C ++ HWND window procedure change at runtime

Question

I work in an IDE that creates hwndand its corresponding WndProc LRESULT CALLBACK. I need to change WndProcto custom.

I read that it SetWindowLongwill do the job, but I cannot find any working example. For instance:

HWND hwnd; //My window

SetWindowLong(hwnd, GWL_WNDPROC, myNewWndProc);

The third parameter for SetWindowLongis Longas the name of the function that it calls. How can I make a link from my function WndProcto Long?

My WndProc:

LRESULT CALLBACK WndProcedure(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam){

msg_dev(toString(uMsg));

switch(uMsg){

    case WM_MOUSEMOVE:
        SetCursor(LoadCursor(NULL, IDC_HAND));
        break;

    case WM_LBUTTONDOWN:
        msg_dev("Button down!");
        break;

    default:
        DefWindowProc(hwnd, uMsg, wParam, lParam);
}

return 0;
};

Answer 1

You need to use something like this:

WNDPROC prevWndProc;
...
prevWndProc = (WNDPROC) SetWindowLongPtr(hwnd, GWL_WNDPROC, (LONG_PTR)&myNewWndProc);
...    
LRESULT CALLBACK myNewWndProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    msg_dev(toString(uMsg));

    switch(uMsg)
    {
        case WM_MOUSEMOVE:
            SetCursor(LoadCursor(NULL, IDC_HAND));
            break;

        case WM_LBUTTONDOWN:
            msg_dev("Button down!");
            break;
    }

    return CallWindowProc(prevWndProc, hwnd, uMsg, wParam, lParam);
}

See this article:

, , , , .

SetWindowSubclass() SetWindowLongPtr(). :

:

SetWindowSubclass(hwnd, &mySubClassProc, 1, 0);
...    
LRESULT CALLBACK mySubClassProc(HWND hWnd, UINT uMsg, WPARAM wParam, LPARAM lParam, UINT_PTR uIdSubclass, DWORD_PTR dwRefData)
{
    msg_dev(toString(uMsg));

    switch(uMsg)
    {
        case WM_MOUSEMOVE:
            SetCursor(LoadCursor(NULL, IDC_HAND));
            break;

        case WM_LBUTTONDOWN:
            msg_dev("Button down!");
            break;

        case WM_NCDESTROY:
            RemoveWindowSubclass(hWnd, &mySubClassProc, 1);
            break;
    }

    return DefSubclassProc(hWnd, uMsg, wParam, lParam);
}

Answer 2

MSDN SetWindowLong() , GWL_WNDPROC

.

, . SetWindowLong() :

SetWindowLong(hwnd, GWL_WNDPROC, (LONG_PTR)&myNewWndProc);

"", :

, , , CallWindowProc.

Answer 3

.

SetWindowLongPtr(hwnd, GWL_WNDPROC, (LONG_PTR)&myNewWndProc);

: LRESULT LONG.

Answer 4

setWindowLong .

setWindowLong(hwnd,GWL_WNDPROC,(LONG)newWindowProcedure);

However, you would set the window procedure twice. Once with the default IDE, and then with yours. What you need to do is set up the window procedure when the window is registered.

#include <windows.h>


void registerWindow();
void createWindow();
void messageLoop();


int main()
{
 registerWindow();
 createWindow();
 messageLoop();
}


LRESULT CALLBACK myWindowProcedure(HWND hwnd,UINT msg,WPARAM wparam,LPARAM lparam)
{
 return DefWindowProc(hwnd,msg,wparam,lparam);
}

void registerWindow()
{
 /** This is the important part.
    * Find this part in your code.
    * Set WNDCLASS::lpfnWndProc to what ever 
    * window procedure you want.
 **/

 WNDCLASS wc = {};

 wc.lpfnWndProc   = myWindowProcedure;
 wc.hInstance     = hInstance;
 wc.lpszClassName = "CLASS NAME";

 RegisterClass(&wc);

 // WARNING: Your app will crash at runtime if the 
 // windows procedure is "NOT PROPER"
}

void createWindow()
{
 auto hwnd = CreateWindowEx(
    0,                              // Optional window styles.
    "CLASS NAME",                     // Window class
    "Learn to Program Windows",    // Window text
    WS_OVERLAPPEDWINDOW,            // Window style

    // Size and position
    CW_USEDEFAULT, 
    CW_USEDEFAULT, 
    CW_USEDEFAULT, 
    CW_USEDEFAULT,

    NULL,       // Parent window    
    NULL,       // Menu
    HINSTANCE(),  // Instance handle
    NULL        // Additional application data
    );

   ShowWindow(hwnd, nCmdShow
}

void messageLoop()
{
    MSG msg;
    while( GetMessage(&msg, NULL, 0, 0) )
   {
    TranslateMessage(&msg); 
    DispatchMessage(&msg);
   }
}