view src/video/dummy/SDL_nullvideo.c @ 2042:3908e1f808e1

Fixed bug #292 I might be on crack here. It looks like SDL_ConvertMono() in src/audio/SDL_audiocvt.c adds the left and right channels of a stereo stream together, and clamps the new mono channel if it would overflow. Shouldn't it be dividing by 2 to average the two sample points instead of clamping? Otherwise the mono sample point's volume doubles in the conversion. This would also make the conversion faster, as it replaces two branches per sample frame with a bitwise shift. --ryan.
author Sam Lantinga <slouken@libsdl.org>
date Sun, 24 Sep 2006 15:56:36 +0000
parents a788656ca29a
children b252359547ed
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/*
    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"

/* Dummy SDL video driver implementation; this is just enough to make an
 *  SDL-based application THINK it's got a working video driver, for
 *  applications that call SDL_Init(SDL_INIT_VIDEO) when they don't need it,
 *  and also for use as a collection of stubs when porting SDL to a new
 *  platform for which you haven't yet written a valid video driver.
 *
 * This is also a great way to determine bottlenecks: if you think that SDL
 *  is a performance problem for a given platform, enable this driver, and
 *  then see if your application runs faster without video overhead.
 *
 * Initial work by Ryan C. Gordon (icculus@icculus.org). A good portion
 *  of this was cut-and-pasted from Stephane Peter's work in the AAlib
 *  SDL video driver.  Renamed to "DUMMY" by Sam Lantinga.
 */

#include "SDL_video.h"
#include "SDL_mouse.h"
#include "../SDL_sysvideo.h"
#include "../SDL_pixels_c.h"
#include "../../events/SDL_events_c.h"

#include "SDL_nullvideo.h"
#include "SDL_nullevents_c.h"
#include "SDL_nullrender_c.h"

#define DUMMYVID_DRIVER_NAME "dummy"

/* Initialization/Query functions */
static int DUMMY_VideoInit(_THIS);
static int DUMMY_SetDisplayMode(_THIS, SDL_DisplayMode * mode);
static void DUMMY_VideoQuit(_THIS);

/* DUMMY driver bootstrap functions */

static int
DUMMY_Available(void)
{
    const char *envr = SDL_getenv("SDL_VIDEODRIVER");
    if ((envr) && (SDL_strcmp(envr, DUMMYVID_DRIVER_NAME) == 0)) {
        return (1);
    }

    return (0);
}

static void
DUMMY_DeleteDevice(SDL_VideoDevice * device)
{
    SDL_free(device);
}

static SDL_VideoDevice *
DUMMY_CreateDevice(int devindex)
{
    SDL_VideoDevice *device;

    /* Initialize all variables that we clean on shutdown */
    device = (SDL_VideoDevice *) SDL_calloc(1, sizeof(SDL_VideoDevice));
    if (!device) {
        SDL_OutOfMemory();
        if (device) {
            SDL_free(device);
        }
        return (0);
    }

    /* Set the function pointers */
    device->VideoInit = DUMMY_VideoInit;
    device->VideoQuit = DUMMY_VideoQuit;
    device->SetDisplayMode = DUMMY_SetDisplayMode;
    device->PumpEvents = DUMMY_PumpEvents;

    device->free = DUMMY_DeleteDevice;

    return device;
}

VideoBootStrap DUMMY_bootstrap = {
    DUMMYVID_DRIVER_NAME, "SDL dummy video driver",
    DUMMY_Available, DUMMY_CreateDevice
};


int
DUMMY_VideoInit(_THIS)
{
    SDL_DisplayMode mode;

    /* Use a fake 32-bpp desktop mode */
    mode.format = SDL_PIXELFORMAT_RGB888;
    mode.w = 1024;
    mode.h = 768;
    mode.refresh_rate = 0;
    SDL_AddBasicVideoDisplay(&mode);
    SDL_AddRenderDriver(0, &SDL_DUMMY_RenderDriver);

    SDL_zero(mode);
    SDL_AddDisplayMode(0, &mode);

    /* We're done! */
    return 0;
}

static int
DUMMY_SetDisplayMode(_THIS, SDL_DisplayMode * mode)
{
    return 0;
}

void
DUMMY_VideoQuit(_THIS)
{
}

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