/*******************************************************************
*
* ftextend.h 2.0
*
* Extensions Implementation
*
* Copyright 1996-1999 by
* David Turner, Robert Wilhelm, and Werner Lemberg.
*
* This file is part of the FreeType project, and may only be used
* modified and distributed under the terms of the FreeType project
* license, LICENSE.TXT. By continuing to use, modify, or distribute
* this file you indicate that you have read the license and
* understand and accept it fully.
*
* This is an updated version of the extension component, now
* located in the main library's source directory. It allows
* the dynamic registration/use of various face object extensions
* through a simple API.
*
******************************************************************/
#include "ftextend.h"
#include "ftobjs.h"
/* required by the tracing mode */
#undef FT_COMPONENT
#define FT_COMPONENT trace_extend
typedef struct FT_Extension_Registry_
{
FT_Int num_extensions;
FT_Long cur_offset;
FT_Extension_Class classes[FT_MAX_EXTENSIONS];
} FT_Extension_Registry;
/* Initialize the extension component */
LOCAL_FUNC
FT_Error FT_Init_Extensions( FT_Driver driver )
{
FT_Error error;
FT_Memory memory;
FT_Extension_Registry* registry;
memory = driver->library->memory;
if ( ALLOC( registry, sizeof (*registry) ) )
return error;
registry->num_extensions = 0;
registry->cur_offset = 0;
driver->extensions = registry;
return FT_Err_Ok;
}
/* Finalize the extension component */
LOCAL_FUNC
FT_Error FT_Done_Extensions( FT_Driver driver )
{
FT_Memory memory = driver->memory;
FREE( driver->extensions );
return FT_Err_Ok;
}
/* Register a new extension */
EXPORT_FUNC
FT_Error FT_Register_Extension( FT_Driver driver,
FT_Extension_Class* clazz )
{
FT_Extension_Registry* registry;
registry = (FT_Extension_Registry*)driver->extensions;
if (registry)
{
FT_Int n = registry->num_extensions;
FT_Extension_Class* cur = registry->classes + n;
if ( n >= FT_MAX_EXTENSIONS )
return FT_Err_Too_Many_Extensions;
*cur = *clazz;
cur->offset = registry->cur_offset;
registry->num_extensions++;
registry->cur_offset += ( cur->size + FT_ALIGNMENT-1 ) & -FT_ALIGNMENT;
}
return FT_Err_Ok;
}
/* Query an extension block by extension_ID */
EXPORT_FUNC
void* FT_Get_Extension( FT_Face face,
const char* extension_id,
void* *extension_interface )
{
FT_Extension_Registry* registry;
registry = (FT_Extension_Registry*)face->driver->extensions;
if (registry && face->extensions)
{
FT_Extension_Class* cur = registry->classes;
FT_Extension_Class* limit = cur + registry->num_extensions;
for ( ; cur < limit; cur++ )
if ( strcmp( cur->id, extension_id ) == 0 )
{
*extension_interface = cur->interface;
return (void*)((char*)face->extensions + cur->offset);
}
}
/* could not find the extension id */
*extension_interface = 0;
return 0;
}
/* Destroy all extensions within a face object. Called by the */
/* face object destructor. */
LOCAL_FUNC
FT_Error FT_Destroy_Extensions( FT_Face face )
{
FT_Extension_Registry* registry;
FT_Memory memory;
registry = (FT_Extension_Registry*)face->driver->extensions;
if (registry && face->extensions)
{
FT_Extension_Class* cur = registry->classes;
FT_Extension_Class* limit = cur + registry->num_extensions;
for ( ; cur < limit; cur++ )
{
char* ext = (char*)face->extensions + cur->offset;
if (cur->finalize)
cur->finalize( ext, face );
}
memory = face->driver->memory;
FREE( face->extensions );
}
return FT_Err_Ok;
}
/* Create an extension within a face object. Called by the */
/* face object constructor. */
LOCAL_FUNC
FT_Error FT_Create_Extensions( FT_Face face )
{
FT_Extension_Registry* registry;
FT_Memory memory;
FT_Error error;
face->extensions = 0;
/* load extensions registry, exit succesfully if none is there */
registry = (FT_Extension_Registry*)face->driver->extensions;
if (!registry) return FT_Err_Ok;
memory = face->driver->memory;
if ( ALLOC( face->extensions, registry->cur_offset ) )
return error;
{
FT_Extension_Class* cur = registry->classes;
FT_Extension_Class* limit = cur + registry->num_extensions;
for ( ; cur < limit; cur++ )
{
char* ext = (char*)face->extensions + cur->offset;
if (cur->init)
{
error = cur->init( ext, face );
if (error) break;
}
}
}
return error;
}
/* END */
