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TQFont Class Reference

The TQFont class specifies a font used for drawing text. More...

#include <qfont.h>

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Detailed Description

The TQFont class specifies a font used for drawing text.

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

Use TQApplication::setFont() to set the application's default font.

If a choosen X11 font does not include all the characters that need to be displayed, TQFont will try to find the characters in the nearest equivalent fonts. When a TQPainter draws a character from a font the TQFont will report whether or not it has the character; if it does not, TQPainter will draw an unfilled square.

Create TQFonts like this: 

    TQFont serifFont( "Times", 10, Bold );
    TQFont sansFont( "Helvetica [Cronyx]", 12 );

The attributes set in the constructor can also be set later, e.g. setFamily(), setPointSize(), setPointSizeFloat(), setWeight() and setItalic(). The remaining attributes must be set after contstruction, e.g. setBold(), setUnderline(), setOverline(), setStrikeOut() and setFixedPitch(). TQFontInfo objects should be created after the font's attributes have been set. A TQFontInfo 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 TQFontInfo object.

If the requested font family is unavailable you can influence the font matching algorithm by choosing a particular TQFont::StyleHint and TQFont::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 removeSubstitution(). 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 TQFont 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 TQSettings, 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.

Under the X Window System you can set a font using its system specific name with setRawName().

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

The font matching algorithm works as follows:

  1. The specified font family is searched for.
  2. If not found, the styleHint() is used to select a replacement family.
  3. Each replacement font family is searched for.
  4. If none of these are found or there was no styleHint(), "helvetica" will be searched for.
  5. If "helvetica" isn't found TQt will try the lastResortFamily().
  6. If the lastResortFamily() isn't found TQt will try the lastResortFont() which will always return a name of some kind.

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

  1. fixedPitch()
  2. pointSize() (see below)
  3. weight()
  4. italic()

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 TQFontInfo object can be used to determine the actual values used for drawing the text.

Examples: 

    TQFont f("Helvetica");
If you had both an Adobe and a Cronyx Helvetica, you might get either. 

    TQFont f1( "Helvetica [Cronyx]" );  // TQt 3.x
    TQFont f2( "Cronyx-Helvetica" );    // TQt 2.x compatibility
You can specify the foundry you want in the family name. Both fonts, f1 and f2, 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 TQFontInfo object, e.g. 

    TQFontInfo info( f1 );
    TQString family = info.family();

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

    TQFontMetrics fm( f1 );
    int pixelWidth = fm.width( "How many pixels wide is this text?" );
    int pixelHeight = fm.height();

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

See also TQFontMetrics, TQFontInfo, TQFontDatabase, TQApplication::setFont(), TQWidget::font, TQPainter::setFont(), TQFont::StyleHint, TQFont::Weight, Widget Appearance and Style, Graphics Classes, and Implicitly and Explicitly Shared Classes.

Member Type Documentation

TQFont::Script

This enum represents Unicode allocated scripts. For exhaustive coverage see The Unicode Standard Version 3.0. The following scripts are supported:

Modern European alphabetic scripts (left to right):

Middle Eastern scripts (right to left):

South and Southeast Asian scripts (left to right with few historical exceptions):

East Asian scripts (traditionally top-down, right to left, modern often horizontal left to right):

Additional scripts that do not fit well into the script categories above:

Symbols:

TQFont::Stretch

Predefined stretch values that follow the CSS naming convention.

See also setStretch() and stretch().

TQFont::StyleHint

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

TQFont::StyleStrategy

The style strategy tells the font matching 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:

TQFont::Weight

TQt 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 is ultralight, whilst 99 will be an extremely black.

This enum contains the predefined font weights:

Member Function Documentation

TQFont::TQFont ()

Constructs a font object that uses the application's default font.

See also TQApplication::setFont() and TQApplication::font().

TQFont::TQFont ( const TQString & family, int pointSize = 12, int weight = Normal, bool italic = FALSE )

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

If pointSize is <= 0 it is set to 1.

The family name may optionally also include a foundry name, e.g. "Helvetica [Cronyx]". (The TQt 2.x syntax, i.e. "Cronyx-Helvetica", is also supported.) 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 font matching algorithm.

See also Weight, setFamily(), setPointSize(), setWeight(), setItalic(), setStyleHint(), and TQApplication::font().

TQFont::TQFont ( const TQFont & font )

Constructs a font that is a copy of font.

TQFont::~TQFont ()

Destroys the font object and frees all allocated resources.

bool TQFont::bold () const

Returns TRUE if weight() is a value greater than TQFont::Normal; otherwise returns FALSE.

See also weight(), setBold(), and TQFontInfo::bold().

Example: chart/optionsform.cpp.

int TQFont::deciPointSize () const [protected]

Returns the point size in 1/10ths of a point.

The returned value will be -1 if the font size has been specified in pixels.

See also pointSize() and pointSizeFloat().

TQString TQFont::defaultFamily () const

Returns the family name that corresponds to the current style hint.

See also StyleHint, styleHint(), and setStyleHint().

TQFont TQFont::defaultFont () [static]

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

Please use TQApplication::font() instead.

bool TQFont::dirty () const [protected]

Returns TRUE if the font attributes have been changed and the font has to be (re)loaded; otherwise returns FALSE.

bool TQFont::exactMatch () const

Returns TRUE if a window system font exactly matching the settings of this font is available.

See also TQFontInfo.

TQString TQFont::family () const

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

See also setFamily(), substitutes(), and substitute().

Examples: chart/optionsform.cpp and fonts/simple-qfont-demo/viewer.cpp.

bool TQFont::fixedPitch () const

Returns TRUE if fixed pitch has been set; otherwise returns FALSE.

See also setFixedPitch() and TQFontInfo::fixedPitch().

bool TQFont::fromString ( const TQString & descrip )

Sets this font to match the description descrip. The description is a comma-separated list of the font attributes, as returned by toString().

See also toString() and operator>>().

HFONT TQFont::handle () const

Returns the window system handle to the font, for low-level access. Using this function is not portable.

void TQFont::insertSubstitution ( const TQString & familyName, const TQString & substituteName ) [static]

Inserts the family name substituteName into the substitution table for familyName.

See also insertSubstitutions(), removeSubstitution(), substitutions(), substitute(), and substitutes().

Example: fonts/simple-qfont-demo/viewer.cpp.

void TQFont::insertSubstitutions ( const TQString & familyName, const TQStringList & substituteNames ) [static]

Inserts the list of families substituteNames into the substitution list for familyName.

See also insertSubstitution(), removeSubstitution(), substitutions(), and substitute().

Example: fonts/simple-qfont-demo/viewer.cpp.

bool TQFont::isCopyOf ( const TQFont & 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 has been modified since. This is much stricter than equality.

See also operator=() and operator==().

bool TQFont::italic () const

Returns TRUE if italic has been set; otherwise returns FALSE.

See also setItalic().

Example: chart/optionsform.cpp.

TQString TQFont::key () const

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 TQMap.

TQString TQFont::lastResortFamily () const

Returns the "last resort" font family name.

The current implementation tries a wide variety of common fonts, returning the first one it finds. Is is possible that no family is found in which case a null string is returned.

See also lastResortFont().

TQString TQFont::lastResortFont () const

Returns a "last resort" font name for the font matching algorithm. This is used if the last resort family is not available. It will always return a name, if necessary returning something like "fixed" or "system".

The current implementation tries a wide variety of common fonts, returning the first one it finds. The implementation may change at any time, but this function will always return a string containing something.

It is theoretically possible that there really isn't a lastResortFont() in which case TQt will abort with an error message. We have not been able to identify a case where this happens. Please report it as a bug if it does, preferably with a list of the fonts you have installed.

See also lastResortFamily() and rawName().

bool TQFont::operator!= ( const TQFont & f ) const

Returns TRUE if this font is different from f; otherwise returns FALSE.

Two TQFonts are considered to be different if their font attributes are different. If rawMode() is enabled for both fonts, only the family fields are compared.

See also operator==().

TQFont & TQFont::operator= ( const TQFont & font )

Assigns font to this font and returns a reference to it.

bool TQFont::operator== ( const TQFont & f ) const

Returns TRUE if this font is equal to f; otherwise returns FALSE.

Two TQFonts are considered equal if their font attributes are equal. If rawMode() is enabled for both fonts, only the family fields are compared.

See also operator!=() and isCopyOf().

bool TQFont::overline () const

Returns TRUE if overline has been set; otherwise returns FALSE.

See also setOverline().

int TQFont::pixelSize () const

Returns the pixel size of the font if it was set with setPixelSize(). Returns -1 if the size was set with setPointSize() or setPointSizeFloat().

See also setPixelSize(), pointSize(), TQFontInfo::pointSize(), and TQFontInfo::pixelSize().

int TQFont::pointSize () const

Returns the point size of the font. Returns -1 if the font size was specified in pixels.

See also setPointSize(), deciPointSize(), and pointSizeFloat().

Examples: chart/optionsform.cpp and fonts/simple-qfont-demo/viewer.cpp.

float TQFont::pointSizeFloat () const

Returns the point size of the font. Returns -1 if the font size was specified in pixels.

See also pointSize(), setPointSizeFloat(), pixelSize(), TQFontInfo::pointSize(), and TQFontInfo::pixelSize().

void TQFont::qwsRenderToDisk ( bool all = TRUE )

Saves the glyphs in the font that have previously been accessed as a TQPF file. If all is TRUE (the default), then before saving, all glyphs are marked as used.

If the font is large and you are sure that only a subset of characters will ever be retquired on the target device, passing FALSE for the all parameter can save a significant amount of disk space.

Note that this function is only applicable on TQt/Embedded.

bool TQFont::rawMode () const

Returns TRUE if raw mode is used for font name matching; otherwise returns FALSE.

See also setRawMode() and rawName().

TQString TQFont::rawName () const

Returns the name of the font within the underlying window system.

On Windows, this is usually just the family name of a TrueType font.

On X11, it is an XLFD (X Logical Font Description). When TQt is build with Xft support on X11, the return value can be an Xft pattern or an XLFD.

Using the return value of this function is usually not portable.

See also setRawName().

void TQFont::removeSubstitution ( const TQString & familyName ) [static]

Removes all the substitutions for familyName.

See also insertSubstitutions(), insertSubstitution(), substitutions(), and substitute().

TQFont TQFont::resolve ( const TQFont & other ) const

Returns a new TQFont that has attributes copied from other.

void TQFont::setBold ( bool enable )

If enable is true sets the font's weight to TQFont::Bold; otherwise sets the weight to TQFont::Normal.

For finer boldness control use setWeight().

See also bold() and setWeight().

Examples: menu/menu.cpp and themes/metal.cpp.

void TQFont::setDefaultFont ( const TQFont & f ) [static]

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

Please use TQApplication::setFont() instead.

void TQFont::setFamily ( const TQString & family )

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]". (The TQt 2.x syntax, i.e. "Cronyx-Helvetica", is also supported.) 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 font matching algorithm.

See also family(), setStyleHint(), and TQFontInfo.

void TQFont::setFixedPitch ( bool enable )

If enable is TRUE, sets fixed pitch on; otherwise sets fixed pitch off.

See also fixedPitch() and TQFontInfo.

void TQFont::setItalic ( bool enable )

If enable is TRUE, italic is set on; otherwise italic is set off.

See also italic() and TQFontInfo.

Examples: fileiconview/qfileiconview.cpp, fonts/simple-qfont-demo/viewer.cpp, and themes/metal.cpp.

void TQFont::setOverline ( bool enable )

If enable is TRUE, sets overline on; otherwise sets overline off.

See also overline() and TQFontInfo.

void TQFont::setPixelSize ( int pixelSize )

Sets the font size to pixelSize pixels.

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

See also pixelSize().

Example: qwerty/qwerty.cpp.

void TQFont::setPixelSizeFloat ( float pixelSize )

This function is obsolete. It is provided to keep old source working. We strongly advise against using it in new code.

Sets the logical pixel height of font characters when shown on the screen to pixelSize.

void TQFont::setPointSize ( int pointSize )

Sets the point size to pointSize. The point size must be greater than zero.

See also pointSize() and setPointSizeFloat().

Example: fonts/simple-qfont-demo/viewer.cpp.

void TQFont::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.

See also pointSizeFloat(), setPointSize(), and setPixelSize().

void TQFont::setRawMode ( bool enable )

If enable is TRUE, turns raw mode on; otherwise turns raw mode off. This function only has an effect under X11.

If raw mode is enabled, TQt will search for an X font with a complete font name matching the family name, ignoring all other values set for the TQFont. If the font name matches several fonts, TQt will use the first font returned by X. TQFontInfo cannot be used to fetch information about a TQFont using raw mode (it will return the values set in the TQFont 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 choice.

See also rawMode() and setRawName().

void TQFont::setRawName ( const TQString & name )

Sets a font by its system specific name. The function is particularly useful under X, where system font settings (for example X resources) are usually available in XLFD (X Logical Font Description) form only. You can pass an XLFD as name to this function.

A font set with setRawName() is still a full-featured TQFont. It can be queried (for example with italic()) or modified (for example with setItalic()) and is therefore also suitable for rendering rich text.

If TQt's internal font database cannot resolve the raw name, the font becomes a raw font with name as its family.

Note that the present implementation does not 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 TQFont::setStretch ( int factor )

Sets the stretch factor for the font.

The stretch factor 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 default stretch factor is 100. The minimum stretch factor is 1, and the maximum stretch factor is 4000.

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

NOTE: TQFont cannot stretch XLFD fonts. When loading XLFD fonts on X11, the stretch factor is matched against a predefined set of values for the SETWIDTH_NAME field of the XLFD.

See also stretch() and TQFont::StyleStrategy.

void TQFont::setStrikeOut ( bool enable )

If enable is TRUE, sets strikeout on; otherwise sets strikeout off.

See also strikeOut() and TQFontInfo.

void TQFont::setStyleHint ( StyleHint hint, StyleStrategy strategy = PreferDefault )

Sets the style hint and strategy to hint and strategy, respectively.

If these aren't set explicitly the style hint will default to AnyStyle and the style strategy to PreferDefault.

TQt does not support style hints on X11 since this information is not provided by the window system.

See also StyleHint, styleHint(), StyleStrategy, styleStrategy(), and TQFontInfo.

Examples: desktop/desktop.cpp and fonts/simple-qfont-demo/viewer.cpp.

void TQFont::setStyleStrategy ( StyleStrategy s )

Sets the style strategy for the font to s.

See also TQFont::StyleStrategy.

void TQFont::setUnderline ( bool enable )

If enable is TRUE, sets underline on; otherwise sets underline off.

See also underline() and TQFontInfo.

Examples: fonts/simple-qfont-demo/viewer.cpp and menu/menu.cpp.

void TQFont::setWeight ( int weight )

Sets the weight the font to weight, which should be a value from the TQFont::Weight enumeration.

See also weight() and TQFontInfo.

Example: fonts/simple-qfont-demo/viewer.cpp.

int TQFont::stretch () const

Returns the stretch factor for the font.

See also setStretch().

bool TQFont::strikeOut () const

Returns TRUE if strikeout has been set; otherwise returns FALSE.

See also setStrikeOut().

StyleHint TQFont::styleHint () const

Returns the StyleHint.

The style hint affects the font matching algorithm. See TQFont::StyleHint for the list of strategies.

See also setStyleHint(), TQFont::StyleStrategy, and TQFontInfo::styleHint().

StyleStrategy TQFont::styleStrategy () const

Returns the StyleStrategy.

The style strategy affects the font matching algorithm. See TQFont::StyleStrategy for the list of strategies.

See also setStyleHint() and TQFont::StyleHint.

TQString TQFont::substitute ( const TQString & familyName ) [static]

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().

See also setFamily(), insertSubstitutions(), insertSubstitution(), and removeSubstitution().

TQStringList TQFont::substitutes ( const TQString & familyName ) [static]

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.

See also substitute(), insertSubstitutions(), insertSubstitution(), and removeSubstitution().

Example: fonts/simple-qfont-demo/viewer.cpp.

TQStringList TQFont::substitutions () [static]

Returns a sorted list of substituted family names.

See also insertSubstitution(), removeSubstitution(), and substitute().

TQString TQFont::toString () const

Returns a description of the font. The description is a comma-separated list of the attributes, perfectly suited for use in TQSettings.

See also fromString() and operator<<().

bool TQFont::underline () const

Returns TRUE if underline has been set; otherwise returns FALSE.

See also setUnderline().

int TQFont::weight () const

Returns the weight of the font which is one of the enumerated values from TQFont::Weight.

See also setWeight(), Weight, and TQFontInfo.

Related Functions

TQDataStream & operator<< ( TQDataStream & s, const TQFont & font )

Writes the font font to the data stream s. (toString() writes to a text stream.)

See also Format of the TQDataStream operators.

TQDataStream & operator>> ( TQDataStream & s, TQFont & font )

Reads the font font from the data stream s. (fromString() reads from a text stream.)

See also Format of the TQDataStream operators.

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TQt 3.3.8