Reputation: 167
Edit: I think the WM_CREATE message isn't sent during the creation of child windows (namely my button). So by calling SendMessage during WM_CREATE, I'm sending a message to a window that hasn't been created yet. The solution for now is to call SendMessage() during the WM_SHOWWINDOW message. Do child windows send WM_CREATE messages at creation?
Why isn't the bitmap displaying on the button? The bitmap is 180x180 pixels.
I have a resource file with:
Bit BITMAP bit.bmp
I then create the main window and a child "BUTTON" window with:
HWND b, d;
b = CreateWindow(L"a", NULL, WS_OVERLAPPEDWINDOW, 0, 0, 500, 500, 0, 0,
hInstance, 0);
d = CreateWindow(L"BUTTON", NULL, WS_CHILD | WS_VISIBLE | BS_BITMAP,
10, 10, 180, 180, b, 200, hInstance, 0);
Then, in my windows procedure, I send the "BUTTON" window the "BM_SETIMAGE" message with:
HBITMAP hbit;
case WM_CREATE: // It works if I change this to: case WM_SHOWWINDOW
hbit = LoadBitmap(hInstance, L"Bit");
SendMessage(d, BM_SETIMAGE, (WPARAM)IMAGE_BITMAP, (LPARAM)hbit);
LoadBitmap() is returning a valid handle because It isn't returning NULL, and I'm able to display the bitmap in the client area using the BitBlt() function. So I'm either not sending the message correctly, or I'm not creating the "BUTTON" window correctly.
What am I doing wrong?
Thanks!
Upvotes: 5
Views: 14191
Reputation: 281835
The window procedure for for your window class "a" gets called with WM_CREATE
when a window of that class is created. This is during your first call to CreateWindow
, which is before you create the child BUTTON
window. WM_CREATE
means "you are being created" - it doesn't mean "a child is being created".
The solution is to call d = CreateWindow(L"BUTTON"...)
in the WM_CREATE
handler for class "a":
case WM_CREATE:
d = CreateWindow(L"BUTTON", NULL, WS_CHILD | WS_VISIBLE | BS_BITMAP,
10, 10, 180, 180, hwnd, 200, hInstance, 0);
hbit = LoadBitmap(hInstance, L"Bit");
SendMessage(d, BM_SETIMAGE, (WPARAM)IMAGE_BITMAP, (LPARAM)hbit);
Upvotes: 5
Reputation: 30418
How are you verifying that WM_CREATE
isn't getting called? Since BUTTON
isn't your window class (but rather defined by the OS) it owns the WndProc
for the window, not you - therefore WM_CREATE
shouldn't be called for the button in your code, because BUTTON
isn't your class.
If you want to receive messages for the button, you'll have to subclass it, and then provide your own WndProc
.
Upvotes: 0