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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#include "qfont.h"
#include "qpaintdevice.h"
#include "qfontmetrics.h"
#include "qfont_p.h"
#include "qfontengine_p.h"
QT_BEGIN_NAMESPACE
extern void qt_format_text(const QFont& font, const QRectF &_r,
int tf, const QString &text, QRectF *brect,
int tabStops, int *tabArray, int tabArrayLen,
QPainter *painter);
/*****************************************************************************
QFontMetrics member functions
*****************************************************************************/
/*!
\class QFontMetrics
\reentrant
\inmodule QtGui
\brief The QFontMetrics class provides font metrics information.
\ingroup painting
\ingroup shared
QFontMetrics functions calculate the size of characters and
strings for a given font. The class is an integer-based version
of QFontMetricsF and will round all numbers to the nearest
integer. This means its results will be inaccurate for any font
with fractional metrics. In most cases QFontMetricsF should be
used instead.
There are three ways you can create a QFontMetrics object:
\list 1
\li Calling the QFontMetrics constructor with a QFont creates a
font metrics object for a screen-compatible font, i.e. the font
cannot be a printer font. If the font is changed
later, the font metrics object is \e not updated.
(Note: If you use a printer font the values returned may be
inaccurate. Printer fonts are not always accessible so the nearest
screen font is used if a printer font is supplied.)
\li QWidget::fontMetrics() returns the font metrics for a widget's
font. This is equivalent to QFontMetrics(widget->font()). If the
widget's font is changed later, the font metrics object is \e not
updated.
\li QPainter::fontMetrics() returns the font metrics for a
painter's current font. If the painter's font is changed later, the
font metrics object is \e not updated.
\endlist
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 advance
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.
QFontMetrics has two different functions for calculating the bounds of a string, each with
multiple overloads: boundingRect() and tightBoundingRect(). If a precise bounding rect is
needed, then tightBoundingRect() should be preferred. This will measure each glyph individually
to return a bounding rect that fits tightly around the rendered text. Depending on the platform,
the boundingRect() function may return approximated bounds, but require less computation.
\note The advance width can be different from the width of the actual
rendered text. It refers to the distance from the origin of the string to
where you would append additional characters. As text may have overhang
(in the case of an italic font for instance) or padding between
characters, the advance width can be either smaller or larger than the
actual rendering of the text. This is called the right bearing of the
text.
Example:
\snippet code/src_gui_text_qfontmetrics.cpp 0
\sa QFont, QFontInfo, QFontDatabase
*/
/*!
\fn QRect QFontMetrics::boundingRect(int x, int y, int width, int height,
int flags, const QString &text, int tabStops, int *tabArray) const
\overload
Returns the bounding rectangle for the given \a text within the
rectangle specified by the \a x and \a y coordinates, \a width, and
\a height.
If Qt::TextExpandTabs is set in \a flags and \a tabArray is
non-null, it specifies a 0-terminated sequence of pixel-positions
for tabs; otherwise, if \a tabStops is non-zero, it is used as the
tab spacing (in pixels).
*/
/*!
Constructs a font metrics object for \a font.
The font metrics will be compatible with the paintdevice used to
create \a 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 QFontMetrics(const QFont &, QPaintDevice *) to get the font
metrics that are compatible with a certain paint device.
*/
QFontMetrics::QFontMetrics(const QFont &font)
: d(font.d)
{
}
/*!
\since 5.13
\fn QFontMetrics::QFontMetrics(const QFont &font, const QPaintDevice *paintdevice)
Constructs a font metrics object for \a font and \a paintdevice.
The font metrics will be compatible with the paintdevice passed.
If the \a paintdevice is \nullptr, the metrics will be screen-compatible,
ie. the metrics you get if you use the font for drawing text on a
\l{QWidget}{widgets} or \l{QPixmap}{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.
*/
QFontMetrics::QFontMetrics(const QFont &font, const QPaintDevice *paintdevice)
{
const int dpi = paintdevice ? paintdevice->logicalDpiY() : qt_defaultDpi();
if (font.d->dpi != dpi) {
d = new QFontPrivate(*font.d);
d->dpi = dpi;
} else {
d = font.d;
}
}
/*!
Constructs a copy of \a fm.
*/
QFontMetrics::QFontMetrics(const QFontMetrics &fm)
: d(fm.d)
{
}
/*!
Destroys the font metrics object and frees all allocated
resources.
*/
QFontMetrics::~QFontMetrics()
{
}
/*!
Assigns the font metrics \a fm.
*/
QFontMetrics &QFontMetrics::operator=(const QFontMetrics &fm)
{
d = fm.d;
return *this;
}
/*!
\fn QFontMetrics &QFontMetrics::operator=(QFontMetrics &&other)
Move-assigns \a other to this QFontMetrics instance.
\since 5.2
*/
/*!
\fn QFontMetricsF &QFontMetricsF::operator=(QFontMetricsF &&other)
Move-assigns \a other to this QFontMetricsF instance.
*/
/*!
\fn void QFontMetrics::swap(QFontMetrics &other)
\since 5.0
\memberswap{font metrics instance}
*/
/*!
Returns \c true if \a other is equal to this object; otherwise
returns \c 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 compatible.
\sa operator!=()
*/
bool QFontMetrics::operator ==(const QFontMetrics &other) const
{
return d == other.d;
}
/*!
\fn bool QFontMetrics::operator !=(const QFontMetrics &other) const
Returns \c true if \a other is not equal to this object; otherwise returns \c 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 compatible.
\sa operator==()
*/
/*!
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.
\sa descent()
*/
int QFontMetrics::ascent() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return qRound(engine->ascent());
}
/*!
Returns the cap height of the font.
\since 5.8
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.
\sa ascent()
*/
int QFontMetrics::capHeight() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return qRound(engine->capHeight());
}
/*!
Returns the descent of the font.
The descent is the distance from the base line to the lowest point
characters extend to. 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.
\sa ascent()
*/
int QFontMetrics::descent() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return qRound(engine->descent());
}
/*!
Returns the height of the font.
This is always equal to ascent()+descent().
\sa leading(), lineSpacing()
*/
int QFontMetrics::height() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return qRound(engine->ascent()) + qRound(engine->descent());
}
/*!
Returns the leading of the font.
This is the natural inter-line spacing.
\sa height(), lineSpacing()
*/
int QFontMetrics::leading() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return qRound(engine->leading());
}
/*!
Returns the distance from one base line to the next.
This value is always equal to leading()+height().
\sa height(), leading()
*/
int QFontMetrics::lineSpacing() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return qRound(engine->leading()) + qRound(engine->ascent()) + qRound(engine->descent());
}
/*!
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.
\sa minRightBearing(), leftBearing()
*/
int QFontMetrics::minLeftBearing() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return qRound(engine->minLeftBearing());
}
/*!
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.
\sa minLeftBearing(), rightBearing()
*/
int QFontMetrics::minRightBearing() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return qRound(engine->minRightBearing());
}
/*!
Returns the width of the widest character in the font.
*/
int QFontMetrics::maxWidth() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return qRound(engine->maxCharWidth());
}
/*!
Returns the 'x' height of the font. This is often but not always
the same as the height of the character 'x'.
*/
int QFontMetrics::xHeight() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
if (d->capital == QFont::SmallCaps)
return qRound(d->smallCapsFontPrivate()->engineForScript(QChar::Script_Common)->ascent());
return qRound(engine->xHeight());
}
/*!
\since 4.2
Returns the average width of glyphs in the font.
*/
int QFontMetrics::averageCharWidth() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return qRound(engine->averageCharWidth());
}
/*!
Returns \c true if character \a ch is a valid character in the font;
otherwise returns \c false.
*/
bool QFontMetrics::inFont(QChar ch) const
{
return inFontUcs4(ch.unicode());
}
/*!
Returns \c true if the character \a ucs4 encoded in UCS-4/UTF-32 is a valid
character in the font; otherwise returns \c false.
*/
bool QFontMetrics::inFontUcs4(uint ucs4) const
{
constexpr auto Ignore = QFontPrivate::EngineQueryOption::IgnoreSmallCapsEngine;
QFontEngine *engine = d->engineForCharacter(ucs4, Ignore);
if (engine->type() == QFontEngine::Box)
return false;
return engine->canRender(ucs4);
}
/*!
Returns the left bearing of character \a 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.
\sa rightBearing(), minLeftBearing(), horizontalAdvance()
*/
int QFontMetrics::leftBearing(QChar ch) const
{
QFontEngine *engine = d->engineForCharacter(ch.unicode());
if (engine->type() == QFontEngine::Box)
return 0;
d->alterCharForCapitalization(ch);
glyph_t glyph = engine->glyphIndex(ch.unicode());
qreal lb;
engine->getGlyphBearings(glyph, &lb);
return qRound(lb);
}
/*!
Returns the right bearing of character \a 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.
\sa leftBearing(), minRightBearing(), horizontalAdvance()
*/
int QFontMetrics::rightBearing(QChar ch) const
{
QFontEngine *engine = d->engineForCharacter(ch.unicode());
Q_ASSERT(engine != nullptr);
if (engine->type() == QFontEngine::Box)
return 0;
d->alterCharForCapitalization(ch);
glyph_t glyph = engine->glyphIndex(ch.unicode());
qreal rb;
engine->getGlyphBearings(glyph, nullptr, &rb);
return qRound(rb);
}
static constexpr QLatin1Char s_variableLengthStringSeparator('\x9c');
/*!
Returns the horizontal advance in pixels of the first \a len characters of \a
text. If \a len is negative (the default), the entire string is
used. The entire length of \a text is analysed even if \a len is substantially
shorter.
This is the distance appropriate for drawing a subsequent character
after \a text.
\since 5.11
\sa boundingRect()
*/
int QFontMetrics::horizontalAdvance(const QString &text, int len) const
{
int pos = (len >= 0)
? QStringView(text).left(len).indexOf(s_variableLengthStringSeparator)
: text.indexOf(s_variableLengthStringSeparator);
if (pos != -1) {
len = pos;
} else if (len < 0) {
len = text.size();
}
if (len == 0)
return 0;
Q_DECL_UNINITIALIZED QStackTextEngine layout(text, QFont(d.data()));
return qRound(layout.width(0, len));
}
/*!
Returns the horizontal advance in pixels of \a text laid out using \a option.
The advance is the distance appropriate for drawing a subsequent
character after \a text.
\since 6.3
\sa boundingRect()
*/
int QFontMetrics::horizontalAdvance(const QString &text, const QTextOption &option) const
{
int pos = text.indexOf(s_variableLengthStringSeparator);
int len = -1;
if (pos != -1) {
len = pos;
} else {
len = text.size();
}
if (len == 0)
return 0;
Q_DECL_UNINITIALIZED QStackTextEngine layout(text, QFont(d.data()));
layout.option = option;
return qRound(layout.width(0, len));
}
/*!
\overload
\image bearings.png Bearings
Returns the horizontal advance of character \a ch in pixels. This is a
distance appropriate for drawing a subsequent character after \a
ch.
Some of the metrics are described in the image. The
central dark rectangles cover the logical horizontalAdvance() 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.
\since 5.11
\sa boundingRect()
*/
int QFontMetrics::horizontalAdvance(QChar ch) const
{
if (QChar::category(ch.unicode()) == QChar::Mark_NonSpacing)
return 0;
QFontEngine *engine = d->engineForCharacter(ch.unicode());
d->alterCharForCapitalization(ch);
glyph_t glyph = engine->glyphIndex(ch.unicode());
QFixed advance;
QGlyphLayout glyphs;
glyphs.numGlyphs = 1;
glyphs.glyphs = &glyph;
glyphs.advances = &advance;
engine->recalcAdvances(&glyphs, { });
return qRound(advance);
}
/*!
Returns the bounding rectangle of the characters in the string
specified by \a 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, \e not as
linebreaks.
The height of the bounding rectangle is at least as large as the
value returned by height().
\sa horizontalAdvance(), height(), QPainter::boundingRect(),
tightBoundingRect()
*/
QRect QFontMetrics::boundingRect(const QString &text) const
{
if (text.size() == 0)
return QRect();
Q_DECL_UNINITIALIZED QStackTextEngine layout(text, QFont(d.data()));
layout.itemize();
glyph_metrics_t gm = layout.boundingBox(0, text.size());
return QRect(qRound(gm.x), qRound(gm.y), qRound(gm.width), qRound(gm.height));
}
/*!
Returns the bounding rectangle of the characters in the string
specified by \a text laid out using \a 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, \e not as
linebreaks.
The height of the bounding rectangle is at least as large as the
value returned by height().
\since 6.3
\sa horizontalAdvance(), height(), QPainter::boundingRect(),
tightBoundingRect()
*/
QRect QFontMetrics::boundingRect(const QString &text, const QTextOption &option) const
{
if (text.size() == 0)
return QRect();
Q_DECL_UNINITIALIZED QStackTextEngine layout(text, QFont(d.data()));
layout.option = option;
layout.itemize();
glyph_metrics_t gm = layout.boundingBox(0, text.size());
return QRect(qRound(gm.x), qRound(gm.y), qRound(gm.width), qRound(gm.height));
}
/*!
Returns the rectangle that is covered by ink if character \a ch
were to be drawn at the origin of the coordinate system.
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 \e
all pixels in the bounding rectangle. For a space character the rectangle
will usually be empty.
Note that the rectangle usually extends both above and below the
base line.
\warning The width of the returned rectangle is not the advance width
of the character. Use boundingRect(const QString &) or horizontalAdvance() instead.
\sa horizontalAdvance()
*/
QRect QFontMetrics::boundingRect(QChar ch) const
{
QFontEngine *engine = d->engineForCharacter(ch.unicode());
d->alterCharForCapitalization(ch);
glyph_t glyph = engine->glyphIndex(ch.unicode());
glyph_metrics_t gm = engine->boundingBox(glyph);
return QRect(qRound(gm.x), qRound(gm.y), qRound(gm.width), qRound(gm.height));
}
/*!
\overload
Returns the bounding rectangle of the characters in the string
specified by \a text, which is the set of pixels the text would
cover if drawn at (0, 0). The drawing, and hence the bounding
rectangle, is constrained to the rectangle \a rect.
The \a flags argument is the bitwise OR of the following flags:
\list
\li Qt::AlignLeft aligns to the left border, except for
Arabic and Hebrew where it aligns to the right.
\li Qt::AlignRight aligns to the right border, except for
Arabic and Hebrew where it aligns to the left.
\li Qt::AlignJustify produces justified text.
\li Qt::AlignHCenter aligns horizontally centered.
\li Qt::AlignTop aligns to the top border.
\li Qt::AlignBottom aligns to the bottom border.
\li Qt::AlignVCenter aligns vertically centered
\li Qt::AlignCenter (== \c{Qt::AlignHCenter | Qt::AlignVCenter})
\li Qt::TextSingleLine ignores newline characters in the text.
\li Qt::TextExpandTabs expands tabs (see below)
\li Qt::TextShowMnemonic interprets "&x" as \underline{x}; i.e., underlined.
\li Qt::TextWordWrap breaks the text to fit the rectangle.
\endlist
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.
If Qt::TextExpandTabs is set in \a flags, then: if \a tabArray is
non-null, it specifies a 0-terminated sequence of pixel-positions
for tabs; otherwise if \a 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, and that the text output may cover \e
all pixels in the bounding rectangle.
Newline characters are processed as linebreaks.
Despite the different actual character heights, the heights of the
bounding rectangles of "Yes" and "yes" are the same.
\sa horizontalAdvance(), QPainter::boundingRect(), Qt::Alignment
*/
QRect QFontMetrics::boundingRect(const QRect &rect, int flags, const QString &text, int tabStops,
int *tabArray) const
{
int tabArrayLen = 0;
if (tabArray)
while (tabArray[tabArrayLen])
tabArrayLen++;
QRectF rb;
QRectF rr(rect);
qt_format_text(QFont(d.data()), rr, flags | Qt::TextDontPrint, text, &rb, tabStops, tabArray,
tabArrayLen, nullptr);
return rb.toAlignedRect();
}
/*!
Returns the size in pixels of \a text.
The \a flags argument is the bitwise OR of the following flags:
\list
\li Qt::TextSingleLine ignores newline characters.
\li Qt::TextExpandTabs expands tabs (see below)
\li Qt::TextShowMnemonic interprets "&x" as \underline{x}; i.e., underlined.
\li Qt::TextWordWrap breaks the text to fit the rectangle.
\endlist
If Qt::TextExpandTabs is set in \a flags, then: if \a tabArray is
non-null, it specifies a 0-terminated sequence of pixel-positions
for tabs; otherwise if \a tabStops is non-zero, it is used as the
tab spacing (in pixels).
Newline characters are processed as linebreaks.
Despite the different actual character heights, the heights of the
bounding rectangles of "Yes" and "yes" are the same.
\sa boundingRect()
*/
QSize QFontMetrics::size(int flags, const QString &text, int tabStops, int *tabArray) const
{
return boundingRect(QRect(0,0,0,0), flags | Qt::TextLongestVariant, text, tabStops, tabArray).size();
}
/*!
Returns a tight bounding rectangle around the characters in the
string specified by \a 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, \e not as
linebreaks.
\since 4.3
\sa horizontalAdvance(), height(), boundingRect()
*/
QRect QFontMetrics::tightBoundingRect(const QString &text) const
{
if (text.size() == 0)
return QRect();
Q_DECL_UNINITIALIZED QStackTextEngine layout(text, QFont(d.data()));
layout.itemize();
glyph_metrics_t gm = layout.tightBoundingBox(0, text.size());
return QRect(qRound(gm.x), qRound(gm.y), qRound(gm.width), qRound(gm.height));
}
/*!
Returns a tight bounding rectangle around the characters in the
string specified by \a text laid out using \a 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, \e not as
linebreaks.
\since 6.3
\sa horizontalAdvance(), height(), boundingRect()
*/
QRect QFontMetrics::tightBoundingRect(const QString &text, const QTextOption &option) const
{
if (text.size() == 0)
return QRect();
Q_DECL_UNINITIALIZED QStackTextEngine layout(text, QFont(d.data()));
layout.option = option;
layout.itemize();
glyph_metrics_t gm = layout.tightBoundingBox(0, text.size());
return QRect(qRound(gm.x), qRound(gm.y), qRound(gm.width), qRound(gm.height));
}
/*!
\since 4.2
If the string \a text is wider than \a width, returns an elided
version of the string (i.e., a string with "..." in it).
Otherwise, returns the original string.
The \a mode parameter specifies whether the text is elided on the
left (e.g., "...tech"), in the middle (e.g., "Tr...ch"), or on
the right (e.g., "Trol...").
The \a width is specified in pixels, not characters.
The \a flags argument is optional and currently only supports
Qt::TextShowMnemonic as value.
The elide mark follows the \l{Qt::LayoutDirection}{layoutdirection}.
For example, it will be on the right side of the text for right-to-left
layouts if the \a mode is \c{Qt::ElideLeft}, and on the left side of the
text if the \a mode is \c{Qt::ElideRight}.
*/
QString QFontMetrics::elidedText(const QString &text, Qt::TextElideMode mode, int width, int flags) const
{
QString _text = text;
if (!(flags & Qt::TextLongestVariant)) {
int posA = 0;
int posB = _text.indexOf(s_variableLengthStringSeparator);
while (posB >= 0) {
QString portion = _text.mid(posA, posB - posA);
if (size(flags, portion).width() <= width)
return portion;
posA = posB + 1;
posB = _text.indexOf(s_variableLengthStringSeparator, posA);
}
_text = _text.mid(posA);
}
Q_DECL_UNINITIALIZED QStackTextEngine engine(_text, QFont(d.data()));
return engine.elidedText(mode, width, flags);
}
/*!
Returns the distance from the base line to where an underscore
should be drawn.
\sa overlinePos(), strikeOutPos(), lineWidth()
*/
int QFontMetrics::underlinePos() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return qRound(engine->underlinePosition());
}
/*!
Returns the distance from the base line to where an overline
should be drawn.
\sa underlinePos(), strikeOutPos(), lineWidth()
*/
int QFontMetrics::overlinePos() const
{
return ascent() + 1;
}
/*!
Returns the distance from the base line to where the strikeout
line should be drawn.
\sa underlinePos(), overlinePos(), lineWidth()
*/
int QFontMetrics::strikeOutPos() const
{
int pos = ascent() / 3;
return pos > 0 ? pos : 1;
}
/*!
Returns the width of the underline and strikeout lines, adjusted
for the point size of the font.
\sa underlinePos(), overlinePos(), strikeOutPos()
*/
int QFontMetrics::lineWidth() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return qRound(engine->lineThickness());
}
/*!
\since 5.14
Returns the font DPI.
*/
qreal QFontMetrics::fontDpi() const
{
return d->dpi;
}
/*****************************************************************************
QFontMetricsF member functions
*****************************************************************************/
/*!
\class QFontMetricsF
\reentrant
\inmodule QtGui
\brief The QFontMetricsF class provides font metrics information.
\ingroup painting
\ingroup shared
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 \e 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.
QFontMetrics has two different functions for calculating the bounds of a string, each with
multiple overloads: boundingRect() and tightBoundingRect(). If a precise bounding rect is
needed, then tightBoundingRect() should be preferred. This will measure each glyph individually
to return a bounding rect that fits tightly around the rendered text. Depending on the platform,
the boundingRect() function may return approximated bounds, but require less computation.
Example:
\snippet code/src_gui_text_qfontmetrics.cpp 1
\sa QFont, QFontInfo, QFontDatabase
*/
/*!
\since 4.2
Constructs a font metrics object with floating point precision
from the given \a fontMetrics object.
*/
QFontMetricsF::QFontMetricsF(const QFontMetrics &fontMetrics)
: d(fontMetrics.d)
{
}
/*!
\since 4.2
Assigns \a other to this object.
*/
QFontMetricsF &QFontMetricsF::operator=(const QFontMetrics &other)
{
d = other.d;
return *this;
}
/*!
\fn void QFontMetricsF::swap(QFontMetricsF &other)
\since 5.0
\memberswap{font metrics instance}
*/
/*!
Constructs a font metrics object for \a font.
The font metrics will be compatible with the paintdevice used to
create \a 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.
*/
QFontMetricsF::QFontMetricsF(const QFont &font)
: d(font.d)
{
}
/*!
\fn QFontMetricsF::QFontMetricsF(const QFont &font, const QPaintDevice *paintdevice)
\since 5.13
Constructs a font metrics object for \a font and \a paintdevice.
The font metrics will be compatible with the paintdevice passed.
If the \a paintdevice is \nullptr, the metrics will be screen-compatible,
ie. the metrics you get if you use the font for drawing text on a
\l{QWidget}{widgets} or \l{QPixmap}{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.
*/
QFontMetricsF::QFontMetricsF(const QFont &font, const QPaintDevice *paintdevice)
{
int dpi = paintdevice ? paintdevice->logicalDpiY() : qt_defaultDpi();
if (font.d->dpi != dpi) {
d = new QFontPrivate(*font.d);
d->dpi = dpi;
} else {
d = font.d;
}
}
/*!
Constructs a copy of \a fm.
*/
QFontMetricsF::QFontMetricsF(const QFontMetricsF &fm)
: d(fm.d)
{
}
/*!
Destroys the font metrics object and frees all allocated
resources.
*/
QFontMetricsF::~QFontMetricsF()
{
}
/*!
Assigns the font metrics \a fm to this font metrics object.
*/
QFontMetricsF &QFontMetricsF::operator=(const QFontMetricsF &fm)
{
d = fm.d;
return *this;
}
/*!
Returns \c true if the font metrics are equal to the \a other font
metrics; otherwise returns \c 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.
*/
bool QFontMetricsF::operator ==(const QFontMetricsF &other) const
{
return d == other.d;
}
/*!
\fn bool QFontMetricsF::operator !=(const QFontMetricsF &other) const
\overload
Returns \c true if the font metrics are not equal to the \a other font
metrics; otherwise returns \c false.
\sa operator==()
*/
/*!
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.
\sa descent()
*/
qreal QFontMetricsF::ascent() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return engine->ascent().toReal();
}
/*!
Returns the cap height of the font.
\since 5.8
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.
\sa ascent()
*/
qreal QFontMetricsF::capHeight() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return engine->capHeight().toReal();
}
/*!
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.
\sa ascent()
*/
qreal QFontMetricsF::descent() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return engine->descent().toReal();
}
/*!
Returns the height of the font.
This is always equal to ascent()+descent().
\sa leading(), lineSpacing()
*/
qreal QFontMetricsF::height() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return (engine->ascent() + engine->descent()).toReal();
}
/*!
Returns the leading of the font.
This is the natural inter-line spacing.
\sa height(), lineSpacing()
*/
qreal QFontMetricsF::leading() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return engine->leading().toReal();
}
/*!
Returns the distance from one base line to the next.
This value is always equal to leading()+height().
\sa height(), leading()
*/
qreal QFontMetricsF::lineSpacing() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return (engine->leading() + engine->ascent() + engine->descent()).toReal();
}
/*!
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.
\sa minRightBearing(), leftBearing()
*/
qreal QFontMetricsF::minLeftBearing() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return engine->minLeftBearing();
}
/*!
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.
\sa minLeftBearing(), rightBearing()
*/
qreal QFontMetricsF::minRightBearing() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return engine->minRightBearing();
}
/*!
Returns the width of the widest character in the font.
*/
qreal QFontMetricsF::maxWidth() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return engine->maxCharWidth();
}
/*!
Returns the 'x' height of the font. This is often but not always
the same as the height of the character 'x'.
*/
qreal QFontMetricsF::xHeight() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
if (d->capital == QFont::SmallCaps)
return d->smallCapsFontPrivate()->engineForScript(QChar::Script_Common)->ascent().toReal();
return engine->xHeight().toReal();
}
/*!
\since 4.2
Returns the average width of glyphs in the font.
*/
qreal QFontMetricsF::averageCharWidth() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return engine->averageCharWidth().toReal();
}
/*!
Returns \c true if character \a ch is a valid character in the font;
otherwise returns \c false.
*/
bool QFontMetricsF::inFont(QChar ch) const
{
return inFontUcs4(ch.unicode());
}
/*!
\fn bool QFontMetricsF::inFontUcs4(uint ch) const
Returns \c true if the character given by \a ch, encoded in UCS-4/UTF-32,
is a valid character in the font; otherwise returns \c false.
*/
bool QFontMetricsF::inFontUcs4(uint ucs4) const
{
const int script = QChar::script(ucs4);
QFontEngine *engine = d->engineForScript(script);
Q_ASSERT(engine != nullptr);
if (engine->type() == QFontEngine::Box)
return false;
return engine->canRender(ucs4);
}
/*!
Returns the left bearing of character \a 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.
\sa rightBearing(), minLeftBearing(), horizontalAdvance()
*/
qreal QFontMetricsF::leftBearing(QChar ch) const
{
QFontEngine *engine = d->engineForCharacter(ch.unicode());
if (engine->type() == QFontEngine::Box)
return 0;
d->alterCharForCapitalization(ch);
glyph_t glyph = engine->glyphIndex(ch.unicode());
qreal lb;
engine->getGlyphBearings(glyph, &lb);
return lb;
}
/*!
Returns the right bearing of character \a 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.
\sa leftBearing(), minRightBearing(), horizontalAdvance()
*/
qreal QFontMetricsF::rightBearing(QChar ch) const
{
const int script = ch.script();
QFontEngine *engine;
if (d->capital == QFont::SmallCaps && ch.isLower())
engine = d->smallCapsFontPrivate()->engineForScript(script);
else
engine = d->engineForScript(script);
Q_ASSERT(engine != nullptr);
if (engine->type() == QFontEngine::Box)
return 0;
d->alterCharForCapitalization(ch);
glyph_t glyph = engine->glyphIndex(ch.unicode());
qreal rb;
engine->getGlyphBearings(glyph, nullptr, &rb);
return rb;
}
/*!
Returns the horizontal advance in pixels of the first \a length characters of \a
text. If \a length is negative (the default), the entire string is
used. The entire length of \a text is analysed even if \a length is substantially
shorter.
The advance is the distance appropriate for drawing a subsequent
character after \a text.
\since 5.11
\sa boundingRect()
*/
qreal QFontMetricsF::horizontalAdvance(const QString &text, int length) const
{
int pos = (length >= 0)
? QStringView(text).left(length).indexOf(s_variableLengthStringSeparator)
: text.indexOf(s_variableLengthStringSeparator);
if (pos != -1)
length = pos;
else if (length < 0)
length = text.size();
if (length == 0)
return 0;
Q_DECL_UNINITIALIZED QStackTextEngine layout(text, QFont(d.data()));
layout.itemize();
return layout.width(0, length).toReal();
}
/*!
Returns the horizontal advance in pixels of \a text laid out using \a option.
The advance is the distance appropriate for drawing a subsequent
character after \a text.
\since 6.3
\sa boundingRect()
*/
qreal QFontMetricsF::horizontalAdvance(const QString &text, const QTextOption &option) const
{
int pos = text.indexOf(s_variableLengthStringSeparator);
int length = -1;
if (pos != -1)
length = pos;
else
length = text.size();
if (length == 0)
return 0;
Q_DECL_UNINITIALIZED QStackTextEngine layout(text, QFont(d.data()));
layout.option = option;
layout.itemize();
return layout.width(0, length).toReal();
}
/*!
\overload
\image bearings.png Bearings
Returns the horizontal advance of character \a ch in pixels. This is a
distance appropriate for drawing a subsequent character after \a
ch.
Some of the metrics are described in the image to the right. The
central dark rectangles cover the logical horizontalAdvance() 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.
\since 5.11
\sa boundingRect()
*/
qreal QFontMetricsF::horizontalAdvance(QChar ch) const
{
if (ch.category() == QChar::Mark_NonSpacing)
return 0.;
const int script = ch.script();
QFontEngine *engine;
if (d->capital == QFont::SmallCaps && ch.isLower())
engine = d->smallCapsFontPrivate()->engineForScript(script);
else
engine = d->engineForScript(script);
Q_ASSERT(engine != nullptr);
d->alterCharForCapitalization(ch);
glyph_t glyph = engine->glyphIndex(ch.unicode());
QFixed advance;
QGlyphLayout glyphs;
glyphs.numGlyphs = 1;
glyphs.glyphs = &glyph;
glyphs.advances = &advance;
engine->recalcAdvances(&glyphs, { });
return advance.toReal();
}
/*!
Returns the bounding rectangle of the characters in the string
specified by \a 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, \e not as
linebreaks.
The height of the bounding rectangle is at least as large as the
value returned height().
\sa horizontalAdvance(), height(), QPainter::boundingRect()
*/
QRectF QFontMetricsF::boundingRect(const QString &text) const
{
int len = text.size();
if (len == 0)
return QRectF();
Q_DECL_UNINITIALIZED QStackTextEngine layout(text, QFont(d.data()));
layout.itemize();
glyph_metrics_t gm = layout.boundingBox(0, len);
return QRectF(gm.x.toReal(), gm.y.toReal(),
gm.width.toReal(), gm.height.toReal());
}
/*!
Returns the bounding rectangle of the characters in the string
specified by \a text laid out using \a 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, \e not as
linebreaks.
The height of the bounding rectangle is at least as large as the
value returned height().
\since 6.3
\sa horizontalAdvance(), height(), QPainter::boundingRect()
*/
QRectF QFontMetricsF::boundingRect(const QString &text, const QTextOption &option) const
{
if (text.size() == 0)
return QRectF();
Q_DECL_UNINITIALIZED QStackTextEngine layout(text, QFont(d.data()));
layout.option = option;
layout.itemize();
glyph_metrics_t gm = layout.boundingBox(0, text.size());
return QRectF(gm.x.toReal(), gm.y.toReal(),
gm.width.toReal(), gm.height.toReal());
}
/*!
Returns the bounding rectangle of the character \a 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 \e
all pixels in the bounding rectangle.
Note that the rectangle usually extends both above and below the
base line.
\sa horizontalAdvance()
*/
QRectF QFontMetricsF::boundingRect(QChar ch) const
{
const int script = ch.script();
QFontEngine *engine;
if (d->capital == QFont::SmallCaps && ch.isLower())
engine = d->smallCapsFontPrivate()->engineForScript(script);
else
engine = d->engineForScript(script);
Q_ASSERT(engine != nullptr);
d->alterCharForCapitalization(ch);
glyph_t glyph = engine->glyphIndex(ch.unicode());
glyph_metrics_t gm = engine->boundingBox(glyph);
return QRectF(gm.x.toReal(), gm.y.toReal(), gm.width.toReal(), gm.height.toReal());
}
/*!
\overload
Returns the bounding rectangle of the characters in the given \a text.
This is the set of pixels the text would cover if drawn when constrained
to the bounding rectangle specified by \a rect. If \a rect is a reference
to a \nullptr object, e.g. when passing a default constructed QRectF, the
bounding rectangle will not constrain itself to the size.
The \a flags argument is the bitwise OR of the following flags:
\list
\li Qt::AlignLeft aligns to the left border, except for
Arabic and Hebrew where it aligns to the right.
\li Qt::AlignRight aligns to the right border, except for
Arabic and Hebrew where it aligns to the left.
\li Qt::AlignJustify produces justified text.
\li Qt::AlignHCenter aligns horizontally centered.
\li Qt::AlignTop aligns to the top border.
\li Qt::AlignBottom aligns to the bottom border.
\li Qt::AlignVCenter aligns vertically centered
\li Qt::AlignCenter (== \c{Qt::AlignHCenter | Qt::AlignVCenter})
\li Qt::TextSingleLine ignores newline characters in the text.
\li Qt::TextExpandTabs expands tabs (see below)
\li Qt::TextShowMnemonic interprets "&x" as \underline{x}; i.e., underlined.
\li Qt::TextWordWrap breaks the text to fit the rectangle.
\endlist
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 \l{Qt::AlignmentFlag}.
If Qt::TextExpandTabs is set in \a flags, the following behavior is
used to interpret tab characters in the text:
\list
\li If \a tabArray is non-null, it specifies a 0-terminated sequence of
pixel-positions for tabs in the text.
\li If \a tabStops is non-zero, it is used as the tab spacing (in pixels).
\endlist
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 \l{minLeftBearing()}{maximum left} and
\l{minRightBearing()}{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.
\sa horizontalAdvance(), QPainter::boundingRect(), Qt::Alignment
*/
QRectF QFontMetricsF::boundingRect(const QRectF &rect, int flags, const QString& text,
int tabStops, int *tabArray) const
{
int tabArrayLen = 0;
if (tabArray)
while (tabArray[tabArrayLen])
tabArrayLen++;
QRectF rb;
qt_format_text(QFont(d.data()), rect, flags | Qt::TextDontPrint, text, &rb, tabStops, tabArray,
tabArrayLen, nullptr);
return rb;
}
/*!
Returns the size in pixels of the characters in the given \a text.
The \a flags argument is the bitwise OR of the following flags:
\list
\li Qt::TextSingleLine ignores newline characters.
\li Qt::TextExpandTabs expands tabs (see below)
\li Qt::TextShowMnemonic interprets "&x" as \underline{x}; i.e., underlined.
\li Qt::TextWordWrap breaks the text to fit the rectangle.
\endlist
These flags are defined in the \l{Qt::TextFlag} enum.
If Qt::TextExpandTabs is set in \a flags, the following behavior is
used to interpret tab characters in the text:
\list
\li If \a tabArray is non-null, it specifies a 0-terminated sequence of
pixel-positions for tabs in the text.
\li If \a tabStops is non-zero, it is used as the tab spacing (in pixels).
\endlist
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.
\sa boundingRect()
*/
QSizeF QFontMetricsF::size(int flags, const QString &text, int tabStops, int *tabArray) const
{
return boundingRect(QRectF(), flags | Qt::TextLongestVariant, text, tabStops, tabArray).size();
}
/*!
\since 4.3
Returns a tight bounding rectangle around the characters in the
string specified by \a 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, \e not as
linebreaks.
\sa horizontalAdvance(), height(), boundingRect()
*/
QRectF QFontMetricsF::tightBoundingRect(const QString &text) const
{
if (text.size() == 0)
return QRectF();
Q_DECL_UNINITIALIZED QStackTextEngine layout(text, QFont(d.data()));
layout.itemize();
glyph_metrics_t gm = layout.tightBoundingBox(0, text.size());
return QRectF(gm.x.toReal(), gm.y.toReal(), gm.width.toReal(), gm.height.toReal());
}
/*!
Returns a tight bounding rectangle around the characters in the
string specified by \a text laid out using \a 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, \e not as
linebreaks.
\since 6.3
\sa horizontalAdvance(), height(), boundingRect()
*/
QRectF QFontMetricsF::tightBoundingRect(const QString &text, const QTextOption &option) const
{
if (text.size() == 0)
return QRectF();
Q_DECL_UNINITIALIZED QStackTextEngine layout(text, QFont(d.data()));
layout.option = option;
layout.itemize();
glyph_metrics_t gm = layout.tightBoundingBox(0, text.size());
return QRectF(gm.x.toReal(), gm.y.toReal(), gm.width.toReal(), gm.height.toReal());
}
/*!
\since 4.2
If the string \a text is wider than \a width, returns an elided
version of the string (i.e., a string with "..." in it).
Otherwise, returns the original string.
The \a 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 \a width is specified in pixels, not characters.
The \a flags argument is optional and currently only supports
Qt::TextShowMnemonic as value.
The elide mark follows the \l{Qt::LayoutDirection}{layoutdirection}.
For example, it will be on the right side of the text for right-to-left
layouts if the \a mode is \c{Qt::ElideLeft}, and on the left side of the
text if the \a mode is \c{Qt::ElideRight}.
*/
QString QFontMetricsF::elidedText(const QString &text, Qt::TextElideMode mode, qreal width, int flags) const
{
QString _text = text;
if (!(flags & Qt::TextLongestVariant)) {
int posA = 0;
int posB = _text.indexOf(s_variableLengthStringSeparator);
while (posB >= 0) {
QString portion = _text.mid(posA, posB - posA);
if (size(flags, portion).width() <= width)
return portion;
posA = posB + 1;
posB = _text.indexOf(s_variableLengthStringSeparator, posA);
}
_text = _text.mid(posA);
}
Q_DECL_UNINITIALIZED QStackTextEngine engine(_text, QFont(d.data()));
return engine.elidedText(mode, QFixed::fromReal(width), flags);
}
/*!
Returns the distance from the base line to where an underscore
should be drawn.
\sa overlinePos(), strikeOutPos(), lineWidth()
*/
qreal QFontMetricsF::underlinePos() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return engine->underlinePosition().toReal();
}
/*!
Returns the distance from the base line to where an overline
should be drawn.
\sa underlinePos(), strikeOutPos(), lineWidth()
*/
qreal QFontMetricsF::overlinePos() const
{
return ascent() + 1;
}
/*!
Returns the distance from the base line to where the strikeout
line should be drawn.
\sa underlinePos(), overlinePos(), lineWidth()
*/
qreal QFontMetricsF::strikeOutPos() const
{
return ascent() / 3.;
}
/*!
Returns the width of the underline and strikeout lines, adjusted
for the point size of the font.
\sa underlinePos(), overlinePos(), strikeOutPos()
*/
qreal QFontMetricsF::lineWidth() const
{
QFontEngine *engine = d->engineForScript(QChar::Script_Common);
Q_ASSERT(engine != nullptr);
return engine->lineThickness().toReal();
}
/*!
\since 5.14
Returns the font DPI.
*/
qreal QFontMetricsF::fontDpi() const
{
return d->dpi;
}
QT_END_NAMESPACE