NAME
QFont - Font used for drawing text
SYNOPSIS
#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
enum StyleHint { Helvetica, Times, Courier, OldEnglish,
System, AnyStyle, SansSerif = Helvetica, Serif = Times,
TypeWriter = Courier, Decorative = OldEnglish}
enum Weight { Light = 25, Normal = 50, DemiBold = 63, Bold =
75, Black = 87 }
QFont ()
QFont ( const QString & family, int pointSize = 12, int
weight
QFont ( const QString & family, int pointSize, int weight
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 )
bool strikeOut () const
void setStrikeOut ( bool )
bool fixedPitch () const
void setFixedPitch ( bool )
StyleHint styleHint () const
void setStyleHint ( StyleHint )
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 )
const QFont defaultFont ()
void setDefaultFont ( const QFont & )
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.
The most important attributes of a QFont are family, point
size, weight and italic. 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 the
application's default 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 functions it
uses.
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 listSubstitutions().
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. \endlink Of course, the initialization algorithm has
a default, too: The default default default font!
For more general information on fonts, see the comp.fonts
FAQ and for more general information on encodings, see or
Roman Czyborra's font encodings.
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 drawdemo/drawdemo.cpp desktop/desktop.cpp
scrollview/scrollview.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
character set
QFont::ISO_8859_2 - Latin2, Central and Eastern European
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::AnyCharSet - whatever is handiest.
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::Weight
Contains the predefined font weights:
QFont::Light (25)
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 character set is
copied from the default font and the rest of the settings
ser 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 ()
Destroys 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().
Use QFontInfo to find the CharSet of the window system font
actually used.
See also: setCharSet().
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.
const 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 and font matching
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 requested is : \"%s\"", font.family() );
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(), listSubstitutions() 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.
See also: lastResortFont().
QString QFont::lastResortFont () const [protected]
Returns a last resort raw font name for the font matching
algorithm.
This is used if not even the last resort family is
available.
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:
QFont font( "helvetica" );
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(), listSubstitutions() 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().
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 priority to finding the
correct character set.
You can test that the character set is correct using the
QFontInfo class.
Example:
QFont font( "times", 14 ); // default character set is Latin1
QFontInfo info( font );
if ( info.charSet() != Latin1 ) // check actual font
qFatal( "Cannot find a Latin 1 Times font" );
See also: charSet(), QFontInfo and font matching
void QFont::setDefaultFont ( const QFont & f ) [static]
This function is obsolete. It is provided to keep old
programs working. We strongly advise against using it in new
code.
Sets the QApplication default font.
This function will be removed in a future version of Qt.
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(), QFontInfo and font
matching
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(), QFontInfo and font matching
void QFont::setItalic ( bool enable )
Sets italic on or off.
See also: italic(), QFontInfo and font matching
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 );
See also: pointSize(), QFontInfo and font matching
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::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.
The big advantage over Qt-1.x' concept of raw fonts is, that
a font after 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.
See also: rawName(), setRawMode() and setFamily().
Bugs and limitations:
descriptions. Aliases (file fonts.alias in the font directory on
X11) are not supported.
Doesn't handle wildcards in XLFDs well, only complete
void QFont::setStrikeOut ( bool enable )
Sets strike out on or off.
See also: strikeOut(), QFontInfo and font matching
void QFont::setStyleHint ( StyleHint hint )
Sets the style hint.
The style hint has a default value of AnyStyle which leaves
the task of finding a good default family to the font
matching algorithm.
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(), QFontInfo and font
matching
Examples: desktop/desktop.cpp
void QFont::setUnderline ( bool enable )
Sets underline on or off.
See also: underline(), QFontInfo and font matching.
void QFont::setWeight ( int weight )
Sets the weight (or boldness), which should be a value from
the QFont::Weight enumeration.
Example:
QFont font( "courier" );
font.setWeight( QFont::Bold );
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(), QFontInfo and font matching
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().
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.
See also: insertSubstitution(), removeSubstitution() and
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
Writes a font to the stream.
QDataStream & operator>> (QDataStream & s, QFont & f)
Reads a font from the stream.
SEE ALSO
http://www.troll.no/qt/qfont.html
COPYRIGHT
Copyright 1992-1999 Troll Tech AS. See the license file
included in the distribution for a complete license
statement.
AUTHOR
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