FreeType 1.31.1

lib/ttextend.c

@@ -0,0 +1,212 @@
+/*******************************************************************
+ *
+ *  ttextend.h                                                   2.0
+ *
+ *    Extensions Interface
+ *
+ *  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 "ttextend.h"
+#include "ttengine.h"
+#include "ttmemory.h"
+
+/* required by the tracing mode */
+#undef  TT_COMPONENT
+#define TT_COMPONENT      trace_extend
+
+
+  struct TExtension_Registry_
+  {
+    Int               num_extensions;
+    Long              cur_offset;
+    TExtension_Class  classes[TT_MAX_EXTENSIONS];
+  };
+
+  typedef struct TExtension_Registry_  TExtension_Registry;
+  typedef TExtension_Registry*         PExtension_Registry;
+
+
+
+  /* Initialize the extension component */
+
+  LOCAL_FUNC
+  TT_Error  TTExtend_Init( PEngine_Instance  engine )
+  {
+    TT_Error             error;
+    PExtension_Registry  exts;
+
+
+    if ( ALLOC( exts, sizeof ( TExtension_Registry ) ) )
+      return error;
+
+    exts->num_extensions        = 0;
+    exts->cur_offset            = 0;
+    engine->extension_component = (void*)exts;
+
+    return TT_Err_Ok;
+  }
+
+
+  /* Finalize the extension component */
+
+  LOCAL_FUNC
+  TT_Error  TTExtend_Done( PEngine_Instance  engine )
+  {
+    FREE( engine->extension_component );
+    return TT_Err_Ok;
+  }
+
+
+  /* Register a new extension */
+
+  EXPORT_FUNC
+  TT_Error  TT_Register_Extension( PEngine_Instance  engine,
+                                   Long              id,
+                                   Long              size,
+                                   PExt_Constructor  create,
+                                   PExt_Destructor   destroy )
+  {
+    PExtension_Registry  exts;
+    PExtension_Class     clazz;
+    Int                  p;
+
+
+    exts = (PExtension_Registry)engine->extension_component;
+    if ( !exts )
+      return TT_Err_Ok;
+
+    p = exts->num_extensions;
+
+    if ( p >= TT_MAX_EXTENSIONS )
+      return TT_Err_Too_Many_Extensions;
+
+    clazz          = exts->classes + p;
+    clazz->id      = id;
+    clazz->size    = size;
+    clazz->build   = create;
+    clazz->destroy = destroy;
+
+    clazz->offset  = exts->cur_offset;
+
+    exts->num_extensions++;
+    exts->cur_offset += ( size + ALIGNMENT-1 ) & -ALIGNMENT;
+
+    return TT_Err_Ok;
+  }
+
+
+  /* Query an extension block by extension_ID */
+
+  EXPORT_FUNC
+  TT_Error  TT_Extension_Get( PFace   face,
+                              Long    extension_id,
+                              void**  extension_block )
+  {
+    PExtension_Registry  registry;
+    PExtension_Class     clazz;
+    Int                  n;
+
+
+    if ( !face->extension )
+      return TT_Err_Extensions_Unsupported;
+
+    registry = (PExtension_Registry)face->engine->extension_component;
+
+    for ( n = 0; n < face->n_extensions; n++ )
+    {
+      clazz = registry->classes + n;
+      if ( clazz->id == extension_id )
+      {
+        *extension_block = (PByte)face->extension + clazz->offset;
+        return TT_Err_Ok;
+      }
+    }
+
+    return TT_Err_Invalid_Extension_Id;
+  }
+
+
+  /* Destroy all extensions within a face object.  Called by the */
+  /* face object destructor.                                     */
+
+  LOCAL_FUNC
+  TT_Error  Extension_Destroy( PFace  face )
+  {
+    PEngine_Instance     engine = face->engine;
+    PExtension_Registry  registry;
+    PExtension_Class     clazz;
+    Int                  n;
+    PByte                ext;
+
+
+    registry = (PExtension_Registry)engine->extension_component;
+
+    for ( n = 0; n < face->n_extensions; n++ )
+    {
+      clazz = registry->classes + n;
+      ext   = (PByte)face->extension + clazz->offset;
+
+      /* the destructor is optional */
+      if ( clazz->destroy )
+        clazz->destroy( (void*)ext, face );
+    }
+
+    /* destroy the face's extension block too */
+    FREE( face->extension );
+    face->n_extensions = 0;
+
+    return TT_Err_Ok;
+  }
+
+
+  /* Create an extension within a face object.  Called by the */
+  /* face object constructor.                                 */
+
+  LOCAL_FUNC
+  TT_Error  Extension_Create( PFace  face )
+  {
+    PEngine_Instance     engine = face->engine;
+    PExtension_Registry  registry;
+    PExtension_Class     clazz;
+    TT_Error             error;
+    Int                  n;
+    PByte                ext;
+
+
+    registry = (PExtension_Registry)engine->extension_component;
+
+    face->n_extensions = registry->num_extensions;
+    if ( ALLOC( face->extension, registry->cur_offset ) )
+      return error;
+
+    for ( n = 0; n < face->n_extensions; n++ )
+    {
+      clazz = registry->classes + n;
+      ext   = (PByte)face->extension + clazz->offset;
+      error = clazz->build( (void*)ext, face );
+      if ( error )
+        goto Fail;
+    }
+    return TT_Err_Ok;
+
+  Fail:
+    Extension_Destroy( face );
+    return error;
+  }
+
+
+/* END */