src/video/windows/SDL_windowsevents.c

/*
  Simple DirectMedia Layer
  Copyright (C) 1997-2012 Sam Lantinga <slouken@libsdl.org>

  This software is provided 'as-is', without any express or implied
  warranty.  In no event will the authors be held liable for any damages
  arising from the use of this software.

  Permission is granted to anyone to use this software for any purpose,
  including commercial applications, and to alter it and redistribute it
  freely, subject to the following restrictions:

  1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.
  2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.
  3. This notice may not be removed or altered from any source distribution.
*/
#include "SDL_config.h"

#if SDL_VIDEO_DRIVER_WINDOWS

#include "SDL_windowsvideo.h"
#include "SDL_windowsshape.h"
#include "SDL_syswm.h"
#include "SDL_vkeys.h"
#include "../../events/SDL_events_c.h"
#include "../../events/SDL_touch_c.h"

/* Dropfile support */
#include <shellapi.h>


/*#define WMMSG_DEBUG*/
#ifdef WMMSG_DEBUG
#include <stdio.h>	
#include "wmmsg.h"
#endif

/* Masks for processing the windows KEYDOWN and KEYUP messages */
#define REPEATED_KEYMASK    (1<<30)
#define EXTENDED_KEYMASK    (1<<24)

#define VK_ENTER    10          /* Keypad Enter ... no VKEY defined? */

/* Make sure XBUTTON stuff is defined that isn't in older Platform SDKs... */
#ifndef WM_XBUTTONDOWN
#define WM_XBUTTONDOWN 0x020B
#endif
#ifndef WM_XBUTTONUP
#define WM_XBUTTONUP 0x020C
#endif
#ifndef GET_XBUTTON_WPARAM
#define GET_XBUTTON_WPARAM(w) (HIWORD(w))
#endif
#ifndef WM_INPUT
#define WM_INPUT 0x00ff
#endif
#ifndef WM_TOUCH
#define WM_TOUCH 0x0240
#endif


static WPARAM
RemapVKEY(WPARAM wParam, LPARAM lParam)
{
    int i;
    BYTE scancode = (BYTE) ((lParam >> 16) & 0xFF);

    /* Windows remaps alphabetic keys based on current layout.
       We try to provide USB scancodes, so undo this mapping.
     */
    if (wParam >= 'A' && wParam <= 'Z') {
        if (scancode != alpha_scancodes[wParam - 'A']) {
            for (i = 0; i < SDL_arraysize(alpha_scancodes); ++i) {
                if (scancode == alpha_scancodes[i]) {
                    wParam = 'A' + i;
                    break;
                }
            }
        }
    }

    /* Keypad keys are a little trickier, we always scan for them.
       Keypad arrow keys have the same scancode as normal arrow keys,
       except they don't have the extended bit (0x1000000) set.
     */
    if (!(lParam & 0x1000000)) {
        if (wParam == VK_DELETE) {
            wParam = VK_DECIMAL;
        } else {
            for (i = 0; i < SDL_arraysize(keypad_scancodes); ++i) {
                if (scancode == keypad_scancodes[i]) {
                    wParam = VK_NUMPAD0 + i;
                    break;
                }
            }
        }
    }

    return wParam;
}

LRESULT CALLBACK
WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
    SDL_WindowData *data;
    LRESULT returnCode = -1;

    /* Send a SDL_SYSWMEVENT if the application wants them */
    if (SDL_GetEventState(SDL_SYSWMEVENT) == SDL_ENABLE) {
        SDL_SysWMmsg wmmsg;

        SDL_VERSION(&wmmsg.version);
        wmmsg.subsystem = SDL_SYSWM_WINDOWS;
        wmmsg.msg.win.hwnd = hwnd;
        wmmsg.msg.win.msg = msg;
        wmmsg.msg.win.wParam = wParam;
        wmmsg.msg.win.lParam = lParam;
        SDL_SendSysWMEvent(&wmmsg);
    }

    /* Get the window data for the window */
    data = (SDL_WindowData *) GetProp(hwnd, TEXT("SDL_WindowData"));
    if (!data) {
        return CallWindowProc(DefWindowProc, hwnd, msg, wParam, lParam);
    }

#ifdef WMMSG_DEBUG
    {		
        FILE *log = fopen("wmmsg.txt", "a");		
        fprintf(log, "Received windows message: %p ", hwnd);
        if (msg > MAX_WMMSG) {
            fprintf(log, "%d", msg);
        } else {
            fprintf(log, "%s", wmtab[msg]);
        }
        fprintf(log, " -- 0x%X, 0x%X\n", wParam, lParam);
        fclose(log);
    }
#endif

    if (IME_HandleMessage(hwnd, msg, wParam, &lParam, data->videodata))
        return 0;

    switch (msg) {

    case WM_SHOWWINDOW:
        {
            if (wParam) {
                SDL_SendWindowEvent(data->window, SDL_WINDOWEVENT_SHOWN, 0, 0);
            } else {
                SDL_SendWindowEvent(data->window, SDL_WINDOWEVENT_HIDDEN, 0, 0);
            }
        }
        break;

    case WM_ACTIVATE:
        {
            BOOL minimized;

            minimized = HIWORD(wParam);
            if (!minimized && (LOWORD(wParam) != WA_INACTIVE)) {
                SDL_SendWindowEvent(data->window, SDL_WINDOWEVENT_SHOWN, 0, 0);
                SDL_SendWindowEvent(data->window,
                                    SDL_WINDOWEVENT_RESTORED, 0, 0);
                if (IsZoomed(hwnd)) {
                    SDL_SendWindowEvent(data->window,
                                        SDL_WINDOWEVENT_MAXIMIZED, 0, 0);
                }
                if (SDL_GetKeyboardFocus() != data->window) {
                    SDL_SetKeyboardFocus(data->window);
                }

				if(SDL_GetMouse()->relative_mode) {
					LONG cx, cy;
					RECT rect;
					GetWindowRect(hwnd, &rect);

					cx = (rect.left + rect.right) / 2;
					cy = (rect.top + rect.bottom) / 2;

					/* Make an absurdly small clip rect */
					rect.left = cx-1;
					rect.right = cx+1;
					rect.top = cy-1;
					rect.bottom = cy+1;

					ClipCursor(&rect);
				}

                /*
                 * FIXME: Update keyboard state
                 */
                WIN_CheckClipboardUpdate(data->videodata);
            } else {
                if (SDL_GetKeyboardFocus() == data->window) {
                    SDL_SetKeyboardFocus(NULL);
                }
                if (minimized) {
                    SDL_SendWindowEvent(data->window,
                                        SDL_WINDOWEVENT_MINIMIZED, 0, 0);
                }
            }
        }
        returnCode = 0;
        break;

	case WM_MOUSEMOVE:
		if(SDL_GetMouse()->relative_mode)
			break;
        SDL_SendMouseMotion(data->window, 0, LOWORD(lParam), HIWORD(lParam));
        break;

	case WM_INPUT:
	{
		HRAWINPUT hRawInput = (HRAWINPUT)lParam;
		RAWINPUT inp;
		UINT size = sizeof(inp);

		if(!SDL_GetMouse()->relative_mode)
			break;

		GetRawInputData(hRawInput, RID_INPUT, &inp, &size, sizeof(RAWINPUTHEADER));

		/* Mouse data */
		if(inp.header.dwType == RIM_TYPEMOUSE)
		{
			RAWMOUSE* mouse = &inp.data.mouse;

			if((mouse->usFlags & 0x01) == MOUSE_MOVE_RELATIVE)
			{
				SDL_SendMouseMotion(data->window, 1, (int)mouse->lLastX, (int)mouse->lLastY);
			}
			else
			{
				// synthesize relative moves from the abs position
				static SDL_Point initialMousePoint;
				if ( initialMousePoint.x == 0 && initialMousePoint.y == 0 )
				{
					initialMousePoint.x = mouse->lLastX;
					initialMousePoint.y = mouse->lLastY;
				}

				SDL_SendMouseMotion(data->window, 1, (int)(mouse->lLastX-initialMousePoint.x), (int)(mouse->lLastY-initialMousePoint.y) );

				initialMousePoint.x = mouse->lLastX;
				initialMousePoint.y = mouse->lLastY;
			}
		}
		break;
	}

    case WM_LBUTTONDOWN:
        SDL_SendMouseButton(data->window, SDL_PRESSED, SDL_BUTTON_LEFT);
        break;

    case WM_LBUTTONUP:
        SDL_SendMouseButton(data->window, SDL_RELEASED, SDL_BUTTON_LEFT);
        break;

    case WM_RBUTTONDOWN:
        SDL_SendMouseButton(data->window, SDL_PRESSED, SDL_BUTTON_RIGHT);
        break;

    case WM_RBUTTONUP:
        SDL_SendMouseButton(data->window, SDL_RELEASED, SDL_BUTTON_RIGHT);
        break;

    case WM_MBUTTONDOWN:
        SDL_SendMouseButton(data->window, SDL_PRESSED, SDL_BUTTON_MIDDLE);
        break;

    case WM_MBUTTONUP:
        SDL_SendMouseButton(data->window, SDL_RELEASED, SDL_BUTTON_MIDDLE);
        break;

    case WM_XBUTTONDOWN:
        SDL_SendMouseButton(data->window, SDL_PRESSED, SDL_BUTTON_X1 + GET_XBUTTON_WPARAM(wParam) - 1);
        returnCode = TRUE;
        break;

    case WM_XBUTTONUP:
        SDL_SendMouseButton(data->window, SDL_RELEASED, SDL_BUTTON_X1 + GET_XBUTTON_WPARAM(wParam) - 1);
        returnCode = TRUE;
        break;

    case WM_MOUSEWHEEL:
        {
            // FIXME: This may need to accumulate deltas up to WHEEL_DELTA
            short motion = GET_WHEEL_DELTA_WPARAM(wParam) / WHEEL_DELTA;

            SDL_SendMouseWheel(data->window, 0, motion);
            break;
        }

#ifdef WM_MOUSELEAVE
    /* FIXME: Do we need the SDL 1.2 hack to generate WM_MOUSELEAVE now? */
    case WM_MOUSELEAVE:
        if (SDL_GetMouseFocus() == data->window) {
            SDL_SetMouseFocus(NULL);
        }
        returnCode = 0;
        break;
#endif /* WM_MOUSELEAVE */

    case WM_SYSKEYDOWN:
    case WM_KEYDOWN:
        {
            wParam = RemapVKEY(wParam, lParam);
            switch (wParam) {
            case VK_CONTROL:
                if (lParam & EXTENDED_KEYMASK)
                    wParam = VK_RCONTROL;
                else
                    wParam = VK_LCONTROL;
                break;
            case VK_SHIFT:
                /* EXTENDED trick doesn't work here */
                {
                    Uint8 *state = SDL_GetKeyboardState(NULL);
                    if (state[SDL_SCANCODE_LSHIFT] == SDL_RELEASED
                        && (GetKeyState(VK_LSHIFT) & 0x8000)) {
                        wParam = VK_LSHIFT;
                    } else if (state[SDL_SCANCODE_RSHIFT] == SDL_RELEASED
                               && (GetKeyState(VK_RSHIFT) & 0x8000)) {
                        wParam = VK_RSHIFT;
                    } else {
                        /* Probably a key repeat */
                        wParam = 256;
                    }
                }
                break;
            case VK_MENU:
                if (lParam & EXTENDED_KEYMASK)
                    wParam = VK_RMENU;
                else
                    wParam = VK_LMENU;
                break;
            case VK_RETURN:
                if (lParam & EXTENDED_KEYMASK)
                    wParam = VK_ENTER;
                break;
            }
            if (wParam < 256) {
                SDL_SendKeyboardKey(SDL_PRESSED,
                                    data->videodata->key_layout[wParam]);
            }
        }
        returnCode = 0;
        break;

    case WM_SYSKEYUP:
    case WM_KEYUP:
        {
            wParam = RemapVKEY(wParam, lParam);
            switch (wParam) {
            case VK_CONTROL:
                if (lParam & EXTENDED_KEYMASK)
                    wParam = VK_RCONTROL;
                else
                    wParam = VK_LCONTROL;
                break;
            case VK_SHIFT:
                /* EXTENDED trick doesn't work here */
                {
                    Uint8 *state = SDL_GetKeyboardState(NULL);
                    if (state[SDL_SCANCODE_LSHIFT] == SDL_PRESSED
                        && !(GetKeyState(VK_LSHIFT) & 0x8000)) {
                        wParam = VK_LSHIFT;
                    } else if (state[SDL_SCANCODE_RSHIFT] == SDL_PRESSED
                               && !(GetKeyState(VK_RSHIFT) & 0x8000)) {
                        wParam = VK_RSHIFT;
                    } else {
                        /* Probably a key repeat */
                        wParam = 256;
                    }
                }
                break;
            case VK_MENU:
                if (lParam & EXTENDED_KEYMASK)
                    wParam = VK_RMENU;
                else
                    wParam = VK_LMENU;
                break;
            case VK_RETURN:
                if (lParam & EXTENDED_KEYMASK)
                    wParam = VK_ENTER;
                break;
            }

            /* Windows only reports keyup for print screen */
            if (wParam == VK_SNAPSHOT
                && SDL_GetKeyboardState(NULL)[SDL_SCANCODE_PRINTSCREEN] ==
                SDL_RELEASED) {
                SDL_SendKeyboardKey(SDL_PRESSED,
                                    data->videodata->key_layout[wParam]);
            }
            if (wParam < 256) {
                SDL_SendKeyboardKey(SDL_RELEASED,
                                    data->videodata->key_layout[wParam]);
            }
        }
        returnCode = 0;
        break;

    case WM_CHAR:
        {
            char text[4];

            /* Convert to UTF-8 and send it on... */
            if (wParam <= 0x7F) {
                text[0] = (char) wParam;
                text[1] = '\0';
            } else if (wParam <= 0x7FF) {
                text[0] = 0xC0 | (char) ((wParam >> 6) & 0x1F);
                text[1] = 0x80 | (char) (wParam & 0x3F);
                text[2] = '\0';
            } else {
                text[0] = 0xE0 | (char) ((wParam >> 12) & 0x0F);
                text[1] = 0x80 | (char) ((wParam >> 6) & 0x3F);
                text[2] = 0x80 | (char) (wParam & 0x3F);
                text[3] = '\0';
            }
            SDL_SendKeyboardText(text);
        }
        returnCode = 0;
        break;

#ifdef WM_INPUTLANGCHANGE
    case WM_INPUTLANGCHANGE:
        {
            WIN_UpdateKeymap();
        }
        returnCode = 1;
        break;
#endif /* WM_INPUTLANGCHANGE */

#ifdef WM_GETMINMAXINFO
    case WM_GETMINMAXINFO:
        {
            MINMAXINFO *info;
            RECT size;
            int x, y;
            int w, h;
            int min_w, min_h;
            int max_w, max_h;
            int style;
            BOOL menu;
			BOOL constrain_max_size;

            /* If we allow resizing, let the resize happen naturally */
            if (SDL_IsShapedWindow(data->window))
                Win32_ResizeWindowShape(data->window);

            /* Get the current position of our window */
            GetWindowRect(hwnd, &size);
            x = size.left;
            y = size.top;

            /* Calculate current size of our window */
            SDL_GetWindowSize(data->window, &w, &h);
            SDL_GetWindowMinimumSize(data->window, &min_w, &min_h);
            SDL_GetWindowMaximumSize(data->window, &max_w, &max_h);

            /* Store in min_w and min_h difference between current size and minimal 
               size so we don't need to call AdjustWindowRectEx twice */
            min_w -= w;
            min_h -= h;
            if (max_w && max_h) {
                max_w -= w;
                max_h -= h;
                constrain_max_size = TRUE;
            } else {
                constrain_max_size = FALSE;
            }

            size.top = 0;
            size.left = 0;
            size.bottom = h;
            size.right = w;

            style = GetWindowLong(hwnd, GWL_STYLE);
            /* DJM - according to the docs for GetMenu(), the
               return value is undefined if hwnd is a child window.
               Aparently it's too difficult for MS to check
               inside their function, so I have to do it here.
             */
            menu = (style & WS_CHILDWINDOW) ? FALSE : (GetMenu(hwnd) != NULL);
            AdjustWindowRectEx(&size, style, menu, 0);
            w = size.right - size.left;
            h = size.bottom - size.top;

            /* Fix our size to the current size */
            info = (MINMAXINFO *) lParam;
            if (SDL_GetWindowFlags(data->window) & SDL_WINDOW_RESIZABLE) {
                info->ptMinTrackSize.x = w + min_w;
                info->ptMinTrackSize.y = h + min_h;
                if (constrain_max_size) {
                    info->ptMaxTrackSize.x = w + max_w;
                    info->ptMaxTrackSize.y = h + max_h;
                }
            } else {
                info->ptMaxSize.x = w;
                info->ptMaxSize.y = h;
                info->ptMaxPosition.x = x;
                info->ptMaxPosition.y = y;
                info->ptMinTrackSize.x = w;
                info->ptMinTrackSize.y = h;
                info->ptMaxTrackSize.x = w;
                info->ptMaxTrackSize.y = h;
            }
        }
        returnCode = 0;
        break;
#endif /* WM_GETMINMAXINFO */

    case WM_WINDOWPOSCHANGED:
        {
            RECT rect;
            int x, y;
            int w, h;
            Uint32 window_flags;

            if (!GetClientRect(hwnd, &rect) ||
                (rect.right == rect.left && rect.bottom == rect.top)) {
                break;
            }
            ClientToScreen(hwnd, (LPPOINT) & rect);
            ClientToScreen(hwnd, (LPPOINT) & rect + 1);

            window_flags = SDL_GetWindowFlags(data->window);
            if ((window_flags & SDL_WINDOW_INPUT_GRABBED) &&
                (window_flags & SDL_WINDOW_INPUT_FOCUS)) {
                ClipCursor(&rect);
            }

            x = rect.left;
            y = rect.top;
            SDL_SendWindowEvent(data->window, SDL_WINDOWEVENT_MOVED, x, y);

            w = rect.right - rect.left;
            h = rect.bottom - rect.top;
            SDL_SendWindowEvent(data->window, SDL_WINDOWEVENT_RESIZED, w,
                                h);
        }
        break;

    case WM_SETCURSOR:
        {
            Uint16 hittest;

            hittest = LOWORD(lParam);
            if (hittest == HTCLIENT) {
                SetCursor(SDL_cursor);
                returnCode = TRUE;
            }
        }
        break;

        /* We were occluded, refresh our display */
    case WM_PAINT:
        {
            RECT rect;
            if (GetUpdateRect(hwnd, &rect, FALSE)) {
                ValidateRect(hwnd, &rect);
                SDL_SendWindowEvent(data->window, SDL_WINDOWEVENT_EXPOSED,
                                    0, 0);
            }
        }
        returnCode = 0;
        break;

        /* We'll do our own drawing, prevent flicker */
    case WM_ERASEBKGND:
        {
        }
        return (1);

#if defined(SC_SCREENSAVE) || defined(SC_MONITORPOWER)
    case WM_SYSCOMMAND:
        {
            /* Don't start the screensaver or blank the monitor in fullscreen apps */
            if ((wParam & 0xFFF0) == SC_SCREENSAVE ||
                (wParam & 0xFFF0) == SC_MONITORPOWER) {
                if (SDL_GetVideoDevice()->suspend_screensaver) {
                    return (0);
                }
            }
        }
        break;
#endif /* System has screensaver support */

    case WM_CLOSE:
        {
            SDL_SendWindowEvent(data->window, SDL_WINDOWEVENT_CLOSE, 0, 0);
        }
        returnCode = 0;
        break;

	case WM_TOUCH:
		{
			UINT i, num_inputs = LOWORD(wParam);
			PTOUCHINPUT inputs = SDL_stack_alloc(TOUCHINPUT, num_inputs);
			if (data->videodata->GetTouchInputInfo((HTOUCHINPUT)lParam, num_inputs, inputs, sizeof(TOUCHINPUT))) {
				RECT rect;
				float x, y;

				if (!GetClientRect(hwnd, &rect) ||
				    (rect.right == rect.left && rect.bottom == rect.top)) {
					break;
				}
				ClientToScreen(hwnd, (LPPOINT) & rect);
				ClientToScreen(hwnd, (LPPOINT) & rect + 1);
				rect.top *= 100;
				rect.left *= 100;
				rect.bottom *= 100;
				rect.right *= 100;

				for (i = 0; i < num_inputs; ++i) {
					PTOUCHINPUT input = &inputs[i];

					const SDL_TouchID touchId = (SDL_TouchID)
												((size_t)input->hSource);
					if (!SDL_GetTouch(touchId)) {
						SDL_Touch touch;

						touch.id = touchId;
						touch.x_min = 0;
						touch.x_max = 1;
						touch.native_xres = touch.x_max - touch.x_min;
						touch.y_min = 0;
						touch.y_max = 1;
						touch.native_yres = touch.y_max - touch.y_min;
						touch.pressure_min = 0;
						touch.pressure_max = 1;
						touch.native_pressureres = touch.pressure_max - touch.pressure_min;

						if (SDL_AddTouch(&touch, "") < 0) {
							continue;
						}
					}

					// Get the normalized coordinates for the window
					x = (float)(input->x - rect.left)/(rect.right - rect.left);
					y = (float)(input->y - rect.top)/(rect.bottom - rect.top);

					if (input->dwFlags & TOUCHEVENTF_DOWN) {
						SDL_SendFingerDown(touchId, input->dwID, SDL_TRUE, x, y, 1);
					}
					if (input->dwFlags & TOUCHEVENTF_MOVE) {
						SDL_SendTouchMotion(touchId, input->dwID, SDL_FALSE, x, y, 1);
					}
					if (input->dwFlags & TOUCHEVENTF_UP) {
						SDL_SendFingerDown(touchId, input->dwID, SDL_FALSE, x, y, 1);
					}
				}
			}
			SDL_stack_free(inputs);

			data->videodata->CloseTouchInputHandle((HTOUCHINPUT)lParam);
			return 0;
		}
		break;

    case WM_DROPFILES:
        {
            UINT i;
            HDROP drop = (HDROP) wParam;
            UINT count = DragQueryFile(drop, 0xFFFFFFFF, NULL, 0);
            for (i = 0; i < count; ++i) {
                UINT size = DragQueryFile(drop, i, NULL, 0) + 1;
                LPTSTR buffer = SDL_stack_alloc(TCHAR, size);
                if (buffer) {
                    if (DragQueryFile(drop, i, buffer, size)) {
                        char *file = WIN_StringToUTF8(buffer);
                        SDL_SendDropFile(file);
                        SDL_free(file);
                    }
                    SDL_stack_free(buffer);
                }
            }
            DragFinish(drop);
            return 0;
        }
        break;
    }

    /* If there's a window proc, assume it's going to handle messages */
    if (data->wndproc) {
        return CallWindowProc(data->wndproc, hwnd, msg, wParam, lParam);
    } else if (returnCode >= 0) {
        return returnCode;
    } else {
        return CallWindowProc(DefWindowProc, hwnd, msg, wParam, lParam);
    }
}

void
WIN_PumpEvents(_THIS)
{
    MSG msg;
    while (PeekMessage(&msg, NULL, 0, 0, PM_REMOVE)) {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
}

static int app_registered = 0;
LPTSTR SDL_Appname = NULL;
Uint32 SDL_Appstyle = 0;
HINSTANCE SDL_Instance = NULL;

/* Register the class for this application */
int
SDL_RegisterApp(char *name, Uint32 style, void *hInst)
{
    WNDCLASS class;

    /* Only do this once... */
    if (app_registered) {
        ++app_registered;
        return (0);
    }
    if (!name && !SDL_Appname) {
        name = "SDL_app";
#if defined(CS_BYTEALIGNCLIENT) || defined(CS_OWNDC)
        SDL_Appstyle = (CS_BYTEALIGNCLIENT | CS_OWNDC);
#endif
        SDL_Instance = hInst ? hInst : GetModuleHandle(NULL);
    }

    if (name) {
        SDL_Appname = WIN_UTF8ToString(name);
        SDL_Appstyle = style;
        SDL_Instance = hInst ? hInst : GetModuleHandle(NULL);
    }

    /* Register the application class */
    class.hCursor = NULL;
    class.hIcon =
        LoadImage(SDL_Instance, SDL_Appname, IMAGE_ICON, 0, 0,
                  LR_DEFAULTCOLOR);
    class.lpszMenuName = NULL;
    class.lpszClassName = SDL_Appname;
    class.hbrBackground = NULL;
    class.hInstance = SDL_Instance;
    class.style = SDL_Appstyle;
    class.lpfnWndProc = WIN_WindowProc;
    class.cbWndExtra = 0;
    class.cbClsExtra = 0;
    if (!RegisterClass(&class)) {
        SDL_SetError("Couldn't register application class");
        return (-1);
    }

    app_registered = 1;
    return (0);
}

/* Unregisters the windowclass registered in SDL_RegisterApp above. */
void
SDL_UnregisterApp()
{
    WNDCLASS class;

    /* SDL_RegisterApp might not have been called before */
    if (!app_registered) {
        return;
    }
    --app_registered;
    if (app_registered == 0) {
        /* Check for any registered window classes. */
        if (GetClassInfo(SDL_Instance, SDL_Appname, &class)) {
            UnregisterClass(SDL_Appname, SDL_Instance);
        }
        SDL_free(SDL_Appname);
        SDL_Appname = NULL;
    }
}

#endif /* SDL_VIDEO_DRIVER_WINDOWS */

/* vi: set ts=4 sw=4 expandtab: */