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QFontDatabase 类

QFontDatabase 类提供底层窗口系统中可用字体的有关信息。 更多...

头： #include <QFontDatabase>
CMake: find_package(Qt6 COMPONENTS Gui REQUIRED)
target_link_libraries(mytarget PRIVATE Qt6::Gui)
qmake: QT += gui

注意： 此类的所有函数 thread-safe .

公共类型

enum SystemFont { GeneralFont, FixedFont, TitleFont, SmallestReadableFont }
enum WritingSystem { Any, Latin, Greek, Cyrillic, Armenian, …, Nko }

静态公共成员

int addApplicationFont (const QString & fileName )
int addApplicationFontFromData (const QByteArray & fontData )
QStringList applicationFontFamilies (int id )
bool bold (const QString & family , const QString & style )
QStringList families (QFontDatabase::WritingSystem writingSystem = Any)
QFont font (const QString & family , const QString & style , int pointSize )
bool isBitmapScalable (const QString & family , const QString & style = QString())
bool isFixedPitch (const QString & family , const QString & style = QString())
bool isPrivateFamily (const QString & family )
bool isScalable (const QString & family , const QString & style = QString())
bool isSmoothlyScalable (const QString & family , const QString & style = QString())
bool italic (const QString & family , const QString & style )
QList<int> pointSizes (const QString & family , const QString & styleName = QString())
bool removeAllApplicationFonts ()
bool removeApplicationFont (int id )
QList<int> smoothSizes (const QString & family , const QString & styleName )
QList<int> standardSizes ()
QString styleString (const QFont & font )
QString styleString (const QFontInfo & fontInfo )
QStringList styles (const QString & family )
QFont systemFont (QFontDatabase::SystemFont type )
int weight (const QString & family , const QString & style )
QString writingSystemName (QFontDatabase::WritingSystem writingSystem )
QString writingSystemSample (QFontDatabase::WritingSystem writingSystem )
QList<QFontDatabase::WritingSystem> writingSystems ()
QList<QFontDatabase::WritingSystem> writingSystems (const QString & family )

详细描述

此类的最常见用法是查询数据库为列表字体 families () 和为 pointSizes () 和 styles () 可用于各系列。替代 pointSizes () 是 smoothSizes () 返回给定系列的大小且风格看起来很有吸引力。

若字体系列可用于两个或更多铸造厂，则铸造厂名包括在系列名中；例如：Helvetica [Adobe] 和 Helvetica [Cronyx]。当指定系列时，可以使用以连字符连接的旧 foundry-family 格式，或括在方括号内的 family [foundry] 格式；例如：Cronyx-Helvetica 或 Helvetica [Cronyx]。若有铸造厂，系列始终使用括在方括号内的格式，情况就像值返回通过 families ().

font () 函数返回 QFont 的给定系列、样式及点大小。

可以校验系列和风格的组合，看它是否为 italic () 或 bold ()，及检索其 weight ()。同样，可以调用 isBitmapScalable (), isSmoothlyScalable (), isScalable () 和 isFixedPitch ().

使用 styleString () 以获取样式的文本版本。

QFontDatabase 类提供了一些帮手函数，例如 standardSizes ()。可以检索书写系统的描述使用 writingSystemName ()，和书写系统的字符样本采用 writingSystemSample ().

范例： 

QTreeWidget fontTree;
fontTree.setColumnCount(2);
fontTree.setHeaderLabels(QStringList() << "Font" << "Smooth Sizes");
const QStringList fontFamilies = QFontDatabase::families();
for (const QString &family : fontFamilies) {
    QTreeWidgetItem *familyItem = new QTreeWidgetItem(&fontTree);
    familyItem->setText(0, family);
    const QStringList fontStyles = QFontDatabase::styles(family);
    for (const QString &style : fontStyles) {
        QTreeWidgetItem *styleItem = new QTreeWidgetItem(familyItem);
        styleItem->setText(0, style);
        QString sizes;
        const QList<int> smoothSizes = QFontDatabase::smoothSizes(family, style);
        for (const auto &points : smoothSizes)
            sizes += QString::number(points) + ' ';
        styleItem->setText(1, sizes.trimmed());
    }
}

此范例获取字体系列的列表，各系列的样式列表，及可用于系列和样式的各组合的点大小，在树视图中显示此信息。

另请参阅 QFont , QFontInfo , QFontMetrics ，和 字符映射范例 .

成员类型文档编制

[since 5.2] enum QFontDatabase:: SystemFont

常量 值 描述
QFontDatabase::GeneralFont 0 默认系统字体。
QFontDatabase::FixedFont 1 系统推荐的固定字体。
QFontDatabase::TitleFont 2 用于标题的系统标准字体。
QFontDatabase::SmallestReadableFont 3 最小可读系统字体。

该枚举在 Qt 5.2 引入或被修改。

enum QFontDatabase:: WritingSystem

常量 值 描述
QFontDatabase::Any 0
QFontDatabase::Latin 1
QFontDatabase::Greek 2
QFontDatabase::Cyrillic 3
QFontDatabase::Armenian 4
QFontDatabase::Hebrew 5
QFontDatabase::Arabic 6
QFontDatabase::Syriac 7
QFontDatabase::Thaana 8
QFontDatabase::Devanagari 9
QFontDatabase::Bengali 10
QFontDatabase::Gurmukhi 11
QFontDatabase::Gujarati 12
QFontDatabase::Oriya 13
QFontDatabase::Tamil 14
QFontDatabase::Telugu 15
QFontDatabase::Kannada 16
QFontDatabase::Malayalam 17
QFontDatabase::Sinhala 18
QFontDatabase::Thai 19
QFontDatabase::Lao 20
QFontDatabase::Tibetan 21
QFontDatabase::Myanmar 22
QFontDatabase::Georgian 23
QFontDatabase::Khmer 24
QFontDatabase::SimplifiedChinese 25
QFontDatabase::TraditionalChinese 26
QFontDatabase::Japanese 27
QFontDatabase::Korean 28
QFontDatabase::Vietnamese 29
QFontDatabase::Symbol 30
QFontDatabase::Other Symbol (如同 Symbol)
QFontDatabase::Ogham 31
QFontDatabase::Runic 32
QFontDatabase::Nko 33

成员函数文档编制

[static] int QFontDatabase:: addApplicationFont (const QString & fileName )

Loads the font from the file specified by fileName and makes it available to the application. An ID is returned that can be used to remove the font again with removeApplicationFont () or to retrieve the list of family names contained in the font.

函数返回 -1，若无法加载字体。

Currently only TrueType fonts, TrueType font collections, and OpenType fonts are supported.

注意： Adding application fonts on Unix/X11 platforms without fontconfig is currently not supported.

另请参阅 addApplicationFontFromData (), applicationFontFamilies ()，和 removeApplicationFont ().

[static] int QFontDatabase:: addApplicationFontFromData (const QByteArray & fontData )

Loads the font from binary data specified by fontData and makes it available to the application. An ID is returned that can be used to remove the font again with removeApplicationFont () or to retrieve the list of family names contained in the font.

函数返回 -1，若无法加载字体。

Currently only TrueType fonts and TrueType font collections are supported.

注意： Adding application fonts on Unix/X11 platforms without fontconfig is currently not supported.

另请参阅 addApplicationFont (), applicationFontFamilies ()，和 removeApplicationFont ().

[static] QStringList QFontDatabase:: applicationFontFamilies ( int id )

Returns a list of font families for the given application font identified by id .

另请参阅 addApplicationFont () 和 addApplicationFontFromData ().

[static] bool QFontDatabase:: bold (const QString & family , const QString & style )

返回 true 若字体拥有系列 family 和样式 style 为加粗；否则返回 false .

另请参阅 italic () 和 weight ().

[static] QStringList QFontDatabase:: families ( QFontDatabase::WritingSystem writingSystem = Any)

返回可用字体系列的排序列表，支持 writingSystem .

若系列存在于几个铸造厂，则该字体的返回名称形式为 family [foundry]。范例：Times [Adobe]、Times [Cronyx]、Palatino。

另请参阅 writingSystems ().

[static] QFont QFontDatabase:: font (const QString & family , const QString & style , int pointSize )

返回 QFont object that has family family , style style and point size pointSize . If no matching font could be created, a QFont object that uses the application's default font is returned.

[static] bool QFontDatabase:: isBitmapScalable (const QString & family , const QString & style = QString())

返回 true 若字体拥有系列 family 和样式 style is a scalable bitmap font; otherwise returns false . Scaling a bitmap font usually produces an unattractive hardly readable result, because the pixels of the font are scaled. If you need to scale a bitmap font it is better to scale it to one of the fixed sizes returned by smoothSizes ().

另请参阅 isScalable () 和 isSmoothlyScalable ().

[static] bool QFontDatabase:: isFixedPitch (const QString & family , const QString & style = QString())

返回 true 若字体拥有系列 family 和样式 style is fixed pitch; otherwise returns false .

[static, since 5.5] bool QFontDatabase:: isPrivateFamily (const QString & family )

返回 true if and only if the family font family is private.

This happens, for instance, on macOS and iOS, where the system UI fonts are not accessible to the user. For completeness, QFontDatabase::families () returns all font families, including the private ones. You should use this function if you are developing a font selection control in order to keep private fonts hidden.

该函数在 Qt 5.5 引入。

另请参阅 families ().

[static] bool QFontDatabase:: isScalable (const QString & family , const QString & style = QString())

返回 true 若字体拥有系列 family 和样式 style is scalable; otherwise returns false .

另请参阅 isBitmapScalable () 和 isSmoothlyScalable ().

[static] bool QFontDatabase:: isSmoothlyScalable (const QString & family , const QString & style = QString())

返回 true 若字体拥有系列 family 和样式 style is smoothly scalable; otherwise returns false 。若此函数返回 true , it's safe to scale this font to any size, and the result will always look attractive.

另请参阅 isScalable () 和 isBitmapScalable ().

[static] bool QFontDatabase:: italic (const QString & family , const QString & style )

返回 true 若字体拥有系列 family 和样式 style 为斜体；否则返回 false .

另请参阅 weight () 和 bold ().

[static] QList < int > QFontDatabase:: pointSizes (const QString & family , const QString & styleName = QString())

Returns a list of the point sizes available for the font that has family family 和样式 styleName . The list may be empty.

另请参阅 smoothSizes () 和 standardSizes ().

[static] bool QFontDatabase:: removeAllApplicationFonts ()

Removes all application-local fonts previously added using addApplicationFont () 和 addApplicationFontFromData ().

返回 true 若字体卸载成功；否则返回 false .

另请参阅 removeApplicationFont (), addApplicationFont ()，和 addApplicationFontFromData ().

[static] bool QFontDatabase:: removeApplicationFont ( int id )

Removes the previously loaded application font identified by id 。返回 true if unloading of the font succeeded; otherwise returns false .

另请参阅 removeAllApplicationFonts (), addApplicationFont ()，和 addApplicationFontFromData ().

[static] QList < int > QFontDatabase:: smoothSizes (const QString & family , const QString & styleName )

Returns the point sizes of a font that has family family 和样式 styleName that will look attractive. The list may be empty. For non-scalable fonts and bitmap scalable fonts, this function is equivalent to pointSizes ().

另请参阅 pointSizes () 和 standardSizes ().

[static] QList < int > QFontDatabase:: standardSizes ()

返回标准字体大小的列表。

另请参阅 smoothSizes () 和 pointSizes ().

[static] QString QFontDatabase:: styleString (const QFont & font )

Returns a string that describes the style of the font . For example, "Bold Italic", "Bold", "Italic" or "Normal". An empty string may be returned.

[static] QString QFontDatabase:: styleString (const QFontInfo & fontInfo )

Returns a string that describes the style of the fontInfo . For example, "Bold Italic", "Bold", "Italic" or "Normal". An empty string may be returned.

[static] QStringList QFontDatabase:: styles (const QString & family )

Returns a list of the styles available for the font family family . Some example styles: "Light", "Light Italic", "Bold", "Oblique", "Demi". The list may be empty.

另请参阅 families ().

[static, since 5.2] QFont QFontDatabase:: systemFont ( QFontDatabase::SystemFont type )

Returns the most adequate font for a given type case for proper integration with the system's look and feel.

该函数在 Qt 5.2 引入。

另请参阅 QGuiApplication::font ().

[static] int QFontDatabase:: weight (const QString & family , const QString & style )

Returns the weight of the font that has family family 和样式 style . If there is no such family and style combination, returns -1.

另请参阅 italic () 和 bold ().

[static] QString QFontDatabase:: writingSystemName ( QFontDatabase::WritingSystem writingSystem )

Returns the names the writingSystem (e.g. for displaying to the user in a dialog).

[static] QString QFontDatabase:: writingSystemSample ( QFontDatabase::WritingSystem writingSystem )

Returns a string with sample characters from writingSystem .

[static] QList < QFontDatabase::WritingSystem > QFontDatabase:: writingSystems ()

Returns a sorted list of the available writing systems. This is list generated from information about all installed fonts on the system.

另请参阅 families ().

[static] QList < QFontDatabase::WritingSystem > QFontDatabase:: writingSystems (const QString & family )

Returns a sorted list of the writing systems supported by a given font family .

另请参阅 families ().