src/egl/main/eglcontext.c

#include <assert.h>
#include <stdlib.h>
#include <string.h>
#include "eglconfig.h"
#include "eglcontext.h"
#include "egldisplay.h"
#include "egldriver.h"
#include "eglglobals.h"
#include "eglsurface.h"


/**
 * Initialize the given _EGLContext object to defaults and/or the values
 * in the attrib_list.
 */
EGLBoolean
_eglInitContext(_EGLDriver *drv, _EGLContext *ctx,
                _EGLConfig *conf, const EGLint *attrib_list)
{
   EGLint i;
   const EGLenum api = eglQueryAPI();

   if (api == EGL_NONE) {
      _eglError(EGL_BAD_MATCH, "eglCreateContext(no client API)");
      return EGL_FALSE;
   }

   memset(ctx, 0, sizeof(_EGLContext));

   ctx->ClientVersion = 1; /* the default, per EGL spec */

   for (i = 0; attrib_list && attrib_list[i] != EGL_NONE; i++) {
      switch (attrib_list[i]) {
      case EGL_CONTEXT_CLIENT_VERSION:
         i++;
         ctx->ClientVersion = attrib_list[i];
         break;
      default:
         _eglError(EGL_BAD_ATTRIBUTE, "_eglInitContext");
         return EGL_FALSE;
      }
   }

   ctx->Config = conf;
   ctx->DrawSurface = EGL_NO_SURFACE;
   ctx->ReadSurface = EGL_NO_SURFACE;
   ctx->ClientAPI = api;
   ctx->WindowRenderBuffer = EGL_NONE;

   return EGL_TRUE;
}


/**
 * Just a placeholder/demo function.  Real driver will never use this!
 */
_EGLContext *
_eglCreateContext(_EGLDriver *drv, _EGLDisplay *dpy, _EGLConfig *conf,
                  _EGLContext *share_list, const EGLint *attrib_list)
{
#if 0 /* example code */
   _EGLContext *context;

   context = (_EGLContext *) calloc(1, sizeof(_EGLContext));
   if (!context)
      return NULL;

   if (!_eglInitContext(drv, context, conf, attrib_list)) {
      free(context);
      return NULL;
   }

   return context;
#endif
   return NULL;
}


/**
 * Default fallback routine - drivers should usually override this.
 */
EGLBoolean
_eglDestroyContext(_EGLDriver *drv, _EGLDisplay *dpy, _EGLContext *ctx)
{
   if (!_eglIsContextBound(ctx))
      free(ctx);
   return EGL_TRUE;
}


#ifdef EGL_VERSION_1_2
static EGLint
_eglQueryContextRenderBuffer(_EGLContext *ctx)
{
   _EGLSurface *surf = ctx->DrawSurface;
   EGLint rb;

   if (!surf)
      return EGL_NONE;
   if (surf->Type == EGL_WINDOW_BIT && ctx->WindowRenderBuffer != EGL_NONE)
      rb = ctx->WindowRenderBuffer;
   else
      rb = surf->RenderBuffer;
   return rb;
}
#endif /* EGL_VERSION_1_2 */


EGLBoolean
_eglQueryContext(_EGLDriver *drv, _EGLDisplay *dpy, _EGLContext *c,
                 EGLint attribute, EGLint *value)
{
   (void) drv;
   (void) dpy;

   if (!value)
      return _eglError(EGL_BAD_PARAMETER, "eglQueryContext");

   switch (attribute) {
   case EGL_CONFIG_ID:
      *value = GET_CONFIG_ATTRIB(c->Config, EGL_CONFIG_ID);
      break;
   case EGL_CONTEXT_CLIENT_VERSION:
      *value = c->ClientVersion;
      break;
#ifdef EGL_VERSION_1_2
   case EGL_CONTEXT_CLIENT_TYPE:
      *value = c->ClientAPI;
      break;
   case EGL_RENDER_BUFFER:
      *value = _eglQueryContextRenderBuffer(c);
      break;
#endif /* EGL_VERSION_1_2 */
   default:
      return _eglError(EGL_BAD_ATTRIBUTE, "eglQueryContext");
   }

   return EGL_TRUE;
}


/**
 * Drivers will typically call this to do the error checking and
 * update the various flags.
 * Then, the driver will do its device-dependent Make-Current stuff.
 */
EGLBoolean
_eglMakeCurrent(_EGLDriver *drv, _EGLDisplay *dpy, _EGLSurface *draw,
                _EGLSurface *read, _EGLContext *ctx)
{
   _EGLThreadInfo *t = _eglGetCurrentThread();
   _EGLContext *oldContext = NULL;
   _EGLSurface *oldDrawSurface = NULL;
   _EGLSurface *oldReadSurface = NULL;
   EGLint apiIndex;

   if (_eglIsCurrentThreadDummy())
      return _eglError(EGL_BAD_ALLOC, "eglMakeCurrent");

   if (ctx) {
      /* error checking */
      if (ctx->Binding && ctx->Binding != t)
         return _eglError(EGL_BAD_ACCESS, "eglMakeCurrent");
      if (draw == NULL || read == NULL)
         return _eglError(EGL_BAD_MATCH, "eglMakeCurrent");
      if (draw->Config != ctx->Config || read->Config != ctx->Config)
         return _eglError(EGL_BAD_MATCH, "eglMakeCurrent");
      if ((draw->Binding && draw->Binding->Binding != t) ||
          (read->Binding && read->Binding->Binding != t))
         return _eglError(EGL_BAD_ACCESS, "eglMakeCurrent");

#ifdef EGL_VERSION_1_4
      /* OpenGL and OpenGL ES are conflicting */
      switch (ctx->ClientAPI) {
      case EGL_OPENGL_ES_API:
         if (t->CurrentContexts[_eglConvertApiToIndex(EGL_OPENGL_API)])
            return _eglError(EGL_BAD_ACCESS, "eglMakeCurrent");
         break;
      case EGL_OPENGL_API:
         if (t->CurrentContexts[_eglConvertApiToIndex(EGL_OPENGL_ES_API)])
            return _eglError(EGL_BAD_ACCESS, "eglMakeCurrent");
         break;
      default:
         break;
      }
#endif
      apiIndex = _eglConvertApiToIndex(ctx->ClientAPI);
   }
   else {
      if (draw != NULL || read != NULL)
         return _eglError(EGL_BAD_MATCH, "eglMakeCurrent");
      apiIndex = t->CurrentAPIIndex;
   }

   oldContext = t->CurrentContexts[apiIndex];
   if (oldContext) {
      oldDrawSurface = oldContext->DrawSurface;
      oldReadSurface = oldContext->ReadSurface;
      assert(oldDrawSurface);
      assert(oldReadSurface);

      /* break old bindings */
      t->CurrentContexts[apiIndex] = NULL;
      oldContext->Binding = NULL;
      oldContext->DrawSurface = NULL;
      oldContext->ReadSurface = NULL;
      oldDrawSurface->Binding = NULL;
      oldReadSurface->Binding = NULL;

      /*
       * check if the old context or surfaces need to be deleted
       */
      if (!_eglIsSurfaceLinked(oldDrawSurface)) {
         assert(draw != oldDrawSurface && read != oldDrawSurface);
         drv->API.DestroySurface(drv, dpy, oldDrawSurface);
      }
      if (oldReadSurface != oldDrawSurface &&
          !_eglIsSurfaceLinked(oldReadSurface)) {
         assert(draw != oldReadSurface && read != oldReadSurface);
         drv->API.DestroySurface(drv, dpy, oldReadSurface);
      }
      if (!_eglIsContextLinked(oldContext)) {
         assert(ctx != oldContext);
         drv->API.DestroyContext(drv, dpy, oldContext);
      }
   }

   /* build new bindings */
   if (ctx) {
      t->CurrentContexts[apiIndex] = ctx;
      ctx->Binding = t;
      ctx->DrawSurface = draw;
      ctx->ReadSurface = read;
      draw->Binding = ctx;
      read->Binding = ctx;
   }

   return EGL_TRUE;
}


/**
 * This is defined by the EGL_MESA_copy_context extension.
 */
EGLBoolean
_eglCopyContextMESA(_EGLDriver *drv, EGLDisplay dpy, EGLContext source,
                    EGLContext dest, EGLint mask)
{
   /* This function will always have to be overridden/implemented in the
    * device driver.  If the driver is based on Mesa, use _mesa_copy_context().
    */
   return EGL_FALSE;
}


/**
 * Link a context to a display and return the handle of the link.
 * The handle can be passed to client directly.
 */
EGLContext
_eglLinkContext(_EGLContext *ctx, _EGLDisplay *dpy)
{
   ctx->Display = dpy;
   ctx->Next = dpy->ContextList;
   dpy->ContextList = ctx;
   return (EGLContext) ctx;
}


/**
 * Unlink a linked context from its display.
 * Accessing an unlinked context should generate EGL_BAD_CONTEXT error.
 */
void
_eglUnlinkContext(_EGLContext *ctx)
{
   _EGLContext *prev;

   prev = ctx->Display->ContextList;
   if (prev != ctx) {
      while (prev) {
         if (prev->Next == ctx)
            break;
         prev = prev->Next;
      }
      assert(prev);
      prev->Next = ctx->Next;
   }
   else {
      ctx->Display->ContextList = ctx->Next;
   }

   ctx->Next = NULL;
   ctx->Display = NULL;
}


#ifndef _EGL_SKIP_HANDLE_CHECK


/**
 * Return EGL_TRUE if the given handle is a valid handle to a context.
 */
EGLBoolean
_eglCheckContextHandle(EGLContext ctx, _EGLDisplay *dpy)
{
   _EGLContext *cur = NULL;

   if (dpy)
      cur = dpy->ContextList;
   while (cur) {
      if (cur == (_EGLContext *) ctx) {
         assert(cur->Display == dpy);
         break;
      }
      cur = cur->Next;
   }
   return (cur != NULL);
}


#endif /* !_EGL_SKIP_HANDLE_CHECK */