QFontMetricsF¶

PyQt5.QtGui.QFontMetricsF

Description¶

The QFontMetricsF class provides font metrics information.

QFontMetricsF functions calculate the size of characters and strings for a given font. You can construct a QFontMetricsF object with an existing QFont to obtain metrics for that font. If the font is changed later, the font metrics object is not updated.

Once created, the object provides functions to access the individual metrics of the font, its characters, and for strings rendered in the font.

There are several functions that operate on the font: ascent(), descent(), height(), leading() and lineSpacing() return the basic size properties of the font. The underlinePos(), overlinePos(), strikeOutPos() and lineWidth() functions, return the properties of the line that underlines, overlines or strikes out the characters. These functions are all fast.

There are also some functions that operate on the set of glyphs in the font: minLeftBearing(), minRightBearing() and maxWidth(). These are by necessity slow, and we recommend avoiding them if possible.

For each character, you can get its width(), leftBearing() and rightBearing() and find out whether it is in the font using inFont(). You can also treat the character as a string, and use the string functions on it.

The string functions include width(), to return the width of a string in pixels (or points, for a printer), boundingRect(), to return a rectangle large enough to contain the rendered string, and size(), to return the size of that rectangle.

Example:

# QFont font("times", 24);
# QFontMetricsF fm(font);
# qreal pixelsWide = fm.horizontalAdvance("What's the width of this text?");
# qreal pixelsHigh = fm.height();

See also

QFont, QFontInfo, QFontDatabase.

Methods¶

__init__(QFont)

Constructs a font metrics object for font.

The font metrics will be compatible with the paintdevice used to create font.

The font metrics object holds the information for the font that is passed in the constructor at the time it is created, and is not updated if the font’s attributes are changed later.

Use QFontMetricsF(const QFont &, QPaintDevice *) to get the font metrics that are compatible with a certain paint device.

__init__(QFontMetrics): Constructs a font metrics object with floating point precision from the given fontMetrics object.

__init__(QFontMetricsF): Constructs a copy of fm.

__init__(QFont, QPaintDevice)

Constructs a font metrics object for font and paintdevice.

The font metrics will be compatible with the paintdevice passed. If the paintdevice is 0, the metrics will be screen-compatible, ie. the metrics you get if you use the font for drawing text on a QWidget or QPixmap, not on a QPicture or QPrinter.

The font metrics object holds the information for the font that is passed in the constructor at the time it is created, and is not updated if the font’s attributes are changed later.

ascent() → float

Returns the ascent of the font.

The ascent of a font is the distance from the baseline to the highest position characters extend to. In practice, some font designers break this rule, e.g. when they put more than one accent on top of a character, or to accommodate an unusual character in an exotic language, so it is possible (though rare) that this value will be too small.

See also

descent().

averageCharWidth() → float: Returns the average width of glyphs in the font.

boundingRect(str) → QRectF

Returns the bounding rectangle of the characters in the string specified by text. The bounding rectangle always covers at least the set of pixels the text would cover if drawn at (0, 0).

Note that the bounding rectangle may extend to the left of (0, 0), e.g. for italicized fonts, and that the width of the returned rectangle might be different than what the width() method returns.

If you want to know the advance width of the string (to lay out a set of strings next to each other), use horizontalAdvance() instead.

Newline characters are processed as normal characters, not as linebreaks.

The height of the bounding rectangle is at least as large as the value returned height().

See also

width(), height(), boundingRect().

boundingRect(QRectF, int, str, tabStops: int = 0, tabArray: Optional[List[int]] = 0) → QRectF: TODO

boundingRectChar(str) → QRectF

Returns the bounding rectangle of the character ch relative to the left-most point on the base line.

Note that the bounding rectangle may extend to the left of (0, 0), e.g. for italicized fonts, and that the text output may cover all pixels in the bounding rectangle.

Note that the rectangle usually extends both above and below the base line.

See also

width().

capHeight() → float: TODO

descent() → float

Returns the descent of the font.

The descent is the distance from the base line to the lowest point characters extend to. (Note that this is different from X, which adds 1 pixel.) In practice, some font designers break this rule, e.g. to accommodate an unusual character in an exotic language, so it is possible (though rare) that this value will be too small.

See also

ascent().

elidedText(str, TextElideMode, float, flags: int = 0) → str

If the string text is wider than width, returns an elided version of the string (i.e., a string with “…” in it). Otherwise, returns the original string.

The mode parameter specifies whether the text is elided on the left (for example, “…tech”), in the middle (for example, “Tr…ch”), or on the right (for example, “Trol…”).

The width is specified in pixels, not characters.

The flags argument is optional and currently only supports TextShowMnemonic as value.

The elide mark follows the LayoutDirection. For example, it will be on the right side of the text for right-to-left layouts if the mode is Qt::ElideLeft, and on the left side of the text if the mode is Qt::ElideRight.

__eq__(QFontMetricsF) → bool: TODO

fontDpi() → float: TODO

height() → float

Returns the height of the font.

This is always equal to descent.

See also

leading(), lineSpacing().

horizontalAdvance(str, length: int = -1) → float: TODO

inFont(str) → bool: Returns true if character ch is a valid character in the font; otherwise returns false.

inFontUcs4(int) → bool: TODO

leading() → float

Returns the leading of the font.

This is the natural inter-line spacing.

See also

height(), lineSpacing().

leftBearing(str) → float

Returns the left bearing of character ch in the font.

The left bearing is the right-ward distance of the left-most pixel of the character from the logical origin of the character. This value is negative if the pixels of the character extend to the left of the logical origin.

See width() for a graphical description of this metric.

lineSpacing() → float

Returns the distance from one base line to the next.

This value is always equal to height.

See also

height(), leading().

lineWidth() → float: Returns the width of the underline and strikeout lines, adjusted for the point size of the font.

See also

underlinePos(), overlinePos(), strikeOutPos().

maxWidth() → float: Returns the width of the widest character in the font.

minLeftBearing() → float

Returns the minimum left bearing of the font.

This is the smallest leftBearing()(char) of all characters in the font.

Note that this function can be very slow if the font is large.

See also

minRightBearing(), leftBearing().

minRightBearing() → float

Returns the minimum right bearing of the font.

This is the smallest rightBearing()(char) of all characters in the font.

Note that this function can be very slow if the font is large.

See also

minLeftBearing(), rightBearing().

__ne__(QFontMetricsF) → bool: TODO

overlinePos() → float: Returns the distance from the base line to where an overline should be drawn.

See also

underlinePos(), strikeOutPos(), lineWidth().

rightBearing(str) → float

Returns the right bearing of character ch in the font.

The right bearing is the left-ward distance of the right-most pixel of the character from the logical origin of a subsequent character. This value is negative if the pixels of the character extend to the right of the width() of the character.

See width() for a graphical description of this metric.

size(int, str, tabStops: int = 0, tabArray: Optional[List[int]] = 0) → QSizeF: TODO

strikeOutPos() → float: Returns the distance from the base line to where the strikeout line should be drawn.

See also

underlinePos(), overlinePos(), lineWidth().

swap(QFontMetricsF): TODO

tightBoundingRect(str) → QRectF

Returns a tight bounding rectangle around the characters in the string specified by text. The bounding rectangle always covers at least the set of pixels the text would cover if drawn at (0, 0).

Note that the bounding rectangle may extend to the left of (0, 0), e.g. for italicized fonts, and that the width of the returned rectangle might be different than what the width() method returns.

If you want to know the advance width of the string (to lay out a set of strings next to each other), use horizontalAdvance() instead.

Newline characters are processed as normal characters, not as linebreaks.

Warning: Calling this method is very slow on Windows.

See also

width(), height(), boundingRect().

underlinePos() → float: Returns the distance from the base line to where an underscore should be drawn.

See also

overlinePos(), strikeOutPos(), lineWidth().

width(str) → float: TODO

widthChar(str) → float: TODO

xHeight() → float: Returns the ‘x’ height of the font. This is often but not always the same as the height of the character ‘x’.