QFont - Font used for drawing text
#include <qfont.h>
Public Members
enum CharSet { ISO_8859_1, Latin1 = ISO_8859_1,
AnyCharSet, ISO_8859_2, Latin2 = ISO_8859_2,
ISO_8859_3, Latin3 = ISO_8859_3, ISO_8859_4, Latin4 =
ISO_8859_4, ISO_8859_5, ISO_8859_6, ISO_8859_7,
ISO_8859_8, ISO_8859_9, Latin5 = ISO_8859_9,
ISO_8859_10, Latin6 = ISO_8859_10, ISO_8859_11, TIS620
= ISO_8859_11, ISO_8859_12, ISO_8859_13, Latin7 =
ISO_8859_13, ISO_8859_14, Latin8 = ISO_8859_14,
ISO_8859_15, Latin9 = ISO_8859_15, KOI8R, Set_Ja,
Set_1 = Set_Ja, Set_Ko, Set_Th_TH, Set_Zh, Set_Zh_TW,
Set_N = Set_Zh_TW, Unicode, Set_GBK, Set_Big5, TSCII,
KOI8U, CP1251, PT154, JIS_X_0201 = 0xa0, JIS_X_0208 =
0xc0, Enc16 = JIS_X_0208, KSC_5601, GB_2312, Big5 }
enum StyleHint { Helvetica, Times, Courier, OldEnglish,
System, AnyStyle, SansSerif = Helvetica, Serif =
Times, TypeWriter = Courier, Decorative = OldEnglish}
enum StyleStrategy { PreferDefault = 0x0001, PreferBitmap
= 0x0002, PreferDevice = 0x0004, PreferOutline =
0x0008, ForceOutline = 0x0010, PreferMatch = 0x0020,
PreferQuality = 0x0040 }
enum Weight { Light = 25, Normal = 50, DemiBold = 63, Bold
= 75, Black = 87 }
QFont ()
QFont ( const QString & family, int pointSize = 12, int
weight = Normal, bool italic = FALSE )
QFont ( const QString & family, int pointSize, int weight,
bool italic, CharSet charSet )
QFont ( const QFont & )
~QFont ()
QFont& operator= ( const QFont & )
QString family () const
void setFamily ( const QString & )
int pointSize () const
float pointSizeFloat () const
void setPointSize ( int )
void setPointSizeFloat ( float )
int pixelSize () const
void setPixelSize ( int )
void setPixelSizeFloat ( float )
int weight () const
void setWeight ( int )
bool bold () const
void setBold ( bool )
bool italic () const
void setItalic ( bool )
bool underline () const
void setUnderline ( bool )
void setStrikeOut ( bool )
bool fixedPitch () const
void setFixedPitch ( bool )
StyleHint styleHint () const
void setStyleHint ( StyleHint )
StyleStrategy styleStrategy () const
void setStyleHint ( StyleHint, StyleStrategy )
CharSet charSet () const
void setCharSet ( CharSet )
bool rawMode () const
void setRawMode ( bool )
bool exactMatch () const
bool operator== ( const QFont & ) const
bool operator!= ( const QFont & ) const
bool isCopyOf ( const QFont & ) const
void setRawName ( const QString & )
QString rawName () const
QString key () const
Static Public Members
CharSet charSetForLocale ()
QString encodingName ( CharSet )
QFont defaultFont ()
void setDefaultFont ( const QFont & ) (obsolete)
QString substitute ( const QString & familyName )
void insertSubstitution ( const QString &, const QString &
)
void removeSubstitution ( const QString & )
QStringList substitutions ()
void initialize ()
void locale_init ()
void cleanup ()
void cacheStatistics ()
Protected Members
bool dirty () const
QString defaultFamily () const
QString lastResortFamily () const
QString lastResortFont () const
int deciPointSize () const
RELATED FUNCTION DOCUMENTATION
(Note that these are not member functions.)
QDataStream & operator<< (QDataStream & s, const QFont &
f)
QDataStream & operator>> (QDataStream & s, QFont & f)
DESCRIPTION
The QFont class specifies a font used for drawing text.
QFont, more precisely, is a collection of attributes of a
font. When Qt needs to draw text, it will look up and load
the closest matching installed font and draw using that.
pointSize(), weight() and whether it is italic() or not.
There are QFont constructors that take these attributes as
arguments, as shown in this example:
void MyWidget::paintEvent( QPaintEvent * )
{
QPainter p( this );
// times, 12pt, normal
p.setFont( QFont( "times" ) );
p.drawText( 10, 20, "Text1" );
// helvetica, 18pt, normal
p.setFont( QFont( "helvetica", 18 ) );
p.drawText( 10, 120, "Text2" );
// courier, 24pt, bold
p.setFont( QFont( "courier", 24, QFont::Bold ) );
p.drawText( 10, 220, "Text3" );
// lucida, 36pt, bold, italic
p.setFont( QFont( "lucida", 36, QFont::Bold, TRUE ) );
p.drawText( 10, 320, "Text4" );
}
The default QFont constructor makes a copy of
application's default font, QApplication::font().
You can also change these attributes of an existing QFont
object using functions such as setFamily(),
setPointSize(), setWeight() and setItalic().
There are also some less-used attributes. setUnderline()
decides whether the font is underlined or not;
setStrikeOut() can be used to get overstrike (a horizontal
line through the middle of the characters);
setFixedPitch() determines whether Qt should give
preference to fixed-pitch (also known as fixed-width) or
variable-pitch fonts when it needs to choose an installed
font; setStyleHint() can be used to offer more general
help to the font matching algorithm, and on X11
setRawName() can be used to bypass the entire font
matching and use an X11 XLFD.
Of course there is also a reader function for each of
these set*() functions. Note that the reader functions
return the values previously set, not the attributes of
the actual window system font that will be used for
drawing. You can get information about the font that will
be used for drawing by using QFontInfo, but be aware that
QFontInfo may be slow and that its results depend on what
fonts are installed.
In general font handling and loading are costly
operations, especially on X11. The QFont class contains
extensive optimizations to make copying of QFont objects
fast, and to cache the results of the slow window system
QFont also offers a few static functions, mostly to tune
the font matching algorithm: You can control what happens
if a font's family isn't installed using
insertSubstitution() and removeSubstitution(), ask what
happens for a single family using substitute() and you can
get a complete list of the fallback families using
substitutions().
cacheStatistics() offers cache effectiveness information;
this is useful mostly for debugging.
Finally, QApplication::setFont() allows you to set the
default font. The default default font is chosen at
application startup from a set of common installed fonts
that support the correct character set for the current
locale. Of course, the initialization algorithm has a
default, too: The default default default font!
The font matching algorithm works as follows:
First an available font family is found. If the requested
is not available the styleHint() is used to select a
replacement family. If the style hint has not been set,
"helvetica" will be used.
If even the replacement family is not found, "helvetica"
is searched for, if that too is not found Qt will search
for a last resort font, i.e. a specific font to match to,
ignoring the attribute settings. Qt searches through a
built-in list of very common fonts. If none of these are
available, Qt gives you an error message and aborts (of
course this only happens if you are using fonts and Qt has
to load a font). We have not been able to find a case
where this happens. Please report it as a bug if it does,
preferably with a list of the fonts you have installed.
The following attributes are then matched, in order of
priority:
1 charSet()
2 fixedPitch()
3 pointSize() (see below)
4 weight()
5 italic()
If, for example, a font with the correct character set is
found, but with all other attributes in the list
unmatched, it will be chosen before a font with the wrong
The point size is defined to match if it is within 20% of
the requested point size. Of course, when several fonts
match and only point size differs the closest point size
to the one requested will be chosen.
For more general information on fonts, see the comp.fonts
FAQ and for more general information on encodings, see
Roman Czyborra's page about that.
See also QFontMetrics, QFontInfo, QApplication::setFont(),
QWidget::setFont(), QPainter::setFont(), QFont::StyleHint,
QFont::CharSet and QFont::Weight.
Examples: showimg/main.cpp grapher/grapher.cpp
xform/xform.cpp i18n/main.cpp drawdemo/drawdemo.cpp
menu/menu.cpp desktop/desktop.cpp
scrollview/scrollview.cpp qfd/qfd.cpp movies/main.cpp
picture/picture.cpp hello/main.cpp
Member Type Documentation
QFont::CharSet
The following character set encodings are available:
QFont::ISO_8859_1 - Latin1 , common in much of Europe
QFont::ISO_8859_2 - Latin2, Central and Eastern European
character set
QFont::ISO_8859_3 - Latin3, less common European character
set
QFont::ISO_8859_4 - Latin4, less common European character
set
QFont::ISO_8859_5, Cyrillic
QFont::ISO_8859_6, Arabic
QFont::ISO_8859_7, Greek
QFont::ISO_8859_8, Hebrew
QFont::ISO_8859_9, Turkish
QFont::ISO_8859_10..15, other ISO 8859 characters sets
QFont::KOI8R - KOI8-R, Cyrillic, defined in RFC 1489.
QFont::KOI8U - KOI8-U, Cyrillic/Ukrainian, defined in RFC
2319.
QFont::PT154, Paratype Asian Cyrillic encoding
QFont::AnyCharSet - whatever is handiest.
QFont::Set_Ja, Japanese
QFont::Set_Ko, Korean
QFont::Set_Th_TH
QFont::Set_Zh
QFont::Set_Zh_TW
QFont::Unicode, Unicode character set
QFont::Set_GBK
QFont::Set_Big5
QFont::StyleHint
Style hints are used by the font matching algorithm when a
selected font family cannot be found and is used to find
an appropriate default family.
The style hint value of AnyStyle leaves the task of
finding a good default family to the font matching
algorithm.
The other available style hints are QFont::SansSerif,
QFont::TypeWriter, QFont::OldEnglish, QFont::System
QFont::StyleStrategy
The style strategy tells the font matching algorithm what
type of fonts should be used to find an appropriate
default family.
The algorithm won't prefer any type of font if NoStratgie
is provided.
The other available strategys are QFont::PreferBitmap,
QFont::PreferDevice, QFont::PreferOutline,
QFont::ForceOutline
Any of these may be ORed with a indicator whether exact
matching or good quality should be preferred.
QFont::PreferMatch, QFont::PreferQuality
QFont::Weight
Contains the predefined font weights:
QFont::Normal (50)
QFont::DemiBold (63)
QFont::Bold (75)
QFont::Black (87)
MEMBER FUNCTION DOCUMENTATION
QFont::QFont ()
Constructs a font object that refers to the default font.
See also QApplication::setFont() and QApplication::font().
QFont::QFont ( const QString & family, int pointSize = 12, int
weight = Normal, bool italic = FALSE )
Constructs a font object with the specified family,
pointSize, weight and italic settings. The charSet() is
copied from the default font and the rest of the settings
are set reasonably.
If pointSize is less than or equal to 0 it is set to 1.
See also setFamily(), setPointSize(), setWeight() and
setItalic().
QFont::QFont ( const QString & family, int pointSize, int weight,
bool italic, CharSet charSet )
Constructs a font object with the specified family,
pointSize, weight, italic and charSet settings. If
pointSize is less than or equal to 0 it is set to 1.
See also setFamily(), setPointSize(), setWeight() and
setItalic().
QFont::QFont ( const QFont & font )
Constructs a font that is a copy of font.
QFont::~QFont ()
Destructs the font object.
bool QFont::bold () const
Returns TRUE if weight() is a value greater than
QFont::Normal, otherwise FALSE.
See also weight(), setBold() and QFontInfo::bold().
void QFont::cacheStatistics () [static]
Internal function that dumps font cache statistics.
QFont::CharSet QFont::charSet() const
Returns the character set by setCharSet().
font actually used.
See also setCharSet().
QFont::CharSet QFont::charSetForLocale() [static]
Returns a guess at the character set most likely to be
appropriate for the locale the application is running in.
This is the character sets fonts will use by default.
void QFont::cleanup () [static]
Internal function that cleans up the font system.
int QFont::deciPointSize () const [protected]
Returns the point size in 1/10ths of a point.
See also pointSize().
QString QFont::defaultFamily () const [protected]
Returns the family name that corresponds to the current
style hint.
QFont QFont::defaultFont () [static]
Returns the QApplication default font.
This function will be removed in a future version of Qt.
Please use QApplication::font() instead.
bool QFont::dirty () const [protected]
Returns TRUE if the font attributes have been changed and
the font has to be (re)loaded, or FALSE if no changes have
been made.
QString QFont::encodingName ( CharSet cs ) [static]
Returns the encoding name of a character set, e.g.
QFont::ISO_8859_1 returns "iso8859-1" and QFont::Unicode
returns "iso10646".
bool QFont::exactMatch () const
Returns TRUE if a window system font exactly matching the
settings of this font is available.
See also QFontInfo.
QString QFont::family () const
Returns the family name set by setFamily().
Use QFontInfo to find the family name of the window system
font that is actually used for drawing.
Example:
QFont font( "Nairobi" );
QFontInfo info( font );
qDebug( "Font family actually used is: \"%s\"", info.family() );
See also setFamily() and substitute().
bool QFont::fixedPitch () const
Returns the value set by setFixedPitch().
Use QFontInfo to find the fixed pitch value of the window
system font actually used.
See also setFixedPitch() and QFontInfo::fixedPitch().
void QFont::initialize () [static]
Internal function that initializes the font system.
void QFont::insertSubstitution ( const QString & familyName,
const QString & replacementName ) [static]
Inserts a new font family name substitution in the family
substitution table.
If familyName already exists in the substitution table, it
will be replaced with this new substitution.
See also removeSubstitution(), substitutions() and
substitute().
bool QFont::isCopyOf ( const QFont & f ) const
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 was subsequently modified. This is much stricter
than equality.
See also operator= and operator==.
bool QFont::italic () const
Returns the value set by setItalic().
Use QFontInfo to find the italic value of the window
system font actually used.
See also setItalic().
QString QFont::key () const
Returns the font's key, which is a textual representation
of the font settings. It is typically used to insert and
find fonts in a dictionary or a cache.
See also QMap.
QString QFont::lastResortFamily () const [protected]
Returns a last resort family name for the font matching
algorithm.
QString QFont::lastResortFont () const [protected]
Returns a last resort raw font name for the font matching
algorithm. This is used if even the last resort family is
not available. It returns something, almost no matter
what.
The current implementation tries a wide variety of common
fonts, returning the first one it finds. The
implementation may change at any time.
See also lastResortFamily().
void QFont::locale_init () [static]
Internal function that uses locale information to find the
preferred character set of loaded fonts.
bool QFont::operator!= ( const QFont & f ) const
Returns TRUE if the this font is different from f, or
FALSE if they are equal.
Two QFonts are different if their font attributes are
different. If rawMode() is enabled for both fonts, then
only the family fields are compared.
See also operator==().
QFont & QFont::operator= ( const QFont & font )
Assigns font to this font and returns a reference to this
font.
bool QFont::operator== ( const QFont & f ) const
Returns TRUE if the this font is equal to f, or FALSE if
they are different.
Two QFonts are equal if their font attributes are equal.
If rawMode() is enabled for both fonts, then only the
family fields are compared.
See also operator!=().
int QFont::pixelSize () const
Returns the logical pixel height of characters in the font
if shown on the screen.
int QFont::pointSize () const
Returns the point size set by setPointSize().
Use QFontInfo to find the point size of the window system
font actually used.
Example of use:
QFontInfo info( font );
font.setPointSize( 53 );
qDebug( "Font size requested is : %d", font.pointSize() );
qDebug( "Font size actually used is: %d", info.pointSize() );
See also setPointSize() and deciPointSize().
float QFont::pointSizeFloat () const
Returns the height of characters in the font in points
(1/72 inch).
See also pointSize().
bool QFont::rawMode () const
Returns the value set by setRawMode().
See also setRawMode().
QString QFont::rawName () const
Returns the name of the font within the underlying window
system. On Windows, this is usually just the family name
of a true type font. Under X, it is a rather complex XLFD
(X Logical Font Description). Using the return value of
this function is usually not portable.
See also setRawName().
void QFont::removeSubstitution ( const QString & familyName )
[static]
Removes a font family name substitution from the family
substitution table.
See also insertSubstitution(), substitutions() and
substitute().
void QFont::setBold ( bool enable )
Sets the weight to QFont::Bold if enable is TRUE, or to
QFont::Normal if enable is FALSE.
Use setWeight() to set the weight to other values.
See also bold() and setWeight().
Examples: menu/menu.cpp
void QFont::setCharSet ( CharSet charset )
Sets the character set encoding (e.g. Latin1).
If the character set encoding is not available another
will be used for drawing. For most non-trivial
applications you will probably not want this to happen
since it can totally obscure the text shown to the user.
This is why the font matching algorithm gives high
You can test that the character set is correct using the
QFontInfo class.
See also charSet() and QFontInfo.
void QFont::setDefaultFont ( const QFont & f ) [static]
This function is obsolete. It is provided to keep old
source working, and will probably be removed in a future
version of Qt. We strongly advise against using it in new
code.
Please use QApplication::setFont() instead.
void QFont::setFamily ( const QString & family )
Sets the family name of the font (e.g. "Helvetica" or
"times").
The family name is case insensitive.
If the family is not available a default family is used.
See also family(), setStyleHint() and QFontInfo.
void QFont::setFixedPitch ( bool enable )
Sets fixed pitch on or off.
A fixed pitch font is a font where all characters have the
same width.
See also fixedPitch() and QFontInfo.
void QFont::setItalic ( bool enable )
Sets italic on or off.
See also italic() and QFontInfo.
void QFont::setPixelSize ( int pixelSize )
Sets the logical height of characters in the font if shown
on the screen.
void QFont::setPixelSizeFloat ( float pixelSize )
Sets the logical pixel height of characters in the font if
shown on the screen.
void QFont::setPointSize ( int pointSize )
Sets the point size to pointSize. The point size must be
greater than zero.
Example:
QFont font( "courier" );
font.setPointSize( 18 );
void QFont::setPointSizeFloat ( float pointSize )
Sets the point size to pointSize. The point size must be
greater than zero. The requested precision may not be
achieved on all platforms.
void QFont::setRawMode ( bool enable )
Turns raw mode on if enable is TRUE, or turns it off if
enable is FALSE.
Calling this function only has effect under X windows. If
raw mode is enabled, Qt will search for an X font with a
complete font name matching the family name, ignoring all
other values set for the QFont. If the font name matches
several fonts, Qt will use the first font returned by X.
QFontInfo cannot be used to fetch information about a
QFont using raw mode (it will return the values set in the
QFont for all parameters, including the family name).
Warning: Do not use raw mode unless you really, really
need it! In most (if not all) cases, setRawName() is a
much better choise.
See also rawMode() and setRawName().
void QFont::setRawName ( const QString & name )
Sets a font by its system specific name. The function is
in particular useful under X, where system font settings (
for example X resources) are usually available as XLFD (X
Logical Font Description) only. You can pass an XLFD as
name to this function.
In Qt 2.0 and later, a font set with setRawName() is still
a full-featured QFont. It can be queried (for example with
italic()) or modified (for example with setItalic() ) and
is therefore also suitable as a basis font for rendering
rich text.
If Qt's internal font database cannot resolve the raw
name, the font becomes a raw font with name as family.
Note that the present implementation does not handle
handle wildcards in XLFDs well, and that font aliases
(file fonts.alias in the font directory on X11) are not
supported.
See also rawName(), setRawMode() and setFamily().
void QFont::setStrikeOut ( bool enable )
Sets strike out on or off.
See also strikeOut() and QFontInfo.
Sets the style hint.
See also setStyleHint().
Examples: desktop/desktop.cpp
void QFont::setStyleHint ( StyleHint hint, StyleStrategy strategy
)
Sets the style hint and strategy.
The style hint has a default value of AnyStyle which
leaves the task of finding a good default family to the
font matching algorithm.
The style strategy has a default value of PreferDefault
which tells the algorithm not to prefer any type of font.
Right now, the X version only supports bitmap fonts.
In the example below the push button will display its text
label with the Bavaria font family if this family is
available, if not it will display its text label with
another serif font:
#include <qapplication.h>
#include <qpushbutton.h>
#include <qfont.h>
int main( int argc, char **argv )
{
QApplication app( argc, argv );
QPushButton push("Push me");
QFont font( "Bavaria", 18 ); // preferred family is Bavaria
font.setStyleHint( QFont::Serif ) // can also use any serif font
push.setFont( font );
return app.exec( &push );
}
See also QFont::StyleHint, styleHint(),
QFont::StyleStrategy, styleStrategy() and QFontInfo.
void QFont::setUnderline ( bool enable )
Sets underline on or off.
See also underline() and QFontInfo.
Examples: menu/menu.cpp
void QFont::setWeight ( int weight )
Sets the weight (or boldness), which should be a value
from the QFont::Weight enumeration.
Example:
QFont font( "courier" );
Strictly speaking you can use all values in the range
[0,99] (where 0 is ultralight and 99 is extremely black),
but there is perhaps asking too much of the underlying
window system.
If the specified weight is not available the closest
available will be used. Use QFontInfo to check the actual
weight.
See also weight() and QFontInfo.
bool QFont::strikeOut () const
Returns the value set by setStrikeOut().
Use QFontInfo to find the strike out value of the window
system font actually used.
See also setStrikeOut() and QFontInfo::strikeOut().
QFont::StyleHint QFont::styleHint() const
Returns the StyleHint set by setStyleHint().
See also setStyleHint() and QFontInfo::styleHint().
QFont::StyleStrategy QFont::styleStrategy() const
Returns the StyleStratgie set by setStyleHint()
See also setStyleHint().
QString QFont::substitute ( const QString & familyName ) [static]
Returns the font family name to be used whenever
familyName is specified. The lookup is case insensitive.
If there is no substitution for familyName, then
familyName is returned.
Example:
QFont::insertSubstitution( "NewYork", "London" );
QFont::insertSubstitution( "Paris", "Texas" );
QFont::substitute( "NewYork" ); // returns "London"
QFont::substitute( "PARIS" ); // returns "Texas"
QFont::substitute( "Rome" ); // returns "Rome"
QFont::removeSubstitution( "newyork" );
QFont::substitute( "NewYork" ); // returns "NewYork"
See also setFamily(), insertSubstitution() and
removeSubstitution().
QStringList QFont::substitutions () [static]
Returns a sorted list of substituted family names.
substitute().
bool QFont::underline () const
Returns the value set by setUnderline().
Use QFontInfo to find the underline value of the window
system font actually used for drawing.
See also setUnderline() and QFontInfo::underline().
int QFont::weight () const
Returns the weight set by setWeight().
Use QFontInfo to find the weight of the window system font
actually used.
See also setWeight() and QFontInfo.
RELATED FUNCTION DOCUMENTATION
QDataStream & operator< (QDataStream & s, const QFont & f)
Writes a font to the stream.
See also Format of the QDataStream operators
QDataStream & operator>> (QDataStream & s, QFont & f)
Reads a font from the stream.
See also Format of the QDataStream operators
SEE ALSO
http://doc.trolltech.com/qfont.html
http://www.trolltech.com/faq/tech.html
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