// Basic Program to Draw a Window
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <windowsx.h>
#include <stdlib.h>
#include <time.h>
LRESULT CALLBACK MsgHandler(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)
{
if(msg == WM_PAINT)
{
PAINTSTRUCT ps;
HDC hdc;
hdc = BeginPaint(hwnd, &ps);
EndPaint(hwnd, &ps);
return(0);
}
return(DefWindowProc(hwnd, msg, wparam, lparam));
}
int WINAPI WinMain(HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpCmdLine,
int nCmdShow)
{
int x, y, red, green, blue;
srand((unsigned)time(NULL));
HDC hdc;
MSG msg;
WNDCLASSEX BasicWindow;
BasicWindow.cbSize = sizeof(WNDCLASSEX);
BasicWindow.style = CS_DBLCLKS | CS_OWNDC | CS_HREDRAW | CS_VREDRAW;
BasicWindow.lpfnWndProc = MsgHandler;
BasicWindow.cbClsExtra = 0;
BasicWindow.cbWndExtra = 0;
BasicWindow.hInstance = hInstance;
BasicWindow.hIcon = LoadIcon(NULL, IDI_WINLOGO);
BasicWindow.hCursor = LoadCursor(NULL, IDC_ARROW);
BasicWindow.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH);
BasicWindow.lpszMenuName = NULL;
BasicWindow.lpszClassName = "Basic Window";
BasicWindow.hIconSm = LoadIcon(NULL, IDI_WINLOGO);
RegisterClassEx(&BasicWindow);
HWND hwnd;
if(!(hwnd = CreateWindowEx(NULL,
"Basic Window",
"Basic Window",
WS_VISIBLE | WS_CAPTION | WS_TILEDWINDOW,
0,
0,
1024,
768,
NULL,
NULL,
hInstance,
NULL)))
{
return(0);
}
hdc = GetDC(hwnd);
while(TRUE)
{
if(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
{
if(msg.message == WM_QUIT)
{
break;
}
if(msg.message == WM_DESTROY)
{
PostQuitMessage(0);
return(0);
}
TranslateMessage(&msg);
DispatchMessage(&msg);
}
x = rand() % 1024 + 1;
y = rand() % 768 + 1;
red = rand() % 255 + 1;
green = rand() % 255 + 1;
blue = rand() % 255 + 1;
SetPixel(hdc, x, y, RGB(red, green, blue));
}
return(msg.wParam);
}
Message Handling and WM_QUIT/WM_DESTROY
September 10, 2002 10:45 PM
Hi Folks,
I finally got around to writing my first little Windows program which uses the native Windows GDI to plot random pixels of random colors over a 1024X768 surface, but I have one problem, when I click the "X" on my window, the program window will close and nothing will show up on the task manager, but if I try and recompile later on, it tells me that it cannot access the .EXE file, which I have taken to mean that the program is still running. If anyone can help I would appreciate it a lot. Here is my source:
Mikehttp://cs.wpunj.edu/~bowersom
148
September 10, 2002 11:00 PM
When you click the X to close your program, Windows sends a WM_DESTROY message to destroy the program, but doesn't actually close the window.
You need to include the WM_DESTROY message in your WinProc handler, and if that message is received, then do a PostQuitMessage(0); like this.
Now, I've only written one windows program myself, so If I'm wrong, sorry =)
~~~~~~~~~~~
Chris Vogel
~~~~~~~~~~~
[edited by - Radagar on September 10, 2002 12:01:06 AM]
You need to include the WM_DESTROY message in your WinProc handler, and if that message is received, then do a PostQuitMessage(0); like this.
LRESULT CALLBACK MsgHandler(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam){ switch(msg) { case WM_PAINT: { PAINTSTRUCT ps; HDC hdc; hdc = BeginPaint(hwnd, &ps); EndPaint(hwnd, &ps); return(0); break; } case WM_DESTROY: { PostQuitMessage(0); return(0); break; } default: {} } return(DefWindowProc(hwnd, msg, wparam, lparam));} Now, I've only written one windows program myself, so If I'm wrong, sorry =)
~~~~~~~~~~~
Chris Vogel
~~~~~~~~~~~
[edited by - Radagar on September 10, 2002 12:01:06 AM]
WyrmSlayer RPG - In Early Development
122
September 10, 2002 11:54 PM
No, that''s correct. You definitely need to test for WM_DESTROY, because clicking the ''X'' to close the window only removes it from the screen. When you send a PostQuitMessage(0), that tells Windows to kill the program itself.
John.
John.
September 11, 2002 10:25 AM
Hey Again,
I tried compiling again, and still when I click the ''X'', the program closes, but still runs in the background. I''m really confused now. My code looks fine and shouldn''t have ANY problems?
I tried compiling again, and still when I click the ''X'', the program closes, but still runs in the background. I''m really confused now. My code looks fine and shouldn''t have ANY problems?
Mikehttp://cs.wpunj.edu/~bowersom
122
September 11, 2002 11:07 AM
bower12345:
Did you put the WM_DESTROY block in your MsgHandler function? I don''t think that Windows will know to let the program end if you''ve got it in WinMain().
John.
Did you put the WM_DESTROY block in your MsgHandler function? I don''t think that Windows will know to let the program end if you''ve got it in WinMain().
John.
September 11, 2002 02:04 PM
Yes, I moved my code from WinMain to the MsgHandler function. I also thought that maybe since I wasn''t releasing the device context at the end of my program that that might have been the problem, but I still see no change in the program. Here is the updated code:
Any help would be appreciate greatly. Thanks!
// Basic Program to Draw a Window#define WIN32_LEAN_AND_MEAN#include <windows.h>#include <windowsx.h>#include <stdlib.h>#include <time.h> LRESULT CALLBACK MsgHandler(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam){ switch(msg) { case WM_PAINT: { PAINTSTRUCT ps; HDC hdc; hdc = BeginPaint(hwnd, &ps); EndPaint(hwnd, &ps); return(0); } case WM_QUIT: { return(0); break; } case WM_DESTROY: { PostQuitMessage(0); return(0); break; } default: { return(DefWindowProc(hwnd, msg, wparam, lparam)); } }}int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow){ int x, y, red, green, blue; srand((unsigned)time(NULL)); HDC hdc; MSG msg; WNDCLASSEX BasicWindow; BasicWindow.cbSize = sizeof(WNDCLASSEX); BasicWindow.style = CS_DBLCLKS | CS_OWNDC | CS_HREDRAW | CS_VREDRAW; BasicWindow.lpfnWndProc = MsgHandler; BasicWindow.cbClsExtra = 0; BasicWindow.cbWndExtra = 0; BasicWindow.hInstance = hInstance; BasicWindow.hIcon = LoadIcon(NULL, IDI_WINLOGO); BasicWindow.hCursor = LoadCursor(NULL, IDC_ARROW); BasicWindow.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH); BasicWindow.lpszMenuName = NULL; BasicWindow.lpszClassName = "Basic Window"; BasicWindow.hIconSm = LoadIcon(NULL, IDI_WINLOGO); RegisterClassEx(&BasicWindow); HWND hwnd; if(!(hwnd = CreateWindowEx(NULL, "Basic Window", "Basic Window", WS_VISIBLE | WS_CAPTION | WS_TILEDWINDOW, 0, 0, 1024, 768, NULL, NULL, hInstance, NULL))) { return(0); } hdc = GetDC(hwnd); while(TRUE) { if(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) { TranslateMessage(&msg); DispatchMessage(&msg); } x = rand() % 1024 + 1; y = rand() % 768 + 1; red = rand() % 255 + 1; green = rand() % 255 + 1; blue = rand() % 255 + 1; SetPixel(hdc, x, y, RGB(red, green, blue)); } ReleaseDC(hwnd, hdc); return(msg.wParam);} Any help would be appreciate greatly. Thanks!
Mikehttp://cs.wpunj.edu/~bowersom
4,095
September 11, 2002 02:15 PM
Hi,
actually the PostQuitMessage() only sends WM_QUIT to your window
it does nothing to your program. The point is that your app is
running an infinite loop:
while (true) {...}
you should use something like
while(bRunApp) {...}
and in your messagehandler:
if (message=wm_quit) bRunApp=false;
I think that''ll work.
good luck.
--::[Madhed]::-
actually the PostQuitMessage() only sends WM_QUIT to your window
it does nothing to your program. The point is that your app is
running an infinite loop:
while (true) {...}
you should use something like
while(bRunApp) {...}
and in your messagehandler:
if (message=wm_quit) bRunApp=false;
I think that''ll work.
good luck.
--::[Madhed]::-
This topic is closed to new replies.
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