Trapping keystrokes in .NET forms...

Hi Mark,

I was just looking into this as well and I found that you have to set Form.KeyPreview first:

http://msdn.microsoft.com/en-us/library/system.windows.forms.form.keypreview.aspx

Then your KeyDown triggers will fire.

HTH

-peter

Thanks, that's just what I was looking for.

Mark.

Now my challenge (and maybe also yours...) is how to catch CTRL-R.

You would think that is easy, but not in .NET!

A collegue claims you need this to achieve it:

http://support.microsoft.com/kb/318804

If anyone has a better idea I would love to hear about it!

-peter

Q&D with VS2005 C#:

namespace

WindowsApplication1

{

public partial class Form1 : Form

{

  public Form1()

  {

   InitializeComponent();

  }

  private void Form1_KeyPress(object sender, KeyPressEventArgs e)

  {

   char c;

   c = e.KeyChar;

   if (Char.IsControl(c) && c == (char)18)

   {

    MessageBox.Show("Identfied CTRL-R");

   }

  }

}

}

private

void InitializeComponent()

{

this.SuspendLayout();

//

// Form1

//

this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);

this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;

this.ClientSize = new System.Drawing.Size(284, 262);

this.KeyPreview = true;

this.Name = "Form1";

this.Text = "Form1";

this.KeyPress += new System.Windows.Forms.KeyPressEventHandler(this.Form1_KeyPress);

this.ResumeLayout(false);

}

I have struggled with this in 11.1 and I am finding that no event fires for CTRL-R.

Events fire for CTRL.

Events fire for R.

But no event fires for CTRL-R.

I am beginning to suspect this is a bug.

Can you try this code in OpenEdge?

-peter

pdam schrieb:
I have struggled with this in 11.1 and I am finding that no event fires for CTRL-R.
Events fire for CTRL.
Events fire for R.

Keypress has no event for CTRL key (standalone), are you really using keypress and not keydown/up?

marquardt wrote:
pdam schrieb:
I have struggled with this in 11.1 and I am finding that no event fires for CTRL-R.
Events fire for CTRL.
Events fire for R.
Keypress has no event for CTRL key (standalone), are you really using keypress and not keydown/up?

IndeedI am finding that KeyPress does not fire when you press CTRL-R.

Have you tested otherwise in OpenEdge?

I can trap CTRL+R in Openedge 10.2B.05 using keydown

Can you share the code? Then I will test it and submit a bug if it does not work in 11.1.

Sure :-)

    /*------------------------------------------------------------------------------
            Purpose:                                                                       
            Notes:                                                                       
    ------------------------------------------------------------------------------*/
    @VisualDesigner.
    METHOD PRIVATE VOID BaseForm_KeyDown( INPUT sender AS System.Object, INPUT e AS System.Windows.Forms.KeyEventArgs ):
       

        IF e:CONTROL
           AND e:KEYCODE:ToString() = "R" THEN
           MESSAGE "Hello world! VIEW-AS ALERT-BOX.

        RETURN.

    END METHOD.

Thanks, this sheds some more light on my problem.

In my application this code does not fire, but when I try it in a separate window it works.

What could be the cause of that? There is a similar ON CRTL-R ANYWHERE trigger in my embedded GUI code, but I don't care which one fires as long as one of them does. However there seems to be some conflict that results in none fireing at all.

We will need to dig deeper.

-peter

BTW I also noticed that this does not work when a .NET input field has focus.

So we are still a long way from ON CTRL-R ANYWHERE....

Have anyone stopped to think that if this is such a problem in .net,

then it is not common behavior, and perhaps there is a "better way" of

achieving the same goal ?

Of course - and in order to convince the customer I need to have solid ammunition.

On a slightly different tack, does anyone know how to prevent ALT+F4 from closing my form?

ALT+F4 is use by the form's embedded ABL window (something I can't change) and I'd like the users to not have to re-open the form everytime ALT-F4 closes it!

Thanks,

Mark.

For certain keyboard events in the GUI for .NET Environment we have created IMessageFilter instances in C#. That's pretty much an EVERYWHERE event handler in .NET. But it should be written in C# for performance reasons.

http://msdn.microsoft.com/en-us//library/system.windows.forms.imessagefilter.aspx

One use case, is to redirect the F10 key, so that it does not always cause the Ribbon to start it's keyboard more, but allows us to continue to handle F10 as an application key.

This is from memory: you could look at the Form_Closing event handler; I believe it has information about how the Close event was triggered. If that is ALT-F4 then e:Cancel = true?

-- peter

wire up ALT-F4 to a electric currrent ...

This is from memory: you could look at the Form_Closing event handler; I believe it has information about how the Close event was triggered. If that is ALT-F4 then e:Cancel = true?

The CloseReason makes no difference between ALT-F4 and the X on the window boarder. Both is UserClosing.

Makes sense.

Did it like this:

    /*------------------------------------------------------------------------------
            Purpose:                                                                       
            Notes:                                                                       
    ------------------------------------------------------------------------------*/
    @VisualDesigner.
    METHOD PRIVATE VOID BaseForm_KeyDown( INPUT sender AS System.Object, INPUT e AS System.Windows.Forms.KeyEventArgs ):
    SuppressKeyStroke("ALT-F4", sender, e).       
    END METHOD.

    METHOD PROTECTED VOID SuppressKeyStroke(INPUT lvcKeyStroke AS CHARACTER,
                                            INPUT sender AS System.Object,
                                            INPUT e AS System.Windows.Forms.KeyEventArgs ):
       
    DEFINE VARIABLE lvcModifier    AS CHARACTER NO-UNDO.
    DEFINE VARIABLE lvcKeyCode     AS CHARACTER NO-UNDO.
    DEFINE VARIABLE lvcEventString AS CHARACTER NO-UNDO.
 
    ASSIGN
      lvcKeyCode  = e:KEYCODE:ToString()
      lvcModifier = IF e:Control THEN
                    "CONTROL"
                  ELSE IF e:Shift THEN
                    "SHIFT"
                  ELSE IF e:Alt THEN
                    "ALT"
                  ELSE "".           
 
    lvcEventString = (IF lvcModifier <> "" THEN lvcModifier + "-" + lvcKeyCode ELSE lvcKeyCode).
   
    IF lvcEventString = lvcKeyStroke THEN
      e:SuppressKeyPress = TRUE.

    END METHOD.