Backspace is pressed

How do I know when the Backspace is pressed in a combobox?

you should get a WM_KEYDOWN 8

Yes I should, but I is a combobox so I don't get that message. I may need to subclass it but I don't know.

yeah, that would do

What do you mean you don't know how to subclass it. It is not VB.
Just handle that message in the WindowProc.

Try this:

Add these to your globals

Code:

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LRESULT CALLBACK ComboBoxProc(HWND, UINT, WPARAM, LPARAM);               
WNDPROC wOldProc;

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Add these to the WM_CREATE and WM_CLOSE events of your main WinProc.

Code:

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case WM_CREATE:
{
        hCbo = CreateWindowEx(NULL, "ComboBox", NULL, CBS_DROPDOWNLIST | WS_CHILD | WS_VISIBLE, 32, 32, 128, 128, hWnd, NULL,gInst,NULL);
        SendMessage(hCbo, CB_ADDSTRING, 0, (LPARAM) "Zero");
        SendMessage(hCbo, CB_ADDSTRING, 0, (LPARAM) "One");
        SendMessage(hCbo, CB_ADDSTRING, 0, (LPARAM) "Two");
                // Subclass it
        wOldProc = (WNDPROC)SetWindowLong(hCbo, GWL_WNDPROC, (LONG) &ComboBoxProc);
        return 0;
}
case WM_CLOSE:
        SetWindowLong(hCbo, GWL_WNDPROC, (LONG)wOldProc);
        DestroyWindow(hWnd);
        return 0;

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This will be your ComBox procedure:

Code:

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LRESULT CALLBACK ComboBoxProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
        if( (uMsg == WM_KEYDOWN) && (wParam == 8) )
        {
                // Add code here
                MessageBox(NULL, "Backspace pressed", NULL, NULL);
        }

        return CallWindowProc(wOldProc, hWnd, uMsg, wParam, lParam);
}

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Quote:

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Originally posted by Vlatko
What do you mean you don't know how to subclass it. It is not VB.
Just handle that message in the WindowProc.

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No, you can't capture the messages of the combobox from the window procedure of the parent.

Thanks megatron. I think I was doing some think wrong when handling the "WM_KEYDOWN" message after subclassing.
It is almost autocomplete now but there is just one more problem:

First look at the image

I have some words in the combobox like "C:\", "C:\windows". When I type "C", it completes with the mathcing word which is "C:\", and then it heighlights ":\" as it does in the other autocomplete comboboxes.

Now the problem is that I can't move the caret using the left/right arrow keys...you know

Here is the code I am using in the CB_EDITUPDATE message that actually completes the word:

PHP Code:

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           char edtext[2];
           USHORT theindex;
           
        case CBN_EDITCHANGE:
            if(!isback)
            {
                GetWindowText(cbhwnd, edtext, GetWindowTextLength(cbhwnd) + 1);
                if(SendMessage(cbhwnd, CB_FINDSTRING, (WPARAM)-1, (LPARAM)(LPCSTR)edtext) != CB_ERR)
                {
                    theindex = GetWindowTextLength(cbhwnd);
                    SendMessage(cbhwnd,CB_SETCURSEL, SendMessage(cbhwnd, CB_FINDSTRING, (WPARAM)-1, (LPARAM)(LPCSTR)edtext), 0);
                    SendMessage(cbhwnd, CB_SETEDITSEL,0, MAKELPARAM(theindex,GetWindowTextLength(cbhwnd)));
                }
            }
            
       return TRUE; 


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isback is a global variable that tells if the backspace is pressed or not. Here is code that I am using to tell if it is pressed or not using the subclassing technique:

PHP Code:

---

switch(msg)
    {
    case WM_KEYDOWN:
        if(wparam == 8)
        {
            isback = TRUE;
        }
        else
        {
            isback = FALSE;
        }
        return 0;
    } 


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So, why can't I move the caret using the arrow keys so that I don't have to type the whole word if it highlights it?

It is ok now. I used the message "WM_KEYUP" instead of "WM_KEYDOWN" and it is all working now

Thanks a lot!:D

Ohhh NO!

I got the caret thingy working but then I lots the backspace handling. How do I get both at a time?

I am using the same code except that I am handling the "WM_KEYUP" message instead of "WM_KEYDOWN"

Quote:

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No, you can't capture the messages of the combobox from the window procedure of the parent.

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I know that Megatron. I didn't mean the WindowProc of the parent but the combobox's own procedure.

this thread is stopped:confused: Come on guys, it is not finished yet. I still have the above problem

For some reason, my subclassing isnt working right. I'm trying to do this too, but for some reason, it isnt working. Code:

Code:

---

#include <windows.h>

const char g_szClassName[] = "myWindowClass";

#define IDC_COMBOBOX        9001
#define FixFonts(control) {SendDlgItemMessage(hwnd, control, WM_SETFONT, (WPARAM)GetStockObject(DEFAULT_GUI_FONT), MAKELPARAM(TRUE, 0));}

HINSTANCE hInstance;
WNDPROC wOldProc;

LRESULT CALLBACK ComboBoxProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
        switch(uMsg)
        {
        case WM_KEYUP:
                MessageBox(hwnd,"","",0);
                break;
        default:
                return(DefWindowProc(hwnd,uMsg,wParam,lParam));
        }
        return(0);
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch(msg)
    {
        case WM_CLOSE:
                        SetWindowLong(GetDlgItem(hwnd,IDC_COMBOBOX), GWL_WNDPROC, (LONG)wOldProc);
            DestroyWindow(hwnd);
                        break;
        case WM_DESTROY:
            PostQuitMessage(0);
                        break;
                case WM_CREATE:
                        CreateWindow("COMBOBOX","",WS_CHILD | WS_VISIBLE | CBS_DROPDOWN,0,0,100,100,hwnd,(HMENU)IDC_COMBOBOX,hInstance,0);
                        FixFonts(IDC_COMBOBOX);
                        SendMessage(GetDlgItem(hwnd,IDC_COMBOBOX), CB_ADDSTRING, 0, (LPARAM) "Zero");
                        SendMessage(GetDlgItem(hwnd,IDC_COMBOBOX), CB_ADDSTRING, 0, (LPARAM) "One");
                        SendMessage(GetDlgItem(hwnd,IDC_COMBOBOX), CB_ADDSTRING, 0, (LPARAM) "Two");
                        wOldProc = (WNDPROC)SetWindowLong(GetDlgItem(hwnd,IDC_COMBOBOX), GWL_WNDPROC, (LONG) &ComboBoxProc);
                        SetWindowLong(GetDlgItem(hwnd,IDC_COMBOBOX), GWL_STYLE        , WS_CHILD | WS_VISIBLE | CBS_DROPDOWN);
                        break;
        default:
            return DefWindowProc(hwnd, msg, wParam, lParam);
    }
    return 0;
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
    LPSTR lpCmdLine, int nCmdShow)
{
    WNDCLASSEX wc;
    HWND hwnd;
    MSG Msg;
    ::hInstance=hInstance;
    wc.cbSize        = sizeof(WNDCLASSEX);
    wc.style        = 0;
    wc.lpfnWndProc  = WndProc;
    wc.cbClsExtra    = 0;
    wc.cbWndExtra    = 0;
    wc.hInstance    = hInstance;
    wc.hIcon        = LoadIcon(NULL, IDI_APPLICATION);
    wc.hCursor      = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(COLOR_BTNFACE+1);
    wc.lpszMenuName  = NULL;
    wc.lpszClassName = g_szClassName;
    wc.hIconSm      = LoadIcon(NULL, IDI_APPLICATION);

    if(!RegisterClassEx(&wc))
    {
        MessageBox(NULL, "Window Registration Failed!", "Error!",
            MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }

    hwnd = CreateWindowEx(
        0,
        g_szClassName,
        "Autocomplete Combobox Test",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT, 240, 120,
        NULL, NULL, hInstance, NULL);

    if(hwnd == NULL)
    {
        MessageBox(NULL, "Window Creation Failed!", "Error!",
            MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }

    ShowWindow(hwnd, nCmdShow);
    UpdateWindow(hwnd);

    while(GetMessage(&Msg, NULL, 0, 0))
    {
        TranslateMessage(&Msg);
        DispatchMessage(&Msg);
    }
    return Msg.wParam;
}

---

Any ideas?

Try this code. I have put the comments on which line is added or changed:

PHP Code:

---

#include <windows.h>

const char g_szClassName[] = "myWindowClass";

#define IDC_COMBOBOX    9001
#define FixFonts(control) {SendDlgItemMessage(hwnd, control, WM_SETFONT, (WPARAM)GetStockObject(DEFAULT_GUI_FONT), MAKELPARAM(TRUE, 0));}

HINSTANCE hInstance;
WNDPROC wOldProc;
//A new declaration for the Handle of the editbox in the combobox
HWND edhwnd;

LRESULT CALLBACK ComboBoxProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    switch(uMsg)
    {
    case WM_KEYUP:
        MessageBox(hwnd,"","",0);
        break;
    default:
        return CallWindowProc(wOldProc, hwnd,uMsg,wParam,lParam); //Changed to CallWindowProc
    }
    return(0);
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch(msg)
    {
        case WM_CLOSE:
            //This is also changed. Changed the handle to editbox handle
            SetWindowLong(edhwnd, GWL_WNDPROC, (LONG)wOldProc);
            DestroyWindow(hwnd);
            break;
        case WM_DESTROY:
            PostQuitMessage(0);
            break;
        case WM_CREATE:
            CreateWindow("COMBOBOX","",WS_CHILD | WS_VISIBLE | CBS_DROPDOWN,0,0,100,100,hwnd,(HMENU)IDC_COMBOBOX,hInstance,0);
            FixFonts(IDC_COMBOBOX);
            SendMessage(GetDlgItem(hwnd,IDC_COMBOBOX), CB_ADDSTRING, 0, (LPARAM) "Zero");
            SendMessage(GetDlgItem(hwnd,IDC_COMBOBOX), CB_ADDSTRING, 0, (LPARAM) "One");
            SendMessage(GetDlgItem(hwnd,IDC_COMBOBOX), CB_ADDSTRING, 0, (LPARAM) "Two");
            //New Stuff Added here
            //We get the handle of the editbox in the combobox because that
            //is the window in which WM_KEYUP message occurs
            POINT pt;
            pt.x = 3;
            pt.y = 3;
            edhwnd = ChildWindowFromPoint(GetDlgItem(hwnd,IDC_COMBOBOX), pt);
            //-----------------------------------------------------------
            //Now we use the editbox handle - not the combobox handle
            wOldProc = (WNDPROC)SetWindowLong(edhwnd, GWL_WNDPROC, (LONG) &ComboBoxProc);
            SetWindowLong(GetDlgItem(hwnd,IDC_COMBOBOX), GWL_STYLE    , GetWindowLong(GetDlgItem(hwnd,IDC_COMBOBOX), GWL_STYLE) | WS_CHILD | WS_VISIBLE | CBS_DROPDOWN); //Changed this line
            break;
        default:
            return DefWindowProc(hwnd, msg, wParam, lParam);
    }
    return 0;
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
    LPSTR lpCmdLine, int nCmdShow)
{
    WNDCLASSEX wc;
    HWND hwnd;
    MSG Msg;
    ::hInstance=hInstance;
    wc.cbSize        = sizeof(WNDCLASSEX);
    wc.style         = 0;
    wc.lpfnWndProc   = WndProc;
    wc.cbClsExtra    = 0;
    wc.cbWndExtra    = 0;
    wc.hInstance     = hInstance;
    wc.hIcon         = LoadIcon(NULL, IDI_APPLICATION);
    wc.hCursor       = LoadCursor(NULL, IDC_ARROW);
    wc.hbrBackground = (HBRUSH)(COLOR_BTNFACE+1);
    wc.lpszMenuName  = NULL;
    wc.lpszClassName = g_szClassName;
    wc.hIconSm       = LoadIcon(NULL, IDI_APPLICATION);

    if(!RegisterClassEx(&wc))
    {
        MessageBox(NULL, "Window Registration Failed!", "Error!",
            MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }

    hwnd = CreateWindowEx(
        0,
        g_szClassName,
        "Autocomplete Combobox Test",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT, 240, 120,
        NULL, NULL, hInstance, NULL);

    if(hwnd == NULL)
    {
        MessageBox(NULL, "Window Creation Failed!", "Error!",
            MB_ICONEXCLAMATION | MB_OK);
        return 0;
    }

    ShowWindow(hwnd, nCmdShow);
    UpdateWindow(hwnd);

    while(GetMessage(&Msg, NULL, 0, 0))
    {
        TranslateMessage(&Msg);
        DispatchMessage(&Msg);
    }
    return Msg.wParam;
}
//-------------------------------------------------------------------------------- 


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