class QFontMetricsF

The QFontMetricsF class provides font metrics information. More…

Synopsis

Methods

Note

This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE

Detailed Description

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

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 horizontalAdvance() , 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 horizontalAdvance() , 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.horizontalAdvance("What's the advance width of self text?")
pixelsHigh = fm.height()

See also

QFont QFontInfo QFontDatabase

__init__(font)
Parameters:

font – 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__(arg__1)
Parameters:

arg__1 – QFontMetrics

Constructs a font metrics object with floating point precision from the given fontMetrics object.

__init__(arg__1)
Parameters:

arg__1 – QFontMetricsF

Constructs a copy of fm.

__init__(font, pd)
Parameters:

Constructs a font metrics object for font and paintdevice.

The font metrics will be compatible with the paintdevice passed. If the paintdevice is None, the metrics will be screen-compatible, ie. the metrics you get if you use the font for drawing text on a widgets or pixmaps , 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()
Return type:

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 a certain character, so it is possible (though rare) that this value will be too small.

See also

descent()

averageCharWidth()
Return type:

float

Returns the average width of glyphs in the font.

boundingRect(string)
Parameters:

string – str

Return type:

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 horizontalAdvance() 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() .

boundingRect(text, textOption)
Parameters:
Return type:

QRectF

Returns the bounding rectangle of the characters in the string specified by text laid out using option. 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 horizontalAdvance() 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() .

boundingRect(r, flags, string[, tabstops=0[, tabarray=None]])
Parameters:

  • r – QRectF

  • flags – int

  • string – str

  • tabstops – int

  • tabarray – int

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. If rect is a reference to a None object, e.g. when passing a default constructed QRectF, the bounding rectangle will not constrain itself to the size.

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

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

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

  • Qt::AlignJustify produces justified text.

  • Qt::AlignHCenter aligns horizontally centered.

  • Qt::AlignTop aligns to the top border.

  • Qt::AlignBottom aligns to the bottom border.

  • Qt::AlignVCenter aligns vertically centered

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

  • Qt::TextSingleLine ignores newline characters in the text.

  • Qt::TextExpandTabs expands tabs (see below)

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

  • Qt::TextWordWrap breaks the text to fit the rectangle.

Qt::Horizontal alignment defaults to Qt::AlignLeft and vertical alignment defaults to Qt::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 Qt::AlignmentFlag.

If Qt::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

horizontalAdvance() boundingRect() Alignment

boundingRectChar(arg__1)
Parameters:

arg__1 – QChar

Return type:

QRectF

capHeight()
Return type:

float

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()

descent()
Return type:

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 a certain character, so it is possible (though rare) that this value will be too small.

See also

ascent()

elidedText(text, mode, width[, flags=0])
Parameters:

  • text – str

  • mode – TextElideMode

  • width – float

  • flags – int

Return type:

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 Qt::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.

fontDpi()
Return type:

float

Returns the font DPI.

height()
Return type:

float

Returns the height of the font.

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

horizontalAdvance(string, textOption)
Parameters:
Return type:

float

Returns the horizontal advance in pixels of text laid out using option.

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

See also

boundingRect()

horizontalAdvance(string[, length=-1])
Parameters:

  • string – str

  • length – int

Return type:

float

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 entire length of text is analysed even if length is substantially shorter.

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

See also

boundingRect()

horizontalAdvanceChar(arg__1)
Parameters:

arg__1 – QChar

Return type:

float

inFont(arg__1)
Parameters:

arg__1 – QChar

Return type:

bool

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

inFontUcs4(ucs4)
Parameters:

ucs4 – int

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.

leading()
Return type:

float

Returns the leading of the font.

This is the natural inter-line spacing.

leftBearing(arg__1)
Parameters:

arg__1 – QChar

Return type:

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 horizontalAdvance() for a graphical description of this metric.

lineSpacing()
Return type:

float

Returns the distance from one base line to the next.

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

See also

height() leading()

lineWidth()
Return type:

float

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

maxWidth()
Return type:

float

Returns the width of the widest character in the font.

minLeftBearing()
Return type:

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.

minRightBearing()
Return type:

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.

__ne__(other)
Parameters:

other – QFontMetricsF

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==()

__eq__(other)
Parameters:

other – QFontMetricsF

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.

overlinePos()
Return type:

float

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

rightBearing(arg__1)
Parameters:

arg__1 – QChar

Return type:

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 horizontalAdvance() of the character.

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

size(flags, str[, tabstops=0[, tabarray=None]])
Parameters:

  • flags – int

  • str – str

  • tabstops – int

  • tabarray – int

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:

  • Qt::TextSingleLine ignores newline characters.

  • Qt::TextExpandTabs expands tabs (see below)

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

  • Qt::TextWordWrap breaks the text to fit the rectangle.

These flags are defined in the Qt::TextFlag enum.

If Qt::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()

strikeOutPos()
Return type:

float

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

swap(other)
Parameters:

other – QFontMetricsF

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

tightBoundingRect(text)
Parameters:

text – str

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 horizontalAdvance() 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.

tightBoundingRect(text, textOption)
Parameters:
Return type:

QRectF

Returns a tight bounding rectangle around the characters in the string specified by text laid out using option. 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 horizontalAdvance() 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.

underlinePos()
Return type:

float

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

xHeight()
Return type:

float

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