FontDescription

class FontDescription(*args, **kwargs)

A PangoFontDescription describes a font in an implementation-independent manner.

PangoFontDescription structures are used both to list what fonts are available on the system and also for specifying the characteristics of a font to load.

Constructors

class FontDescription

classmethod new() → FontDescription

Creates a new font description structure with all fields unset.

Methods

class FontDescription

better_match(old_match: FontDescription | None, new_match: FontDescription) → bool

Determines if the style attributes of new_match are a closer match for desc than those of old_match are, or if old_match is None, determines if new_match is a match at all.

Approximate matching is done for weight and style; other style attributes must match exactly. Style attributes are all attributes other than family and size-related attributes. Approximate matching for style considers OBLIQUE and ITALIC as matches, but not as good a match as when the styles are equal.

Note that old_match must match desc.

Parameters:

• old_match – a PangoFontDescription, or None

• new_match – a PangoFontDescription

equal(desc2: FontDescription) → bool

Compares two font descriptions for equality.

Two font descriptions are considered equal if the fonts they describe are provably identical. This means that their masks do not have to match, as long as other fields are all the same. (Two font descriptions may result in identical fonts being loaded, but still compare False.)

Parameters:

desc2 – another PangoFontDescription

free() → None

Frees a font description.

from_string(str: str) → FontDescription

Creates a new font description from a string representation.

The string must have the form

“[FAMILY-LIST] [STYLE-OPTIONS] [SIZE] [VARIATIONS]”,

where FAMILY-LIST is a comma-separated list of families optionally terminated by a comma, STYLE_OPTIONS is a whitespace-separated list of words where each word describes one of style, variant, weight, stretch, or gravity, and SIZE is a decimal number (size in points) or optionally followed by the unit modifier “px” for absolute size. VARIATIONS is a comma-separated list of font variation specifications of the form “``axis``=value” (the = sign is optional).

The following words are understood as styles: “Normal”, “Roman”, “Oblique”, “Italic”.

The following words are understood as variants: “Small-Caps”, “All-Small-Caps”, “Petite-Caps”, “All-Petite-Caps”, “Unicase”, “Title-Caps”.

The following words are understood as weights: “Thin”, “Ultra-Light”, “Extra-Light”, “Light”, “Semi-Light”, “Demi-Light”, “Book”, “Regular”, “Medium”, “Semi-Bold”, “Demi-Bold”, “Bold”, “Ultra-Bold”, “Extra-Bold”, “Heavy”, “Black”, “Ultra-Black”, “Extra-Black”.

The following words are understood as stretch values: “Ultra-Condensed”, “Extra-Condensed”, “Condensed”, “Semi-Condensed”, “Semi-Expanded”, “Expanded”, “Extra-Expanded”, “Ultra-Expanded”.

The following words are understood as gravity values: “Not-Rotated”, “South”, “Upside-Down”, “North”, “Rotated-Left”, “East”, “Rotated-Right”, “West”.

Any one of the options may be absent. If FAMILY-LIST is absent, then the family_name field of the resulting font description will be initialized to None. If STYLE-OPTIONS is missing, then all style options will be set to the default values. If SIZE is missing, the size in the resulting font description will be set to 0.

A typical example:

“Cantarell Italic Light 15 ``wght``=200”

Parameters:

str – string representation of a font description.

get_family() → str | None

Gets the family name field of a font description.

See set_family.

get_gravity() → Gravity

Gets the gravity field of a font description.

See set_gravity.

Added in version 1.16.

get_set_fields() → FontMask

Determines which fields in a font description have been set.

get_size() → int

Gets the size field of a font description.

See set_size.

get_size_is_absolute() → bool

Determines whether the size of the font is in points (not absolute) or device units (absolute).

See set_size and set_absolute_size.

Added in version 1.8.

get_stretch() → Stretch

Gets the stretch field of a font description.

See set_stretch.

get_style() → Style

Gets the style field of a PangoFontDescription.

See set_style.

get_variant() → Variant

Gets the variant field of a PangoFontDescription.

See set_variant.

get_variations() → str | None

Gets the variations field of a font description.

See set_variations.

Added in version 1.42.

get_weight() → Weight

Gets the weight field of a font description.

See set_weight.

hash() → int

Computes a hash of a PangoFontDescription structure.

This is suitable to be used, for example, as an argument to new(). The hash value is independent of desc->mask.

merge(desc_to_merge: FontDescription | None, replace_existing: bool) → None

Merges the fields that are set in desc_to_merge into the fields in desc.

If replace_existing is False, only fields in desc that are not already set are affected. If True, then fields that are already set will be replaced as well.

If desc_to_merge is None, this function performs nothing.

Parameters:

• desc_to_merge – the PangoFontDescription to merge from, or None

• replace_existing – if True, replace fields in desc with the corresponding values from desc_to_merge, even if they are already exist.

merge_static(desc_to_merge: FontDescription, replace_existing: bool) → None

Merges the fields that are set in desc_to_merge into the fields in desc, without copying allocated fields.

This is like merge, but only a shallow copy is made of the family name and other allocated fields. desc can only be used until desc_to_merge is modified or freed. This is meant to be used when the merged font description is only needed temporarily.

Parameters:

• desc_to_merge – the PangoFontDescription to merge from

• replace_existing – if True, replace fields in desc with the corresponding values from desc_to_merge, even if they are already exist.

set_absolute_size(size: float) → None

Sets the size field of a font description, in device units.

This is mutually exclusive with set_size which sets the font size in points.

Added in version 1.8.

Parameters:

size – the new size, in Pango units. There are SCALE Pango units in one device unit. For an output backend where a device unit is a pixel, a size value of 10 * PANGO_SCALE gives a 10 pixel font.

set_family(family: str) → None

Sets the family name field of a font description.

The family name represents a family of related font styles, and will resolve to a particular PangoFontFamily. In some uses of PangoFontDescription, it is also possible to use a comma separated list of family names for this field.

Parameters:

family – a string representing the family name.

set_family_static(family: str) → None

Sets the family name field of a font description, without copying the string.

This is like set_family, except that no copy of family is made. The caller must make sure that the string passed in stays around until desc has been freed or the name is set again. This function can be used if family is a static string such as a C string literal, or if desc is only needed temporarily.

Parameters:

family – a string representing the family name

set_gravity(gravity: Gravity) → None

Sets the gravity field of a font description.

The gravity field specifies how the glyphs should be rotated. If gravity is AUTO, this actually unsets the gravity mask on the font description.

This function is seldom useful to the user. Gravity should normally be set on a PangoContext.

Added in version 1.16.

Parameters:

gravity – the gravity for the font description.

set_size(size: int) → None

Sets the size field of a font description in fractional points.

This is mutually exclusive with set_absolute_size.

Parameters:

size – the size of the font in points, scaled by SCALE. (That is, a size value of 10 * PANGO_SCALE is a 10 point font. The conversion factor between points and device units depends on system configuration and the output device. For screen display, a logical DPI of 96 is common, in which case a 10 point font corresponds to a 10 * (96 / 72) = 13.3 pixel font. Use set_absolute_size if you need a particular size in device units.

set_stretch(stretch: Stretch) → None

Sets the stretch field of a font description.

The Stretch field specifies how narrow or wide the font should be.

Parameters:

stretch – the stretch for the font description

set_style(style: Style) → None

Sets the style field of a PangoFontDescription.

The Style enumeration describes whether the font is slanted and the manner in which it is slanted; it can be either NORMAL, ITALIC, or OBLIQUE.

Most fonts will either have a italic style or an oblique style, but not both, and font matching in Pango will match italic specifications with oblique fonts and vice-versa if an exact match is not found.

Parameters:

style – the style for the font description

set_variant(variant: Variant) → None

Sets the variant field of a font description.

The Variant can either be NORMAL or SMALL_CAPS.

Parameters:

variant – the variant type for the font description.

set_variations(variations: str | None = None) → None

Sets the variations field of a font description.

OpenType font variations allow to select a font instance by specifying values for a number of axes, such as width or weight.

The format of the variations string is

AXIS1=VALUE,AXIS2=VALUE…

with each AXIS a 4 character tag that identifies a font axis, and each VALUE a floating point number. Unknown axes are ignored, and values are clamped to their allowed range.

Pango does not currently have a way to find supported axes of a font. Both harfbuzz and freetype have API for this. See for example hb_ot_var_get_axis_infos.

Added in version 1.42.

Parameters:

variations – a string representing the variations

set_variations_static(variations: str) → None

Sets the variations field of a font description.

This is like set_variations, except that no copy of variations is made. The caller must make sure that the string passed in stays around until desc has been freed or the name is set again. This function can be used if variations is a static string such as a C string literal, or if desc is only needed temporarily.

Added in version 1.42.

Parameters:

variations – a string representing the variations

set_weight(weight: Weight) → None

Sets the weight field of a font description.

The weight field specifies how bold or light the font should be. In addition to the values of the Weight enumeration, other intermediate numeric values are possible.

Parameters:

weight – the weight for the font description.

to_filename() → str | None

Creates a filename representation of a font description.

The filename is identical to the result from calling to_string, but with underscores instead of characters that are untypical in filenames, and in lower case only.

to_string() → str

Creates a string representation of a font description.

See from_string for a description of the format of the string representation. The family list in the string description will only have a terminating comma if the last word of the list is a valid style option.

unset_fields(to_unset: FontMask) → None

Unsets some of the fields in a PangoFontDescription.

The unset fields will get back to their default values.

Parameters:

to_unset – bitmask of fields in the desc to unset.