. Any other methods for this ?

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Pete O'Hanlon18-Jun-08 0:13

Pete O'Hanlon

18-Jun-08 0:13

Certain types are restricted from being used as generic constraints. Unfortunately, this is one of them (enum is another).

Deja View - the feeling that you've seen this post before.

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N a v a n e e t h18-Jun-08 0:43

N a v a n e e t h

18-Jun-08 0:43

Thanks Pete. Any alternative method to ensure it ?

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led mike18-Jun-08 5:18

led mike

18-Jun-08 5:18

How does typing a generic parameter to System.Delegate help? It might be that you have a design issue that needs a different solution or perhaps requires a better understanding of the problem to begin with.

led mike

IFormatProvider.GetFormat

N a v a n e e t h18-Jun-08 6:43

N a v a n e e t h

18-Jun-08 6:43

Yes you are correct. I had a design issue and I solved it. Your help is much appreciated.

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George_George17-Jun-08 23:08

George_George

17-Jun-08 23:08

Hello everyone,

I debugged the sample carefully. But one question I can not find from MSDN, who calls method IFormatProvider.GetFormat of class AnyRadix? When we call String.Format, this function is called?

http://msdn.microsoft.com/en-us/library/system.iformatprovider.getformat(VS.80).aspx

thanks in advance,
George

Re: IFormatProvider.GetFormat

Simon P Stevens17-Jun-08 23:19

Re: IFormatProvider.GetFormat

17-Jun-08 23:19

This line passes the format provider to the String.Format method

Console.WriteLine( String.Format( provider, messageStr, argToConvert ) );

String.Format calls the GetFormat method on the provider to get the formatter. You can look at the Code in for String.Format in reflector to see what's going on. (Haven't tried this myself)

You can see this in the debugger by sticking a breakpoint in the GetFormat method and waiting till it is hit then looking at the call stack. (Debug->Windows->CallStack (Ctrl+D,C))

Simon

George_George17-Jun-08 23:52

George_George

17-Jun-08 23:52

Thanks Simon!

My study result is, when calling String.Format( provider, messageStr, argToConvert ),

1.

provider.GetFormat is called and returned an intance of AnyRadix;

2.

Then Format method is called on the returned instance of AnyRadix, and messageStr/argToConvert are passed as formatString/argToBeFormatted parameter, and a string is returned from Format method -- the returned string is also treated as the result of String.Format call -- String.Format( provider, messageStr, argToConvert ).

My analysis correct?

regards,
George

Re: IFormatProvider.GetFormat

Simon P Stevens18-Jun-08 0:18