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Functions
Types and Values
| typedef | cairo_font_options_t |
| enum | cairo_subpixel_order_t |
| enum | cairo_hint_style_t |
| enum | cairo_hint_metrics_t |
Description
The font options specify how fonts should be rendered. Most of the time the font options implied by a surface are just right and do not need any changes, but for pixel-based targets tweaking font options may result in superior output on a particular display.
Functions
cairo_font_options_create ()
cairo_font_options_t *
cairo_font_options_create (void);
Allocates a new font options object with all options initialized to default values.
Returns
a newly allocated cairo_font_options_t. Free with
cairo_font_options_destroy(). This function always returns a
valid pointer; if memory cannot be allocated, then a special
error object is returned where all operations on the object do nothing.
You can check for this with cairo_font_options_status().
Since: 1.0
cairo_font_options_copy ()
cairo_font_options_t *
cairo_font_options_copy (const cairo_font_options_t *original);
Allocates a new font options object copying the option values from
original
.
Returns
a newly allocated cairo_font_options_t. Free with
cairo_font_options_destroy(). This function always returns a
valid pointer; if memory cannot be allocated, then a special
error object is returned where all operations on the object do nothing.
You can check for this with cairo_font_options_status().
Since: 1.0
cairo_font_options_destroy ()
void
cairo_font_options_destroy (cairo_font_options_t *options);
Destroys a cairo_font_options_t object created with
cairo_font_options_create() or cairo_font_options_copy().
Since: 1.0
cairo_font_options_status ()
cairo_status_t
cairo_font_options_status (cairo_font_options_t *options);
Checks whether an error has previously occurred for this font options object
Since: 1.0
cairo_font_options_merge ()
void cairo_font_options_merge (cairo_font_options_t *options,const cairo_font_options_t *other);
Merges non-default options from other
into options
, replacing
existing values. This operation can be thought of as somewhat
similar to compositing other
onto options
with the operation
of CAIRO_OPERATOR_OVER.
Since: 1.0
cairo_font_options_hash ()
unsigned long
cairo_font_options_hash (const cairo_font_options_t *options);
Compute a hash for the font options object; this value will be useful when storing an object containing a cairo_font_options_t in a hash table.
Returns
the hash value for the font options object. The return value can be cast to a 32-bit type if a 32-bit hash value is needed.
Since: 1.0
cairo_font_options_equal ()
cairo_bool_t cairo_font_options_equal (const cairo_font_options_t *options,const cairo_font_options_t *other);
Compares two font options objects for equality.
Returns
TRUE if all fields of the two font options objects match.
Note that this function will return FALSE if either object is in
error.
Since: 1.0
cairo_font_options_set_antialias ()
void cairo_font_options_set_antialias (cairo_font_options_t *options,cairo_antialias_t antialias);
Sets the antialiasing mode for the font options object. This specifies the type of antialiasing to do when rendering text.
Since: 1.0
cairo_font_options_get_antialias ()
cairo_antialias_t
cairo_font_options_get_antialias (const cairo_font_options_t *options);
Gets the antialiasing mode for the font options object.
Since: 1.0
cairo_font_options_set_subpixel_order ()
void cairo_font_options_set_subpixel_order (cairo_font_options_t *options,cairo_subpixel_order_t subpixel_order);
Sets the subpixel order for the font options object. The subpixel
order specifies the order of color elements within each pixel on
the display device when rendering with an antialiasing mode of
CAIRO_ANTIALIAS_SUBPIXEL. See the documentation for
cairo_subpixel_order_t for full details.
Since: 1.0
cairo_font_options_get_subpixel_order ()
cairo_subpixel_order_t
cairo_font_options_get_subpixel_order (const cairo_font_options_t *options);
Gets the subpixel order for the font options object. See the documentation for cairo_subpixel_order_t for full details.
Since: 1.0
cairo_font_options_set_hint_style ()
void cairo_font_options_set_hint_style (cairo_font_options_t *options,cairo_hint_style_t hint_style);
Sets the hint style for font outlines for the font options object. This controls whether to fit font outlines to the pixel grid, and if so, whether to optimize for fidelity or contrast. See the documentation for cairo_hint_style_t for full details.
Since: 1.0
cairo_font_options_get_hint_style ()
cairo_hint_style_t
cairo_font_options_get_hint_style (const cairo_font_options_t *options);
Gets the hint style for font outlines for the font options object. See the documentation for cairo_hint_style_t for full details.
Since: 1.0
cairo_font_options_set_hint_metrics ()
void cairo_font_options_set_hint_metrics (cairo_font_options_t *options,cairo_hint_metrics_t hint_metrics);
Sets the metrics hinting mode for the font options object. This controls whether metrics are quantized to integer values in device units. See the documentation for cairo_hint_metrics_t for full details.
Since: 1.0
cairo_font_options_get_hint_metrics ()
cairo_hint_metrics_t
cairo_font_options_get_hint_metrics (const cairo_font_options_t *options);
Gets the metrics hinting mode for the font options object. See the documentation for cairo_hint_metrics_t for full details.
Since: 1.0
cairo_font_options_get_variations ()
const char *
cairo_font_options_get_variations (cairo_font_options_t *options);
Gets the OpenType font variations for the font options object.
See cairo_font_options_set_variations() for details about the
string format.
Returns
the font variations for the font options object. The
returned string belongs to the options
and must not be modified.
It is valid until either the font options object is destroyed or
the font variations in this object is modified with
cairo_font_options_set_variations().
Since: 1.16
cairo_font_options_set_variations ()
void cairo_font_options_set_variations (cairo_font_options_t *options,const char *variations);
Sets the OpenType font variations for the font options object. Font variations are specified as a string with a format that is similar to the CSS font-variation-settings. The string contains a comma-separated list of axis assignments, which each assignment consists of a 4-character axis name and a value, separated by whitespace and optional equals sign.
Examples:
wght=200,wdth=140.5
wght 200 , wdth 140.5
Since: 1.16
Types and Values
cairo_font_options_t
typedef struct _cairo_font_options cairo_font_options_t;
An opaque structure holding all options that are used when rendering fonts.
Individual features of a cairo_font_options_t can be set or
accessed using functions named
cairo_font_options_set_feature_name() and
cairo_font_options_get_feature_name(), like
cairo_font_options_set_antialias() and
cairo_font_options_get_antialias().
New features may be added to a cairo_font_options_t in the
future. For this reason, cairo_font_options_copy(),
cairo_font_options_equal(), cairo_font_options_merge(), and
cairo_font_options_hash() should be used to copy, check
for equality, merge, or compute a hash value of
cairo_font_options_t objects.
Since: 1.0
enum cairo_subpixel_order_t
The subpixel order specifies the order of color elements within
each pixel on the display device when rendering with an
antialiasing mode of CAIRO_ANTIALIAS_SUBPIXEL.
Members
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Use the default subpixel order for for the target device, since 1.0 |
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Subpixel elements are arranged horizontally with red at the left, since 1.0 |
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Subpixel elements are arranged horizontally with blue at the left, since 1.0 |
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Subpixel elements are arranged vertically with red at the top, since 1.0 |
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Subpixel elements are arranged vertically with blue at the top, since 1.0 |
Since: 1.0
enum cairo_hint_style_t
Specifies the type of hinting to do on font outlines. Hinting is the process of fitting outlines to the pixel grid in order to improve the appearance of the result. Since hinting outlines involves distorting them, it also reduces the faithfulness to the original outline shapes. Not all of the outline hinting styles are supported by all font backends.
New entries may be added in future versions.
Members
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Use the default hint style for font backend and target device, since 1.0 |
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Do not hint outlines, since 1.0 |
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Hint outlines slightly to improve contrast while retaining good fidelity to the original shapes, since 1.0 |
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Hint outlines with medium strength giving a compromise between fidelity to the original shapes and contrast, since 1.0 |
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Hint outlines to maximize contrast, since 1.0 |
Since: 1.0
enum cairo_hint_metrics_t
Specifies whether to hint font metrics; hinting font metrics means quantizing them so that they are integer values in device space. Doing this improves the consistency of letter and line spacing, however it also means that text will be laid out differently at different zoom factors.
Since: 1.0