view src/video/win32/SDL_win32window.c @ 3474:1edb86163d62

Of COURSE that trick wouldn't work on all renderers. Fall back to something for now, hopefully figure out a better way to do this later. If we have to, we can use vertical line and horizontal line textures for vertical and horizontal lines, and then create custom textures for diagonal lines and software render those. It's terrible, but at least it would be pixel perfect.
author Sam Lantinga <slouken@libsdl.org>
date Sat, 21 Nov 2009 07:22:59 +0000
parents 413672b09bb3
children 59ff7a2beb57
line wrap: on
line source

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2009 Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    Sam Lantinga
    slouken@libsdl.org
*/

/* we need to define it, so that raw input is included */

#if (_WIN32_WINNT < 0x0501)
#undef _WIN32_WINNT
#define _WIN32_WINNT 0x0501
#endif

#include "SDL_config.h"

#include "../SDL_sysvideo.h"
#include "../SDL_pixels_c.h"
#include "../../events/SDL_keyboard_c.h"

#include "SDL_win32video.h"

/* This is included after SDL_win32video.h, which includes windows.h */
#include "SDL_syswm.h"


#define SHFS_SHOWTASKBAR            0x0001
#define SHFS_HIDETASKBAR            0x0002
#define SHFS_SHOWSIPBUTTON          0x0004
#define SHFS_HIDESIPBUTTON          0x0008
#define SHFS_SHOWSTARTICON          0x0010
#define SHFS_HIDESTARTICON          0x0020

#ifdef _WIN32_WCE
// dynamically load aygshell dll because we want SDL to work on HPC and be300
int aygshell_loaded = 0;
BOOL(WINAPI * SHFullScreen) (HWND hwndRequester, DWORD dwState) = 0;


static BOOL
CE_SHFullScreen(HWND hwndRequester, DWORD dwState)
{
    if (SHFullScreen == 0 && aygshell_loaded == 0) {
        aygshell_loaded = 0;
        void *lib = SDL_LoadObject("aygshell.dll");
        if (lib) {
            SHFullScreen =
                (BOOL(WINAPI *) (HWND, DWORD)) SDL_LoadFunction(lib,
                                                                "SHFullScreen");
        }
    }

    if (SHFullScreen) {
        SHFullScreen(hwndRequester, dwState);
        //printf("SHFullscreen(%i)\n",dwState);
    }
}

#endif

extern HCTX *g_hCtx;            /* the table of tablet event contexts, each windows has to have it's own tablet context */
static Uint32 highestId = 0;    /* the highest id of the tablet context */

/* Fake window to help with DirectInput events. */
HWND SDL_HelperWindow = NULL;
static WCHAR *SDL_HelperWindowClassName = TEXT("SDLHelperWindowInputCatcher");
static WCHAR *SDL_HelperWindowName = TEXT("SDLHelperWindowInputMsgWindow");
static ATOM SDL_HelperWindowClass = 0;

static int
SetupWindowData(_THIS, SDL_Window * window, HWND hwnd, SDL_bool created)
{
    SDL_VideoData *videodata = (SDL_VideoData *) _this->driverdata;
    SDL_WindowData *data;

    /* Allocate the window data */
    data = (SDL_WindowData *) SDL_malloc(sizeof(*data));
    if (!data) {
        SDL_OutOfMemory();
        return -1;
    }
    data->windowID = window->id;
    data->hwnd = hwnd;
    data->hdc = GetDC(hwnd);
    data->created = created;
    data->mouse_pressed = SDL_FALSE;
    data->videodata = videodata;

    /* Associate the data with the window */
    if (!SetProp(hwnd, TEXT("SDL_WindowData"), data)) {
        ReleaseDC(hwnd, data->hdc);
        SDL_free(data);
        WIN_SetError("SetProp() failed");
        return -1;
    }

    /* Set up the window proc function */
    data->wndproc = (WNDPROC) GetWindowLongPtr(hwnd, GWLP_WNDPROC);
    if (data->wndproc == NULL) {
        data->wndproc = DefWindowProc;
    } else {
        SetWindowLongPtr(hwnd, GWLP_WNDPROC, (LONG_PTR) WIN_WindowProc);
    }

    /* Fill in the SDL window with the window data */
    {
        POINT point;
        point.x = 0;
        point.y = 0;
        if (ClientToScreen(hwnd, &point)) {
            window->x = point.x;
            window->y = point.y;
        }
    }
    {
        RECT rect;
        if (GetClientRect(hwnd, &rect)) {
            window->w = rect.right;
            window->h = rect.bottom;
        }
    }
    {
        DWORD style = GetWindowLong(hwnd, GWL_STYLE);
        if (style & WS_VISIBLE) {
            window->flags |= SDL_WINDOW_SHOWN;
        } else {
            window->flags &= ~SDL_WINDOW_SHOWN;
        }
        if (style & (WS_BORDER | WS_THICKFRAME)) {
            window->flags &= ~SDL_WINDOW_BORDERLESS;
        } else {
            window->flags |= SDL_WINDOW_BORDERLESS;
        }
        if (style & WS_THICKFRAME) {
            window->flags |= SDL_WINDOW_RESIZABLE;
        } else {
            window->flags &= ~SDL_WINDOW_RESIZABLE;
        }
        if (style & WS_MAXIMIZE) {
            window->flags |= SDL_WINDOW_MAXIMIZED;
        } else {
            window->flags &= ~SDL_WINDOW_MAXIMIZED;
        }
        if (style & WS_MINIMIZE) {
            window->flags |= SDL_WINDOW_MINIMIZED;
        } else {
            window->flags &= ~SDL_WINDOW_MINIMIZED;
        }
    }
    if (GetFocus() == hwnd) {
        int index = data->videodata->keyboard;
        window->flags |= SDL_WINDOW_INPUT_FOCUS;
        SDL_SetKeyboardFocus(index, data->windowID);

        if (window->flags & SDL_WINDOW_INPUT_GRABBED) {
            RECT rect;
            GetClientRect(hwnd, &rect);
            ClientToScreen(hwnd, (LPPOINT) & rect);
            ClientToScreen(hwnd, (LPPOINT) & rect + 1);
            ClipCursor(&rect);
        }
    }

    /* All done! */
    window->driverdata = data;
    return 0;
}

int
WIN_CreateWindow(_THIS, SDL_Window * window)
{
    SDL_VideoData *videodata = (SDL_VideoData *) _this->driverdata;
    RAWINPUTDEVICE Rid;
    AXIS TabX, TabY;
    LOGCONTEXTA lc;
    HWND hwnd;
    HWND top;
    RECT rect;
    DWORD style = (WS_CLIPSIBLINGS | WS_CLIPCHILDREN);
    int x, y;
    int w, h;

    if (window->flags & (SDL_WINDOW_BORDERLESS | SDL_WINDOW_FULLSCREEN)) {
        style |= WS_POPUP;
    } else {
        style |= (WS_OVERLAPPED | WS_CAPTION | WS_SYSMENU | WS_MINIMIZEBOX);
    }
    if ((window->flags & SDL_WINDOW_RESIZABLE)
        && !(window->flags & SDL_WINDOW_FULLSCREEN)) {
        style |= (WS_THICKFRAME | WS_MAXIMIZEBOX);
    }

    /* Figure out what the window area will be */
    if (window->flags & SDL_WINDOW_FULLSCREEN) {
        top = HWND_TOPMOST;
    } else {
        top = HWND_NOTOPMOST;
    }
    rect.left = 0;
    rect.top = 0;
    rect.right = window->w;
    rect.bottom = window->h;
    AdjustWindowRectEx(&rect, style, FALSE, 0);
    w = (rect.right - rect.left);
    h = (rect.bottom - rect.top);

    if ((window->flags & SDL_WINDOW_FULLSCREEN)
        || window->x == SDL_WINDOWPOS_CENTERED) {
        x = (GetSystemMetrics(SM_CXSCREEN) - w) / 2;
    } else if (window->x == SDL_WINDOWPOS_UNDEFINED) {
        x = CW_USEDEFAULT;
    } else {
        x = window->x + rect.left;
    }
    if ((window->flags & SDL_WINDOW_FULLSCREEN)
        || window->y == SDL_WINDOWPOS_CENTERED) {
        y = (GetSystemMetrics(SM_CYSCREEN) - h) / 2;
    } else if (window->y == SDL_WINDOWPOS_UNDEFINED) {
        y = CW_USEDEFAULT;
    } else {
        y = window->y + rect.top;
    }

    hwnd =
        CreateWindow(SDL_Appname, TEXT(""), style, x, y, w, h, NULL, NULL,
                     SDL_Instance, NULL);
    if (!hwnd) {
        WIN_SetError("Couldn't create window");
        return -1;
    }

    /* we're configuring the tablet data. See Wintab reference for more info */
    if (videodata->wintabDLL
        && videodata->WTInfoA(WTI_DEFSYSCTX, 0, &lc) != 0) {
        lc.lcPktData = PACKETDATA;
        lc.lcPktMode = PACKETMODE;
        lc.lcOptions |= CXO_MESSAGES;
        lc.lcOptions |= CXO_SYSTEM;
        lc.lcMoveMask = PACKETDATA;
        lc.lcBtnDnMask = lc.lcBtnUpMask = PACKETDATA;
        videodata->WTInfoA(WTI_DEVICES, DVC_X, &TabX);
        videodata->WTInfoA(WTI_DEVICES, DVC_Y, &TabY);
        lc.lcInOrgX = 0;
        lc.lcInOrgY = 0;
        lc.lcInExtX = TabX.axMax;
        lc.lcInExtY = TabY.axMax;
        lc.lcOutOrgX = 0;
        lc.lcOutOrgY = 0;
        lc.lcOutExtX = GetSystemMetrics(SM_CXSCREEN);
        lc.lcOutExtY = -GetSystemMetrics(SM_CYSCREEN);
        if (window->id > highestId) {
            HCTX *tmp_hctx;
            highestId = window->id;
            tmp_hctx =
                (HCTX *) SDL_realloc(g_hCtx, (highestId + 1) * sizeof(HCTX));
            if (!tmp_hctx) {
                SDL_OutOfMemory();
                DestroyWindow(hwnd);
                return -1;
            }
            g_hCtx = tmp_hctx;
        }
        g_hCtx[window->id] = videodata->WTOpenA(hwnd, &lc, TRUE);
    }
#ifndef _WIN32_WCE              /* has no RawInput */
    /* we're telling the window, we want it to report raw input events from mice */
    Rid.usUsagePage = 0x01;
    Rid.usUsage = 0x02;
    Rid.dwFlags = RIDEV_INPUTSINK;
    Rid.hwndTarget = hwnd;
    RegisterRawInputDevices(&Rid, 1, sizeof(Rid));
#endif

    WIN_PumpEvents(_this);

    if (SetupWindowData(_this, window, hwnd, SDL_TRUE) < 0) {
        DestroyWindow(hwnd);
        return -1;
    }
#ifdef SDL_VIDEO_OPENGL_WGL
    if (window->flags & SDL_WINDOW_OPENGL) {
        if (WIN_GL_SetupWindow(_this, window) < 0) {
            WIN_DestroyWindow(_this, window);
            return -1;
        }
    }
#endif
    return 0;
}

int
WIN_CreateWindowFrom(_THIS, SDL_Window * window, const void *data)
{
    HWND hwnd = (HWND) data;
    LPTSTR title;
    int titleLen;

    /* Query the title from the existing window */
    titleLen = GetWindowTextLength(hwnd);
    title = SDL_stack_alloc(TCHAR, titleLen + 1);
    if (title) {
        titleLen = GetWindowText(hwnd, title, titleLen);
    } else {
        titleLen = 0;
    }
    if (titleLen > 0) {
        window->title = WIN_StringToUTF8(title);
    }
    if (title) {
        SDL_stack_free(title);
    }

    if (SetupWindowData(_this, window, hwnd, SDL_FALSE) < 0) {
        return -1;
    }
    return 0;
}

void
WIN_SetWindowTitle(_THIS, SDL_Window * window)
{
    HWND hwnd = ((SDL_WindowData *) window->driverdata)->hwnd;
    LPTSTR title;

    if (window->title) {
        title = WIN_UTF8ToString(window->title);
    } else {
        title = NULL;
    }
    SetWindowText(hwnd, title ? title : TEXT(""));
    if (title) {
        SDL_free(title);
    }
}

void
WIN_SetWindowIcon(_THIS, SDL_Window * window, SDL_Surface * icon)
{
    HWND hwnd = ((SDL_WindowData *) window->driverdata)->hwnd;
    HICON hicon = NULL;

    if (icon) {
        BYTE *icon_bmp;
        int icon_len;
        SDL_RWops *dst;
        SDL_PixelFormat format;
        SDL_Surface *surface;

        /* Create temporary bitmap buffer */
        icon_len = 40 + icon->h * icon->w * 4;
        icon_bmp = SDL_stack_alloc(BYTE, icon_len);
        dst = SDL_RWFromMem(icon_bmp, icon_len);
        if (!dst) {
            SDL_stack_free(icon_bmp);
            return;
        }

        /* Write the BITMAPINFO header */
        SDL_WriteLE32(dst, 40);
        SDL_WriteLE32(dst, icon->w);
        SDL_WriteLE32(dst, icon->h * 2);
        SDL_WriteLE16(dst, 1);
        SDL_WriteLE16(dst, 32);
        SDL_WriteLE32(dst, BI_RGB);
        SDL_WriteLE32(dst, icon->h * icon->w * 4);
        SDL_WriteLE32(dst, 0);
        SDL_WriteLE32(dst, 0);
        SDL_WriteLE32(dst, 0);
        SDL_WriteLE32(dst, 0);

        /* Convert the icon to a 32-bit surface with alpha channel */
        SDL_InitFormat(&format, 32,
                       0x00FF0000, 0x0000FF00, 0x000000FF, 0xFF000000);
        surface = SDL_ConvertSurface(icon, &format, 0);
        if (surface) {
            /* Write the pixels upside down into the bitmap buffer */
            int y = surface->h;
            while (y--) {
                Uint8 *src = (Uint8 *) surface->pixels + y * surface->pitch;
                SDL_RWwrite(dst, src, surface->pitch, 1);
            }
            SDL_FreeSurface(surface);

/* TODO: create the icon in WinCE (CreateIconFromResource isn't available) */
#ifndef _WIN32_WCE
            hicon =
                CreateIconFromResource(icon_bmp, icon_len, TRUE, 0x00030000);
#endif
        }
        SDL_RWclose(dst);
        SDL_stack_free(icon_bmp);
    }

    /* Set the icon for the window */
    SendMessage(hwnd, WM_SETICON, ICON_SMALL, (LPARAM) hicon);

    /* Set the icon in the task manager (should we do this?) */
    SendMessage(hwnd, WM_SETICON, ICON_BIG, (LPARAM) hicon);
}

void
WIN_SetWindowPosition(_THIS, SDL_Window * window)
{
    HWND hwnd = ((SDL_WindowData *) window->driverdata)->hwnd;
    RECT rect;
    DWORD style;
    HWND top;
    BOOL menu;
    int x, y;

    /* Figure out what the window area will be */
    if (window->flags & SDL_WINDOW_FULLSCREEN) {
        top = HWND_TOPMOST;
    } else {
        top = HWND_NOTOPMOST;
    }
    style = GetWindowLong(hwnd, GWL_STYLE);
    rect.left = 0;
    rect.top = 0;
    rect.right = window->w;
    rect.bottom = window->h;
#ifdef _WIN32_WCE
    menu = FALSE;
#else
    menu = (style & WS_CHILDWINDOW) ? FALSE : (GetMenu(hwnd) != NULL);
#endif
    AdjustWindowRectEx(&rect, style, menu, 0);

    if ((window->flags & SDL_WINDOW_FULLSCREEN)
        || window->x == SDL_WINDOWPOS_CENTERED) {
        x = (GetSystemMetrics(SM_CXSCREEN) - window->w) / 2;
    } else {
        x = window->x + rect.left;
    }
    if ((window->flags & SDL_WINDOW_FULLSCREEN)
        || window->y == SDL_WINDOWPOS_CENTERED) {
        y = (GetSystemMetrics(SM_CYSCREEN) - window->h) / 2;
    } else {
        y = window->y + rect.top;
    }

    SetWindowPos(hwnd, top, x, y, 0, 0, (SWP_NOCOPYBITS | SWP_NOSIZE));
}

void
WIN_SetWindowSize(_THIS, SDL_Window * window)
{
    HWND hwnd = ((SDL_WindowData *) window->driverdata)->hwnd;
    RECT rect;
    DWORD style;
    HWND top;
    BOOL menu;
    int w, h;

    /* Figure out what the window area will be */
    if (window->flags & SDL_WINDOW_FULLSCREEN) {
        top = HWND_TOPMOST;
    } else {
        top = HWND_NOTOPMOST;
    }
    style = GetWindowLong(hwnd, GWL_STYLE);
    rect.left = 0;
    rect.top = 0;
    rect.right = window->w;
    rect.bottom = window->h;
#ifdef _WIN32_WCE
    menu = FALSE;
#else
    menu = (style & WS_CHILDWINDOW) ? FALSE : (GetMenu(hwnd) != NULL);
#endif
    AdjustWindowRectEx(&rect, style, menu, 0);
    w = (rect.right - rect.left);
    h = (rect.bottom - rect.top);

    SetWindowPos(hwnd, top, 0, 0, w, h, (SWP_NOCOPYBITS | SWP_NOMOVE));
}

void
WIN_ShowWindow(_THIS, SDL_Window * window)
{
    HWND hwnd = ((SDL_WindowData *) window->driverdata)->hwnd;

    ShowWindow(hwnd, SW_SHOW);

#ifdef _WIN32_WCE
    if (window->flags & SDL_WINDOW_FULLSCREEN) {
        CE_SHFullScreen(hwnd,
                        SHFS_HIDESTARTICON | SHFS_HIDETASKBAR |
                        SHFS_HIDESIPBUTTON);
    }
#endif
}

void
WIN_HideWindow(_THIS, SDL_Window * window)
{
    HWND hwnd = ((SDL_WindowData *) window->driverdata)->hwnd;

    ShowWindow(hwnd, SW_HIDE);

#ifdef _WIN32_WCE
    if (window->flags & SDL_WINDOW_FULLSCREEN) {
        CE_SHFullScreen(hwnd,
                        SHFS_SHOWSTARTICON | SHFS_SHOWTASKBAR |
                        SHFS_SHOWSIPBUTTON);
    }
#endif
}

void
WIN_RaiseWindow(_THIS, SDL_Window * window)
{
    HWND hwnd = ((SDL_WindowData *) window->driverdata)->hwnd;
    HWND top;

    if (window->flags & SDL_WINDOW_FULLSCREEN) {
        top = HWND_TOPMOST;
    } else {
        top = HWND_NOTOPMOST;
    }
    SetWindowPos(hwnd, top, 0, 0, 0, 0, (SWP_NOMOVE | SWP_NOSIZE));

#ifdef _WIN32_WCE
    if (window->flags & SDL_WINDOW_FULLSCREEN) {
        CE_SHFullScreen(hwnd,
                        SHFS_HIDESTARTICON | SHFS_HIDETASKBAR |
                        SHFS_HIDESIPBUTTON);
    }
#endif
}

void
WIN_MaximizeWindow(_THIS, SDL_Window * window)
{
    HWND hwnd = ((SDL_WindowData *) window->driverdata)->hwnd;

    ShowWindow(hwnd, SW_MAXIMIZE);

#ifdef _WIN32_WCE
    if (window->flags & SDL_WINDOW_FULLSCREEN) {
        CE_SHFullScreen(hwnd,
                        SHFS_HIDESTARTICON | SHFS_HIDETASKBAR |
                        SHFS_HIDESIPBUTTON);
    }
#endif
}

void
WIN_MinimizeWindow(_THIS, SDL_Window * window)
{
    HWND hwnd = ((SDL_WindowData *) window->driverdata)->hwnd;

    ShowWindow(hwnd, SW_MINIMIZE);

#ifdef _WIN32_WCE
    if (window->flags & SDL_WINDOW_FULLSCREEN) {
        CE_SHFullScreen(hwnd,
                        SHFS_SHOWSTARTICON | SHFS_SHOWTASKBAR |
                        SHFS_SHOWSIPBUTTON);
    }
#endif
}

void
WIN_RestoreWindow(_THIS, SDL_Window * window)
{
    HWND hwnd = ((SDL_WindowData *) window->driverdata)->hwnd;

    ShowWindow(hwnd, SW_RESTORE);
}

void
WIN_SetWindowGrab(_THIS, SDL_Window * window)
{
    HWND hwnd = ((SDL_WindowData *) window->driverdata)->hwnd;

    if ((window->flags & (SDL_WINDOW_INPUT_GRABBED | SDL_WINDOW_FULLSCREEN))
        && (window->flags & SDL_WINDOW_INPUT_FOCUS)) {
        RECT rect;
        GetClientRect(hwnd, &rect);
        ClientToScreen(hwnd, (LPPOINT) & rect);
        ClientToScreen(hwnd, (LPPOINT) & rect + 1);
        ClipCursor(&rect);
    } else {
        ClipCursor(NULL);
    }
}

void
WIN_DestroyWindow(_THIS, SDL_Window * window)
{
    SDL_VideoData *videodata = (SDL_VideoData *) _this->driverdata;
    SDL_WindowData *data = (SDL_WindowData *) window->driverdata;

    if (data) {
        ReleaseDC(data->hwnd, data->hdc);
        if (data->created) {
            if (videodata->wintabDLL) {
                videodata->WTClose(g_hCtx[window->id]);
            }
            DestroyWindow(data->hwnd);
        }
        SDL_free(data);
    }
}

SDL_bool
WIN_GetWindowWMInfo(_THIS, SDL_Window * window, SDL_SysWMinfo * info)
{
    HWND hwnd = ((SDL_WindowData *) window->driverdata)->hwnd;
    if (info->version.major <= SDL_MAJOR_VERSION) {
        info->window = hwnd;
        return SDL_TRUE;
    } else {
        SDL_SetError("Application not compiled with SDL %d.%d\n",
                     SDL_MAJOR_VERSION, SDL_MINOR_VERSION);
        return SDL_FALSE;
    }
}


/*
 * Creates a HelperWindow used for DirectInput events.
 */
int
SDL_HelperWindowCreate(void)
{
    HINSTANCE hInstance = GetModuleHandle(NULL);
    WNDCLASS wce;
    HWND hWndParent = NULL;

    /* Make sure window isn't created twice. */
    if (SDL_HelperWindow != NULL) {
        return 0;
    }

    /* Create the class. */
    SDL_zero(wce);
    wce.lpfnWndProc = DefWindowProc;
    wce.lpszClassName = (LPCWSTR) SDL_HelperWindowClassName;
    wce.hInstance = hInstance;

    /* Register the class. */
    SDL_HelperWindowClass = RegisterClass(&wce);
    if (SDL_HelperWindowClass == 0) {
        SDL_SetError("Unable to create Helper Window Class: error %d.",
                     GetLastError());
        return -1;
    }

#ifndef _WIN32_WCE
    /* WinCE doesn't have HWND_MESSAGE */
    hWndParent = HWND_MESSAGE;
#endif

    /* Create the window. */
    SDL_HelperWindow = CreateWindowEx(0, SDL_HelperWindowClassName,
                                      SDL_HelperWindowName,
                                      WS_OVERLAPPED, CW_USEDEFAULT,
                                      CW_USEDEFAULT, CW_USEDEFAULT,
                                      CW_USEDEFAULT, hWndParent, NULL,
                                      hInstance, NULL);
    if (SDL_HelperWindow == NULL) {
        UnregisterClass(SDL_HelperWindowClassName, hInstance);
        SDL_SetError("Unable to create Helper Window: error %d.",
                     GetLastError());
        return -1;
    }

    return 0;
}


/*
 * Destroys the HelperWindow previously created with SDL_HelperWindowCreate.
 */
void
SDL_HelperWindowDestroy(void)
{
    HINSTANCE hInstance = GetModuleHandle(NULL);

    /* Destroy the window. */
    if (SDL_HelperWindow != NULL) {
        if (DestroyWindow(SDL_HelperWindow) == 0) {
            SDL_SetError("Unable to destroy Helper Window: error %d.",
                         GetLastError());
            return;
        }
        SDL_HelperWindow = NULL;
    }

    /* Unregister the class. */
    if (SDL_HelperWindowClass != 0) {
        if ((UnregisterClass(SDL_HelperWindowClassName, hInstance)) == 0) {
            SDL_SetError("Unable to destroy Helper Window Class: error %d.",
                         GetLastError());
            return;
        }
        SDL_HelperWindowClass = 0;
    }
}


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