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The PangoContext structure stores global information influencing Pango's operation, such as the fontmap used to look up fonts, and default values such as the default language, default gravity, or default font.
PangoContext *
pango_context_new (void
);
Creates a new PangoContext initialized to default values.
This function is not particularly useful as it should always
be followed by a pango_context_set_font_map()
call, and the
function pango_font_map_create_context()
does these two steps
together and hence users are recommended to use that.
If you are using Pango as part of a higher-level system,
that system may have it's own way of create a PangoContext.
For instance, the GTK+ toolkit has, among others,
gdk_pango_context_get_for_screen()
, and
gtk_widget_get_pango_context()
. Use those instead.
void
pango_context_changed (PangoContext *context
);
Forces a change in the context, which will cause any PangoLayout using this context to re-layout.
This function is only useful when implementing a new backend for Pango, something applications won't do. Backends should call this function if they have attached extra data to the context and such data is changed.
Since: 1.32.4
guint
pango_context_get_serial (PangoContext *context
);
Returns the current serial number of context
. The serial number is
initialized to an small number larger than zero when a new context
is created and is increased whenever the context is changed using any
of the setter functions, or the PangoFontMap it uses to find fonts has
changed. The serial may wrap, but will never have the value 0. Since it
can wrap, never compare it with "less than", always use "not equals".
This can be used to automatically detect changes to a PangoContext, and is only useful when implementing objects that need update when their PangoContext changes, like PangoLayout.
Since: 1.32.4
void pango_context_set_font_map (PangoContext *context
,PangoFontMap *font_map
);
Sets the font map to be searched when fonts are looked-up in this context. This is only for internal use by Pango backends, a PangoContext obtained via one of the recommended methods should already have a suitable font map.
PangoFontMap *
pango_context_get_font_map (PangoContext *context
);
Gets the PangoFontMap used to look up fonts for this context.
the font map for the PangoContext. This value is owned by Pango and should not be unreferenced.
[transfer none]
Since: 1.6
PangoFontDescription *
pango_context_get_font_description (PangoContext *context
);
Retrieve the default font description for the context.
void pango_context_set_font_description (PangoContext *context
,const PangoFontDescription *desc
);
Set the default font description for the context
PangoLanguage *
pango_context_get_language (PangoContext *context
);
Retrieves the global language tag for the context.
void pango_context_set_language (PangoContext *context
,PangoLanguage *language
);
Sets the global language tag for the context. The default language
for the locale of the running process can be found using
pango_language_get_default()
.
PangoDirection
pango_context_get_base_dir (PangoContext *context
);
Retrieves the base direction for the context. See
pango_context_set_base_dir()
.
void pango_context_set_base_dir (PangoContext *context
,PangoDirection direction
);
Sets the base direction for the context.
The base direction is used in applying the Unicode bidirectional
algorithm; if the direction
is PANGO_DIRECTION_LTR
or
PANGO_DIRECTION_RTL
, then the value will be used as the paragraph
direction in the Unicode bidirectional algorithm. A value of
PANGO_DIRECTION_WEAK_LTR
or PANGO_DIRECTION_WEAK_RTL
is used only
for paragraphs that do not contain any strong characters themselves.
PangoGravity
pango_context_get_base_gravity (PangoContext *context
);
Retrieves the base gravity for the context. See
pango_context_set_base_gravity()
.
Since: 1.16
void pango_context_set_base_gravity (PangoContext *context
,PangoGravity gravity
);
Sets the base gravity for the context.
The base gravity is used in laying vertical text out.
Since: 1.16
PangoGravity
pango_context_get_gravity (PangoContext *context
);
Retrieves the gravity for the context. This is similar to
pango_context_get_base_gravity()
, except for when the base gravity
is PANGO_GRAVITY_AUTO
for which pango_gravity_get_for_matrix()
is used
to return the gravity from the current context matrix.
Since: 1.16
PangoGravityHint
pango_context_get_gravity_hint (PangoContext *context
);
Retrieves the gravity hint for the context. See
pango_context_set_gravity_hint()
for details.
Since: 1.16
void pango_context_set_gravity_hint (PangoContext *context
,PangoGravityHint hint
);
Sets the gravity hint for the context.
The gravity hint is used in laying vertical text out, and is only relevant
if gravity of the context as returned by pango_context_get_gravity()
is set PANGO_GRAVITY_EAST
or PANGO_GRAVITY_WEST
.
Since: 1.16
const PangoMatrix *
pango_context_get_matrix (PangoContext *context
);
Gets the transformation matrix that will be applied when
rendering with this context. See pango_context_set_matrix()
.
the matrix, or NULL
if no matrix has
been set (which is the same as the identity matrix). The returned
matrix is owned by Pango and must not be modified or freed.
[nullable]
Since: 1.6
void pango_context_set_matrix (PangoContext *context
,const PangoMatrix *matrix
);
Sets the transformation matrix that will be applied when rendering with this context. Note that reported metrics are in the user space coordinates before the application of the matrix, not device-space coordinates after the application of the matrix. So, they don't scale with the matrix, though they may change slightly for different matrices, depending on how the text is fit to the pixel grid.
context |
||
matrix |
a PangoMatrix, or |
[allow-none] |
Since: 1.6
gboolean
pango_context_get_round_glyph_positions
(PangoContext *context
);
Returns whether font rendering with this context should round glyph positions and widths.
Since: 1.44
void pango_context_set_round_glyph_positions (PangoContext *context
,gboolean round_positions
);
Sets whether font rendering with this context should round glyph positions and widths to integral positions, in device units.
This is useful when the renderer can't handle subpixel positioning of glyphs.
The default value is to round glyph positions, to remain compatible with previous Pango behavior.
Since: 1.44
PangoFont * pango_context_load_font (PangoContext *context
,const PangoFontDescription *desc
);
Loads the font in one of the fontmaps in the context
that is the closest match for desc
.
PangoFontset * pango_context_load_fontset (PangoContext *context
,const PangoFontDescription *desc
,PangoLanguage *language
);
Load a set of fonts in the context that can be used to render
a font matching desc
.
context |
||
desc |
a PangoFontDescription describing the fonts to load |
|
language |
a PangoLanguage the fonts will be used for |
the newly allocated
PangoFontset loaded, or NULL
if no font matched.
[transfer full][nullable]
PangoFontMetrics * pango_context_get_metrics (PangoContext *context
,const PangoFontDescription *desc
,PangoLanguage *language
);
Get overall metric information for a particular font description. Since the metrics may be substantially different for different scripts, a language tag can be provided to indicate that the metrics should be retrieved that correspond to the script(s) used by that language.
The PangoFontDescription is interpreted in the same way as
by pango_itemize()
, and the family name may be a comma separated
list of figures. If characters from multiple of these families
would be used to render the string, then the returned fonts would
be a composite of the metrics for the fonts loaded for the
individual families.
context |
||
desc |
a PangoFontDescription structure. |
[allow-none] |
language |
language tag used to determine which script to get
the metrics for. |
[allow-none] |
a PangoFontMetrics object. The caller must call pango_font_metrics_unref()
when finished using the object.
void pango_context_list_families (PangoContext *context
,PangoFontFamily ***families
,int *n_families
);
List all families for a context.
context |
||
families |
location to store a pointer to
an array of PangoFontFamily *. This array should be freed
with |
[out][array length=n_families][transfer container] |
n_families |
location to store the number of elements in |
[out] |
typedef struct _PangoContext PangoContext;
The PangoContext structure stores global information used to control the itemization process.