gstreamer/gst-libs/gst/gl/gstglfeature.c

/*
 * GStreamer
 * Copyright (C) 2012 Matthew Waters <ystreet00@gmail.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library 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.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <string.h>

#include "gstglfeature.h"

#include "gstglapi.h"

gboolean
gst_gl_check_extension (const char *name, const gchar * ext)
{
  char *end;
  int name_len, n;

  if (name == NULL || ext == NULL)
    return FALSE;

  end = (char *) (ext + strlen (ext));

  name_len = strlen (name);

  while (ext < end) {
    n = strcspn (ext, " ");

    if ((name_len == n) && (!strncmp (name, ext, n)))
      return TRUE;
    ext += (n + 1);
  }

  return FALSE;
}

/* Define a set of arrays containing the functions required from GL
   for each feature */
#define GST_GL_EXT_BEGIN(name,                                            \
                       min_gl_major, min_gl_minor,                      \
                       gles_availability,                               \
                       namespaces, extension_names)                     \
  static const GstGLFeatureFunction gst_gl_ext_ ## name ## _funcs[] = {
#define GST_GL_EXT_FUNCTION(ret, name, args)                          \
  { G_STRINGIFY (name), G_STRUCT_OFFSET (GstGLFuncs, name) },
#define GST_GL_EXT_END()                      \
  { NULL, 0 },                                  \
  };
#include "glprototypes/all_functions.h"

#undef GST_GL_EXT_BEGIN
#define GST_GL_EXT_BEGIN(name,                                          \
                       min_gl_major, min_gl_minor,                      \
                       gles_availability,                               \
                       namespaces, extension_names)                     \
  { min_gl_major, min_gl_minor, gles_availability, namespaces,          \
      extension_names,                                                  \
    gst_gl_ext_ ## name ## _funcs },
#undef GST_GL_EXT_FUNCTION
#define GST_GL_EXT_FUNCTION(ret, name, args)
#undef GST_GL_EXT_END
#define GST_GL_EXT_END()

static const GstGLFeatureData gst_gl_feature_ext_functions_data[] = {
#include "glprototypes/all_functions.h"
};

#undef GST_GL_EXT_BEGIN
#undef GST_GL_EXT_FUNCTION
#undef GST_GL_EXT_END

gboolean
_gst_gl_feature_check (GstGLDisplay * display,
    const char *driver_prefix,
    const GstGLFeatureData * data,
    int gl_major, int gl_minor, const char *extensions_string)
{
  const char *suffix = NULL;
  int func_num;
  GstGLFuncs *gst_gl = display->gl_vtable;

  /* First check whether the functions should be directly provided by
     GL */
  if (((display->gl_api & GST_GL_API_OPENGL) &&
          GST_GL_CHECK_GL_VERSION (gl_major, gl_minor,
              data->min_gl_major, data->min_gl_minor)) ||
      ((display->gl_api & GST_GL_API_GLES2) &&
          (data->gl_availability & GST_GL_API_GLES2))) {
    suffix = "";
  } else {
    /* Otherwise try all of the extensions */
    const char *namespace, *namespace_suffix;
    unsigned int namespace_len;

    for (namespace = data->namespaces; *namespace;
        namespace += strlen (namespace) + 1) {
      const char *extension;
      GString *full_extension_name = g_string_new ("");

      /* If the namespace part contains a ':' then the suffix for
         the function names is different from the name space */
      if ((namespace_suffix = strchr (namespace, ':'))) {
        namespace_len = namespace_suffix - namespace;
        namespace_suffix++;
      } else {
        namespace_len = strlen (namespace);
        namespace_suffix = namespace;
      }

      for (extension = data->extension_names; *extension;
          extension += strlen (extension) + 1) {
        g_string_assign (full_extension_name, driver_prefix);
        g_string_append_c (full_extension_name, '_');
        g_string_append_len (full_extension_name, namespace, namespace_len);
        g_string_append_c (full_extension_name, '_');
        g_string_append (full_extension_name, extension);
        if (gst_gl_check_extension (full_extension_name->str,
                extensions_string))
          break;
      }

      g_string_free (full_extension_name, TRUE);

      /* If we found an extension with this namespace then use it
         as the suffix */
      if (*extension) {
        suffix = namespace_suffix;
        break;
      }
    }
  }

  /* If we couldn't find anything that provides the functions then
     give up */
  if (suffix == NULL)
    goto error;

  /* Try to get all of the entry points */
  for (func_num = 0; data->functions[func_num].name; func_num++) {
    void *func;
    char *full_function_name;

    full_function_name = g_strconcat ("gl", data->functions[func_num].name,
        suffix, NULL);
    func =
        gst_gl_window_get_proc_address (display->gl_window, full_function_name);
    g_free (full_function_name);

    if (func == NULL)
      goto error;

    /* Set the function pointer in the context */
    *(void **) ((guint8 *) gst_gl +
        data->functions[func_num].pointer_offset) = func;
  }

  return TRUE;

  /* If the extension isn't found or one of the functions wasn't found
   * then set all of the functions pointers to NULL so we can safely
   * do feature testing by just looking at the function pointers */
error:
  for (func_num = 0; data->functions[func_num].name; func_num++) {
    *(void **) ((guint8 *) gst_gl +
        data->functions[func_num].pointer_offset) = NULL;
  }

  return FALSE;
}

void
_gst_gl_feature_check_ext_functions (GstGLDisplay * display,
    int gl_major, int gl_minor, const char *gl_extensions)
{
  int i;

  for (i = 0; i < G_N_ELEMENTS (gst_gl_feature_ext_functions_data); i++) {
    _gst_gl_feature_check (display, "GL",
        gst_gl_feature_ext_functions_data + i, gl_major, gl_minor,
        gl_extensions);
  }
}