/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997-2011 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"

#if SDL_VIDEO_DRIVER_X11

#include "SDL_x11video.h"
#include "SDL_x11framebuffer.h"


#ifndef NO_SHARED_MEMORY

/* Shared memory error handler routine */
static int shm_error;
static int (*X_handler)(Display *, XErrorEvent *) = NULL;
static int shm_errhandler(Display *d, XErrorEvent *e)
{
        if ( e->error_code == BadAccess ) {
            shm_error = True;
            return(0);
        } else
        return(X_handler(d,e));
}

static SDL_bool have_mitshm(void)
{
    /* Only use shared memory on local X servers */
    if ( (SDL_strncmp(XDisplayName(NULL), ":", 1) == 0) ||
         (SDL_strncmp(XDisplayName(NULL), "unix:", 5) == 0) ) {
        return SDL_X11_HAVE_SHM;
    }
    return SDL_FALSE;
}

#endif /* !NO_SHARED_MEMORY */

int
X11_CreateWindowFramebuffer(_THIS, SDL_Window * window, Uint32 * format,
                            void ** pixels, int *pitch)
{
    SDL_WindowData *data = (SDL_WindowData *) window->driverdata;
    Display *display = data->videodata->display;
    XGCValues gcv;
    XVisualInfo vinfo;

    /* Free the old framebuffer surface */
    X11_DestroyWindowFramebuffer(_this, window);

    /* Create the graphics context for drawing */
    gcv.graphics_exposures = False;
    data->gc = XCreateGC(display, data->xwindow, GCGraphicsExposures, &gcv);
    if (!data->gc) {
        SDL_SetError("Couldn't create graphics context");
        return -1;
    }

    /* Find out the pixel format and depth */
    if (X11_GetVisualInfoFromVisual(display, data->visual, &vinfo) < 0) {
        SDL_SetError("Couldn't get window visual information");
        return -1;
    }

    *format = X11_GetPixelFormatFromVisualInfo(display, &vinfo);
    if (*format == SDL_PIXELFORMAT_UNKNOWN) {
        SDL_SetError("Unknown window pixel format");
        return -1;
    }

    /* Calculate pitch */
    *pitch = (((window->w * SDL_BYTESPERPIXEL(*format)) + 3) & ~3);

    /* Create the actual image */
#ifndef NO_SHARED_MEMORY
    if (have_mitshm()) {
        XShmSegmentInfo *shminfo = &data->shminfo;

        shminfo->shmid = shmget(IPC_PRIVATE, window->h*(*pitch), IPC_CREAT | 0777);
        if ( shminfo->shmid >= 0 ) {
            shminfo->shmaddr = (char *)shmat(shminfo->shmid, 0, 0);
            shminfo->readOnly = False;
            if ( shminfo->shmaddr != (char *)-1 ) {
                shm_error = False;
                X_handler = XSetErrorHandler(shm_errhandler);
                XShmAttach(display, shminfo);
                XSync(display, True);
                XSetErrorHandler(X_handler);
                if ( shm_error )
                    shmdt(shminfo->shmaddr);
            } else {
                shm_error = True;
            }
            shmctl(shminfo->shmid, IPC_RMID, NULL);
        } else {
            shm_error = True;
        }
        if (!shm_error) {
            data->ximage = XShmCreateImage(display, data->visual,
                             vinfo.depth, ZPixmap,
                             shminfo->shmaddr, shminfo, 
                             window->w, window->h);
            if (!data->ximage) {
                XShmDetach(display, shminfo);
                XSync(display, False);
                shmdt(shminfo->shmaddr);
            } else {
                /* Done! */
                data->use_mitshm = SDL_TRUE;
                *pixels = shminfo->shmaddr;
                return 0;
            }
        }
    }
#endif /* not NO_SHARED_MEMORY */

    *pixels = SDL_malloc(window->h*(*pitch));
    if (*pixels == NULL) {
        SDL_OutOfMemory();
        return -1;
    }

    data->ximage = XCreateImage(display, data->visual,
                      vinfo.depth, ZPixmap, 0, (char *)(*pixels), 
                      window->w, window->h, 32, 0);
    if (!data->ximage) {
        SDL_free(*pixels);
        SDL_SetError("Couldn't create XImage");
        return -1;
    }
    return 0;
}

int
X11_UpdateWindowFramebuffer(_THIS, SDL_Window * window, SDL_Rect * rects,
                            int numrects)
{
    SDL_WindowData *data = (SDL_WindowData *) window->driverdata;
    Display *display = data->videodata->display;
    int i;
    SDL_Rect *rect;

#ifndef NO_SHARED_MEMORY
    if (data->use_mitshm) {
        for (i = 0; i < numrects; ++i) {
            rect = &rects[i];

            if (rect->w == 0 || rect->h == 0) { /* Clipped? */
                continue;
            }
            XShmPutImage(display, data->xwindow, data->gc, data->ximage,
                    rect->x, rect->y,
                    rect->x, rect->y, rect->w, rect->h, False);
        }
    }
    else
#endif /* !NO_SHARED_MEMORY */
    {
        for (i = 0; i < numrects; ++i) {
            rect = &rects[i];

            if (rect->w == 0 || rect->h == 0) { /* Clipped? */
                continue;
            }
            XPutImage(display, data->xwindow, data->gc, data->ximage,
                  rect->x, rect->y,
                  rect->x, rect->y, rect->w, rect->h);
        }
    }
    XSync(display, False);
}

void
X11_DestroyWindowFramebuffer(_THIS, SDL_Window * window)
{
    SDL_WindowData *data = (SDL_WindowData *) window->driverdata;
    Display *display = data->videodata->display;

    if (data->ximage) {
        XDestroyImage(data->ximage);

#ifndef NO_SHARED_MEMORY
        if (data->use_mitshm) {
            XShmDetach(display, &data->shminfo);
            XSync(display, False);
            shmdt(data->shminfo.shmaddr);
            data->use_mitshm = SDL_FALSE;
        }
#endif /* !NO_SHARED_MEMORY */

        data->ximage = NULL;
    }
    if (data->gc) {
        XFreeGC(display, data->gc);
        data->gc = NULL;
    }
}

#endif /* SDL_VIDEO_DRIVER_X11 */

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