PangoEngineShape: Pango Reference Manual

PangoEngineShape

PangoEngineShape — Rendering-system dependent script engines

Stability Level

Unstable, unless otherwise indicated

Functions

#define

Types and Values

	PangoEngineShape
struct	PangoEngineShapeClass
#define	PANGO_ENGINE_TYPE_SHAPE

Object Hierarchy

    GObject
    ╰── PangoEngine
        ╰── PangoEngineShape

Description

The shape engines are rendering-system dependent engines that convert character strings into glyph strings. These engines are used in pango_shape().

Functions

PANGO_ENGINE_SHAPE_DEFINE_TYPE()

#define             PANGO_ENGINE_SHAPE_DEFINE_TYPE(name, prefix, class_init, instance_init)

PANGO_ENGINE_SHAPE_DEFINE_TYPE has been deprecated since version 1.38 and should not be used in newly-written code.

Outputs the necessary code for GObject type registration for a PangoEngineShape class defined in a module. Two static symbols are defined.

 static GType prefix_type;
 static void prefix_register_type (GTypeModule module);

The prefix_register_type() function should be called in your script_engine_init() function for each type that your module implements, and then your script_engine_create() function can create instances of the object as follows:

1	PangoEngine *engine = g_object_new (<em class="replaceable"><code>prefix</code></em>_type, NULL);

Parameters

name	Name of the the type to register (for example:, `ArabicEngineFc`
prefix	Prefix for symbols that will be defined (for example:, `arabic_engine_fc`
class_init	Class initialization function for the new type, or `NULL`.	[nullable]
instance_init	Instance initialization function for the new type, or `NULL`.	[nullable]

Types and Values

PangoEngineShape

typedef struct _PangoEngineShape PangoEngineShape;

PangoEngineShape has been deprecated since version 1.38 and should not be used in newly-written code.

The PangoEngineShape class is implemented by engines that customize the rendering-system dependent part of the Pango pipeline for a particular script or language. A PangoEngineShape implementation is then specific to both a particular rendering system or group of rendering systems and to a particular script. For instance, there is one PangoEngineShape implementation to handle shaping Arabic for Fontconfig-based backends.

struct PangoEngineShapeClass

struct PangoEngineShapeClass {
  void (*script_shape) (PangoEngineShape    *engine,
			PangoFont           *font,
			const char          *item_text,
			unsigned int         item_length,
			const PangoAnalysis *analysis,
			PangoGlyphString    *glyphs,
			const char          *paragraph_text,
			unsigned int         paragraph_length);
  PangoCoverageLevel (*covers)   (PangoEngineShape *engine,
				  PangoFont        *font,
				  PangoLanguage    *language,
				  gunichar          wc);
};

PangoEngineShapeClass has been deprecated since version 1.38 and should not be used in newly-written code.

Class structure for PangoEngineShape

Members

`script_shape` ()	Given a font, a piece of text, and a PangoAnalysis structure, converts characters to glyphs and positions the resulting glyphs. The results are stored in the PangoGlyphString that is passed in. (The implementation should resize it appropriately using `pango_glyph_string_set_size()`). All fields of the `log_clusters` and `glyphs` array must be filled in, with the exception that Pango will automatically generate `glyphs->glyphs[i].attr.is_cluster_start` using the `log_clusters` array. Each input character must occur in one of the output logical clusters; if no rendering is desired for a character, this may involve inserting glyphs with the PangoGlyph ID PANGO_GLYPH_EMPTY, which is guaranteed never to render. If the shaping fails for any reason, the shaper should return with an empty (zero-size) glyph string. If the shaper has not set the size on the glyph string yet, simply returning signals the failure too.
`covers` ()	Returns the characters that this engine can cover with a given font for a given language. If not overridden, the default implementation simply returns the coverage information for the font itself unmodified.

PANGO_ENGINE_TYPE_SHAPE

#define PANGO_ENGINE_TYPE_SHAPE "PangoEngineShape"

PANGO_ENGINE_TYPE_SHAPE has been deprecated since version 1.38 and should not be used in newly-written code.

A string constant defining the engine type for shaping engines. These engines derive from PangoEngineShape.