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Fix documentation of TrueType bytecode interpreter debug hook.

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This commit is contained in:
Werner Lemberg 2018-12-12 14:05:03 +01:00
parent 2b4e61e4d6
commit e8bbef85c0
2 changed files with 53 additions and 14 deletions
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62
include/freetype/ftmodapi.h
View File

@ -592,12 +592,54 @@ FT_BEGIN_HEADER
FT_EXPORT( FT_Error )
FT_Done_Library( FT_Library library );
/* */
/**************************************************************************
*
* @functype:
* FT_DebugHook_Func
*
* @description:
* A drop-in replacement (or rather a wrapper) for the bytecode or
* charstring interpreter's main loop function.
*
* Its job is essentially
*
* - to activate debug mode to enforce single-stepping,
* - to call the main loop function to interpret the next opcode, and
* - to show the changed context to the user.
*
* An example for such a main loop function is `TT_RunIns` (declared in
* FreeType's internal header file `src/truetype/ttinterp.h`).
*
* Have a look at the source code of the `ttdebug` FreeType demo program
* for an example of a drop-in replacement.
*
* @inout:
* arg ::
* A typeless pointer, to be cast to the main loop function's data
* structure (which depends on the font module). For TrueType fonts
* it is bytecode interpreter's execution context, `TT_ExecContext`,
* which is declared in FreeType's internal header file `tttypes.h`.
*/
typedef void
(*FT_DebugHook_Func)( void* arg );
/**************************************************************************
*
* @enum:
* FT_DEBUG_HOOK_XXX
*
* @description:
* A list of named debug hook indices.
*
* @values:
* FT_DEBUG_HOOK_TRUETYPE::
* This hook index identifies the TrueType bytecode debugger.
*/
#define FT_DEBUG_HOOK_TRUETYPE 0
/**************************************************************************
*
* @function:
@ -607,25 +649,27 @@ FT_BEGIN_HEADER
* Set a debug hook function for debugging the interpreter of a font
* format.
*
* While this is a public API function, an application needs access to
* FreeType's internal header files to do something useful.
*
* Have a look at the source code of the `ttdebug` FreeType demo program
* for an example of its usage.
*
* @inout:
* library ::
* A handle to the library object.
*
* @input:
* hook_index ::
* The index of the debug hook. You should use the values defined in
* `ftobjs.h`, e.g., `FT_DEBUG_HOOK_TRUETYPE`.
* The index of the debug hook. You should use defined enumeration
* macros like @FT_DEBUG_HOOK_TRUETYPE.
*
* debug_hook ::
* The function used to debug the interpreter.
*
* @note:
* Currently, four debug hook slots are available, but only two (for the
* TrueType and the Type~1 interpreter) are defined.
*
* Since the internal headers of FreeType are no longer installed, the
* symbol `FT_DEBUG_HOOK_TRUETYPE` isn't available publicly. This is a
* bug and will be fixed in a forthcoming release.
* Currently, four debug hook slots are available, but only one (for the
* TrueType interpreter) is defined.
*/
FT_EXPORT( void )
FT_Set_Debug_Hook( FT_Library library,

5
include/freetype/internal/ftobjs.h
View File

@ -821,11 +821,6 @@ FT_BEGIN_HEADER
/*************************************************************************/
/* This hook is used by the TrueType debugger. It must be set to an */
/* alternate truetype bytecode interpreter function. */
#define FT_DEBUG_HOOK_TRUETYPE 0
/**************************************************************************
*
* @struct: