Question

I have a textbox on a form and i want to set it to match the height/width of the window. Is there any way to do this in C? To be clear this is C not C-Sharp (C#). I’m using DevC++

Code i have to create TextBox:

HWND hwndText = CreateWindow(
    TEXT("edit"),
    TEXT(""),
    WS_VISIBLE | WS_CHILD | WS_BORDER | WS_HSCROLL | WS_VSCROLL| ES_MULTILINE | ES_AUTOHSCROLL,
    0,0,
    630,470, //Height & Width
    hwnd,
    (HMENU)ID_MYTEXT,
    hInstance,
    NULL
);

Full Source:

#include <windows.h>

const char g_szClassName[] = "myWindowClass";

LRESULT CALLBACK WndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    switch(msg)
    {
        case WM_CLOSE:
            DestroyWindow(hwnd);
        break;
        case WM_DESTROY:
            PostQuitMessage(0);
        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;
    HMENU ID_MYTEXT;
    MSG Msg;

    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_WINDOW+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(
        WS_EX_CLIENTEDGE,
        g_szClassName,
        "Title",
        WS_OVERLAPPEDWINDOW,
        CW_USEDEFAULT, CW_USEDEFAULT, 640, 480,
        NULL, NULL, hInstance, NULL
    );

    HWND hwndText = CreateWindow(
        TEXT("edit"),
        TEXT(""),
        WS_VISIBLE | WS_CHILD | WS_BORDER | WS_HSCROLL | WS_VSCROLL| ES_MULTILINE | ES_AUTOHSCROLL,
        0,0,
        630,470,
        hwnd,
        (HMENU)ID_MYTEXT,
        hInstance,
        NULL
    );

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

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

    SendMessage(hwndText, WM_SETTEXT, 0, (LPARAM)"");

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

Answer 1

If this is all you want to have in your window, then why not remove the WS_CHILD style and make the button the whole window?

The other alternative is to handle WM_SIZE message and resize your child button window there.

The shortest version of first example looks like this:

#include "stdafx.h"

BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
   HWND hWnd;


   hWnd = CreateWindow(_T("BUTTON"), L"testButton", WS_OVERLAPPEDWINDOW,
      CW_USEDEFAULT, 0, CW_USEDEFAULT, 0, NULL, NULL, hInstance, NULL);

   if (!hWnd)
   {
      return FALSE;
   }

   ShowWindow(hWnd, nCmdShow);
   UpdateWindow(hWnd);

   return TRUE;
}

int APIENTRY _tWinMain(_In_ HINSTANCE hInstance,
                     _In_opt_ HINSTANCE hPrevInstance,
                     _In_ LPTSTR    lpCmdLine,
                     _In_ int       nCmdShow)
{
    UNREFERENCED_PARAMETER(hPrevInstance);
    UNREFERENCED_PARAMETER(lpCmdLine);

    // TODO: Place code here.
    MSG msg;

    // Perform application initialization:
    if (!InitInstance (hInstance, nCmdShow))
    {
        return FALSE;
    }

    // Main message loop:
    while (GetMessage(&msg, NULL, 0, 0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return (int) msg.wParam;
}