WinAPI Window Closes Instantly - c++

Question

I have been experimenting with the WINAPI trying to learn it but the window I have created closes instantly. As you see when the W key is pressed or the left button is pressed it will close the program but when running it with no buttons being pressed it still closes.
#include <windows.h>
#include <windowsx.h>
// the WindowProc function prototype
LRESULT CALLBACK WindowProc(HWND hWnd,
UINT message,
WPARAM wParam,
LPARAM lParam);
// the entry point for any Windows program
int WINAPI WinMain(HINSTANCE hInstance,
HINSTANCE hPrevInstance,
LPSTR lpCmdLine,
int nCmdShow)
{
// the handle for the window, filled by a function
HWND hWnd;
// this struct holds information for the window class
WNDCLASSEX wc;
// clear out the window class for use
ZeroMemory(&wc, sizeof(WNDCLASSEX));
// fill in the struct with the needed information
wc.cbSize = sizeof(WNDCLASSEX);
wc.style = CS_HREDRAW | CS_VREDRAW;
wc.lpfnWndProc = WindowProc;
wc.hInstance = hInstance;
wc.hCursor = LoadCursor(NULL, IDC_ARROW);
wc.hbrBackground = (HBRUSH)COLOR_WINDOW;
wc.lpszClassName = L"WindowClass1";
// register the window class
RegisterClassEx(&wc);
// create the window and use the result as the handle
hWnd = CreateWindowEx(NULL,
L"WindowClass1", // name of the window class
L"Game", // title of the window
WS_OVERLAPPEDWINDOW, // window style
1, // x-position of the window
1, // y-position of the window
1800, // width of the window
1000, // height of the window
NULL, // we have no parent window, NULL
NULL, // we aren't using menus, NULL
hInstance, // application handle
NULL); // used with multiple windows, NULL
// display the window on the screen
ShowWindow(hWnd, nCmdShow);
// enter the main loop:
// this struct holds Windows event messages
MSG msg;
// wait for the next message in the queue, store the result in 'msg'
while (GetMessage(&msg, NULL, 0, 0))
{
// translate keystroke messages into the right format
TranslateMessage(&msg);
// send the message to the WindowProc function
DispatchMessage(&msg);
}
// return this part of the WM_QUIT message to Windows
return msg.wParam;
}
// this is the main message handler for the program
LRESULT CALLBACK WindowProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
// sort through and find what code to run for the message given
switch (message)
{
// this message is read when the window is closed
case WM_MOUSEMOVE:
{
// Retrieve mouse screen position
int x = (short)LOWORD(lParam);
int y = (short)HIWORD(lParam);
// Check to see if the left button is held down:
bool leftButtonDown = wParam & MK_LBUTTON;
// Check if right button down:
bool rightButtonDown = wParam & MK_RBUTTON;
if (leftButtonDown == true)
{
//left click
//example lets close the program when press w
PostQuitMessage(0);
return 0;
}
}
case WM_KEYDOWN:
{
switch (wParam)
{
case 'W':
//w pressed
//example lets close the program when press w
PostQuitMessage(0);
return 0;
}
}
case WM_DESTROY:
{
// close the application entirely
PostQuitMessage(0);
return 0;
}
default:
break;
}
// Handle any messages the switch statement didn't
return DefWindowProc(hWnd, message, wParam, lParam);
}

Answer 1

You're missing some break statements in your switch, so for example, if you get the WM_MOUSEMOVE message and the leftButtonDown != true, execution will fall through to WM_KEYDOWN, etc.
Eventually you get to case WM_DESTROY:, which will Post you a lovely QuitMessage.
As an aside, this would be very easy to spot by stepping through, statement-by-statement, in a debugger.

Answer 2

There is no break in your switch statement.
You end up exetuting
PostQuitMessage(0);
You could do something like this:
case WM_FOO:
{
if ( bar ) {
return 0;
}
break;
}

Answer 3

Don't detect clicks via the WM_MOUSEMOVE message, use the WM_MOUSEDOWN instead.
The problem is that your code is probably launched by you clicking on something, so when your window gets its first WM_MOUSEMOVE message, the button is still actually pressed. Code runs much faster than fingers..