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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, smooth-lcd, smooth-lcdv truetype type1 type42 t1cid winfonts
Note that the FreeType Cache sub-system is not a FreeType module.
Defined in FT_FREETYPE_H (freetype/freetype.h).
typedef struct FT_ModuleRec_* FT_Module;
A handle to a given FreeType module object. A module can be a font driver, a renderer, or anything else that provides services to the former.
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Defined in FT_MODULE_H (freetype/ftmodapi.h).
typedef FT_Error (*FT_Module_Constructor)( FT_Module module );
A function used to initialize (not create) a new module object.
| module |
The module to initialize. |
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Defined in FT_MODULE_H (freetype/ftmodapi.h).
typedef void (*FT_Module_Destructor)( FT_Module module );
A function used to finalize (not destroy) a given module object.
| module |
The module to finalize. |
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Defined in FT_MODULE_H (freetype/ftmodapi.h).
typedef FT_Module_Interface (*FT_Module_Requester)( FT_Module module, const char* name );
A function used to query a given module for a specific interface.
| module |
The module to be searched. |
| name |
The name of the interface in the module. |
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Defined in FT_MODULE_H (freetype/ftmodapi.h).
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;
The module class descriptor.
| 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_init |
The initializing function. |
| module_done |
The finalizing function. |
| get_interface |
The interface requesting function. |
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Defined in FT_MODULE_H (freetype/ftmodapi.h).
FT_EXPORT( FT_Error ) FT_Add_Module( FT_Library library, const FT_Module_Class* clazz );
Add a new module to a given library instance.
| library |
A handle to the library object. |
| clazz |
A pointer to class descriptor for the module. |
FreeType error code. 0 means success.
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.
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Defined in FT_MODULE_H (freetype/ftmodapi.h).
FT_EXPORT( FT_Module ) FT_Get_Module( FT_Library library, const char* module_name );
Find a module by its name.
| library |
A handle to the library object. |
| module_name |
The module's name (as an ASCII string). |
A module handle. 0 if none was found.
FreeType's internal modules aren't documented very well, and you should look up the source code for details.
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Defined in FT_MODULE_H (freetype/ftmodapi.h).
FT_EXPORT( FT_Error ) FT_Remove_Module( FT_Library library, FT_Module module );
Remove a given module from a library instance.
| library |
A handle to a library object. |
| module |
A handle to a module object. |
FreeType error code. 0 means success.
The module object is destroyed by the function in case of success.
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Defined in FT_MODULE_H (freetype/ftmodapi.h).
FT_EXPORT( void ) FT_Add_Default_Modules( FT_Library library );
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).
| library |
A handle to a new library object. |
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Defined in FT_MODULE_H (freetype/ftmodapi.h).
FT_EXPORT( FT_Error ) FT_Property_Set( FT_Library library, const FT_String* module_name, const FT_String* property_name, const void* value );
Set a property for a given module.
| 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 the ‘Synopsis’ subsection of the module's documentation. 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 the ‘Synopsis’ subsection of the module's documentation. |
FreeType error code. 0 means success.
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.
2.4.11
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Defined in FT_MODULE_H (freetype/ftmodapi.h).
FT_EXPORT( FT_Error ) FT_Property_Get( FT_Library library, const FT_String* module_name, const FT_String* property_name, void* value );
Get a module's property value.
| 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 the ‘Synopsis’ subsection of the module's documentation. |
| 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 the ‘Synopsis’ subsection of the module's documentation. |
FreeType error code. 0 means success.
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.
2.4.11
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Defined in FT_MODULE_H (freetype/ftmodapi.h).
FT_EXPORT( void ) FT_Set_Default_Properties( FT_Library library );
If compilation option FT_CONFIG_OPTION_ENVIRONMENT_PROPERTIES is set, this function reads the ‘FREETYPE_PROPERTIES’ environment variable to control driver properties. See sections ‘The auto-hinter’, ‘The CFF driver’, ‘The PCF driver’, and ‘The TrueType driver’ 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>
':'
'=' <property-value1>
':'
'=' <property-value2> ... }
Example:
FREETYPE_PROPERTIES=truetype:interpreter-version=35 \
cff:no-stem-darkening=1 \
autofitter:warping=1
| library |
A handle to a new library object. |
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Defined in FT_MODULE_H (freetype/ftmodapi.h).
FT_EXPORT( FT_Error ) FT_New_Library( FT_Memory memory, FT_Library *alibrary );
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.
| memory |
A handle to the original memory object. |
| alibrary |
A pointer to handle of a new library object. |
FreeType error code. 0 means success.
See the discussion of reference counters in the description of FT_Reference_Library.
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Defined in FT_MODULE_H (freetype/ftmodapi.h).
FT_EXPORT( FT_Error ) FT_Done_Library( FT_Library library );
Discard a given library object. This closes all drivers and discards all resource objects.
| library |
A handle to the target library. |
FreeType error code. 0 means success.
See the discussion of reference counters in the description of FT_Reference_Library.
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Defined in FT_MODULE_H (freetype/ftmodapi.h).
FT_EXPORT( FT_Error ) FT_Reference_Library( FT_Library library );
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.
| library |
A handle to a target library object. |
FreeType error code. 0 means success.
2.4.2
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Defined in FT_FREETYPE_H (freetype/freetype.h).
typedef struct FT_RendererRec_* FT_Renderer;
A handle to a given FreeType renderer. A renderer is a module in charge of converting a glyph's outline image to a bitmap. It supports a single glyph image format, and one or more target surface depths.
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Defined in FT_RENDER_H (freetype/ftrender.h).
typedef struct FT_Renderer_Class_ { FT_Module_Class root; FT_Glyph_Format glyph_format; FT_Renderer_RenderFunc render_glyph; FT_Renderer_TransformFunc transform_glyph; FT_Renderer_GetCBoxFunc get_glyph_cbox; FT_Renderer_SetModeFunc set_mode; FT_Raster_Funcs* raster_class; } FT_Renderer_Class;
The renderer module class descriptor.
| root |
The root FT_Module_Class fields. |
| glyph_format |
The glyph image format this renderer handles. |
| render_glyph |
A method used to render the image that is in a given glyph slot into a bitmap. |
| transform_glyph |
A method used to transform the image that is in a given glyph slot. |
| get_glyph_cbox |
A method used to access the glyph's cbox. |
| set_mode |
A method used to pass additional parameters. |
| raster_class |
For FT_GLYPH_FORMAT_OUTLINE renderers only. This is a pointer to its raster's class. |
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Defined in FT_RENDER_H (freetype/ftrender.h).
FT_EXPORT( FT_Renderer ) FT_Get_Renderer( FT_Library library, FT_Glyph_Format format );
Retrieve the current renderer for a given glyph format.
| library |
A handle to the library object. |
| format |
The glyph format. |
A renderer handle. 0 if none found.
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.
To add a new renderer, simply use FT_Add_Module. To retrieve a renderer by its name, use FT_Get_Module.
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Defined in FT_RENDER_H (freetype/ftrender.h).
FT_EXPORT( FT_Error ) FT_Set_Renderer( FT_Library library, FT_Renderer renderer, FT_UInt num_params, FT_Parameter* parameters );
Set the current renderer to use, and set additional mode.
| library |
A handle to the library object. |
| renderer |
A handle to the renderer object. |
| num_params |
The number of additional parameters. |
| parameters |
Additional parameters. |
FreeType error code. 0 means success.
In case of success, the renderer will be used to convert glyph images in the renderer's known format into bitmaps.
This doesn't change the current renderer for other formats.
Currently, no FreeType renderer module uses ‘parameters’; you should thus always pass NULL as the value.
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Defined in FT_MODULE_H (freetype/ftmodapi.h).
FT_EXPORT( void ) FT_Set_Debug_Hook( FT_Library library, FT_UInt hook_index, FT_DebugHook_Func debug_hook );
Set a debug hook function for debugging the interpreter of a font format.
| library |
A handle to the library object. |
| hook_index |
The index of the debug hook. You should use the values defined in ‘ftobjs.h’, e.g., ‘FT_DEBUG_HOOK_TRUETYPE’. |
| debug_hook |
The function used to debug the interpreter. |
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.
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