QFont¶

PyQt5.QtGui.QFont

Description¶

The QFont class specifies a font used for drawing text.

When you create a QFont object you specify various attributes that you want the font to have. Qt will use the font with the specified attributes, or if no matching font exists, Qt will use the closest matching installed font. The attributes of the font that is actually used are retrievable from a QFontInfo object. If the window system provides an exact match exactMatch() returns true. Use QFontMetrics to get measurements, e.g. the pixel length of a string using width().

Note that a QGuiApplication instance must exist before a QFont can be used. You can set the application’s default font with setFont().

If a chosen font does not include all the characters that need to be displayed, QFont will try to find the characters in the nearest equivalent fonts. When a QPainter draws a character from a font the QFont will report whether or not it has the character; if it does not, QPainter will draw an unfilled square.

Create QFonts like this:

# QFont serifFont("Times", 10, QFont::Bold);
# QFont sansFont("Helvetica [Cronyx]", 12);

The attributes set in the constructor can also be set later, e.g. setFamily(), setPointSize(), setPointSizeF(), setWeight() and setItalic(). The remaining attributes must be set after contstruction, e.g. setBold(), setUnderline(), setOverline(), setStrikeOut() and setFixedPitch(). QFontInfo objects should be created after the font’s attributes have been set. A QFontInfo object will not change, even if you change the font’s attributes. The corresponding “get” functions, e.g. family(), pointSize(), etc., return the values that were set, even though the values used may differ. The actual values are available from a QFontInfo object.

If the requested font family is unavailable you can influence the font matching algorithm by choosing a particular StyleHint and StyleStrategy with setStyleHint(). The default family (corresponding to the current style hint) is returned by defaultFamily().

The font-matching algorithm has a lastResortFamily() and lastResortFont() in cases where a suitable match cannot be found. You can provide substitutions for font family names using insertSubstitution() and insertSubstitutions(). Substitutions can be removed with removeSubstitutions(). Use substitute() to retrieve a family’s first substitute, or the family name itself if it has no substitutes. Use substitutes() to retrieve a list of a family’s substitutes (which may be empty).

Every QFont has a key() which you can use, for example, as the key in a cache or dictionary. If you want to store a user’s font preferences you could use QSettings, writing the font information with toString() and reading it back with fromString(). The operator<<() and operator>>() functions are also available, but they work on a data stream.

It is possible to set the height of characters shown on the screen to a specified number of pixels with setPixelSize(); however using setPointSize() has a similar effect and provides device independence.

Loading fonts can be expensive, especially on X11. QFont contains extensive optimizations to make the copying of QFont objects fast, and to cache the results of the slow window system functions it depends upon.

The font matching algorithm works as follows:

The specified font family is searched for.
If not found, the styleHint() is used to select a replacement family.
Each replacement font family is searched for.
If none of these are found or there was no styleHint(), “helvetica” will be searched for.
If “helvetica” isn’t found Qt will try the lastResortFamily().
If the lastResortFamily() isn’t found Qt will try the lastResortFont() which will always return a name of some kind.

Note that the actual font matching algorithm varies from platform to platform.

In Windows a request for the “Courier” font is automatically changed to “Courier New”, an improved version of Courier that allows for smooth scaling. The older “Courier” bitmap font can be selected by setting the PreferBitmap style strategy (see setStyleStrategy()).

Once a font is found, the remaining attributes are matched in order of priority:

fixedPitch()
pointSize() (see below)
weight()
style()

If you have a font which matches on family, even if none of the other attributes match, this font will be chosen in preference to a font which doesn’t match on family but which does match on the other attributes. This is because font family is the dominant search criteria.

The point size is defined to match if it is within 20% of the requested point size. When several fonts match and are only distinguished by point size, the font with the closest point size to the one requested will be chosen.

The actual family, font size, weight and other font attributes used for drawing text will depend on what’s available for the chosen family under the window system. A QFontInfo object can be used to determine the actual values used for drawing the text.

Examples:

# QFont f("Helvetica");

If you had both an Adobe and a Cronyx Helvetica, you might get either.

# QFont f("Helvetica [Cronyx]");

You can specify the foundry you want in the family name. The font f in the above example will be set to “Helvetica [Cronyx]”.

To determine the attributes of the font actually used in the window system, use a QFontInfo object, e.g.

# QFontInfo info(f1);
# QString family = info.family();

To find out font metrics use a QFontMetrics object, e.g.

# QFontMetrics fm(f1);
# int textWidthInPixels = fm.horizontalAdvance("How many pixels wide is this text?");
# int textHeightInPixels = fm.height();

For more general information on fonts, see the comp.fonts FAQ. Information on encodings can be found from Roman Czyborra’s page.

Enums¶

Capitalization

Rendering option for text this font applies to.

Member	Value	Description
AllLowercase	2	This alters the text to be rendered in all lowercase type.
AllUppercase	1	This alters the text to be rendered in all uppercase type.
Capitalize	4	This alters the text to be rendered with the first character of each word as an uppercase character.
MixedCase	0	This is the normal text rendering option where no capitalization change is applied.
SmallCaps	3	This alters the text to be rendered in small-caps type.

HintingPreference

This enum describes the different levels of hinting that can be applied to glyphs to improve legibility on displays where it might be warranted by the density of pixels.

Please note that this enum only describes a preference, as the full range of hinting levels are not supported on all of Qt’s supported platforms. The following table details the effect of a given hinting preference on a selected set of target platforms.


Windows Vista (w/o Platform Update) and earlier	Full hinting	Full hinting	Full hinting	Full hinting
Windows 7 and Windows Vista (w/Platform Update) and DirectWrite enabled in Qt	Full hinting	Vertical hinting	Vertical hinting	Full hinting
FreeType	Operating System setting	No hinting	Vertical hinting (light)	Full hinting
Cocoa on macOS	No hinting	No hinting	No hinting	No hinting

Note: Please be aware that altering the hinting preference on Windows is available through the DirectWrite font engine. This is available on Windows Vista after installing the platform update, and on Windows 7. In order to use this extension, configure Qt using -directwrite. The target application will then depend on the availability of DirectWrite on the target system.

Member	Value	Description
PreferDefaultHinting	0	Use the default hinting level for the target platform.
PreferFullHinting	3	If possible, render text with hinting in both horizontal and vertical directions. The text will be altered to optimize legibility on the target device, but since the metrics will depend on the target size of the text, the positions of glyphs, line breaks, and other typographical detail will not scale, meaning that a text layout may look different on devices with different pixel densities.
PreferNoHinting	1	If possible, render text without hinting the outlines of the glyphs. The text layout will be typographically accurate and scalable, using the same metrics as are used e.g. when printing.
PreferVerticalHinting	2	If possible, render text with no horizontal hinting, but align glyphs to the pixel grid in the vertical direction. The text will appear crisper on displays where the density is too low to give an accurate rendering of the glyphs. But since the horizontal metrics of the glyphs are unhinted, the text’s layout will be scalable to higher density devices (such as printers) without impacting details such as line breaks.

SpacingType

Member	Value	Description
AbsoluteSpacing	1	A positive value increases the letter spacing by the corresponding pixels; a negative value decreases the spacing.
PercentageSpacing	0	A value of 100 will keep the spacing unchanged; a value of 200 will enlarge the spacing after a character by the width of the character itself.

Stretch

Predefined stretch values that follow the CSS naming convention. The higher the value, the more stretched the text is.

See also

setStretch(), stretch().

Member	Value	Description
AnyStretch	TODO	0 Accept any stretch matched using the other QFont properties (added in Qt 5.8)
Condensed	75	75
Expanded	125	125
ExtraCondensed	62	62
ExtraExpanded	150	150
SemiCondensed	87	87
SemiExpanded	112	112
UltraCondensed	50	50
UltraExpanded	200	200
Unstretched	100	100

Style

This enum describes the different styles of glyphs that are used to display text.

See also

Weight.

Member	Value	Description
StyleItalic	1	Italic glyphs that are specifically designed for the purpose of representing italicized text.
StyleNormal	0	Normal glyphs used in unstyled text.
StyleOblique	2	Glyphs with an italic appearance that are typically based on the unstyled glyphs, but are not fine-tuned for the purpose of representing italicized text.

StyleHint

Style hints are used by the QFont algorithm to find an appropriate default family if a selected font family is not available.

Member	Value	Description
AnyStyle	5	leaves the font matching algorithm to choose the family. This is the default.
Courier	2	a synonym for `TypeWriter`.
Cursive	6	the font matcher prefers fonts that map to the CSS generic font-family ‘cursive’.
Decorative	OldEnglish	is a synonym for `OldEnglish`.
Fantasy	8	the font matcher prefers fonts that map to the CSS generic font-family ‘fantasy’.
Helvetica	0	is a synonym for `SansSerif`.
Monospace	7	the font matcher prefers fonts that map to the CSS generic font-family ‘monospace’.
OldEnglish	3	the font matcher prefers decorative fonts.
SansSerif	Helvetica	the font matcher prefer sans serif fonts.
Serif	Times	the font matcher prefers serif fonts.
System	4	the font matcher prefers system fonts.
Times	1	is a synonym for `Serif`.
TypeWriter	Courier	the font matcher prefers fixed pitch fonts.

StyleStrategy

The style strategy tells the QFont algorithm what type of fonts should be used to find an appropriate default family.

The following strategies are available:

Any of these may be OR-ed with one of these flags:

Member	Value	Description
ForceIntegerMetrics	0x0400	forces the use of integer values in font engines that support fractional font metrics.
ForceOutline	0x0010	forces the use of outline fonts.
NoAntialias	0x0100	don’t antialias the fonts.
NoFontMerging	0x8000	If the font selected for a certain writing system does not contain a character requested to draw, then Qt automatically chooses a similar looking font that contains the character. The flag disables this feature. Please note that enabling this flag will not prevent Qt from automatically picking a suitable font when the selected font does not support the writing system of the text.
NoSubpixelAntialias	TODO	avoid subpixel antialiasing on the fonts if possible.
OpenGLCompatible	0x0200	forces the use of OpenGL compatible fonts.
PreferAntialias	0x0080	antialias if possible.
PreferBitmap	0x0002	prefers bitmap fonts (as opposed to outline fonts).
PreferDefault	0x0001	the default style strategy. It does not prefer any type of font.
PreferDevice	0x0004	prefers device fonts.
PreferMatch	0x0020	prefer an exact match. The font matcher will try to use the exact font size that has been specified.
PreferNoShaping	TODO	Sometimes, a font will apply complex rules to a set of characters in order to display them correctly. In some writing systems, such as Brahmic scripts, this is required in order for the text to be legible, but in e.g. Latin script, it is merely a cosmetic feature. The PreferNoShaping flag will disable all such features when they are not required, which will improve performance in most cases (since Qt 5.10).
PreferOutline	0x0008	prefers outline fonts (as opposed to bitmap fonts).
PreferQuality	0x0040	prefer the best quality font. The font matcher will use the nearest standard point size that the font supports.

Weight

Qt uses a weighting scale from 0 to 99 similar to, but not the same as, the scales used in Windows or CSS. A weight of 0 will be thin, whilst 99 will be extremely black.

This enum contains the predefined font weights:

Member	Value	Description
Black	87	87
Bold	75	75
DemiBold	63	63
ExtraBold	TODO	81
ExtraLight	TODO	12
Light	25	25
Medium	TODO	57
Normal	50	50
Thin	TODO	0

Methods¶

__init__(): Constructs a font object that uses the application’s default font.

See also

setFont(), font().

__init__(QFont): Constructs a font that is a copy of font.

__init__(Any): TODO

__init__(QFont, QPaintDevice): Constructs a font from font for use on the paint device pd.

__init__(str, pointSize: int = -1, weight: int = -1, italic: bool = False)

Constructs a font object with the specified family, pointSize, weight and italic settings.

If pointSize is zero or negative, the point size of the font is set to a system-dependent default value. Generally, this is 12 points.

The family name may optionally also include a foundry name, e.g. “Helvetica [Cronyx]”. If the family is available from more than one foundry and the foundry isn’t specified, an arbitrary foundry is chosen. If the family isn’t available a family will be set using the QFont algorithm.

bold() → bool: See also

setBold().

@staticmethod cacheStatistics(): TODO

capitalization() → Capitalization: Returns the current capitalization type of the font.

See also

setCapitalization().

@staticmethod cleanup(): TODO

defaultFamily() → str: TODO

__eq__(QFont) → bool: TODO

exactMatch() → bool: Returns true if a window system font exactly matching the settings of this font is available.

See also

QFontInfo.

families() → List[str]: TODO

family() → str: Returns the requested font family name, i.e. the name set in the constructor or the last setFont() call.

See also

setFamily(), substitutes(), substitute().

fixedPitch() → bool: Returns true if fixed pitch has been set; otherwise returns false.

See also

setFixedPitch(), fixedPitch().

fromString(str) → bool: TODO

__ge__(QFont) → bool: TODO

__hash__() → int: TODO

hintingPreference() → HintingPreference: Returns the currently preferred hinting level for glyphs rendered with this font.

See also

setHintingPreference().

@staticmethod initialize(): TODO

@staticmethod insertSubstitution(str, str): Inserts substituteName into the substitution table for the family familyName.

See also

insertSubstitutions(), substitutions(), substitute(), substitutes().

@staticmethod insertSubstitutions(str, Iterable[str]): Inserts the list of families substituteNames into the substitution list for familyName.

See also

insertSubstitution(), substitutions(), substitute().

isCopyOf(QFont) → bool: Returns true if this font and f are copies of each other, i.e. one of them was created as a copy of the other and neither has been modified since. This is much stricter than equality.

See also

operator=(), operator==().

italic() → bool: See also

setItalic().

kerning() → bool: Returns true if kerning should be used when drawing text with this font.

See also

setKerning().

key() → str: Returns the font’s key, a textual representation of a font. It is typically used as the key for a cache or dictionary of fonts.

See also

QMap.

lastResortFamily() → str: TODO

lastResortFont() → str: TODO

letterSpacing() → float: Returns the letter spacing for the font.

See also

setLetterSpacing(), letterSpacingType(), setWordSpacing().

letterSpacingType() → SpacingType: Returns the spacing type used for letter spacing.

See also

letterSpacing(), setLetterSpacing(), setWordSpacing().

__lt__(QFont) → bool: TODO

__ne__(QFont) → bool: TODO

overline() → bool: Returns true if overline has been set; otherwise returns false.

See also

setOverline().

pixelSize() → int: Returns the pixel size of the font if it was set with setPixelSize(). Returns -1 if the size was set with setPointSize() or setPointSizeF().

See also

setPixelSize(), pointSize(), pointSize(), pixelSize().

pointSize() → int: Returns the point size of the font. Returns -1 if the font size was specified in pixels.

See also

setPointSize(), pointSizeF().

pointSizeF() → float: Returns the point size of the font. Returns -1 if the font size was specified in pixels.

See also

pointSize(), setPointSizeF(), pixelSize(), pointSize(), pixelSize().

rawMode() → bool: See also

setRawMode().

rawName() → str: See also

setRawName().

@staticmethod removeSubstitutions(str): TODO

resolve(QFont) → QFont: Returns a new QFont that has attributes copied from other that have not been previously set on this font.

setBold(bool): See also

bold().

setCapitalization(Capitalization): See also

capitalization().

setFamilies(Iterable[str]): TODO

setFamily(str)

Sets the family name of the font. The name is case insensitive and may include a foundry name.

The family name may optionally also include a foundry name, e.g. “Helvetica [Cronyx]”. If the family is available from more than one foundry and the foundry isn’t specified, an arbitrary foundry is chosen. If the family isn’t available a family will be set using the QFont algorithm.

See also

family(), setStyleHint(), QFontInfo.

setFixedPitch(bool): If enable is true, sets fixed pitch on; otherwise sets fixed pitch off.

See also

fixedPitch(), QFontInfo.

setHintingPreference(HintingPreference): See also

hintingPreference().

setItalic(bool): See also

italic().

setKerning(bool)

Enables kerning for this font if enable is true; otherwise disables it. By default, kerning is enabled.

When kerning is enabled, glyph metrics do not add up anymore, even for Latin text. In other words, the assumption that width(‘a’) + width(‘b’) is equal to width(“ab”) is not necessarily true.

See also

kerning(), QFontMetrics.

setLetterSpacing(SpacingType, float): See also

letterSpacing().

setOverline(bool): If enable is true, sets overline on; otherwise sets overline off.

See also

overline(), QFontInfo.

setPixelSize(int)

Sets the font size to pixelSize pixels.

Using this function makes the font device dependent. Use setPointSize() or setPointSizeF() to set the size of the font in a device independent manner.

See also

pixelSize().

setPointSize(int): Sets the point size to pointSize. The point size must be greater than zero.

See also

pointSize(), setPointSizeF().

setPointSizeF(float): Sets the point size to pointSize. The point size must be greater than zero. The requested precision may not be achieved on all platforms.

See also

pointSizeF(), setPointSize(), setPixelSize().

setRawMode(bool): See also

rawMode().

setRawName(str): See also

rawName().

setStretch(int)

Sets the stretch factor for the font.

The stretch factor matches a condensed or expanded version of the font or applies a stretch transform that changes the width of all characters in the font by factor percent. For example, setting factor to 150 results in all characters in the font being 1.5 times (ie. 150%) wider. The minimum stretch factor is 1, and the maximum stretch factor is 4000. The default stretch factor is AnyStretch, which will accept any stretch factor and not apply any transform on the font.

The stretch factor is only applied to outline fonts. The stretch factor is ignored for bitmap fonts.

Note: When matching a font with a native non-default stretch factor, requesting a stretch of 100 will stretch it back to a medium width font.

See also

stretch(), Stretch.

setStrikeOut(bool): If enable is true, sets strikeout on; otherwise sets strikeout off.

See also

strikeOut(), QFontInfo.

setStyle(Style): See also

style().

setStyleHint(StyleHint, strategy: StyleStrategy = PreferDefault): See also

styleHint().

setStyleName(str)

Sets the style name of the font to styleName. When set, other style properties like style() and weight() will be ignored for font matching, though they may be simulated afterwards if supported by the platform’s font engine.

Due to the lower quality of artificially simulated styles, and the lack of full cross platform support, it is not recommended to use matching by style name together with matching by style properties

See also

styleName().

setStyleStrategy(StyleStrategy): See also

styleStrategy().

setUnderline(bool): If enable is true, sets underline on; otherwise sets underline off.

See also

underline(), QFontInfo.

setWeight(int)

Sets the weight of the font to weight, using the scale defined by Weight enumeration.

Note: If styleName() is set, this value may be ignored for font selection.

See also

weight(), QFontInfo.

setWordSpacing(float)

Sets the word spacing for the font to spacing.

Word spacing changes the default spacing between individual words. A positive value increases the word spacing by a corresponding amount of pixels, while a negative value decreases the inter-word spacing accordingly.

Word spacing will not apply to writing systems, where indiviaul words are not separated by white space.

See also

wordSpacing(), setLetterSpacing().

stretch() → int: Returns the stretch factor for the font.

See also

setStretch().

strikeOut() → bool: Returns true if strikeout has been set; otherwise returns false.

See also

setStrikeOut().

style() → Style: Returns the style of the font.

See also

setStyle().

styleHint() → StyleHint

Returns the StyleHint.

The style hint affects the font matching algorithm. See StyleHint for the list of available hints.

styleName() → str: Returns the requested font style name. This can be used to match the font with irregular styles (that can’t be normalized in other style properties).

See also

setStyleName(), setFamily(), setStyle().

styleStrategy() → StyleStrategy

Returns the StyleStrategy.

The style strategy affects the QFont algorithm. See StyleStrategy for the list of available strategies.

@staticmethod substitute(str) → str

Returns the first family name to be used whenever familyName is specified. The lookup is case insensitive.

If there is no substitution for familyName, familyName is returned.

To obtain a list of substitutions use substitutes().

@staticmethod substitutes(str) → List[str]

Returns a list of family names to be used whenever familyName is specified. The lookup is case insensitive.

If there is no substitution for familyName, an empty list is returned.

@staticmethod substitutions() → List[str]: Returns a sorted list of substituted family names.

See also

insertSubstitution(), removeSubstitution(), substitute().

swap(QFont): TODO

toString() → str: Returns a description of the font. The description is a comma-separated list of the attributes, perfectly suited for use in QSettings.

See also

fromString().

underline() → bool: Returns true if underline has been set; otherwise returns false.

See also

setUnderline().

weight() → int: Returns the weight of the font, using the same scale as the Weight enumeration.

See also

setWeight(), Weight, QFontInfo.

wordSpacing() → float: Returns the word spacing for the font.

See also

setWordSpacing(), setLetterSpacing().