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freetype2/include/freetype/ftmodapi.h

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/****************************************************************************
*
* ftmodapi.h
*
* FreeType modules public interface (specification).
*
* Copyright (C) 1996-2020 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.
*
*/
#ifndef FTMODAPI_H_
#define FTMODAPI_H_
#include <freetype/freetype.h>
#ifdef FREETYPE_H
#error "freetype.h of FreeType 1 has been loaded!"
#error "Please fix the directory search order for header files"
#error "so that freetype.h of FreeType 2 is found first."
#endif
FT_BEGIN_HEADER
/**************************************************************************
*
* @section:
* module_management
*
* @title:
* Module Management
*
* @abstract:
* How to add, upgrade, remove, and control modules from FreeType.
*
* @description:
* The definitions below are used to manage modules within FreeType.
* Modules can be added, upgraded, and removed at runtime. Additionally,
* some module properties can be controlled also.
*
* Here is a list of possible values of the `module_name` field in the
* @FT_Module_Class structure.
*
* ```
* autofitter
* bdf
* cff
* gxvalid
* otvalid
* pcf
* pfr
* psaux
* pshinter
* psnames
* raster1
* sfnt
* smooth
* truetype
* type1
* type42
* t1cid
* winfonts
* ```
*
* Note that the FreeType Cache sub-system is not a FreeType module.
*
* @order:
* FT_Module
* FT_Module_Constructor
* FT_Module_Destructor
* FT_Module_Requester
* FT_Module_Class
*
* FT_Add_Module
* FT_Get_Module
* FT_Remove_Module
* FT_Add_Default_Modules
*
* FT_Property_Set
* FT_Property_Get
* FT_Set_Default_Properties
*
* FT_New_Library
* FT_Done_Library
* FT_Reference_Library
*
* FT_Renderer
* FT_Renderer_Class
*
* FT_Get_Renderer
* FT_Set_Renderer
*
* FT_Set_Debug_Hook
*
*/
/* module bit flags */
#define FT_MODULE_FONT_DRIVER 1 /* this module is a font driver */
#define FT_MODULE_RENDERER 2 /* this module is a renderer */
#define FT_MODULE_HINTER 4 /* this module is a glyph hinter */
#define FT_MODULE_STYLER 8 /* this module is a styler */
#define FT_MODULE_DRIVER_SCALABLE 0x100 /* the driver supports */
/* scalable fonts */
#define FT_MODULE_DRIVER_NO_OUTLINES 0x200 /* the driver does not */
/* support vector outlines */
#define FT_MODULE_DRIVER_HAS_HINTER 0x400 /* the driver provides its */
/* own hinter */
#define FT_MODULE_DRIVER_HINTS_LIGHTLY 0x800 /* the driver's hinter */
/* produces LIGHT hints */
/* deprecated values */
#define ft_module_font_driver FT_MODULE_FONT_DRIVER
#define ft_module_renderer FT_MODULE_RENDERER
#define ft_module_hinter FT_MODULE_HINTER
#define ft_module_styler FT_MODULE_STYLER
#define ft_module_driver_scalable FT_MODULE_DRIVER_SCALABLE
#define ft_module_driver_no_outlines FT_MODULE_DRIVER_NO_OUTLINES
#define ft_module_driver_has_hinter FT_MODULE_DRIVER_HAS_HINTER
#define ft_module_driver_hints_lightly FT_MODULE_DRIVER_HINTS_LIGHTLY
typedef FT_Pointer FT_Module_Interface;
/**************************************************************************
*
* @functype:
* FT_Module_Constructor
*
* @description:
* A function used to initialize (not create) a new module object.
*
* @input:
* module ::
* The module to initialize.
*/
typedef FT_Error
(*FT_Module_Constructor)( FT_Module module );
/**************************************************************************
*
* @functype:
* FT_Module_Destructor
*
* @description:
* A function used to finalize (not destroy) a given module object.
*
* @input:
* module ::
* The module to finalize.
*/
typedef void
(*FT_Module_Destructor)( FT_Module module );
/**************************************************************************
*
* @functype:
* FT_Module_Requester
*
* @description:
* A function used to query a given module for a specific interface.
*
* @input:
* module ::
* The module to be searched.
*
* name ::
* The name of the interface in the module.
*/
typedef FT_Module_Interface
(*FT_Module_Requester)( FT_Module module,
const char* name );
/**************************************************************************
*
* @struct:
* FT_Module_Class
*
* @description:
* The module class descriptor. While being a public structure necessary
* for FreeType's module bookkeeping, most of the fields are essentially
* internal, not to be used directly by an application.
*
* @fields:
* module_flags ::
* Bit flags describing the module.
*
* module_size ::
* The size of one module object/instance in bytes.
*
* module_name ::
* The name of the module.
*
* module_version ::
* The version, as a 16.16 fixed number (major.minor).
*
* module_requires ::
* The version of FreeType this module requires, as a 16.16 fixed
* number (major.minor). Starts at version 2.0, i.e., 0x20000.
*
* module_interface ::
* A typeless pointer to a structure (which varies between different
* modules) that holds the module's interface functions. This is
* essentially what `get_interface` returns.
*
* module_init ::
* The initializing function.
*
* module_done ::
* The finalizing function.
*
* get_interface ::
* The interface requesting function.
*/
typedef struct FT_Module_Class_
{
FT_ULong module_flags;
FT_Long module_size;
const FT_String* module_name;
FT_Fixed module_version;
FT_Fixed module_requires;
const void* module_interface;
FT_Module_Constructor module_init;
FT_Module_Destructor module_done;
FT_Module_Requester get_interface;
} FT_Module_Class;
/**************************************************************************
*
* @function:
* FT_Add_Module
*
* @description:
* Add a new module to a given library instance.
*
* @inout:
* library ::
* A handle to the library object.
*
* @input:
* clazz ::
* A pointer to class descriptor for the module.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* An error will be returned if a module already exists by that name, or
* if the module requires a version of FreeType that is too great.
*/
FT_EXPORT( FT_Error )
FT_Add_Module( FT_Library library,
const FT_Module_Class* clazz );
/**************************************************************************
*
* @function:
* FT_Get_Module
*
* @description:
* Find a module by its name.
*
* @input:
* library ::
* A handle to the library object.
*
* module_name ::
* The module's name (as an ASCII string).
*
* @return:
* A module handle. 0~if none was found.
*
* @note:
* FreeType's internal modules aren't documented very well, and you
* should look up the source code for details.
*/
FT_EXPORT( FT_Module )
FT_Get_Module( FT_Library library,
const char* module_name );
/**************************************************************************
*
* @function:
* FT_Remove_Module
*
* @description:
* Remove a given module from a library instance.
*
* @inout:
* library ::
* A handle to a library object.
*
* @input:
* module ::
* A handle to a module object.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* The module object is destroyed by the function in case of success.
*/
FT_EXPORT( FT_Error )
FT_Remove_Module( FT_Library library,
FT_Module module );
/**************************************************************************
*
* @function:
* FT_Property_Set
*
* @description:
* Set a property for a given module.
*
* @input:
* library ::
* A handle to the library the module is part of.
*
* module_name ::
* The module name.
*
* property_name ::
* The property name. Properties are described in section
* @properties.
*
* Note that only a few modules have properties.
*
* value ::
* A generic pointer to a variable or structure that gives the new
* value of the property. The exact definition of `value` is
* dependent on the property; see section @properties.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* If `module_name` isn't a valid module name, or `property_name`
* doesn't specify a valid property, or if `value` doesn't represent a
* valid value for the given property, an error is returned.
*
* The following example sets property 'bar' (a simple integer) in
* module 'foo' to value~1.
*
* ```
* FT_UInt bar;
*
*
* bar = 1;
* FT_Property_Set( library, "foo", "bar", &bar );
* ```
*
* Note that the FreeType Cache sub-system doesn't recognize module
* property changes. To avoid glyph lookup confusion within the cache
* you should call @FTC_Manager_Reset to completely flush the cache if a
* module property gets changed after @FTC_Manager_New has been called.
*
* It is not possible to set properties of the FreeType Cache sub-system
* itself with FT_Property_Set; use @FTC_Property_Set instead.
*
* @since:
* 2.4.11
*
*/
FT_EXPORT( FT_Error )
FT_Property_Set( FT_Library library,
const FT_String* module_name,
const FT_String* property_name,
const void* value );
/**************************************************************************
*
* @function:
* FT_Property_Get
*
* @description:
* Get a module's property value.
*
* @input:
* library ::
* A handle to the library the module is part of.
*
* module_name ::
* The module name.
*
* property_name ::
* The property name. Properties are described in section
* @properties.
*
* @inout:
* value ::
* A generic pointer to a variable or structure that gives the value
* of the property. The exact definition of `value` is dependent on
* the property; see section @properties.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* If `module_name` isn't a valid module name, or `property_name`
* doesn't specify a valid property, or if `value` doesn't represent a
* valid value for the given property, an error is returned.
*
* The following example gets property 'baz' (a range) in module 'foo'.
*
* ```
* typedef range_
* {
* FT_Int32 min;
* FT_Int32 max;
*
* } range;
*
* range baz;
*
*
* FT_Property_Get( library, "foo", "baz", &baz );
* ```
*
* It is not possible to retrieve properties of the FreeType Cache
* sub-system with FT_Property_Get; use @FTC_Property_Get instead.
*
* @since:
* 2.4.11
*
*/
FT_EXPORT( FT_Error )
FT_Property_Get( FT_Library library,
const FT_String* module_name,
const FT_String* property_name,
void* value );
/**************************************************************************
*
* @function:
* FT_Set_Default_Properties
*
* @description:
* If compilation option `FT_CONFIG_OPTION_ENVIRONMENT_PROPERTIES` is
* set, this function reads the `FREETYPE_PROPERTIES` environment
* variable to control driver properties. See section @properties for
* more.
*
* If the compilation option is not set, this function does nothing.
*
* `FREETYPE_PROPERTIES` has the following syntax form (broken here into
* multiple lines for better readability).
*
* ```
* <optional whitespace>
* <module-name1> ':'
* <property-name1> '=' <property-value1>
* <whitespace>
* <module-name2> ':'
* <property-name2> '=' <property-value2>
* ...
* ```
*
* Example:
*
* ```
* FREETYPE_PROPERTIES=truetype:interpreter-version=35 \
* cff:no-stem-darkening=0 \
* autofitter:warping=1
* ```
*
* @inout:
* library ::
* A handle to a new library object.
*
* @since:
* 2.8
*/
FT_EXPORT( void )
FT_Set_Default_Properties( FT_Library library );
/**************************************************************************
*
* @function:
* FT_Reference_Library
*
* @description:
* A counter gets initialized to~1 at the time an @FT_Library structure
* is created. This function increments the counter. @FT_Done_Library
* then only destroys a library if the counter is~1, otherwise it simply
* decrements the counter.
*
* This function helps in managing life-cycles of structures that
* reference @FT_Library objects.
*
* @input:
* library ::
* A handle to a target library object.
*
* @return:
* FreeType error code. 0~means success.
*
* @since:
* 2.4.2
*/
FT_EXPORT( FT_Error )
FT_Reference_Library( FT_Library library );
/**************************************************************************
*
* @function:
* FT_New_Library
*
* @description:
* This function is used to create a new FreeType library instance from a
* given memory object. It is thus possible to use libraries with
* distinct memory allocators within the same program. Note, however,
* that the used @FT_Memory structure is expected to remain valid for the
* life of the @FT_Library object.
*
* Normally, you would call this function (followed by a call to
* @FT_Add_Default_Modules or a series of calls to @FT_Add_Module, and a
* call to @FT_Set_Default_Properties) instead of @FT_Init_FreeType to
* initialize the FreeType library.
*
* Don't use @FT_Done_FreeType but @FT_Done_Library to destroy a library
* instance.
*
* @input:
* memory ::
* A handle to the original memory object.
*
* @output:
* alibrary ::
* A pointer to handle of a new library object.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* See the discussion of reference counters in the description of
* @FT_Reference_Library.
*/
FT_EXPORT( FT_Error )
FT_New_Library( FT_Memory memory,
FT_Library *alibrary );
/**************************************************************************
*
* @function:
* FT_Done_Library
*
* @description:
* Discard a given library object. This closes all drivers and discards
* all resource objects.
*
* @input:
* library ::
* A handle to the target library.
*
* @return:
* FreeType error code. 0~means success.
*
* @note:
* See the discussion of reference counters in the description of
* @FT_Reference_Library.
*/
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 FT_Error
(*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:
* FT_Set_Debug_Hook
*
* @description:
* 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 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 one (for the
* TrueType interpreter) is defined.
*/
FT_EXPORT( void )
FT_Set_Debug_Hook( FT_Library library,
FT_UInt hook_index,
FT_DebugHook_Func debug_hook );
/**************************************************************************
*
* @function:
* FT_Add_Default_Modules
*
* @description:
* Add the set of default drivers to a given library object. This is
* only useful when you create a library object with @FT_New_Library
* (usually to plug a custom memory manager).
*
* @inout:
* library ::
* A handle to a new library object.
*/
FT_EXPORT( void )
FT_Add_Default_Modules( FT_Library library );
/**************************************************************************
*
* @section:
* truetype_engine
*
* @title:
* The TrueType Engine
*
* @abstract:
* TrueType bytecode support.
*
* @description:
* This section contains a function used to query the level of TrueType
* bytecode support compiled in this version of the library.
*
*/
/**************************************************************************
*
* @enum:
* FT_TrueTypeEngineType
*
* @description:
* A list of values describing which kind of TrueType bytecode engine is
* implemented in a given FT_Library instance. It is used by the
* @FT_Get_TrueType_Engine_Type function.
*
* @values:
* FT_TRUETYPE_ENGINE_TYPE_NONE ::
* The library doesn't implement any kind of bytecode interpreter.
*
* FT_TRUETYPE_ENGINE_TYPE_UNPATENTED ::
* Deprecated and removed.
*
* FT_TRUETYPE_ENGINE_TYPE_PATENTED ::
* The library implements a bytecode interpreter that covers the full
* instruction set of the TrueType virtual machine (this was governed
* by patents until May 2010, hence the name).
*
* @since:
* 2.2
*
*/
typedef enum FT_TrueTypeEngineType_
{
FT_TRUETYPE_ENGINE_TYPE_NONE = 0,
FT_TRUETYPE_ENGINE_TYPE_UNPATENTED,
FT_TRUETYPE_ENGINE_TYPE_PATENTED
} FT_TrueTypeEngineType;
/**************************************************************************
*
* @function:
* FT_Get_TrueType_Engine_Type
*
* @description:
* Return an @FT_TrueTypeEngineType value to indicate which level of the
* TrueType virtual machine a given library instance supports.
*
* @input:
* library ::
* A library instance.
*
* @return:
* A value indicating which level is supported.
*
* @since:
* 2.2
*
*/
FT_EXPORT( FT_TrueTypeEngineType )
FT_Get_TrueType_Engine_Type( FT_Library library );
/* */
FT_END_HEADER
#endif /* FTMODAPI_H_ */
/* END */
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