CopperSpice API  1.7.2
QRawFont Class Reference

The QRawFont class provides access to a single physical instance of a font. More...

Public Types

enum  AntialiasingType
 

Public Methods

 QRawFont ()
 
 QRawFont (const QByteArray &fontData, qreal pixelSize, QFont::HintingPreference hintingPreference=QFont::PreferDefaultHinting)
 
 QRawFont (const QRawFont &other)
 
 QRawFont (const QString &fileName, qreal pixelSize, QFont::HintingPreference hintingPreference=QFont::PreferDefaultHinting)
 
 ~QRawFont ()
 
bool advancesForGlyphIndexes (const quint32 *glyphIndexes, QPointF *advances, int numGlyphs) const
 
bool advancesForGlyphIndexes (const quint32 *glyphIndexes, QPointF *advances, int numGlyphs, LayoutFlags layoutFlags) const
 
QVector< QPointFadvancesForGlyphIndexes (const QVector< quint32 > &glyphIndexes) const
 
QVector< QPointFadvancesForGlyphIndexes (const QVector< quint32 > &glyphIndexes, LayoutFlags layoutFlags) const
 
QImage alphaMapForGlyph (quint32 glyphIndex, AntialiasingType antialiasingType=SubPixelAntialiasing, const QTransform &transform=QTransform ()) const
 
qreal ascent () const
 
qreal averageCharWidth () const
 
QRectF boundingRect (quint32 glyphIndex) const
 
qreal descent () const
 
QString familyName () const
 
QByteArray fontTable (const char *tagName) const
 
bool glyphIndexesForChars (QStringView str, quint32 *glyphIndexes, int *numGlyphs) const
 
QVector< quint32glyphIndexesForString (const QString &text) const
 
QFont::HintingPreference hintingPreference () const
 
bool isValid () const
 
qreal leading () const
 
qreal lineThickness () const
 
void loadFromData (const QByteArray &fontData, qreal pixelSize, QFont::HintingPreference hintingPreference)
 
void loadFromFile (const QString &fileName, qreal pixelSize, QFont::HintingPreference hintingPreference)
 
qreal maxCharWidth () const
 
bool operator!= (const QRawFont &other) const
 
QRawFont & operator= (const QRawFont &other)
 
QRawFont & operator= (QRawFont &&other)
 
bool operator== (const QRawFont &other) const
 
QPainterPath pathForGlyph (quint32 glyphIndex) const
 
qreal pixelSize () const
 
void setPixelSize (qreal pixelSize)
 
QFont::Style style () const
 
QString styleName () const
 
QList< QFontDatabase::WritingSystemsupportedWritingSystems () const
 
bool supportsCharacter (QChar character) const
 
bool supportsCharacter (quint32 ucs4) const
 
void swap (QRawFont &other)
 
qreal underlinePosition () const
 
qreal unitsPerEm () const
 
int weight () const
 
qreal xHeight () const
 

Static Public Methods

static QRawFont fromFont (const QFont &font, QFontDatabase::WritingSystem writingSystem=QFontDatabase::Any)
 

Friends

class QTextLayout
 

Detailed Description

The QRawFont class provides access to a single physical instance of a font.

Note
QRawFont is a low level class. For most purposes QFont is a more appropriate class.

Most commonly, when presenting text in a user interface, the exact fonts used to render the characters is to some extent unknown. This can be the case for several reasons: For instance, the actual, physical fonts present on the target system could be unexpected to the developers, or the text could contain user selected styles, sizes or writing systems that are not supported by font chosen in the code.

The CopperSpice QFont class really represents a query for fonts. When text is interpreted, CopperSpice will do its best to match the text to the query, but depending on the support, different fonts can be used behind the scenes.

For most use cases, this is both expected and necessary, as it minimizes the possibility of text in the user interface being undisplayable. In some cases, however, more direct control over the process might be useful. It is for these use cases the QRawFont class exists.

A QRawFont object represents a single, physical instance of a given font in a given pixel size. I.e. in the typical case it represents a set of TrueType or OpenType font tables and uses a user specified pixel size to convert metrics into logical pixel units. It can be used in combination with the QGlyphRun class to draw specific glyph indexes at specific positions, and also have accessors to some relevant data in the physical font.

QRawFont only provides support for the main font technologies: GDI and DirectWrite on Windows platforms, FreeType on Linux platforms and CoreText on OS X. For other font back-ends, the APIs will be disabled.

QRawFont can be constructed in a number of ways:

  • It can be constructed by calling QTextLayout::glyphs() or QTextFragment::glyphs(). The returned QGlyphs objects will contain QRawFont objects which represent the actual fonts used to render each portion of the text.
  • It can be constructed by passing a QFont object to QRawFont::fromFont(). The function will return a QRawFont object representing the font that will be selected as response to the QFont query and the selected writing system.
  • It can be constructed by passing a file name or QByteArray directly to the QRawFont constructor, or by calling loadFromFile() or loadFromData(). In this case, the font will not be registered in QFontDatabase, and it will not be available as part of regular font selection.

QRawFont is considered local to the thread in which it is constructed (either using a constructor, or by calling loadFromData() or loadFromFile()). The QRawFont can not be moved to a different thread, but will have to be recreated in the thread in question.

Note
For the requirement of caching glyph indexes and font selections for static text to avoid reshaping and relayouting in the inner loop of an application, a better choice is the QStaticText class, since it optimizes the memory cost of the cache and also provides the possibility of paint engine specific caches for an additional speed-up.
See also
QTextLine::horizontalAdvance(), QFontMetricsF::width()

Member Enumeration Documentation

This enum represents the different ways a glyph can be rasterized in the function alphaMapForGlyph().

ConstantValueDescription
QRawFont::PixelAntialiasing0Will rasterize by measuring the coverage of the shape on whole pixels. The returned image contains the alpha values of each pixel based on the coverage of the glyph shape.
QRawFont::SubPixelAntialiasing1Will rasterize by measuring the coverage of each subpixel, returning a separate alpha value for each of the red, green and blue components of each pixel.

Constructor & Destructor Documentation

QRawFont::QRawFont ( )

Constructs an invalid QRawFont.

QRawFont::QRawFont ( const QString fileName,
qreal  pixelSize,
QFont::HintingPreference  hintingPreference = QFont::PreferDefaultHinting 
)

Constructs a QRawFont representing the font contained in the file referenced by fileName for the size (in pixels) given by pixelSize, and using the hinting preference specified by hintingPreference.

Note
The referenced file must contain a TrueType or OpenType font.
QRawFont::QRawFont ( const QByteArray fontData,
qreal  pixelSize,
QFont::HintingPreference  hintingPreference = QFont::PreferDefaultHinting 
)

Constructs a QRawFont representing the font contained in the supplied fontData for the size (in pixels) given by pixelSize, and using the hinting preference specified by hintingPreference.

Note
The data must contain a TrueType or OpenType font.
QRawFont::QRawFont ( const QRawFont &  other)

Creates a QRawFont which is a copy of other.

QRawFont::~QRawFont ( )

Destroys the QRawFont

Method Documentation

bool QRawFont::advancesForGlyphIndexes ( const quint32 glyphIndexes,
QPointF advances,
int  numGlyphs 
) const

Returns the QRawFont's advances for each of the glyphIndexes in pixel units. The advances give the distance from the position of a given glyph to where the next glyph should be drawn to make it appear as if the two glyphs are unspaced. The glyph indexes are given with the array glyphIndexes while the results are returned through advances, both of them must have numGlyphs elements.

See also
QTextLine::horizontalAdvance(), QFontMetricsF::width()
bool QRawFont::advancesForGlyphIndexes ( const quint32 glyphIndexes,
QPointF advances,
int  numGlyphs,
LayoutFlags  layoutFlags 
) const

Documentation pending.

QVector< QPointF > QRawFont::advancesForGlyphIndexes ( const QVector< quint32 > &  glyphIndexes) const
inline

Returns the QRawFont's advances for each of the glyphIndexes in pixel units. The advances give the distance from the position of a given glyph to where the next glyph should be drawn to make it appear as if the two glyphs are unspaced.

See also
QTextLine::horizontalAdvance(), QFontMetricsF::width()
QVector< QPointF > QRawFont::advancesForGlyphIndexes ( const QVector< quint32 > &  glyphIndexes,
QRawFont::LayoutFlags  layoutFlags 
) const
inline

Documentation pending.

QImage QRawFont::alphaMapForGlyph ( quint32  glyphIndex,
AntialiasingType  antialiasingType = SubPixelAntialiasing,
const QTransform transform = QTransform() 
) const

This function returns a rasterized image of the glyph at the given glyphIndex in the underlying font, using the transform specified. If the QRawFont is not valid, this function will return an invalid QImage.

If antialiasingType is set to QRawFont::SubPixelAntialiasing, then the resulting image will be in QImage::Format_RGB32 and the RGB values of each pixel will represent the subpixel opacities of the pixel in the rasterization of the glyph. Otherwise, the image will be in the format of QImage::Format_Indexed8 and each pixel will contain the opacity of the pixel in the rasterization.

See also
pathForGlyph(), QPainter::drawGlyphRun()
qreal QRawFont::ascent ( ) const

Returns the ascent of this QRawFont in pixel units.

See also
QFontMetricsF::ascent()
qreal QRawFont::averageCharWidth ( ) const

Returns the average character width of this QRawFont in pixel units.

See also
QFontMetricsF::averageCharWidth()
QRectF QRawFont::boundingRect ( quint32  glyphIndex) const

Documentation pending.

qreal QRawFont::descent ( ) const

Returns the descent of this QRawFont in pixel units.

See also
QFontMetricsF::descent()
QString QRawFont::familyName ( ) const

Returns the family name of this QRawFont.

QByteArray QRawFont::fontTable ( const char *  tagName) const

Retrieves the sfnt table named tagName from the underlying physical font, or an empty byte array if no such table was found. The returned font table's byte order is Big Endian, like the sfnt format specifies. The tagName must be four characters long and should be formatted in the default endianness of the current platform.

QRawFont QRawFont::fromFont ( const QFont font,
QFontDatabase::WritingSystem  writingSystem = QFontDatabase::Any 
)
static

Fetches the physical representation based on a font query. The physical font returned is the font that will be preferred by CopperSpice in order to display text in the selected writingSystem.

bool QRawFont::glyphIndexesForChars ( QStringView  str,
quint32 glyphIndexes,
int *  numGlyphs 
) const

Converts a string of unicode points to glyph indexes using the CMAP table in the underlying font. The function works like glyphIndexesForString() except it take an array (chars), the results will be returned though glyphIndexes array and number of glyphs will be set in numGlyphs. The size of glyphIndexes array must be at least numChars, if that's still not enough, this function will return false, then you can resize glyphIndexes from the size returned in numGlyphs.

See also
glyphIndexesForString(), advancesForGlyphIndexes(), QGlyphRun, QTextLayout::glyphRuns(), QTextFragment::glyphRuns()
QVector< quint32 > QRawFont::glyphIndexesForString ( const QString text) const

Converts the string of unicode points given by text to glyph indexes using the CMAP table in the underlying font, and returns a vector containing the result.

Note that, in cases where there are other tables in the font that affect the shaping of the text, the returned glyph indexes will not correctly represent the rendering of the text. To get the correctly shaped text, you can use QTextLayout to lay out and shape the text, then call QTextLayout::glyphs() to get the set of glyph index list and QRawFont pairs.

See also
advancesForGlyphIndexes(), glyphIndexesForChars(), QGlyphRun, QTextLayout::glyphRuns(), QTextFragment::glyphRuns()
QFont::HintingPreference QRawFont::hintingPreference ( ) const

Returns the hinting preference used to construct this QRawFont.

See also
QFont::hintingPreference()
bool QRawFont::isValid ( ) const

Returns true if the QRawFont is valid and false otherwise.

qreal QRawFont::leading ( ) const

Returns the leading of this QRawFont in pixel units.

See also
QFontMetricsF::leading()
qreal QRawFont::lineThickness ( ) const

Documentation pending.

void QRawFont::loadFromData ( const QByteArray fontData,
qreal  pixelSize,
QFont::HintingPreference  hintingPreference 
)

Replaces the current QRawFont with the font contained in the supplied fontData for the size (in pixels) given by pixelSize, and using the hinting preference specified by hintingPreference.

The fontData must contain a TrueType or OpenType font.

See also
loadFromFile()
void QRawFont::loadFromFile ( const QString fileName,
qreal  pixelSize,
QFont::HintingPreference  hintingPreference 
)

Replaces the current QRawFont with the contents of the file referenced by fileName for the size (in pixels) given by pixelSize, and using the hinting preference specified by hintingPreference.

The file must reference a TrueType or OpenType font.

See also
loadFromData()
qreal QRawFont::maxCharWidth ( ) const

Returns the width of the widest character in the font.

See also
QFontMetricsF::maxWidth()
bool QRawFont::operator!= ( const QRawFont &  other) const
inline

Returns true if this QRawFont is not equal to other. Otherwise, returns false.

QRawFont & QRawFont::operator= ( const QRawFont &  other)

Assigns other to this QRawFont.

QRawFont & QRawFont::operator= ( QRawFont &&  other)
inline

Move assigns from other and returns a reference to this object.

bool QRawFont::operator== ( const QRawFont &  other) const

Returns true if this QRawFont is equal to other. Otherwise, returns false.

QPainterPath QRawFont::pathForGlyph ( quint32  glyphIndex) const

This function returns the shape of the glyph at a given glyphIndex in the underlying font if the QRawFont is valid. Otherwise, it returns an empty QPainterPath.

The returned glyph will always be unhinted.

See also
alphaMapForGlyph(), QPainterPath::addText()
qreal QRawFont::pixelSize ( ) const

Returns the pixel size set for this QRawFont. The pixel size affects how glyphs are rasterized, the size of glyphs returned by pathForGlyph(), and is used to convert internal metrics from design units to logical pixel units.

See also
setPixelSize()
void QRawFont::setPixelSize ( qreal  pixelSize)

Sets the pixel size with which this font should be rendered to pixelSize.

See also
pixelSize()
QFont::Style QRawFont::style ( ) const

Returns the style of this QRawFont.

See also
QFont::style()
QString QRawFont::styleName ( ) const

Returns the style name of this QRawFont.

See also
QFont::styleName()
QList< QFontDatabase::WritingSystem > QRawFont::supportedWritingSystems ( ) const

Returns a list of writing systems supported by the font according to designer supplied information in the font file. Please note that this does not guarantee support for a specific unicode point in the font. You can use the supportsCharacter() to check support for a single, specific character.

Note
The list is determined based on the unicode ranges and codepage ranges set in the font's OS/2 table and requires such a table to be present in the underlying font file.
See also
supportsCharacter()
bool QRawFont::supportsCharacter ( QChar  character) const

Returns true if the font has a glyph that corresponds to the given character.

See also
supportedWritingSystems()
bool QRawFont::supportsCharacter ( quint32  ucs4) const

Returns true if the font has a glyph that corresponds to the UCS-4 encoded character ucs4.

See also
supportedWritingSystems()
void QRawFont::swap ( QRawFont &  other)
inline

Swaps the raw font other with this raw font. This operation is very fast and never fails.

qreal QRawFont::underlinePosition ( ) const

Documentation pending.

qreal QRawFont::unitsPerEm ( ) const

Returns the number of design units define the width and height of the em square for this QRawFont. This value is used together with the pixel size when converting design metrics to pixel units, as the internal metrics are specified in design units and the pixel size gives the size of 1 em in pixels.

See also
pixelSize(), setPixelSize()
int QRawFont::weight ( ) const

Returns the weight of this QRawFont.

See also
QFont::weight()
qreal QRawFont::xHeight ( ) const

Returns the xHeight of this QRawFont in pixel units.

See also
QFontMetricsF::xHeight()