// 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.

    \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

{

    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()

*/

int QFontMetrics::leftBearing(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 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

{

    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 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;

    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 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

{

    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 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.

    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

*/

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.

    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;