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So i need to handle any change in a WinAPI combobox (its' type = Simple (you can modify the entry in edit box)). Everything is fine, except it always prints previous text, not the current.

C++
void onCommand(WPARAM wparam, LPARAM lparam)
{
    wchar_t str[100] = {0};
    ComboBox_GetText(GetDlgItem(mainWnd, IDC_COMBO1), str, 100);
    avPrint << str << av::endl;

    switch(LOWORD(wparam))
    {
        case IDCANCEL:     EndDialog(mainWnd, 0);   break;
    }
}


What am i doing wrong here?

What I have tried:

1) i've tried to print when ANY command occurs and i still get the previous edit values.
2) If i try to get text later (for example via mouse click) then the text is correct - window procedure code below:

C++
case WM_LBUTTONDOWN: onCommand(0, 0);            return true; // prints actual value
case WM_COMMAND:     onCommand(wparam, lparam);  return true; // prints previous value
Posted
Updated 7-Aug-21 22:24pm
v3
Comments
Avtem 7-Aug-21 12:28pm
   
The only way i could get the current text was:
1) Get Edit handle of the combobox
2) Subclass the edit control
3) Get text on WM_PAINT (WM_SETTEXT gives previous results as well...)
Rick York 7-Aug-21 14:02pm
   
Have you tried catching the EN_CHANGE message and looking for the handle of the combobox's edit control?

I never use this kind of combobox so I am unfamiliar with it.
Avtem 8-Aug-21 14:12pm
   
Yep, it does seem to work, but i think i will stick with "intended" way to use it (if i understood it correctly).
Thank you!
Richard MacCutchan 8-Aug-21 4:21am
   
That is the wrong way to get data from a control. You should always use the control's notification messages which tell you when the data or selection changes.
Avtem 8-Aug-21 12:17pm
   
But that is my question - what is the right way to get data from the control?
Richard MacCutchan 8-Aug-21 12:19pm
   
Follow the link I provided below.
Avtem 8-Aug-21 12:28pm
   
Thank you!

1 solution

You should study Combo Box (Windows Controls) - Win32 apps | Microsoft Docs[^] which explains how to use the control.
   
Comments
Avtem 8-Aug-21 14:09pm
   
Wow. i found how to do this by accident... Turns out if you want to handle combobox changes you have to handle CBN_EDITCHANGE which is not sent when user selects an item in the listbox and handle CBN_SELCHANGE, but not use WM_GETTEXT this time. They decided that programmer must retrieve Edit text by getting item in the listbox by index sent with CBN_SELCHANGE notification.

This is so confusing to me. Why just don't send CBN_EDITCHANGE for any change in the edit?
Richard MacCutchan 9-Aug-21 3:47am
   
If you think this is a bad design then you should tell Microsoft, it's their product.
Avtem 9-Aug-21 4:00am
   
Oh, there are more important things that i told them about, but they do not anything about it (Crashes in Visual Studio).

Anyway - did i understand how to use it properly?
Richard MacCutchan 9-Aug-21 4:13am
   
"did i understand how to use it properly?"
I don't know, you need to test your code to find out.
Avtem 9-Aug-21 4:27am
   
Well, it works perfectly.
Maybe i could not find the answer using Google because others understood it right away

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