WinAPI窗口立即关闭

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..