Unable to use function

Question

Unable to use function

Pankaj tripathi 185

Hi @KOZ6.0 ,
i was using the customtextbox code which you suggested and make some modifications in it as per my need . Now i am stuck at some point as i want to use a function

   protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
        {          
            if (keyData == Keys.Tab && Last)
            {
                return true;
            }
            return base.ProcessCmdKey(ref msg, keyData);
        }

inside my code but found that i am unable to add it to the code . The intention is just to check if the user presses tab and if the Last property is set to true then the tab should do nothing . Please suggest how do i do it .

the code is quite long and i have inserted it in a txt file
micr.txt

Jiale Xue - MSFT 49,831 Microsoft External Staff

Hi @Pankaj tripathi , Welcome to Microsoft Q&A,

base.WndProc(ref m) is called when processing the WM_KEYDOWN message, which means that the keyboard message has been processed and passed to the base class.

For WM_KEYDOWN messages, it may be necessary to remove the call to base.WndProc(ref m) to ensure that it is not passed on to the base class for processing.

Then juxtapose the ProcessCmdKey code and the WndProc code.

protected override void WndProc(ref Message m)
{
     switch (m.Msg)
     {
         // ... other message processing code

         case WM_KEYDOWN:
             Keys keyCode = (Keys)(int)(m.WParam.ToInt64() & 0xffff);
             if (Control.ModifierKeys.HasFlag(Keys.Shift))
             {
                 switch(keyCode)
                 {
                     case Keys.Up:
                     case Keys.Down:
                     case Keys.Right:
                     case Keys.Left:
                     case Keys.Home:
                     case Keys.End:
                         return;
                 }
             }

             // No longer call base.WndProc(ref m) to handle WM_KEYDOWN
             // You may need to add some custom logic to handle keyboard messages
             return;

         // ... other message processing code
     }

     // For other messages, call the WndProc method of the base class to process
     base.WndProc(ref m);
}

protected override bool ProcessCmdKey(ref Message msg, Keys keyData)
{
     if (keyData == Keys.Tab && Last)
     {
         return true;
     }
     return base.ProcessCmdKey(ref msg, keyData);
}

Best Regards,

Jiale

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Pankaj tripathi 185 Reputation points

2023-11-29T04:32:42.0366667+00:00

@Jiale Xue - MSFT , The original problem was about this compilation error . Sorry i forgot to add this screenshot in my question previously . I have uploaded the full code in the txt file earlier for your reference so that you can check .

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Jiale Xue - MSFT 49,831 Reputation points Microsoft External Staff

2023-11-29T03:27:14.15+00:00

Hi @Pankaj tripathi , Welcome to Microsoft Q&A,

base.WndProc(ref m) is called when processing the WM_KEYDOWN message, which means that the keyboard message has been processed and passed to the base class.

For WM_KEYDOWN messages, it may be necessary to remove the call to base.WndProc(ref m) to ensure that it is not passed on to the base class for processing.

Then juxtapose the ProcessCmdKey code and the WndProc code.

protected override void WndProc(ref Message m) { switch (m.Msg) { // ... other message processing code case WM_KEYDOWN: Keys keyCode = (Keys)(int)(m.WParam.ToInt64() & 0xffff); if (Control.ModifierKeys.HasFlag(Keys.Shift)) { switch(keyCode) { case Keys.Up: case Keys.Down: case Keys.Right: case Keys.Left: case Keys.Home: case Keys.End: return; } } // No longer call base.WndProc(ref m) to handle WM_KEYDOWN // You may need to add some custom logic to handle keyboard messages return; // ... other message processing code } // For other messages, call the WndProc method of the base class to process base.WndProc(ref m); } protected override bool ProcessCmdKey(ref Message msg, Keys keyData) { if (keyData == Keys.Tab && Last) { return true; } return base.ProcessCmdKey(ref msg, keyData); }

Best Regards,

Jiale

If the answer is the right solution, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

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Pankaj tripathi 185 Reputation points

2023-11-29T04:32:42.0366667+00:00

@Jiale Xue - MSFT , The original problem was about this compilation error . Sorry i forgot to add this screenshot in my question previously . I have uploaded the full code in the txt file earlier for your reference so that you can check .

Answer 1

To capture the tab key, catch the PreviewKeyDown event.

public static void AttachEvents<T>(T txb) where T : TextBox, ICustomTextBox {
    txb.KeyDown += Txb_KeyDown;
    txb.GotFocus += Txb_GotFocus;
    txb.LostFocus += Txb_LostFocus;
    txb.ParentChanged += Txb_ParentChanged;
    txb.TextChanged += Txb_TextChanged;
    txb.Enter += Txb_enter;
    txb.KeyPress += Txb_KeyPress;
    txb.PreviewKeyDown += Txb_PreviewKeyDown; // ■ Add
    CustomNativeWindows.Add(txb, new CustomNativeWindow(txb));
}

public static void DetachEvents<T>(T txb) where T : TextBox, ICustomTextBox {
    txb.KeyDown -= Txb_KeyDown;
    txb.LostFocus -= Txb_LostFocus;
    txb.ParentChanged -= Txb_ParentChanged;
    txb.TextChanged -= Txb_TextChanged;
    txb.Enter -= Txb_enter;
    txb.GotFocus -= Txb_GotFocus;
    txb.KeyPress -= Txb_KeyPress;
    txb.PreviewKeyDown -= Txb_PreviewKeyDown; // ■ Add
    // remove from dictionary 
    if (OriginalBackColors.ContainsKey(txb)) {
        OriginalBackColors.Remove(txb);
    }
    if (CustomNativeWindows.TryGetValue(txb, out var customNativeWindow)) {
        customNativeWindow.Dispose();
        CustomNativeWindows.Remove(txb);
    }
}
// ■ Add Method
private static void Txb_PreviewKeyDown(object sender, PreviewKeyDownEventArgs e) {
    ICustomTextBox customTextBox = (ICustomTextBox)sender;
    if (e.KeyData == Keys.Tab && customTextBox.Last) {
        e.IsInputKey = true;
    }
}

If you set the IsInputKey property of the PreviewKeyDownEventArgs class to true, you will receive a WM_KEYDOWN message in WndProc. CustomNativeWindow class as follows

    case WM_KEYDOWN:
        Keys keyCode = (Keys)(int)(m.WParam.ToInt64() & 0xffff);
        if (keyCode == Keys.Tab) return; // ■ Add
        if (Control.ModifierKeys.HasFlag(Keys.Shift)) {
            switch (keyCode) {
                case Keys.Up:
                case Keys.Down:
                case Keys.Right:
                case Keys.Left:
                case Keys.Home:
                case Keys.End:
                    return;
            }
        }
        base.WndProc(ref m);
        break;
    ```

Pankaj tripathi 185 Reputation points

2023-11-29T07:33:45.6533333+00:00

@KOZ6.0 , The problem has been solved . Just want to ask where to detect tab key press related actions like the below as capturing tab is not triggering inside the Txb_KeyDown event . and Txb_PreviewKeyDown has no information about SuppressKeyPress
KOZ6.0 6,580 Reputation points

2023-11-29T08:27:44.3766667+00:00

You can't use properties that don't exist.Please read my answer carefully.

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Unable to use function

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