QRawFont 類提供對字體單物理實例的訪問。 更多...
| 頭： | #include <QRawFont> |
| qmake: | QT += gui |
| Since: | Qt 4.8 |
該類在 Qt 4.8 引入。
| enum | AntialiasingType { PixelAntialiasing, SubPixelAntialiasing } |
| enum | LayoutFlag { SeparateAdvances, KernedAdvances, UseDesignMetrics } |
| flags | LayoutFlags |
| QRawFont (const QRawFont & other ) | |
| QRawFont (const QByteArray & fontData , qreal pixelSize , QFont::HintingPreference hintingPreference = QFont::PreferDefaultHinting) | |
| QRawFont (const QString & fileName , qreal pixelSize , QFont::HintingPreference hintingPreference = QFont::PreferDefaultHinting) | |
| QRawFont () | |
| QRawFont & | operator= (const QRawFont & other ) |
| ~QRawFont () | |
| QVector<QPointF> | advancesForGlyphIndexes (const QVector<quint32> & glyphIndexes , QRawFont::LayoutFlags layoutFlags ) const |
| QVector<QPointF> | advancesForGlyphIndexes (const QVector<quint32> & glyphIndexes ) const |
| bool | advancesForGlyphIndexes (const quint32 * glyphIndexes , QPointF * advances , int numGlyphs ) const |
| bool | advancesForGlyphIndexes (const quint32 * glyphIndexes , QPointF * advances , int numGlyphs , QRawFont::LayoutFlags layoutFlags ) const |
| QImage | alphaMapForGlyph (quint32 glyphIndex , QRawFont::AntialiasingType antialiasingType = SubPixelAntialiasing, const QTransform & transform = QTransform()) const |
| qreal | ascent () const |
| qreal | averageCharWidth () const |
| QRectF | boundingRect (quint32 glyphIndex ) const |
| qreal | capHeight () const |
| qreal | descent () const |
| QString | familyName () const |
| QByteArray | fontTable (const char * tagName ) const |
| bool | glyphIndexesForChars (const QChar * chars , int numChars , quint32 * glyphIndexes , int * numGlyphs ) const |
| QVector<quint32> | glyphIndexesForString (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 |
| QPainterPath | pathForGlyph (quint32 glyphIndex ) const |
| qreal | pixelSize () const |
| void | setPixelSize (qreal pixelSize ) |
| QFont::Style | style () const |
| QString | styleName () const |
| QList<QFontDatabase::WritingSystem> | supportedWritingSystems () const |
| bool | supportsCharacter (QChar character ) const |
| bool | supportsCharacter (uint ucs4 ) const |
| void | swap (QRawFont & other ) |
| qreal | underlinePosition () const |
| qreal | unitsPerEm () const |
| int | weight () const |
| qreal | xHeight () const |
| bool | operator!= (const QRawFont & other ) const |
| bool | operator== (const QRawFont & other ) const |
| QRawFont | fromFont (const QFont & font , QFontDatabase::WritingSystem writingSystem = QFontDatabase::Any) |
| uint | qHash (const QRawFont & font , uint seed = 0) |
注意： QrawFont 是低級類。對於大多數目的 QFont 是更閤適的類。
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.
Therefore, Qt's QFont class really represents a query for fonts. When text is interpreted, Qt 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 macOS. For other font back-ends, the APIs will be disabled.
QRawFont can be constructed in a number of ways:
QRawFont is considered local to the thread in which it is constructed (either using a constructor, or by calling loadFromData () 或 loadFromFile ()). The QRawFont cannot be moved to a different thread, but will have to be recreated in the thread in question.
注意： 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.
This enum represents the different ways a glyph can be rasterized in the function alphaMapForGlyph ().
| 常量 | 值 | 描述 |
|---|---|---|
QRawFont::PixelAntialiasing
|
0
|
Will 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::SubPixelAntialiasing
|
1
|
Will 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. |
此枚舉告訴函數 advancesForGlyphIndexes () how to calculate the advances.
| 常量 | 值 | 描述 |
|---|---|---|
QRawFont::SeparateAdvances
|
0
|
Will calculate the advance for each glyph separately. |
QRawFont::KernedAdvances
|
1
|
Will apply kerning between adjacent glyphs. Note that OpenType GPOS based kerning is currently not supported. |
QRawFont::UseDesignMetrics
|
2
|
Use design metrics instead of hinted metrics adjusted to the resolution of the paint device. Can be OR-ed with any of the options above. |
該枚舉在 Qt 5.1 引入或被修改。
LayoutFlags 類型是 typedef 對於 QFlags <LayoutFlag>。它存儲 LayoutFlag 值的 OR 組閤。
Creates a QRawFont which is a copy of other .
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 .
注意： The data must contain a TrueType or OpenType font.
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 .
注意： The referenced file must contain a TrueType or OpenType font.
構造無效 QRawFont。
賦值 other 到此 QRawFont .
銷毀 QRawFont
返迴 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. How the advances are calculated is controlled by layoutFlags .
該函數在 Qt 5.1 引入。
另請參閱 QTextLine::horizontalAdvance () 和 QFontMetricsF::width ().
這是重載函數。
返迴 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 advance of each glyph is calculated separately.
另請參閱 QTextLine::horizontalAdvance () 和 QFontMetricsF::width ().
這是重載函數。
返迴 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. The advance of each glyph is calculated separately
另請參閱 QTextLine::horizontalAdvance () 和 QFontMetricsF::width ().
返迴 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. How the advances are calculated is controlled by layoutFlags .
該函數在 Qt 5.1 引入。
另請參閱 QTextLine::horizontalAdvance () 和 QFontMetricsF::width ().
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 the font is a color font, then the resulting image will contain the rendered glyph at the current pixel size. In this case, the antialiasingType 將被忽略。
否則，若 antialiasingType 被設為 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.
另請參閱 pathForGlyph () 和 QPainter::drawGlyphRun ().
返迴上升為此 QRawFont 以像素為單位。
字體的上升是從基綫到字符最高位置的延伸距離。實踐中，一些字體設計者打破瞭此規則，如：當在字符頂部放置多個重音時 (或為容納外來語言中的不尋常字符)，所以此值很小是可能的 (盡管罕見)。
另請參閱 QFontMetricsF::ascent ().
Returns the average character width of this QRawFont 以像素為單位。
另請參閱 QFontMetricsF::averageCharWidth ().
Returns the smallest rectangle containing the glyph with the given glyphIndex .
該函數在 Qt 5.0 引入。
Returns the cap height of this QRawFont 以像素為單位。
The cap height of a font is the height of a capital letter above the baseline. It specifically is the height of capital letters that are flat - such as H or I - as opposed to round letters such as O, or pointed letters like A, both of which may display overshoot.
該函數在 Qt 5.8 引入。
另請參閱 QFontMetricsF::capHeight ().
返迴下降為此 QRawFont 以像素為單位。
下降是從基綫到字符最低點的延伸距離。實踐中，一些字體設計者打破瞭此規則，如：為容納外來語言中的不尋常字符，所以此值很小是可能的 (盡管罕見)。
另請參閱 QFontMetricsF::descent ().
返迴係列名稱為此 QRawFont .
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.
[static]
QRawFont
QRawFont::
fromFont
(const
QFont
&
font
,
QFontDatabase::WritingSystem
writingSystem
= QFontDatabase::Any)
Fetches the physical representation based on a font query. The physical font returned is the font that will be preferred by Qt in order to display text in the selected writingSystem .
警告： This function is potentially expensive and should not be called in performance sensitive code.
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 .
另請參閱 glyphIndexesForString (), advancesForGlyphIndexes (), QGlyphRun , QTextLayout::glyphRuns ()，和 QTextFragment::glyphRuns ().
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.
另請參閱 advancesForGlyphIndexes (), glyphIndexesForChars (), QGlyphRun , QTextLayout::glyphRuns ()，和 QTextFragment::glyphRuns ().
Returns the hinting preference used to construct this QRawFont .
另請參閱 QFont::hintingPreference ().
返迴
true
若
QRawFont
is valid and false otherwise.
返迴行間距為此 QRawFont 以像素為單位。
這是自然行間的間距。
另請參閱 QFontMetricsF::leading ().
Returns the thickness for drawing lines (underline, overline, etc.) along with text drawn in this font.
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.
另請參閱 loadFromFile ().
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.
另請參閱 loadFromData ().
返迴字體中最寬字符的寬度。
另請參閱 QFontMetricsF::maxWidth ().
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.
另請參閱 alphaMapForGlyph () 和 QPainterPath::addText ().
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.
另請參閱 setPixelSize ().
Sets the pixel size with which this font should be rendered to pixelSize .
另請參閱 pixelSize ().
返迴樣式為此 QRawFont .
另請參閱 QFont::style ().
Returns the style name of this QRawFont .
另請參閱 QFont::styleName ().
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.
注意： 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.
另請參閱 supportsCharacter ().
返迴
true
if the font has a glyph that corresponds to the given
character
.
另請參閱 supportedWritingSystems ().
這是重載函數。
返迴
true
if the font has a glyph that corresponds to the UCS-4 encoded character
ucs4
.
另請參閱 supportedWritingSystems ().
交換此原生字體與 other 。此函數非常快且從不失敗。
該函數在 Qt 5.0 引入。
Returns the position from baseline for drawing underlines below the text rendered with this font.
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.
另請參閱 pixelSize () 和 setPixelSize ().
返迴粗細為此 QRawFont .
另請參閱 QFont::weight ().
返迴 xHeight 為此 QRawFont 以像素為單位。
This is often but not always the same as the height of the character 'x'.
另請參閱 QFontMetricsF::xHeight ().
返迴
true
若此
QRawFont
不等於
other
。否則，返迴
false
.
返迴
true
若此
QRawFont
等於
other
。否則，返迴
false
.
返迴哈希值為 font 。若指定， seed 用於初始化哈希。
該函數在 Qt 5.8 引入。