/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2006 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
*/
#include "SDL_config.h"

/* WGL implementation of SDL OpenGL support */

#if SDL_VIDEO_OPENGL
#include "SDL_opengl.h"
#endif
#include "SDL_lowvideo.h"
#include "SDL_wingl_c.h"

#if SDL_VIDEO_OPENGL
#define DEFAULT_GL_DRIVER_PATH "OPENGL32.DLL"
#endif

/* If setting the HDC fails, we may need to recreate the window (MSDN) */
static int
WIN_GL_ResetWindow(_THIS)
{
    int status = 0;

#ifndef _WIN32_WCE              /* FIXME WinCE needs the UNICODE version of CreateWindow() */
    /* This doesn't work with DirectX code (see CVS comments) */
    /* If we were passed a window, then we can't create a new one */
    if (!SDL_windowid && SDL_strcmp(this->name, "windib") == 0) {
        /* Save the existing window attributes */
        LONG style;
        RECT rect = { 0, 0, 0, 0 };
        style = GetWindowLong(SDL_Window, GWL_STYLE);
        GetWindowRect(SDL_Window, &rect);
        DestroyWindow(SDL_Window);
        WIN_FlushMessageQueue();

        SDL_Window = CreateWindow(SDL_Appname, SDL_Appname,
                                  style,
                                  rect.left, rect.top,
                                  (rect.right - rect.left) + 1,
                                  (rect.top - rect.bottom) + 1,
                                  NULL, NULL, SDL_Instance, NULL);
        WIN_FlushMessageQueue();

        if (SDL_Window) {
            this->SetCaption(this, this->wm_title, this->wm_icon);
        } else {
            SDL_SetError("Couldn't create window");
            status = -1;
        }
    } else
#endif /* !_WIN32_WCE */
    {
        SDL_SetError("Unable to reset window for OpenGL context");
        status = -1;
    }
    return (status);
}

#if SDL_VIDEO_OPENGL

static int
ExtensionSupported(const char *extension, const char *extensions)
{
    const char *start;
    const char *where, *terminator;

    /* Extension names should not have spaces. */
    where = SDL_strchr(extension, ' ');
    if (where || *extension == '\0')
        return 0;

    if (!extensions)
        return 0;

    /* It takes a bit of care to be fool-proof about parsing the
     *      OpenGL extensions string. Don't be fooled by sub-strings,
     *           etc. */

    start = extensions;

    for (;;) {
        where = SDL_strstr(start, extension);
        if (!where)
            break;

        terminator = where + SDL_strlen(extension);
        if (where == start || *(where - 1) == ' ')
            if (*terminator == ' ' || *terminator == '\0')
                return 1;

        start = terminator;
    }

    return 0;
}

static void
Init_WGL_ARB_extensions(_THIS)
{
    HWND hwnd;
    HDC hdc;
    HGLRC hglrc;
    int pformat;
    const char *(WINAPI * wglGetExtensionsStringARB) (HDC) = 0;
    const char *extensions;

    hwnd = CreateWindow(SDL_Appname, SDL_Appname, WS_POPUP | WS_DISABLED,
                        0, 0, 10, 10, NULL, NULL, SDL_Instance, NULL);
    WIN_FlushMessageQueue();

    hdc = GetDC(hwnd);

    pformat = ChoosePixelFormat(hdc, &GL_pfd);
    SetPixelFormat(hdc, pformat, &GL_pfd);

    hglrc = this->gl_data->wglCreateContext(hdc);
    if (hglrc) {
        this->gl_data->wglMakeCurrent(hdc, hglrc);
    }

    wglGetExtensionsStringARB = (const char *(WINAPI *) (HDC))
        this->gl_data->wglGetProcAddress("wglGetExtensionsStringARB");

    if (wglGetExtensionsStringARB) {
        extensions = wglGetExtensionsStringARB(hdc);
    } else {
        extensions = NULL;
    }

    this->gl_data->WGL_ARB_pixel_format = 0;
    if (ExtensionSupported("WGL_ARB_pixel_format", extensions)) {
        this->gl_data->wglChoosePixelFormatARB = (BOOL(WINAPI *)
                                                  (HDC, const int *,
                                                   const FLOAT *, UINT, int *,
                                                   UINT *))
            this->gl_data->wglGetProcAddress("wglChoosePixelFormatARB");
        this->gl_data->wglGetPixelFormatAttribivARB =
            (BOOL(WINAPI *) (HDC, int, int, UINT, const int *, int *))
            this->gl_data->wglGetProcAddress("wglGetPixelFormatAttribivARB");

        if ((this->gl_data->wglChoosePixelFormatARB != NULL) &&
            (this->gl_data->wglGetPixelFormatAttribivARB != NULL)) {
            this->gl_data->WGL_ARB_pixel_format = 1;
        }
    }

    if (hglrc) {
        this->gl_data->wglMakeCurrent(NULL, NULL);
        this->gl_data->wglDeleteContext(hglrc);
    }
    ReleaseDC(hwnd, hdc);
    DestroyWindow(hwnd);
    WIN_FlushMessageQueue();
}

#endif /* SDL_VIDEO_OPENGL */

int
WIN_GL_SetupWindow(_THIS)
{
    int retval;
#if SDL_VIDEO_OPENGL
    int i;
    unsigned int matching;
    int iAttribs[64];
    int *iAttr;
    float fAttribs[1] = { 0 };
    const GLubyte *(WINAPI * glGetStringFunc) (GLenum);
    const char *wglext;

    /* load the gl driver from a default path */
    if (!this->gl_config.driver_loaded) {
        /* no driver has been loaded, use default (ourselves) */
        if (WIN_GL_LoadLibrary(this, NULL) < 0) {
            return (-1);
        }
    }

    for (i = 0;; ++i) {
        /* Get the window device context for our OpenGL drawing */
        GL_hdc = GetDC(SDL_Window);
        if (GL_hdc == NULL) {
            SDL_SetError("Unable to get DC for SDL_Window");
            return (-1);
        }

        /* Set up the pixel format descriptor with our needed format */
        SDL_memset(&GL_pfd, 0, sizeof(GL_pfd));
        GL_pfd.nSize = sizeof(GL_pfd);
        GL_pfd.nVersion = 1;
        GL_pfd.dwFlags = (PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL);
        if (this->gl_config.double_buffer) {
            GL_pfd.dwFlags |= PFD_DOUBLEBUFFER;
        }
        if (this->gl_config.stereo) {
            GL_pfd.dwFlags |= PFD_STEREO;
        }
        GL_pfd.iPixelType = PFD_TYPE_RGBA;
        GL_pfd.cColorBits = this->gl_config.buffer_size;
        GL_pfd.cRedBits = this->gl_config.red_size;
        GL_pfd.cGreenBits = this->gl_config.green_size;
        GL_pfd.cBlueBits = this->gl_config.blue_size;
        GL_pfd.cAlphaBits = this->gl_config.alpha_size;
        GL_pfd.cAccumRedBits = this->gl_config.accum_red_size;
        GL_pfd.cAccumGreenBits = this->gl_config.accum_green_size;
        GL_pfd.cAccumBlueBits = this->gl_config.accum_blue_size;
        GL_pfd.cAccumAlphaBits = this->gl_config.accum_alpha_size;
        GL_pfd.cAccumBits =
            (GL_pfd.cAccumRedBits + GL_pfd.cAccumGreenBits +
             GL_pfd.cAccumBlueBits + GL_pfd.cAccumAlphaBits);
        GL_pfd.cDepthBits = this->gl_config.depth_size;
        GL_pfd.cStencilBits = this->gl_config.stencil_size;

        /* initialize WGL_ARB_pixel_format */
        Init_WGL_ARB_extensions(this);

        /* setup WGL_ARB_pixel_format attribs */
        iAttr = &iAttribs[0];

        *iAttr++ = WGL_DRAW_TO_WINDOW_ARB;
        *iAttr++ = GL_TRUE;
        *iAttr++ = WGL_ACCELERATION_ARB;
        *iAttr++ = WGL_FULL_ACCELERATION_ARB;
        *iAttr++ = WGL_RED_BITS_ARB;
        *iAttr++ = this->gl_config.red_size;
        *iAttr++ = WGL_GREEN_BITS_ARB;
        *iAttr++ = this->gl_config.green_size;
        *iAttr++ = WGL_BLUE_BITS_ARB;
        *iAttr++ = this->gl_config.blue_size;

        if (this->gl_config.alpha_size) {
            *iAttr++ = WGL_ALPHA_BITS_ARB;
            *iAttr++ = this->gl_config.alpha_size;
        }

        *iAttr++ = WGL_DOUBLE_BUFFER_ARB;
        *iAttr++ = this->gl_config.double_buffer;

        *iAttr++ = WGL_DEPTH_BITS_ARB;
        *iAttr++ = this->gl_config.depth_size;

        if (this->gl_config.stencil_size) {
            *iAttr++ = WGL_STENCIL_BITS_ARB;
            *iAttr++ = this->gl_config.stencil_size;
        }

        if (this->gl_config.accum_red_size) {
            *iAttr++ = WGL_ACCUM_RED_BITS_ARB;
            *iAttr++ = this->gl_config.accum_red_size;
        }

        if (this->gl_config.accum_green_size) {
            *iAttr++ = WGL_ACCUM_GREEN_BITS_ARB;
            *iAttr++ = this->gl_config.accum_green_size;
        }

        if (this->gl_config.accum_blue_size) {
            *iAttr++ = WGL_ACCUM_BLUE_BITS_ARB;
            *iAttr++ = this->gl_config.accum_blue_size;
        }

        if (this->gl_config.accum_alpha_size) {
            *iAttr++ = WGL_ACCUM_ALPHA_BITS_ARB;
            *iAttr++ = this->gl_config.accum_alpha_size;
        }

        if (this->gl_config.stereo) {
            *iAttr++ = WGL_STEREO_ARB;
            *iAttr++ = GL_TRUE;
        }

        if (this->gl_config.multisamplebuffers) {
            *iAttr++ = WGL_SAMPLE_BUFFERS_ARB;
            *iAttr++ = this->gl_config.multisamplebuffers;
        }

        if (this->gl_config.multisamplesamples) {
            *iAttr++ = WGL_SAMPLES_ARB;
            *iAttr++ = this->gl_config.multisamplesamples;
        }

        if (this->gl_config.accelerated >= 0) {
            *iAttr++ = WGL_ACCELERATION_ARB;
            *iAttr++ =
                (this->gl_config.
                 accelerated ? WGL_GENERIC_ACCELERATION_ARB :
                 WGL_NO_ACCELERATION_ARB);
        }

        *iAttr = 0;

        /* Choose and set the closest available pixel format */
        if (!this->gl_data->WGL_ARB_pixel_format ||
            !this->gl_data->wglChoosePixelFormatARB(GL_hdc, iAttribs,
                                                    fAttribs, 1,
                                                    &pixel_format, &matching)
            || !matching) {
            pixel_format = ChoosePixelFormat(GL_hdc, &GL_pfd);
            this->gl_data->WGL_ARB_pixel_format = 0;
        }
        if (!pixel_format) {
            SDL_SetError("No matching GL pixel format available");
            return (-1);
        }
        if (!SetPixelFormat(GL_hdc, pixel_format, &GL_pfd)) {
            if (i == 0) {
                /* First time through, try resetting the window */
                if (WIN_GL_ResetWindow(this) < 0) {
                    return (-1);
                }
                continue;
            }
            SDL_SetError("Unable to set HDC pixel format");
            return (-1);
        }
        /* We either succeeded or failed by this point */
        break;
    }
    DescribePixelFormat(GL_hdc, pixel_format, sizeof(GL_pfd), &GL_pfd);

    GL_hrc = this->gl_data->wglCreateContext(GL_hdc);
    if (GL_hrc == NULL) {
        SDL_SetError("Unable to create GL context");
        return (-1);
    }
    if (WIN_GL_MakeCurrent(this) < 0) {
        return (-1);
    }
    gl_active = 1;

    /* Vsync control under Windows.  Checking glGetString here is
     * somewhat a documented and reliable hack - it was originally
     * as a feature added by mistake, but since so many people rely
     * on it, it will not be removed.  strstr should be safe here.*/
    glGetStringFunc = WIN_GL_GetProcAddress(this, "glGetString");
    if (glGetStringFunc) {
        wglext = (const char *) glGetStringFunc(GL_EXTENSIONS);
    } else {
        /* Uh oh, something is seriously wrong here... */
        wglext = NULL;
    }
    if (wglext && SDL_strstr(wglext, "WGL_EXT_swap_control")) {
        this->gl_data->wglSwapIntervalEXT =
            WIN_GL_GetProcAddress(this, "wglSwapIntervalEXT");
        this->gl_data->wglGetSwapIntervalEXT =
            WIN_GL_GetProcAddress(this, "wglGetSwapIntervalEXT");
    } else {
        this->gl_data->wglSwapIntervalEXT = NULL;
        this->gl_data->wglGetSwapIntervalEXT = NULL;
    }
    if (this->gl_config.swap_control >= 0) {
        if (this->gl_data->wglSwapIntervalEXT) {
            this->gl_data->wglSwapIntervalEXT(this->gl_config.swap_control);
        }
    }
#else
    SDL_SetError("WIN driver not configured with OpenGL");
#endif
    if (gl_active) {
        retval = 0;
    } else {
        retval = -1;
    }
    return (retval);
}

void
WIN_GL_ShutDown(_THIS)
{
#if SDL_VIDEO_OPENGL
    /* Clean up OpenGL */
    if (GL_hrc) {
        this->gl_data->wglMakeCurrent(NULL, NULL);
        this->gl_data->wglDeleteContext(GL_hrc);
        GL_hrc = NULL;
    }
    if (GL_hdc) {
        ReleaseDC(SDL_Window, GL_hdc);
        GL_hdc = NULL;
    }
    gl_active = 0;

    WIN_GL_UnloadLibrary(this);
#endif /* SDL_VIDEO_OPENGL */
}

#if SDL_VIDEO_OPENGL

/* Make the current context active */
int
WIN_GL_MakeCurrent(_THIS)
{
    int retval;

    retval = 0;
    if (!this->gl_data->wglMakeCurrent(GL_hdc, GL_hrc)) {
        SDL_SetError("Unable to make GL context current");
        retval = -1;
    }
    return (retval);
}

/* Get attribute data from glX. */
int
WIN_GL_GetAttribute(_THIS, SDL_GLattr attrib, int *value)
{
    int retval;

    if (this->gl_data->WGL_ARB_pixel_format) {
        int wgl_attrib;

        switch (attrib) {
        case SDL_GL_RED_SIZE:
            wgl_attrib = WGL_RED_BITS_ARB;
            break;
        case SDL_GL_GREEN_SIZE:
            wgl_attrib = WGL_GREEN_BITS_ARB;
            break;
        case SDL_GL_BLUE_SIZE:
            wgl_attrib = WGL_BLUE_BITS_ARB;
            break;
        case SDL_GL_ALPHA_SIZE:
            wgl_attrib = WGL_ALPHA_BITS_ARB;
            break;
        case SDL_GL_DOUBLEBUFFER:
            wgl_attrib = WGL_DOUBLE_BUFFER_ARB;
            break;
        case SDL_GL_BUFFER_SIZE:
            wgl_attrib = WGL_COLOR_BITS_ARB;
            break;
        case SDL_GL_DEPTH_SIZE:
            wgl_attrib = WGL_DEPTH_BITS_ARB;
            break;
        case SDL_GL_STENCIL_SIZE:
            wgl_attrib = WGL_STENCIL_BITS_ARB;
            break;
        case SDL_GL_ACCUM_RED_SIZE:
            wgl_attrib = WGL_ACCUM_RED_BITS_ARB;
            break;
        case SDL_GL_ACCUM_GREEN_SIZE:
            wgl_attrib = WGL_ACCUM_GREEN_BITS_ARB;
            break;
        case SDL_GL_ACCUM_BLUE_SIZE:
            wgl_attrib = WGL_ACCUM_BLUE_BITS_ARB;
            break;
        case SDL_GL_ACCUM_ALPHA_SIZE:
            wgl_attrib = WGL_ACCUM_ALPHA_BITS_ARB;
            break;
        case SDL_GL_STEREO:
            wgl_attrib = WGL_STEREO_ARB;
            break;
        case SDL_GL_MULTISAMPLEBUFFERS:
            wgl_attrib = WGL_SAMPLE_BUFFERS_ARB;
            break;
        case SDL_GL_MULTISAMPLESAMPLES:
            wgl_attrib = WGL_SAMPLES_ARB;
            break;
        case SDL_GL_ACCELERATED_VISUAL:
            wgl_attrib = WGL_ACCELERATION_ARB;
            this->gl_data->wglGetPixelFormatAttribivARB(GL_hdc, pixel_format,
                                                        0, 1, &wgl_attrib,
                                                        value);
            if (*value == WGL_NO_ACCELERATION_ARB) {
                *value = SDL_FALSE;
            } else {
                *value = SDL_TRUE;
            }
            return 0;
            break;
        case SDL_GL_SWAP_CONTROL:
            if (this->gl_data->wglGetSwapIntervalEXT) {
                *value = this->gl_data->wglGetSwapIntervalEXT();
                return 0;
            } else {
                return -1;
            }
            break;
        default:
            return (-1);
        }
        this->gl_data->wglGetPixelFormatAttribivARB(GL_hdc, pixel_format, 0,
                                                    1, &wgl_attrib, value);

        return 0;
    }

    retval = 0;
    switch (attrib) {
    case SDL_GL_RED_SIZE:
        *value = GL_pfd.cRedBits;
        break;
    case SDL_GL_GREEN_SIZE:
        *value = GL_pfd.cGreenBits;
        break;
    case SDL_GL_BLUE_SIZE:
        *value = GL_pfd.cBlueBits;
        break;
    case SDL_GL_ALPHA_SIZE:
        *value = GL_pfd.cAlphaBits;
        break;
    case SDL_GL_DOUBLEBUFFER:
        if (GL_pfd.dwFlags & PFD_DOUBLEBUFFER) {
            *value = 1;
        } else {
            *value = 0;
        }
        break;
    case SDL_GL_BUFFER_SIZE:
        *value = GL_pfd.cColorBits;
        break;
    case SDL_GL_DEPTH_SIZE:
        *value = GL_pfd.cDepthBits;
        break;
    case SDL_GL_STENCIL_SIZE:
        *value = GL_pfd.cStencilBits;
        break;
    case SDL_GL_ACCUM_RED_SIZE:
        *value = GL_pfd.cAccumRedBits;
        break;
    case SDL_GL_ACCUM_GREEN_SIZE:
        *value = GL_pfd.cAccumGreenBits;
        break;
    case SDL_GL_ACCUM_BLUE_SIZE:
        *value = GL_pfd.cAccumBlueBits;
        break;
    case SDL_GL_ACCUM_ALPHA_SIZE:
        *value = GL_pfd.cAccumAlphaBits;
        break;
    case SDL_GL_STEREO:
        if (GL_pfd.dwFlags & PFD_STEREO) {
            *value = 1;
        } else {
            *value = 0;
        }
        break;
    case SDL_GL_MULTISAMPLEBUFFERS:
        *value = 0;
        break;
    case SDL_GL_MULTISAMPLESAMPLES:
        *value = 1;
        break;
    case SDL_GL_SWAP_CONTROL:
        if (this->gl_data->wglGetSwapIntervalEXT) {
            *value = this->gl_data->wglGetSwapIntervalEXT();
            return 0;
        } else {
            return -1;
        }
        break;
    default:
        retval = -1;
        break;
    }
    return retval;
}

void
WIN_GL_SwapBuffers(_THIS)
{
    SwapBuffers(GL_hdc);
}

void
WIN_GL_UnloadLibrary(_THIS)
{
    if (this->gl_config.driver_loaded) {
        FreeLibrary((HMODULE) this->gl_config.dll_handle);

        this->gl_data->wglGetProcAddress = NULL;
        this->gl_data->wglCreateContext = NULL;
        this->gl_data->wglDeleteContext = NULL;
        this->gl_data->wglMakeCurrent = NULL;
        this->gl_data->wglChoosePixelFormatARB = NULL;
        this->gl_data->wglGetPixelFormatAttribivARB = NULL;
        this->gl_data->wglSwapIntervalEXT = NULL;
        this->gl_data->wglGetSwapIntervalEXT = NULL;

        this->gl_config.dll_handle = NULL;
        this->gl_config.driver_loaded = 0;
    }
}

/* Passing a NULL path means load pointers from the application */
int
WIN_GL_LoadLibrary(_THIS, const char *path)
{
    HMODULE handle;

    if (gl_active) {
        SDL_SetError("OpenGL context already created");
        return -1;
    }

    if (path == NULL) {
        path = DEFAULT_GL_DRIVER_PATH;
    }
    handle = LoadLibrary(path);
    if (handle == NULL) {
        SDL_SetError("Could not load OpenGL library");
        return -1;
    }

    /* Unload the old driver and reset the pointers */
    WIN_GL_UnloadLibrary(this);

    /* Load new function pointers */
    SDL_memset(this->gl_data, 0, sizeof(*this->gl_data));
    this->gl_data->wglGetProcAddress = (void *(WINAPI *) (const char *))
        GetProcAddress(handle, "wglGetProcAddress");
    this->gl_data->wglCreateContext = (HGLRC(WINAPI *) (HDC))
        GetProcAddress(handle, "wglCreateContext");
    this->gl_data->wglDeleteContext = (BOOL(WINAPI *) (HGLRC))
        GetProcAddress(handle, "wglDeleteContext");
    this->gl_data->wglMakeCurrent = (BOOL(WINAPI *) (HDC, HGLRC))
        GetProcAddress(handle, "wglMakeCurrent");
    this->gl_data->wglSwapIntervalEXT = (void (WINAPI *) (int))
        GetProcAddress(handle, "wglSwapIntervalEXT");
    this->gl_data->wglGetSwapIntervalEXT = (int (WINAPI *) (void))
        GetProcAddress(handle, "wglGetSwapIntervalEXT");

    if ((this->gl_data->wglGetProcAddress == NULL) ||
        (this->gl_data->wglCreateContext == NULL) ||
        (this->gl_data->wglDeleteContext == NULL) ||
        (this->gl_data->wglMakeCurrent == NULL)) {
        SDL_SetError("Could not retrieve OpenGL functions");
        FreeLibrary(handle);
        return -1;
    }

    this->gl_config.dll_handle = handle;
    SDL_strlcpy(this->gl_config.driver_path, path,
                SDL_arraysize(this->gl_config.driver_path));
    this->gl_config.driver_loaded = 1;
    return 0;
}

void *
WIN_GL_GetProcAddress(_THIS, const char *proc)
{
    void *func;

    /* This is to pick up extensions */
    func = this->gl_data->wglGetProcAddress(proc);
    if (!func) {
        /* This is probably a normal GL function */
        func = GetProcAddress(this->gl_config.dll_handle, proc);
    }
    return func;
}

#endif /* SDL_VIDEO_OPENGL */

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