Better Way to programmatically detect a key press? - c++

Question

I'm currently using this:
while (1)
{
if (GetAsyncKeyState(VK_F1))
{
//do something
}
}
to detect if a user presses a certain key, in this case F1. I've found that this eats up cpu usage by quite a bit, my question is, is there a better way to detect key presses?

Answer 1

The better way of doing this is using your WndProc(). So use standard WM_KEYDOWN/WM_KEYUP messages to handle keyboard input. Here is an example:
LRESULT CALLBACK WndProc( HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam )
{
switch ( uMsg )
{
case WM_CLOSE:
DestroyWindow(hwnd);
break;
case WM_DESTROY:
PostQuitMessage(0);
break;
case WM_KEYDOWN:
if ( wParam == VK_F1 )
{
// Do something here
return 0L;
}
break;
}
return DefWindowProc( hwnd, uMsg, wParam, lParam );
}
int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance,
LPSTR lpCmdLine, int nCmdShow)
{
WNDCLASSEX wc;
HWND hwnd;
MSG Msg;
//Step 1: Registering the Window Class
wc.cbSize = sizeof(WNDCLASSEX);
wc.style = 0;
wc.lpfnWndProc = WndProc;
// lots of other attrs ...
wc.lpszClassName = g_szClassName;
wc.hIconSm = LoadIcon(NULL, IDI_APPLICATION);
if(!RegisterClassEx(&wc))
return 0;
// Step 2: Creating the Window
hwnd = CreateWindowEx(
...
g_szClassName,
...);
if(hwnd == NULL)
return 0;
ShowWindow(hwnd, nCmdShow);
UpdateWindow(hwnd);
// Step 3: The Message Loop
while(GetMessage(&Msg, NULL, 0, 0) > 0)
{
TranslateMessage(&Msg);
DispatchMessage(&Msg);
}
return Msg.wParam;
}