kc3-lang/SDL/src/video/SDL_egl.c

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• Hash : 5113fedf
  Author :
  Date : 2021-08-02T23:01:12
  

  video/wayland: use EGL_EXT_present_opaque when available

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• src/video/SDL_egl.c

• /*
   *  Simple DirectMedia Layer
   *  Copyright (C) 1997-2021 Sam Lantinga <slouken@libsdl.org>
   * 
   *  This software is provided 'as-is', without any express or implied
   *  warranty.  In no event will the authors be held liable for any damages
   *  arising from the use of this software.
   * 
   *  Permission is granted to anyone to use this software for any purpose,
   *  including commercial applications, and to alter it and redistribute it
   *  freely, subject to the following restrictions:
   * 
   *  1. The origin of this software must not be misrepresented; you must not
   *     claim that you wrote the original software. If you use this software
   *     in a product, an acknowledgment in the product documentation would be
   *     appreciated but is not required.
   *  2. Altered source versions must be plainly marked as such, and must not be
   *     misrepresented as being the original software.
   *  3. This notice may not be removed or altered from any source distribution.
   */
  #include "../SDL_internal.h"
  
  #if SDL_VIDEO_OPENGL_EGL
  
  #if SDL_VIDEO_DRIVER_WINDOWS || SDL_VIDEO_DRIVER_WINRT
  #include "../core/windows/SDL_windows.h"
  #endif
  #if SDL_VIDEO_DRIVER_ANDROID
  #include <android/native_window.h>
  #include "../core/android/SDL_android.h"
  #include "../video/android/SDL_androidvideo.h"
  #endif
  
  #include "SDL_sysvideo.h"
  #include "SDL_egl_c.h"
  #include "SDL_loadso.h"
  #include "SDL_hints.h"
  
  #ifdef EGL_KHR_create_context
  /* EGL_OPENGL_ES3_BIT_KHR was added in version 13 of the extension. */
  #ifndef EGL_OPENGL_ES3_BIT_KHR
  #define EGL_OPENGL_ES3_BIT_KHR 0x00000040
  #endif
  #endif /* EGL_KHR_create_context */
  
  #ifndef EGL_EXT_present_opaque
  #define EGL_EXT_present_opaque 1
  #define EGL_PRESENT_OPAQUE_EXT            0x31DF
  #endif /* EGL_EXT_present_opaque */
  
  #if SDL_VIDEO_DRIVER_RPI
  /* Raspbian places the OpenGL ES/EGL binaries in a non standard path */
  #define DEFAULT_EGL ( vc4 ? "libEGL.so.1" : "libbrcmEGL.so" )
  #define DEFAULT_OGL_ES2 ( vc4 ? "libGLESv2.so.2" : "libbrcmGLESv2.so" )
  #define ALT_EGL "libEGL.so"
  #define ALT_OGL_ES2 "libGLESv2.so"
  #define DEFAULT_OGL_ES_PVR ( vc4 ? "libGLES_CM.so.1" : "libbrcmGLESv2.so" )
  #define DEFAULT_OGL_ES ( vc4 ? "libGLESv1_CM.so.1" : "libbrcmGLESv2.so" )
  
  #elif SDL_VIDEO_DRIVER_ANDROID || SDL_VIDEO_DRIVER_VIVANTE
  /* Android */
  #define DEFAULT_EGL "libEGL.so"
  #define DEFAULT_OGL_ES2 "libGLESv2.so"
  #define DEFAULT_OGL_ES_PVR "libGLES_CM.so"
  #define DEFAULT_OGL_ES "libGLESv1_CM.so"
  
  #elif SDL_VIDEO_DRIVER_WINDOWS || SDL_VIDEO_DRIVER_WINRT
  /* EGL AND OpenGL ES support via ANGLE */
  #define DEFAULT_EGL "libEGL.dll"
  #define DEFAULT_OGL_ES2 "libGLESv2.dll"
  #define DEFAULT_OGL_ES_PVR "libGLES_CM.dll"
  #define DEFAULT_OGL_ES "libGLESv1_CM.dll"
  
  #elif SDL_VIDEO_DRIVER_COCOA
  /* EGL AND OpenGL ES support via ANGLE */
  #define DEFAULT_EGL "libEGL.dylib"
  #define DEFAULT_OGL_ES2 "libGLESv2.dylib"
  #define DEFAULT_OGL_ES_PVR "libGLES_CM.dylib"   //???
  #define DEFAULT_OGL_ES "libGLESv1_CM.dylib"     //???
  
  #elif defined(__OpenBSD__)
  /* OpenBSD */
  #define DEFAULT_OGL "libGL.so"
  #define DEFAULT_EGL "libEGL.so"
  #define DEFAULT_OGL_ES2 "libGLESv2.so"
  #define DEFAULT_OGL_ES_PVR "libGLES_CM.so"
  #define DEFAULT_OGL_ES "libGLESv1_CM.so"
  
  #else
  /* Desktop Linux/Unix-like */
  #define DEFAULT_OGL "libGL.so.1"
  #define DEFAULT_EGL "libEGL.so.1"
  #define ALT_OGL "libOpenGL.so.0"
  #define DEFAULT_OGL_ES2 "libGLESv2.so.2"
  #define DEFAULT_OGL_ES_PVR "libGLES_CM.so.1"
  #define DEFAULT_OGL_ES "libGLESv1_CM.so.1"
  #endif /* SDL_VIDEO_DRIVER_RPI */
  
  #if SDL_VIDEO_OPENGL
  #include "SDL_opengl.h"
  #endif
  
  /** If we happen to not have this defined because of an older EGL version, just define it 0x0
      as eglGetPlatformDisplayEXT will most likely be NULL if this is missing
  */
  #ifndef EGL_PLATFORM_DEVICE_EXT
  #define EGL_PLATFORM_DEVICE_EXT 0x0
  #endif
  
  #ifdef SDL_VIDEO_STATIC_ANGLE
  #define LOAD_FUNC(NAME) \
  _this->egl_data->NAME = (void *)NAME;
  #else
  #define LOAD_FUNC(NAME) \
  _this->egl_data->NAME = SDL_LoadFunction(_this->egl_data->dll_handle, #NAME); \
  if (!_this->egl_data->NAME) \
  { \
      return SDL_SetError("Could not retrieve EGL function " #NAME); \
  }
  #endif
  
  /* it is allowed to not have some of the EGL extensions on start - attempts to use them will fail later. */
  #define LOAD_FUNC_EGLEXT(NAME) \
      _this->egl_data->NAME = _this->egl_data->eglGetProcAddress(#NAME);
  
  
  static const char * SDL_EGL_GetErrorName(EGLint eglErrorCode)
  {
  #define SDL_EGL_ERROR_TRANSLATE(e) case e: return #e;
      switch (eglErrorCode) {
          SDL_EGL_ERROR_TRANSLATE(EGL_SUCCESS);
          SDL_EGL_ERROR_TRANSLATE(EGL_NOT_INITIALIZED);
          SDL_EGL_ERROR_TRANSLATE(EGL_BAD_ACCESS);
          SDL_EGL_ERROR_TRANSLATE(EGL_BAD_ALLOC);
          SDL_EGL_ERROR_TRANSLATE(EGL_BAD_ATTRIBUTE);
          SDL_EGL_ERROR_TRANSLATE(EGL_BAD_CONTEXT);
          SDL_EGL_ERROR_TRANSLATE(EGL_BAD_CONFIG);
          SDL_EGL_ERROR_TRANSLATE(EGL_BAD_CURRENT_SURFACE);
          SDL_EGL_ERROR_TRANSLATE(EGL_BAD_DISPLAY);
          SDL_EGL_ERROR_TRANSLATE(EGL_BAD_SURFACE);
          SDL_EGL_ERROR_TRANSLATE(EGL_BAD_MATCH);
          SDL_EGL_ERROR_TRANSLATE(EGL_BAD_PARAMETER);
          SDL_EGL_ERROR_TRANSLATE(EGL_BAD_NATIVE_PIXMAP);
          SDL_EGL_ERROR_TRANSLATE(EGL_BAD_NATIVE_WINDOW);
          SDL_EGL_ERROR_TRANSLATE(EGL_CONTEXT_LOST);
      }
      return "";
  }
  
  int SDL_EGL_SetErrorEx(const char * message, const char * eglFunctionName, EGLint eglErrorCode)
  {
      const char * errorText = SDL_EGL_GetErrorName(eglErrorCode);
      char altErrorText[32];
      if (errorText[0] == '\0') {
          /* An unknown-to-SDL error code was reported.  Report its hexadecimal value, instead of its name. */
          SDL_snprintf(altErrorText, SDL_arraysize(altErrorText), "0x%x", (unsigned int)eglErrorCode);
          errorText = altErrorText;
      }
      return SDL_SetError("%s (call to %s failed, reporting an error of %s)", message, eglFunctionName, errorText);
  }
  
  /* EGL implementation of SDL OpenGL ES support */
  
  SDL_bool SDL_EGL_HasExtension(_THIS, SDL_EGL_ExtensionType type, const char *ext)
  {
      size_t ext_len;
      const char *ext_override;
      const char *egl_extstr;
      const char *ext_start;
  
      /* Invalid extensions can be rejected early */
      if (ext == NULL || *ext == 0 || SDL_strchr(ext, ' ') != NULL) {
          /* SDL_LogDebug(SDL_LOG_CATEGORY_VIDEO, "SDL_EGL_HasExtension: Invalid EGL extension"); */
          return SDL_FALSE;
      }
  
      /* Extensions can be masked with an environment variable.
       * Unlike the OpenGL override, this will use the set bits of an integer
       * to disable the extension.
       *  Bit   Action
       *  0     If set, the display extension is masked and not present to SDL.
       *  1     If set, the client extension is masked and not present to SDL.
       */
      ext_override = SDL_getenv(ext);
      if (ext_override != NULL) {
          int disable_ext = SDL_atoi(ext_override);
          if (disable_ext & 0x01 && type == SDL_EGL_DISPLAY_EXTENSION) {
              return SDL_FALSE;
          } else if (disable_ext & 0x02 && type == SDL_EGL_CLIENT_EXTENSION) {
              return SDL_FALSE;
          }
      }
  
      ext_len = SDL_strlen(ext);
      switch (type) {
      case SDL_EGL_DISPLAY_EXTENSION:
          egl_extstr = _this->egl_data->eglQueryString(_this->egl_data->egl_display, EGL_EXTENSIONS);
          break;
      case SDL_EGL_CLIENT_EXTENSION:
          /* EGL_EXT_client_extensions modifies eglQueryString to return client extensions
           * if EGL_NO_DISPLAY is passed. Implementations without it are required to return NULL.
           * This behavior is included in EGL 1.5.
           */
          egl_extstr = _this->egl_data->eglQueryString(EGL_NO_DISPLAY, EGL_EXTENSIONS);
          break;
      default:
          /* SDL_LogDebug(SDL_LOG_CATEGORY_VIDEO, "SDL_EGL_HasExtension: Invalid extension type"); */
          return SDL_FALSE;
      }
  
      if (egl_extstr != NULL) {
          ext_start = egl_extstr;
  
          while (*ext_start) {
              ext_start = SDL_strstr(ext_start, ext);
              if (ext_start == NULL) {
                  return SDL_FALSE;
              }
              /* Check if the match is not just a substring of one of the extensions */
              if (ext_start == egl_extstr || *(ext_start - 1) == ' ') {
                  if (ext_start[ext_len] == ' ' || ext_start[ext_len] == 0) {
                      return SDL_TRUE;
                  }
              }
              /* If the search stopped in the middle of an extension, skip to the end of it */
              ext_start += ext_len;
              while (*ext_start != ' ' && *ext_start != 0) {
                  ext_start++;
              }
          }
      }
  
      return SDL_FALSE;
  }
  
  void *
  SDL_EGL_GetProcAddress(_THIS, const char *proc)
  {
      const Uint32 eglver = (((Uint32) _this->egl_data->egl_version_major) << 16) | ((Uint32) _this->egl_data->egl_version_minor);
      const SDL_bool is_egl_15_or_later = eglver >= ((((Uint32) 1) << 16) | 5);
      void *retval = NULL;
  
      /* EGL 1.5 can use eglGetProcAddress() for any symbol. 1.4 and earlier can't use it for core entry points. */
      if (!retval && is_egl_15_or_later && _this->egl_data->eglGetProcAddress) {
          retval = _this->egl_data->eglGetProcAddress(proc);
      }
  
      #ifndef __EMSCRIPTEN__  /* LoadFunction isn't needed on Emscripten and will call dlsym(), causing other problems. */
      /* Try SDL_LoadFunction() first for EGL <= 1.4, or as a fallback for >= 1.5. */
      if (!retval) {
          static char procname[64];
          retval = SDL_LoadFunction(_this->egl_data->egl_dll_handle, proc);
          /* just in case you need an underscore prepended... */
          if (!retval && (SDL_strlen(proc) < (sizeof (procname) - 1))) {
              procname[0] = '_';
              SDL_strlcpy(procname + 1, proc, sizeof (procname) - 1);
              retval = SDL_LoadFunction(_this->egl_data->egl_dll_handle, procname);
          }
      }
      #endif
  
      /* Try eglGetProcAddress if we're on <= 1.4 and still searching... */
      if (!retval && !is_egl_15_or_later && _this->egl_data->eglGetProcAddress) {
          retval = _this->egl_data->eglGetProcAddress(proc);
          if (retval) {
              return retval;
          }
      }
  
      return retval;
  }
  
  void
  SDL_EGL_UnloadLibrary(_THIS)
  {
      if (_this->egl_data) {
          if (_this->egl_data->egl_display) {
              _this->egl_data->eglTerminate(_this->egl_data->egl_display);
              _this->egl_data->egl_display = NULL;
          }
  
          if (_this->egl_data->dll_handle) {
              SDL_UnloadObject(_this->egl_data->dll_handle);
              _this->egl_data->dll_handle = NULL;
          }
          if (_this->egl_data->egl_dll_handle) {
              SDL_UnloadObject(_this->egl_data->egl_dll_handle);
              _this->egl_data->egl_dll_handle = NULL;
          }
          
          SDL_free(_this->egl_data);
          _this->egl_data = NULL;
      }
  }
  
  int
  SDL_EGL_LoadLibraryOnly(_THIS, const char *egl_path)
  {
      void *dll_handle = NULL, *egl_dll_handle = NULL; /* The naming is counter intuitive, but hey, I just work here -- Gabriel */
      const char *path = NULL;
  #if SDL_VIDEO_DRIVER_WINDOWS || SDL_VIDEO_DRIVER_WINRT
      const char *d3dcompiler;
  #endif
  #if SDL_VIDEO_DRIVER_RPI
      SDL_bool vc4 = (0 == access("/sys/module/vc4/", F_OK));
  #endif
  
      if (_this->egl_data) {
          return SDL_SetError("EGL context already created");
      }
  
      _this->egl_data = (struct SDL_EGL_VideoData *) SDL_calloc(1, sizeof(SDL_EGL_VideoData));
      if (!_this->egl_data) {
          return SDL_OutOfMemory();
      }
  
  #if SDL_VIDEO_DRIVER_WINDOWS || SDL_VIDEO_DRIVER_WINRT
      d3dcompiler = SDL_GetHint(SDL_HINT_VIDEO_WIN_D3DCOMPILER);
      if (d3dcompiler) {
          if (SDL_strcasecmp(d3dcompiler, "none") != 0) {
              if (SDL_LoadObject(d3dcompiler) == NULL) {
                  SDL_ClearError();
              }
          }
      } else {
          if (WIN_IsWindowsVistaOrGreater()) {
              /* Try the newer d3d compilers first */
              const char *d3dcompiler_list[] = {
                  "d3dcompiler_47.dll", "d3dcompiler_46.dll",
              };
              int i;
  
              for (i = 0; i < SDL_arraysize(d3dcompiler_list); ++i) {
                  if (SDL_LoadObject(d3dcompiler_list[i]) != NULL) {
                      break;
                  }
                  SDL_ClearError();
              }
          } else {
              if (SDL_LoadObject("d3dcompiler_43.dll") == NULL) {
                  SDL_ClearError();
              }
          }
      }
  #endif
  
  #ifndef SDL_VIDEO_STATIC_ANGLE
      /* A funny thing, loading EGL.so first does not work on the Raspberry, so we load libGL* first */
      path = SDL_getenv("SDL_VIDEO_GL_DRIVER");
      if (path != NULL) {
          egl_dll_handle = SDL_LoadObject(path);
      }
  
      if (egl_dll_handle == NULL) {
          if (_this->gl_config.profile_mask == SDL_GL_CONTEXT_PROFILE_ES) {
              if (_this->gl_config.major_version > 1) {
                  path = DEFAULT_OGL_ES2;
                  egl_dll_handle = SDL_LoadObject(path);
  #ifdef ALT_OGL_ES2
                  if (egl_dll_handle == NULL && !vc4) {
                      path = ALT_OGL_ES2;
                      egl_dll_handle = SDL_LoadObject(path);
                  }
  #endif
  
              } else {
                  path = DEFAULT_OGL_ES;
                  egl_dll_handle = SDL_LoadObject(path);
                  if (egl_dll_handle == NULL) {
                      path = DEFAULT_OGL_ES_PVR;
                      egl_dll_handle = SDL_LoadObject(path);
                  }
  #ifdef ALT_OGL_ES2
                  if (egl_dll_handle == NULL && !vc4) {
                      path = ALT_OGL_ES2;
                      egl_dll_handle = SDL_LoadObject(path);
                  }
  #endif
              }
          }
  #ifdef DEFAULT_OGL         
          else {
              path = DEFAULT_OGL;
              egl_dll_handle = SDL_LoadObject(path);
  #ifdef ALT_OGL
              if (egl_dll_handle == NULL) {
                  path = ALT_OGL;
                  egl_dll_handle = SDL_LoadObject(path);
              }
  #endif
          }
  #endif        
      }
      _this->egl_data->egl_dll_handle = egl_dll_handle;
  
      if (egl_dll_handle == NULL) {
          return SDL_SetError("Could not initialize OpenGL / GLES library");
      }
  
      /* Loading libGL* in the previous step took care of loading libEGL.so, but we future proof by double checking */
      if (egl_path != NULL) {
          dll_handle = SDL_LoadObject(egl_path);
      }   
      /* Try loading a EGL symbol, if it does not work try the default library paths */
      if (dll_handle == NULL || SDL_LoadFunction(dll_handle, "eglChooseConfig") == NULL) {
          if (dll_handle != NULL) {
              SDL_UnloadObject(dll_handle);
          }
          path = SDL_getenv("SDL_VIDEO_EGL_DRIVER");
          if (path == NULL) {
              path = DEFAULT_EGL;
          }
          dll_handle = SDL_LoadObject(path);
  
  #ifdef ALT_EGL
          if (dll_handle == NULL && !vc4) {
              path = ALT_EGL;
              dll_handle = SDL_LoadObject(path);
          }
  #endif
  
          if (dll_handle == NULL || SDL_LoadFunction(dll_handle, "eglChooseConfig") == NULL) {
              if (dll_handle != NULL) {
                  SDL_UnloadObject(dll_handle);
              }
              return SDL_SetError("Could not load EGL library");
          }
          SDL_ClearError();
      }
  #endif
  
      _this->egl_data->dll_handle = dll_handle;
  
      /* Load new function pointers */
      LOAD_FUNC(eglGetDisplay);
      LOAD_FUNC(eglInitialize);
      LOAD_FUNC(eglTerminate);
      LOAD_FUNC(eglGetProcAddress);
      LOAD_FUNC(eglChooseConfig);
      LOAD_FUNC(eglGetConfigAttrib);
      LOAD_FUNC(eglCreateContext);
      LOAD_FUNC(eglDestroyContext);
      LOAD_FUNC(eglCreatePbufferSurface);
      LOAD_FUNC(eglCreateWindowSurface);
      LOAD_FUNC(eglDestroySurface);
      LOAD_FUNC(eglMakeCurrent);
      LOAD_FUNC(eglSwapBuffers);
      LOAD_FUNC(eglSwapInterval);
      LOAD_FUNC(eglWaitNative);
      LOAD_FUNC(eglWaitGL);
      LOAD_FUNC(eglBindAPI);
      LOAD_FUNC(eglQueryAPI);
      LOAD_FUNC(eglQueryString);
      LOAD_FUNC(eglGetError);
      LOAD_FUNC_EGLEXT(eglQueryDevicesEXT);
      LOAD_FUNC_EGLEXT(eglGetPlatformDisplayEXT);
      /* Atomic functions */
      LOAD_FUNC_EGLEXT(eglCreateSyncKHR);
      LOAD_FUNC_EGLEXT(eglDestroySyncKHR);
      LOAD_FUNC_EGLEXT(eglDupNativeFenceFDANDROID);
      LOAD_FUNC_EGLEXT(eglWaitSyncKHR);
      LOAD_FUNC_EGLEXT(eglClientWaitSyncKHR);
      /* Atomic functions end */
  
      if (path) {
          SDL_strlcpy(_this->gl_config.driver_path, path, sizeof(_this->gl_config.driver_path) - 1);
      } else {
          *_this->gl_config.driver_path = '\0';
      }
  
      return 0;
  }
  
  static void
  SDL_EGL_GetVersion(_THIS) {
      if (_this->egl_data->eglQueryString) {
          const char *egl_version = _this->egl_data->eglQueryString(_this->egl_data->egl_display, EGL_VERSION);
          if (egl_version) {
              int major = 0, minor = 0;
              if (SDL_sscanf(egl_version, "%d.%d", &major, &minor) == 2) {
                  _this->egl_data->egl_version_major = major;
                  _this->egl_data->egl_version_minor = minor;
              } else {
                  SDL_LogWarn(SDL_LOG_CATEGORY_VIDEO, "Could not parse EGL version string: %s", egl_version);
              }
          }
      }
  }
  
  int
  SDL_EGL_LoadLibrary(_THIS, const char *egl_path, NativeDisplayType native_display, EGLenum platform)
  {
      int library_load_retcode = SDL_EGL_LoadLibraryOnly(_this, egl_path);
      if (library_load_retcode != 0) {
          return library_load_retcode;
      }
  
      _this->egl_data->egl_display = EGL_NO_DISPLAY;
  
  #if !defined(__WINRT__)
      if (platform) {
          /* EGL 1.5 allows querying for client version with EGL_NO_DISPLAY
           * --
           * Khronos doc: "EGL_BAD_DISPLAY is generated if display is not an EGL display connection, unless display is EGL_NO_DISPLAY and name is EGL_EXTENSIONS."
           * Therefore SDL_EGL_GetVersion() shouldn't work with uninitialized display.
           * - it actually doesn't work on Android that has 1.5 egl client
           * - it works on desktop X11 (using SDL_VIDEO_X11_FORCE_EGL=1) */
          SDL_EGL_GetVersion(_this);
  
          if (_this->egl_data->egl_version_major == 1 && _this->egl_data->egl_version_minor == 5) {
              LOAD_FUNC(eglGetPlatformDisplay);
          }
  
          if (_this->egl_data->eglGetPlatformDisplay) {
              _this->egl_data->egl_display = _this->egl_data->eglGetPlatformDisplay(platform, (void *)(uintptr_t)native_display, NULL);
          } else {
              if (SDL_EGL_HasExtension(_this, SDL_EGL_CLIENT_EXTENSION, "EGL_EXT_platform_base")) {
                  _this->egl_data->eglGetPlatformDisplayEXT = SDL_EGL_GetProcAddress(_this, "eglGetPlatformDisplayEXT");
                  if (_this->egl_data->eglGetPlatformDisplayEXT) {
                      _this->egl_data->egl_display = _this->egl_data->eglGetPlatformDisplayEXT(platform, (void *)(uintptr_t)native_display, NULL);
                  }
              }
          }
      }
      /* Try the implementation-specific eglGetDisplay even if eglGetPlatformDisplay fails */
      if (_this->egl_data->egl_display == EGL_NO_DISPLAY) {
          _this->egl_data->egl_display = _this->egl_data->eglGetDisplay(native_display);
      }
      if (_this->egl_data->egl_display == EGL_NO_DISPLAY) {
          _this->gl_config.driver_loaded = 0;
          *_this->gl_config.driver_path = '\0';
          return SDL_SetError("Could not get EGL display");
      }
  
      if (_this->egl_data->eglInitialize(_this->egl_data->egl_display, NULL, NULL) != EGL_TRUE) {
          _this->gl_config.driver_loaded = 0;
          *_this->gl_config.driver_path = '\0';
          return SDL_SetError("Could not initialize EGL");
      }
  #endif
  
      /* Get the EGL version with a valid egl_display, for EGL <= 1.4 */
      SDL_EGL_GetVersion(_this);
  
      _this->egl_data->is_offscreen = 0;
  
      return 0;
  }
  
  /**
     On multi GPU machines EGL device 0 is not always the first valid GPU.
     Container environments can restrict access to some GPUs that are still listed in the EGL
     device list. If the requested device is a restricted GPU and cannot be used
     (eglInitialize() will fail) then attempt to automatically and silently select the next
     valid available GPU for EGL to use.
  */
  
  int
  SDL_EGL_InitializeOffscreen(_THIS, int device)
  {
      void *egl_devices[SDL_EGL_MAX_DEVICES];
      EGLint num_egl_devices = 0;
      const char *egl_device_hint;
  
      if (_this->gl_config.driver_loaded != 1) {
          return SDL_SetError("SDL_EGL_LoadLibraryOnly() has not been called or has failed.");
      }
  
      /* Check for all extensions that are optional until used and fail if any is missing */
      if (_this->egl_data->eglQueryDevicesEXT == NULL) {
          return SDL_SetError("eglQueryDevicesEXT is missing (EXT_device_enumeration not supported by the drivers?)");
      }
  
      if (_this->egl_data->eglGetPlatformDisplayEXT == NULL) {
          return SDL_SetError("eglGetPlatformDisplayEXT is missing (EXT_platform_base not supported by the drivers?)");
      }
  
      if (_this->egl_data->eglQueryDevicesEXT(SDL_EGL_MAX_DEVICES, egl_devices, &num_egl_devices) != EGL_TRUE) {
          return SDL_SetError("eglQueryDevicesEXT() failed");
      }
  
      egl_device_hint = SDL_GetHint("SDL_HINT_EGL_DEVICE");
      if (egl_device_hint) {
          device = SDL_atoi(egl_device_hint);
  
          if (device >= num_egl_devices) {
              return SDL_SetError("Invalid EGL device is requested.");
          }
  
          _this->egl_data->egl_display = _this->egl_data->eglGetPlatformDisplayEXT(EGL_PLATFORM_DEVICE_EXT, egl_devices[device], NULL);
  
          if (_this->egl_data->egl_display == EGL_NO_DISPLAY) {
              return SDL_SetError("eglGetPlatformDisplayEXT() failed.");
          }
  
          if (_this->egl_data->eglInitialize(_this->egl_data->egl_display, NULL, NULL) != EGL_TRUE) {
              return SDL_SetError("Could not initialize EGL");
          }
      }
      else {
          int i;
          SDL_bool found = SDL_FALSE;
          EGLDisplay attempted_egl_display;
  
          /* If no hint is provided lets look for the first device/display that will allow us to eglInit */
          for (i = 0; i < num_egl_devices; i++) {
              attempted_egl_display = _this->egl_data->eglGetPlatformDisplayEXT(EGL_PLATFORM_DEVICE_EXT, egl_devices[i], NULL);
  
              if (attempted_egl_display == EGL_NO_DISPLAY) {
                  continue;
              }
  
              if (_this->egl_data->eglInitialize(attempted_egl_display, NULL, NULL) != EGL_TRUE) {
                  _this->egl_data->eglTerminate(attempted_egl_display);
                  continue;
              }
  
              /* We did not fail, we'll pick this one! */
              _this->egl_data->egl_display = attempted_egl_display;
              found = SDL_TRUE;
  
              break;
          }
  
          if (!found) {
              return SDL_SetError("Could not find a valid EGL device to initialize");
          }
      }
  
      /* Get the EGL version with a valid egl_display, for EGL <= 1.4 */
      SDL_EGL_GetVersion(_this);
  
      _this->egl_data->is_offscreen = 1;
  
      return 0;
  }
  
  void
  SDL_EGL_SetRequiredVisualId(_THIS, int visual_id) 
  {
      _this->egl_data->egl_required_visual_id=visual_id;
  }
  
  #ifdef DUMP_EGL_CONFIG
  
  #define ATTRIBUTE(_attr) { _attr, #_attr }
  
  typedef struct {
      EGLint attribute;
      char const* name;
  } Attribute;
  
  static
  Attribute all_attributes[] = {
          ATTRIBUTE( EGL_BUFFER_SIZE ),
          ATTRIBUTE( EGL_ALPHA_SIZE ),
          ATTRIBUTE( EGL_BLUE_SIZE ),
          ATTRIBUTE( EGL_GREEN_SIZE ),
          ATTRIBUTE( EGL_RED_SIZE ),
          ATTRIBUTE( EGL_DEPTH_SIZE ),
          ATTRIBUTE( EGL_STENCIL_SIZE ),
          ATTRIBUTE( EGL_CONFIG_CAVEAT ),
          ATTRIBUTE( EGL_CONFIG_ID ),
          ATTRIBUTE( EGL_LEVEL ),
          ATTRIBUTE( EGL_MAX_PBUFFER_HEIGHT ),
          ATTRIBUTE( EGL_MAX_PBUFFER_WIDTH ),
          ATTRIBUTE( EGL_MAX_PBUFFER_PIXELS ),
          ATTRIBUTE( EGL_NATIVE_RENDERABLE ),
          ATTRIBUTE( EGL_NATIVE_VISUAL_ID ),
          ATTRIBUTE( EGL_NATIVE_VISUAL_TYPE ),
          ATTRIBUTE( EGL_SAMPLES ),
          ATTRIBUTE( EGL_SAMPLE_BUFFERS ),
          ATTRIBUTE( EGL_SURFACE_TYPE ),
          ATTRIBUTE( EGL_TRANSPARENT_TYPE ),
          ATTRIBUTE( EGL_TRANSPARENT_BLUE_VALUE ),
          ATTRIBUTE( EGL_TRANSPARENT_GREEN_VALUE ),
          ATTRIBUTE( EGL_TRANSPARENT_RED_VALUE ),
          ATTRIBUTE( EGL_BIND_TO_TEXTURE_RGB ),
          ATTRIBUTE( EGL_BIND_TO_TEXTURE_RGBA ),
          ATTRIBUTE( EGL_MIN_SWAP_INTERVAL ),
          ATTRIBUTE( EGL_MAX_SWAP_INTERVAL ),
          ATTRIBUTE( EGL_LUMINANCE_SIZE ),
          ATTRIBUTE( EGL_ALPHA_MASK_SIZE ),
          ATTRIBUTE( EGL_COLOR_BUFFER_TYPE ),
          ATTRIBUTE( EGL_RENDERABLE_TYPE ),
          ATTRIBUTE( EGL_MATCH_NATIVE_PIXMAP ),
          ATTRIBUTE( EGL_CONFORMANT ),
  };
  
  
  static void dumpconfig(_THIS, EGLConfig config)
  {
      int attr;
      for (attr = 0 ; attr<sizeof(all_attributes)/sizeof(Attribute) ; attr++) {
          EGLint value;
          _this->egl_data->eglGetConfigAttrib(_this->egl_data->egl_display, config, all_attributes[attr].attribute, &value);
          SDL_Log("\t%-32s: %10d (0x%08x)\n", all_attributes[attr].name, value, value);
      }
  }
  
  #endif /* DUMP_EGL_CONFIG */
  
  static int
  SDL_EGL_PrivateChooseConfig(_THIS, SDL_bool set_config_caveat_none)
  {
      /* 64 seems nice. */
      EGLint attribs[64];
      EGLint found_configs = 0, value;
      /* 128 seems even nicer here */
      EGLConfig configs[128];
      SDL_bool has_matching_format = SDL_FALSE;
      int i, j, best_bitdiff = -1, best_truecolor_bitdiff = -1;
      int truecolor_config_idx = -1;
  
      /* Get a valid EGL configuration */
      i = 0;
      attribs[i++] = EGL_RED_SIZE;
      attribs[i++] = _this->gl_config.red_size;
      attribs[i++] = EGL_GREEN_SIZE;
      attribs[i++] = _this->gl_config.green_size;
      attribs[i++] = EGL_BLUE_SIZE;
      attribs[i++] = _this->gl_config.blue_size;
  
      if (set_config_caveat_none) {
          attribs[i++] = EGL_CONFIG_CAVEAT;
          attribs[i++] = EGL_NONE;
      }
  
      if (_this->gl_config.alpha_size) {
          attribs[i++] = EGL_ALPHA_SIZE;
          attribs[i++] = _this->gl_config.alpha_size;
      }
  
      if (_this->gl_config.buffer_size) {
          attribs[i++] = EGL_BUFFER_SIZE;
          attribs[i++] = _this->gl_config.buffer_size;
      }
  
      if (_this->gl_config.depth_size) {
          attribs[i++] = EGL_DEPTH_SIZE;
          attribs[i++] = _this->gl_config.depth_size;
      }
  
      if (_this->gl_config.stencil_size) {
          attribs[i++] = EGL_STENCIL_SIZE;
          attribs[i++] = _this->gl_config.stencil_size;
      }
  
      if (_this->gl_config.multisamplebuffers) {
          attribs[i++] = EGL_SAMPLE_BUFFERS;
          attribs[i++] = _this->gl_config.multisamplebuffers;
      }
  
      if (_this->gl_config.multisamplesamples) {
          attribs[i++] = EGL_SAMPLES;
          attribs[i++] = _this->gl_config.multisamplesamples;
      }
  
      if (_this->egl_data->is_offscreen) {
          attribs[i++] = EGL_SURFACE_TYPE;
          attribs[i++] = EGL_PBUFFER_BIT;
      }
  
      attribs[i++] = EGL_RENDERABLE_TYPE;
      if (_this->gl_config.profile_mask == SDL_GL_CONTEXT_PROFILE_ES) {
  #ifdef EGL_KHR_create_context
          if (_this->gl_config.major_version >= 3 &&
              SDL_EGL_HasExtension(_this, SDL_EGL_DISPLAY_EXTENSION, "EGL_KHR_create_context")) {
              attribs[i++] = EGL_OPENGL_ES3_BIT_KHR;
          } else
  #endif
          if (_this->gl_config.major_version >= 2) {
              attribs[i++] = EGL_OPENGL_ES2_BIT;
          } else {
              attribs[i++] = EGL_OPENGL_ES_BIT;
          }
          _this->egl_data->eglBindAPI(EGL_OPENGL_ES_API);
      } else {
          attribs[i++] = EGL_OPENGL_BIT;
          _this->egl_data->eglBindAPI(EGL_OPENGL_API);
      }
  
      if (_this->egl_data->egl_surfacetype) {
          attribs[i++] = EGL_SURFACE_TYPE;
          attribs[i++] = _this->egl_data->egl_surfacetype;
      }
  
      attribs[i++] = EGL_NONE;
  
      SDL_assert(i < SDL_arraysize(attribs));
  
      if (_this->egl_data->eglChooseConfig(_this->egl_data->egl_display,
          attribs,
          configs, SDL_arraysize(configs),
          &found_configs) == EGL_FALSE ||
          found_configs == 0) {
          return -1;
      }
  
      /* first ensure that a found config has a matching format, or the function will fall through. */
      if (_this->egl_data->egl_required_visual_id)
      {
          for (i = 0; i < found_configs; i++ ) {
              EGLint format;
              _this->egl_data->eglGetConfigAttrib(_this->egl_data->egl_display,
                                              configs[i],
                                              EGL_NATIVE_VISUAL_ID, &format);
              if (_this->egl_data->egl_required_visual_id == format) {
                  has_matching_format = SDL_TRUE;
                  break;
              }
          }
      }
  
      /* eglChooseConfig returns a number of configurations that match or exceed the requested attribs. */
      /* From those, we select the one that matches our requirements more closely via a makeshift algorithm */
  
      for (i = 0; i < found_configs; i++ ) {
          SDL_bool is_truecolor = SDL_FALSE;
          int bitdiff = 0;
  
          if (has_matching_format && _this->egl_data->egl_required_visual_id) {
              EGLint format;
              _this->egl_data->eglGetConfigAttrib(_this->egl_data->egl_display,
                                              configs[i],
                                              EGL_NATIVE_VISUAL_ID, &format);
              if (_this->egl_data->egl_required_visual_id != format) {
                  continue;
              }
          }
  
          _this->egl_data->eglGetConfigAttrib(_this->egl_data->egl_display, configs[i], EGL_RED_SIZE, &value);
          if (value == 8) {
              _this->egl_data->eglGetConfigAttrib(_this->egl_data->egl_display, configs[i], EGL_GREEN_SIZE, &value);
              if (value == 8) {
                  _this->egl_data->eglGetConfigAttrib(_this->egl_data->egl_display, configs[i], EGL_BLUE_SIZE, &value);
                  if (value == 8) {
                      is_truecolor = SDL_TRUE;
                  }
              }
          }
  
          for (j = 0; j < SDL_arraysize(attribs) - 1; j += 2) {
              if (attribs[j] == EGL_NONE) {
                 break;
              }
  
              if ( attribs[j+1] != EGL_DONT_CARE && (
                  attribs[j] == EGL_RED_SIZE ||
                  attribs[j] == EGL_GREEN_SIZE ||
                  attribs[j] == EGL_BLUE_SIZE ||
                  attribs[j] == EGL_ALPHA_SIZE ||
                  attribs[j] == EGL_DEPTH_SIZE ||
                  attribs[j] == EGL_STENCIL_SIZE)) {
                  _this->egl_data->eglGetConfigAttrib(_this->egl_data->egl_display, configs[i], attribs[j], &value);
                  bitdiff += value - attribs[j + 1]; /* value is always >= attrib */
              }
          }
  
          if ((bitdiff < best_bitdiff) || (best_bitdiff == -1)) {
              _this->egl_data->egl_config = configs[i];
              best_bitdiff = bitdiff;
          }
  
          if (is_truecolor && ((bitdiff < best_truecolor_bitdiff) || (best_truecolor_bitdiff == -1))) {
              truecolor_config_idx = i;
              best_truecolor_bitdiff = bitdiff;
          }
      }
  
      #define FAVOR_TRUECOLOR 1
      #if FAVOR_TRUECOLOR
      /* Some apps request a low color depth, either because they _assume_
         they'll get a larger one but don't want to fail if only smaller ones
         are available, or they just never called SDL_GL_SetAttribute at all and
         got a tiny default. For these cases, a game that would otherwise run
         at 24-bit color might get dithered down to something smaller, which is
         worth avoiding. If the app requested <= 16 bit color and an exact 24-bit
         match is available, favor that. Otherwise, we look for the closest
         match. Note that while the API promises what you request _or better_,
         it's feasible this can be disastrous for performance for custom software
         on small hardware that all expected to actually get 16-bit color. In this
         case, turn off FAVOR_TRUECOLOR (and maybe send a patch to make this more
         flexible). */
      if ( ((_this->gl_config.red_size + _this->gl_config.blue_size + _this->gl_config.green_size) <= 16) ) {
          if (truecolor_config_idx != -1) {
              _this->egl_data->egl_config = configs[truecolor_config_idx];
          }
      }
      #endif
  
  #ifdef DUMP_EGL_CONFIG
      dumpconfig(_this, _this->egl_data->egl_config);
  #endif
  
      return 0;
  }
  
  int
  SDL_EGL_ChooseConfig(_THIS)
  {
      int ret;
  
      if (!_this->egl_data) {
          /* The EGL library wasn't loaded, SDL_GetError() should have info */
          return -1;
      }
  
      /* Try with EGL_CONFIG_CAVEAT set to EGL_NONE, to avoid any EGL_SLOW_CONFIG or EGL_NON_CONFORMANT_CONFIG */
      ret = SDL_EGL_PrivateChooseConfig(_this, SDL_TRUE);
      if (ret == 0) {
          return 0;
      }
  
      /* Fallback with all configs */
      ret = SDL_EGL_PrivateChooseConfig(_this, SDL_FALSE);
      if (ret == 0) {
          SDL_Log("SDL_EGL_ChooseConfig: found a slow EGL config");
          return 0;
      }
  
      return SDL_EGL_SetError("Couldn't find matching EGL config", "eglChooseConfig");
  }
  
  SDL_GLContext
  SDL_EGL_CreateContext(_THIS, EGLSurface egl_surface)
  {
      /* max 14 values plus terminator. */
      EGLint attribs[15];
      int attr = 0;
  
      EGLContext egl_context, share_context = EGL_NO_CONTEXT;
      EGLint profile_mask = _this->gl_config.profile_mask;
      EGLint major_version = _this->gl_config.major_version;
      EGLint minor_version = _this->gl_config.minor_version;
      SDL_bool profile_es = (profile_mask == SDL_GL_CONTEXT_PROFILE_ES);
  
      if (!_this->egl_data) {
          /* The EGL library wasn't loaded, SDL_GetError() should have info */
          return NULL;
      }
  
      if (_this->gl_config.share_with_current_context) {
          share_context = (EGLContext)SDL_GL_GetCurrentContext();
      }
  
  #if SDL_VIDEO_DRIVER_ANDROID
      if ((_this->gl_config.flags & SDL_GL_CONTEXT_DEBUG_FLAG) != 0) {
          /* If SDL_GL_CONTEXT_DEBUG_FLAG is set but EGL_KHR_debug unsupported, unset.
           * This is required because some Android devices like to complain about it
           * by "silently" failing, logging a hint which could be easily overlooked:
           * E/libEGL  (26984): validate_display:255 error 3008 (EGL_BAD_DISPLAY)
           * The following explicitly checks for EGL_KHR_debug before EGL 1.5
           */
          int egl_version_major = _this->egl_data->egl_version_major;
          int egl_version_minor = _this->egl_data->egl_version_minor;
          if (((egl_version_major < 1) || (egl_version_major == 1 && egl_version_minor < 5)) &&
              !SDL_EGL_HasExtension(_this, SDL_EGL_DISPLAY_EXTENSION, "EGL_KHR_debug")) {
              /* SDL profile bits match EGL profile bits. */
              _this->gl_config.flags &= ~SDL_GL_CONTEXT_DEBUG_FLAG;
          }
      }
  #endif
  
      /* Set the context version and other attributes. */
      if ((major_version < 3 || (minor_version == 0 && profile_es)) &&
          _this->gl_config.flags == 0 &&
          (profile_mask == 0 || profile_es)) {
          /* Create a context without using EGL_KHR_create_context attribs.
           * When creating a GLES context without EGL_KHR_create_context we can
           * only specify the major version. When creating a desktop GL context
           * we can't specify any version, so we only try in that case when the
           * version is less than 3.0 (matches SDL's GLX/WGL behavior.)
           */
          if (profile_es) {
              attribs[attr++] = EGL_CONTEXT_CLIENT_VERSION;
              attribs[attr++] = SDL_max(major_version, 1);
          }
      } else {
  #ifdef EGL_KHR_create_context
          /* The Major/minor version, context profiles, and context flags can
           * only be specified when this extension is available.
           */
          if (SDL_EGL_HasExtension(_this, SDL_EGL_DISPLAY_EXTENSION, "EGL_KHR_create_context")) {
              attribs[attr++] = EGL_CONTEXT_MAJOR_VERSION_KHR;
              attribs[attr++] = major_version;
              attribs[attr++] = EGL_CONTEXT_MINOR_VERSION_KHR;
              attribs[attr++] = minor_version;
  
              /* SDL profile bits match EGL profile bits. */
              if (profile_mask != 0 && profile_mask != SDL_GL_CONTEXT_PROFILE_ES) {
                  attribs[attr++] = EGL_CONTEXT_OPENGL_PROFILE_MASK_KHR;
                  attribs[attr++] = profile_mask;
              }
  
              /* SDL flags match EGL flags. */
              if (_this->gl_config.flags != 0) {
                  attribs[attr++] = EGL_CONTEXT_FLAGS_KHR;
                  attribs[attr++] = _this->gl_config.flags;
              }
          } else
  #endif /* EGL_KHR_create_context */
          {
              SDL_SetError("Could not create EGL context (context attributes are not supported)");
              return NULL;
          }
      }
  
      if (_this->gl_config.no_error) {
  #ifdef EGL_KHR_create_context_no_error
          if (SDL_EGL_HasExtension(_this, SDL_EGL_DISPLAY_EXTENSION, "EGL_KHR_create_context_no_error")) {
              attribs[attr++] = EGL_CONTEXT_OPENGL_NO_ERROR_KHR;
              attribs[attr++] = _this->gl_config.no_error;
          } else
  #endif
          {
              SDL_SetError("EGL implementation does not support no_error contexts");
              return NULL;
          }
      }
  
      attribs[attr++] = EGL_NONE;
  
      /* Bind the API */
      if (profile_es) {
          _this->egl_data->eglBindAPI(EGL_OPENGL_ES_API);
      } else {
          _this->egl_data->eglBindAPI(EGL_OPENGL_API);
      }
  
      egl_context = _this->egl_data->eglCreateContext(_this->egl_data->egl_display,
                                        _this->egl_data->egl_config,
                                        share_context, attribs);
  
      if (egl_context == EGL_NO_CONTEXT) {
          SDL_EGL_SetError("Could not create EGL context", "eglCreateContext");
          return NULL;
      }
  
      _this->egl_data->egl_swapinterval = 0;
  
      if (SDL_EGL_MakeCurrent(_this, egl_surface, egl_context) < 0) {
          /* Save the SDL error set by SDL_EGL_MakeCurrent */
          char errorText[1024];
          SDL_strlcpy(errorText, SDL_GetError(), SDL_arraysize(errorText));
  
          /* Delete the context, which may alter the value returned by SDL_GetError() */
          SDL_EGL_DeleteContext(_this, egl_context);
  
          /* Restore the SDL error */
          SDL_SetError("%s", errorText);
  
          return NULL;
      }
  
      /* Check whether making contexts current without a surface is supported.
       * First condition: EGL must support it. That's the case for EGL 1.5
       * or later, or if the EGL_KHR_surfaceless_context extension is present. */
      if ((_this->egl_data->egl_version_major > 1) ||
          ((_this->egl_data->egl_version_major == 1) && (_this->egl_data->egl_version_minor >= 5)) ||
          SDL_EGL_HasExtension(_this, SDL_EGL_DISPLAY_EXTENSION, "EGL_KHR_surfaceless_context"))
      {
          /* Secondary condition: The client API must support it. */
          if (profile_es) {
              /* On OpenGL ES, the GL_OES_surfaceless_context extension must be
               * present. */
              if (SDL_GL_ExtensionSupported("GL_OES_surfaceless_context")) {
                  _this->gl_allow_no_surface = SDL_TRUE;
              }
  #if SDL_VIDEO_OPENGL
          } else {
              /* Desktop OpenGL supports it by default from version 3.0 on. */
              void (APIENTRY * glGetIntegervFunc) (GLenum pname, GLint * params);
              glGetIntegervFunc = SDL_GL_GetProcAddress("glGetIntegerv");
              if (glGetIntegervFunc) {
                  GLint v = 0;
                  glGetIntegervFunc(GL_MAJOR_VERSION, &v);
                  if (v >= 3) {
                      _this->gl_allow_no_surface = SDL_TRUE;
                  }
              }
  #endif
          }
      }
  
      return (SDL_GLContext) egl_context;
  }
  
  int
  SDL_EGL_MakeCurrent(_THIS, EGLSurface egl_surface, SDL_GLContext context)
  {
      EGLContext egl_context = (EGLContext) context;
  
      if (!_this->egl_data) {
          return SDL_SetError("OpenGL not initialized");
      }
  
      if (!_this->egl_data->eglMakeCurrent) {
          if (!egl_surface && !context) {
              /* Can't do the nothing there is to do? Probably trying to cleanup a failed startup, just return. */
              return 0;
          } else {
              return SDL_SetError("OpenGL not initialized");  /* something clearly went wrong somewhere. */
          }
      }
  
      /* The android emulator crashes badly if you try to eglMakeCurrent 
       * with a valid context and invalid surface, so we have to check for both here.
       */
      if (!egl_context || (!egl_surface && !_this->gl_allow_no_surface)) {
           _this->egl_data->eglMakeCurrent(_this->egl_data->egl_display, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
      } else {
          if (!_this->egl_data->eglMakeCurrent(_this->egl_data->egl_display,
              egl_surface, egl_surface, egl_context)) {
              return SDL_EGL_SetError("Unable to make EGL context current", "eglMakeCurrent");
          }
      }
  
      return 0;
  }
  
  int
  SDL_EGL_SetSwapInterval(_THIS, int interval)
  {
      EGLBoolean status;
      
      if (!_this->egl_data) {
          return SDL_SetError("EGL not initialized");
      }
  
      /* FIXME: Revisit this check when EGL_EXT_swap_control_tear is published:
       * https://github.com/KhronosGroup/EGL-Registry/pull/113
       */
      if (interval < 0) {
          return SDL_SetError("Late swap tearing currently unsupported");
      }
      
      status = _this->egl_data->eglSwapInterval(_this->egl_data->egl_display, interval);
      if (status == EGL_TRUE) {
          _this->egl_data->egl_swapinterval = interval;
          return 0;
      }
      
      return SDL_EGL_SetError("Unable to set the EGL swap interval", "eglSwapInterval");
  }
  
  int
  SDL_EGL_GetSwapInterval(_THIS)
  {
      if (!_this->egl_data) {
          SDL_SetError("EGL not initialized");
          return 0;
      }
      
      return _this->egl_data->egl_swapinterval;
  }
  
  int
  SDL_EGL_SwapBuffers(_THIS, EGLSurface egl_surface)
  {
      if (!_this->egl_data->eglSwapBuffers(_this->egl_data->egl_display, egl_surface)) {
          return SDL_EGL_SetError("unable to show color buffer in an OS-native window", "eglSwapBuffers");
      }
      return 0;
  }
  
  void
  SDL_EGL_DeleteContext(_THIS, SDL_GLContext context)
  {
      EGLContext egl_context = (EGLContext) context;
  
      /* Clean up GLES and EGL */
      if (!_this->egl_data) {
          return;
      }
      
      if (egl_context != NULL && egl_context != EGL_NO_CONTEXT) {
          _this->egl_data->eglDestroyContext(_this->egl_data->egl_display, egl_context);
      }
          
  }
  
  EGLSurface *
  SDL_EGL_CreateSurface(_THIS, NativeWindowType nw) 
  {
  #if SDL_VIDEO_DRIVER_ANDROID
      EGLint format_wanted;
      EGLint format_got;
  #endif
      /* max 2 key+value pairs, plus terminator. */
      EGLint attribs[5];
      int attr = 0;
  
      EGLSurface * surface;
  
      if (SDL_EGL_ChooseConfig(_this) != 0) {
          return EGL_NO_SURFACE;
      }
  
  #if SDL_VIDEO_DRIVER_ANDROID
      /* On Android, EGL_NATIVE_VISUAL_ID is an attribute of the EGLConfig that is
       * guaranteed to be accepted by ANativeWindow_setBuffersGeometry(). */
      _this->egl_data->eglGetConfigAttrib(_this->egl_data->egl_display,
              _this->egl_data->egl_config,
              EGL_NATIVE_VISUAL_ID, &format_wanted);
  
      /* Format based on selected egl config. */
      ANativeWindow_setBuffersGeometry(nw, 0, 0, format_wanted);
  #endif
  
      if (_this->gl_config.framebuffer_srgb_capable) {
  #ifdef EGL_KHR_gl_colorspace
          if (SDL_EGL_HasExtension(_this, SDL_EGL_DISPLAY_EXTENSION, "EGL_KHR_gl_colorspace")) {
              attribs[attr++] = EGL_GL_COLORSPACE_KHR;
              attribs[attr++] = EGL_GL_COLORSPACE_SRGB_KHR;
          } else
  #endif
          {
              SDL_SetError("EGL implementation does not support sRGB system framebuffers");
              return EGL_NO_SURFACE;
          }
      }
  
  #ifdef EGL_EXT_present_opaque
      if (SDL_EGL_HasExtension(_this, SDL_EGL_DISPLAY_EXTENSION, "EGL_EXT_present_opaque")) {
          const SDL_bool allow_transparent = SDL_GetHintBoolean(SDL_HINT_VIDEO_EGL_ALLOW_TRANSPARENCY, SDL_FALSE);
          attribs[attr++] = EGL_PRESENT_OPAQUE_EXT;
          attribs[attr++] = allow_transparent ? EGL_FALSE : EGL_TRUE;
      }
  #endif
  
      attribs[attr++] = EGL_NONE;
      
      surface = _this->egl_data->eglCreateWindowSurface(
              _this->egl_data->egl_display,
              _this->egl_data->egl_config,
              nw, &attribs[0]);
      if (surface == EGL_NO_SURFACE) {
          SDL_EGL_SetError("unable to create an EGL window surface", "eglCreateWindowSurface");
      }
  
  #if SDL_VIDEO_DRIVER_ANDROID
      format_got = ANativeWindow_getFormat(nw);
      Android_SetFormat(format_wanted, format_got);
  #endif
  
      return surface;
  }
  
  EGLSurface
  SDL_EGL_CreateOffscreenSurface(_THIS, int width, int height)
  {
      EGLint attributes[] = {
          EGL_WIDTH, width,
          EGL_HEIGHT, height,
          EGL_NONE
      };
  
      if (SDL_EGL_ChooseConfig(_this) != 0) {
          return EGL_NO_SURFACE;
      }
  
      return _this->egl_data->eglCreatePbufferSurface(
          _this->egl_data->egl_display,
          _this->egl_data->egl_config,
          attributes);
  }
  
  void
  SDL_EGL_DestroySurface(_THIS, EGLSurface egl_surface) 
  {
      if (!_this->egl_data) {
          return;
      }
      
      if (egl_surface != EGL_NO_SURFACE) {
          _this->egl_data->eglDestroySurface(_this->egl_data->egl_display, egl_surface);
      }
  }
  
  #endif /* SDL_VIDEO_OPENGL_EGL */
  
  /* vi: set ts=4 sw=4 expandtab: */
  
  

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