QFontMetricsF

The QFontMetricsF class provides font metrics information. More

Inheritance diagram of PySide2.QtGui.QFontMetricsF

Synopsis

Functions

Detailed Description

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:

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

QFontMetricsF(font, pd)

QFontMetricsF(arg__1)

QFontMetricsF(arg__1)

Parameters
PySide2.QtGui.QFontMetricsF.ascent()
Return type

qreal

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()

PySide2.QtGui.QFontMetricsF.averageCharWidth()
Return type

qreal

Returns the average width of glyphs in the font.

PySide2.QtGui.QFontMetricsF.boundingRect(r, flags, string[, tabstops=0[, tabarray=None]])
Parameters
  • rQRectF

  • flagsint

  • string – unicode

  • tabstopsint

  • tabarrayint

Return type

QRectF

This is an overloaded function.

Returns the bounding rectangle of the characters in the given text . This is the set of pixels the text would cover if drawn when constrained to the bounding rectangle specified by rect .

The flags argument is the bitwise OR of the following flags:

  • AlignLeft aligns to the left border, except for Arabic and Hebrew where it aligns to the right.

  • AlignRight aligns to the right border, except for Arabic and Hebrew where it aligns to the left.

  • AlignJustify produces justified text.

  • AlignHCenter aligns horizontally centered.

  • AlignTop aligns to the top border.

  • AlignBottom aligns to the bottom border.

  • AlignVCenter aligns vertically centered

  • AlignCenter (== Qt::AlignHCenter | Qt::AlignVCenter)

  • TextSingleLine ignores newline characters in the text.

  • TextExpandTabs expands tabs (see below)

  • TextShowMnemonic interprets “&x” as x; i.e., underlined.

  • TextWordWrap breaks the text to fit the rectangle.

Horizontal alignment defaults to AlignLeft and vertical alignment defaults to AlignTop .

If several of the horizontal or several of the vertical alignment flags are set, the resulting alignment is undefined.

These flags are defined in AlignmentFlag .

If TextExpandTabs is set in flags , the following behavior is used to interpret tab characters in the text:

  • If tabArray is non-null, it specifies a 0-terminated sequence of pixel-positions for tabs in the text.

  • If tabStops is non-zero, it is used as the tab spacing (in pixels).

Note that the bounding rectangle may extend to the left of (0, 0), e.g. for italicized fonts.

Newline characters are processed as line breaks.

Despite the different actual character heights, the heights of the bounding rectangles of “Yes” and “yes” are the same.

The bounding rectangle returned by this function is somewhat larger than that calculated by the simpler boundingRect() function. This function uses the maximum left and right font bearings as is necessary for multi-line text to align correctly. Also, fontHeight() and lineSpacing() are used to calculate the height, rather than individual character heights.

See also

width() boundingRect() Alignment

PySide2.QtGui.QFontMetricsF.boundingRect(string)
Parameters

string – unicode

Return type

QRectF

PySide2.QtGui.QFontMetricsF.boundingRectChar(arg__1)
Parameters

arg__1QChar

Return type

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()

PySide2.QtGui.QFontMetricsF.capHeight()
Return type

qreal

Returns the cap height of the font.

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.

See also

ascent()

PySide2.QtGui.QFontMetricsF.descent()
Return type

qreal

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()

PySide2.QtGui.QFontMetricsF.elidedText(text, mode, width[, flags=0])
Parameters
  • text – unicode

  • modeTextElideMode

  • widthqreal

  • flagsint

Return type

unicode

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 .

PySide2.QtGui.QFontMetricsF.height()
Return type

qreal

Returns the height of the font.

This is always equal to ascent() + descent() .

PySide2.QtGui.QFontMetricsF.horizontalAdvance(arg__1)
Parameters

arg__1QChar

Return type

qreal

This is an overloaded function.

../../_images/bearings.png

Returns the horizontal advance of character ch in pixels. This is a distance appropriate for drawing a subsequent character after ch .

Some of the metrics are described in the image to the right. The central dark rectangles cover the logical width() of each character. The outer pale rectangles cover the leftBearing() and rightBearing() of each character. Notice that the bearings of “f” in this particular font are both negative, while the bearings of “o” are both positive.

Warning

This function will produce incorrect results for Arabic characters or non-spacing marks in the middle of a string, as the glyph shaping and positioning of marks that happens when processing strings cannot be taken into account. When implementing an interactive text control, use QTextLayout instead.

See also

boundingRect()

PySide2.QtGui.QFontMetricsF.horizontalAdvance(string[, length=-1])
Parameters
  • string – unicode

  • lengthint

Return type

qreal

Returns the horizontal advance in pixels of the first length characters of text . If length is negative (the default), the entire string is used.

The advance is the distance appropriate for drawing a subsequent character after text .

See also

boundingRect()

PySide2.QtGui.QFontMetricsF.inFont(arg__1)
Parameters

arg__1QChar

Return type

bool

Returns true if character ch is a valid character in the font; otherwise returns false .

PySide2.QtGui.QFontMetricsF.inFontUcs4(ucs4)
Parameters

ucs4uint

Return type

bool

Returns true if the character given by ch , encoded in UCS-4/UTF-32, is a valid character in the font; otherwise returns false .

PySide2.QtGui.QFontMetricsF.leading()
Return type

qreal

Returns the leading of the font.

This is the natural inter-line spacing.

PySide2.QtGui.QFontMetricsF.leftBearing(arg__1)
Parameters

arg__1QChar

Return type

qreal

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.

PySide2.QtGui.QFontMetricsF.lineSpacing()
Return type

qreal

Returns the distance from one base line to the next.

This value is always equal to leading() + height() .

See also

height() leading()

PySide2.QtGui.QFontMetricsF.lineWidth()
Return type

qreal

Returns the width of the underline and strikeout lines, adjusted for the point size of the font.

PySide2.QtGui.QFontMetricsF.maxWidth()
Return type

qreal

Returns the width of the widest character in the font.

PySide2.QtGui.QFontMetricsF.minLeftBearing()
Return type

qreal

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.

PySide2.QtGui.QFontMetricsF.minRightBearing()
Return type

qreal

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.

PySide2.QtGui.QFontMetricsF.__ne__(other)
Parameters

otherQFontMetricsF

Return type

bool

This is an overloaded function.

Returns true if the font metrics are not equal to the other font metrics; otherwise returns false .

See also

operator==()

PySide2.QtGui.QFontMetricsF.operator=(arg__1)
Parameters

arg__1QFontMetrics

Return type

QFontMetricsF

PySide2.QtGui.QFontMetricsF.__eq__(other)
Parameters

otherQFontMetricsF

Return type

bool

Returns true if the font metrics are equal to the other font metrics; otherwise returns false .

Two font metrics are considered equal if they were constructed from the same QFont and the paint devices they were constructed for are considered to be compatible.

PySide2.QtGui.QFontMetricsF.overlinePos()
Return type

qreal

Returns the distance from the base line to where an overline should be drawn.

PySide2.QtGui.QFontMetricsF.rightBearing(arg__1)
Parameters

arg__1QChar

Return type

qreal

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.

PySide2.QtGui.QFontMetricsF.size(flags, str[, tabstops=0[, tabarray=None]])
Parameters
  • flagsint

  • str – unicode

  • tabstopsint

  • tabarrayint

Return type

QSizeF

Returns the size in pixels of the characters in the given text .

The flags argument is the bitwise OR of the following flags:

  • TextSingleLine ignores newline characters.

  • TextExpandTabs expands tabs (see below)

  • TextShowMnemonic interprets “&x” as x; i.e., underlined.

  • TextWordWrap breaks the text to fit the rectangle.

These flags are defined in the TextFlag enum.

If TextExpandTabs is set in flags , the following behavior is used to interpret tab characters in the text:

  • If tabArray is non-null, it specifies a 0-terminated sequence of pixel-positions for tabs in the text.

  • If tabStops is non-zero, it is used as the tab spacing (in pixels).

Newline characters are processed as line breaks.

Note: Despite the different actual character heights, the heights of the bounding rectangles of “Yes” and “yes” are the same.

See also

boundingRect()

PySide2.QtGui.QFontMetricsF.strikeOutPos()
Return type

qreal

Returns the distance from the base line to where the strikeout line should be drawn.

PySide2.QtGui.QFontMetricsF.swap(other)
Parameters

otherQFontMetricsF

Swaps this font metrics instance with other . This function is very fast and never fails.

PySide2.QtGui.QFontMetricsF.tightBoundingRect(text)
Parameters

text – unicode

Return type

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.

PySide2.QtGui.QFontMetricsF.underlinePos()
Return type

qreal

Returns the distance from the base line to where an underscore should be drawn.

PySide2.QtGui.QFontMetricsF.width(string)
Parameters

string – unicode

Return type

qreal

PySide2.QtGui.QFontMetricsF.widthChar(arg__1)
Parameters

arg__1QChar

Return type

qreal

This is an overloaded function.

../../_images/bearings.png

Returns the logical width of character ch in pixels. This is a distance appropriate for drawing a subsequent character after ch .

Some of the metrics are described in the image to the right. The central dark rectangles cover the logical width() of each character. The outer pale rectangles cover the leftBearing() and rightBearing() of each character. Notice that the bearings of “f” in this particular font are both negative, while the bearings of “o” are both positive.

Warning

This function will produce incorrect results for Arabic characters or non-spacing marks in the middle of a string, as the glyph shaping and positioning of marks that happens when processing strings cannot be taken into account. When implementing an interactive text control, use QTextLayout instead.

See also

boundingRect()

PySide2.QtGui.QFontMetricsF.xHeight()
Return type

qreal

Returns the ‘x’ height of the font. This is often but not always the same as the height of the character ‘x’.