qtextlayout.cpp

奇趣公司比较新的qt/emd版本

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#include "qtextlayout.h"
#include "qtextengine_p.h"

#include <qfont.h>
#include <qapplication.h>
#include <qpainter.h>
#include <qvarlengtharray.h>
#include <qtextformat.h>
#include <qabstracttextdocumentlayout.h>
#include "qtextdocument_p.h"
#include "qtextformat_p.h"
#include "qstyleoption.h"
#include "qpainterpath.h"
#include <limits.h>

#include <qdebug.h>

#include "qfontengine_p.h"

#define ObjectSelectionBrush (QTextFormat::ForegroundBrush + 1)

static inline QFixed leadingSpaceWidth(QTextEngine *eng, const QScriptLine &line)
{
    if (!line.hasTrailingSpaces
        || (eng->option.flags() & QTextOption::IncludeTrailingSpaces)
        || !(eng->option.alignment() & Qt::AlignRight)
        || (eng->option.textDirection() != Qt::RightToLeft))
        return QFixed();

    int pos = line.length;
    const QCharAttributes *attributes = eng->attributes();
    while (pos > 0 && attributes[line.from + pos - 1].whiteSpace)
        --pos;
    return eng->width(line.from + pos, line.length - pos);
}

static QFixed alignLine(QTextEngine *eng, const QScriptLine &line)
{
    QFixed x = 0;
    eng->justify(line);
    if (!line.justified) {
        int align = eng->option.alignment();
        if (align & Qt::AlignJustify && eng->option.textDirection() == Qt::RightToLeft)
            align = Qt::AlignRight;
        if (align & Qt::AlignRight)
            x = line.width - (line.textWidth + leadingSpaceWidth(eng, line));
        else if (align & Qt::AlignHCenter)
            x = (line.width - line.textWidth)/2;
    }
    return x;
}

/*!
    \class QTextLayout::FormatRange
    \brief The QTextLayout::FormatRange structure is used to apply extra formatting information
    for a specified area in the text layout's content.

    \sa QTextLayout::setAdditionalFormats(), QTextLayout::draw()
*/

/*!
    \variable QTextLayout::FormatRange::start
    Specifies the beginning of the format range within the text layout's text.
*/

/*!
    \variable QTextLayout::FormatRange::length
    Specifies the numer of characters the format range spans.
*/

/*!
    \variable QTextLayout::FormatRange::format
    Specifies the format to apply.
*/

/*!
    \class QTextInlineObject
    \brief The QTextInlineObject class represents an inline object in
    a QTextLayout.

    \ingroup text

    This class is only used if the text layout is used to lay out
    parts of a QTextDocument.

    The inline object has various attributes that can be set, for
    example using, setWidth(), setAscent(), and setDescent(). The
    rectangle it occupies is given by rect(), and its direction by
    isRightToLeft(). Its position in the text layout is given by at(),
    and its format is given by format().
*/

/*!
    \fn QTextInlineObject::QTextInlineObject(int i, QTextEngine *e)

    Creates a new inline object for the item at position \a i in the
    text engine \a e.
*/

/*!
    \fn QTextInlineObject::QTextInlineObject()

    \internal
*/

/*!
    \fn bool QTextInlineObject::isValid() const

    Returns true if this inline object is valid; otherwise returns
    false.
*/

/*!
    Returns the inline object's rectangle.

    \sa ascent() descent() width()
*/
QRectF QTextInlineObject::rect() const
{
    QScriptItem& si = eng->layoutData->items[itm];
    return QRectF(0, -si.ascent.toReal(), si.width.toReal(), si.height().toReal());
}

/*!
    Returns the inline object's width.

    \sa ascent() descent() rect()
*/
qreal QTextInlineObject::width() const
{
    return eng->layoutData->items[itm].width.toReal();
}

/*!
    Returns the inline object's ascent.

    \sa descent() width() rect()
*/
qreal QTextInlineObject::ascent() const
{
    return eng->layoutData->items[itm].ascent.toReal();
}

/*!
    Returns the inline object's descent.

    \sa ascent() width() rect()
*/
qreal QTextInlineObject::descent() const
{
    return eng->layoutData->items[itm].descent.toReal();
}

/*!
    Returns the inline object's total height. This is equal to
    ascent() + descent() + 1.

    \sa ascent() descent() width() rect()
*/
qreal QTextInlineObject::height() const
{
    return eng->layoutData->items[itm].height().toReal();
}


/*!
    Sets the inline object's width to \a w.

    \sa width() ascent() descent() rect()
*/
void QTextInlineObject::setWidth(qreal w)
{
    eng->layoutData->items[itm].width = QFixed::fromReal(w);
}

/*!
    Sets the inline object's ascent to \a a.

    \sa ascent() setDescent() width() rect()
*/
void QTextInlineObject::setAscent(qreal a)
{
    eng->layoutData->items[itm].ascent = QFixed::fromReal(a);
}

/*!
    Sets the inline object's decent to \a d.

    \sa descent() setAscent() width() rect()
*/
void QTextInlineObject::setDescent(qreal d)
{
    eng->layoutData->items[itm].descent = QFixed::fromReal(d);
}

/*!
  The position of the inline object within the text layout.
*/
int QTextInlineObject::textPosition() const
{
    return eng->layoutData->items[itm].position;
}

/*!
  Returns an integer describing the format of the inline object
  within the text layout.
*/
int QTextInlineObject::formatIndex() const
{
    return eng->formatIndex(&eng->layoutData->items[itm]);
}

/*!
  Returns format of the inline object within the text layout.
*/
QTextFormat QTextInlineObject::format() const
{
    if (!eng->block.docHandle())
        return QTextFormat();
    return eng->formats()->format(eng->formatIndex(&eng->layoutData->items[itm]));
}

/*!
  Returns if the object should be laid out right-to-left or left-to-right.
*/
Qt::LayoutDirection QTextInlineObject::textDirection() const
{
    return (eng->layoutData->items[itm].analysis.bidiLevel % 2 ? Qt::RightToLeft : Qt::LeftToRight);
}

/*!
    \class QTextLayout
    \brief The QTextLayout class is used to lay out and paint a single
    paragraph of text.

    \ingroup text

    It offers most features expected from a modern text layout
    engine, including Unicode compliant rendering, line breaking and
    handling of cursor positioning. It can also produce and render
    device independent layout, something that is important for WYSIWYG
    applications.

    The class has a rather low level API and unless you intend to
    implement your own text rendering for some specialized widget, you
    probably won't need to use it directly.

    QTextLayout can currently deal with plain text and rich text
    paragraphs that are part of a QTextDocument.

    QTextLayout can be used to create a sequence of QTextLine's with
    given widths and can position them independently on the screen.
    Once the layout is done, these lines can be drawn on a paint
    device.

    Here's some pseudo code that presents the layout phase:
    \code
        int leading = fontMetrics.leading();
        int height = 0;
        qreal widthUsed = 0;
        textLayout.beginLayout();
        while (1) {
            QTextLine line = textLayout.createLine();
            if (!line.isValid())
                break;

            line.setLineWidth(lineWidth);
            height += leading;
            line.setPosition(QPoint(0, height));
            height += line.height();
            widthUsed = qMax(widthUsed, line.naturalTextWidth());
        }
        textLayout.endLayout();
    \endcode

    The text can be drawn by calling the layout's draw() function:
    \code
        QPainter painter(this);
        textLayout.draw(&painter, QPoint(0, 0));
    \endcode

    The text layout's text is set in the constructor or with
    setText(). The layout can be seen as a sequence of QTextLine
    objects; use lineAt() or lineForTextPosition() to get a QTextLine,
    createLine() to create one. For a given position in the text you
    can find a valid cursor position with isValidCursorPosition(),
    nextCursorPosition(), and previousCursorPosition(). The layout
    itself can be positioned with setPosition(); it has a
    boundingRect(), and a minimumWidth() and a maximumWidth(). A text
    layout can be drawn on a painter device using draw().

*/

/*!
    \enum QTextLayout::CursorMode

    \value SkipCharacters
    \value SkipWords
*/

/*!
    \fn QTextEngine *QTextLayout::engine() const
    \internal

    Returns the text engine used to render the text layout.
*/

/*!
    Constructs an empty text layout.

    \sa setText()
*/
QTextLayout::QTextLayout()
{ d = new QTextEngine(); }

/*!
    Constructs a text layout to lay out the given \a text.
*/
QTextLayout::QTextLayout(const QString& text)
{
    d = new QTextEngine();
    d->text = text;
}

/*!
    Constructs a text layout to lay out the given \a text with the specified
    \a font.

    All the metric and layout calculations will be done in terms of
    the paint device, \a paintdevice. If \a paintdevice is 0 the
    calculations will be done in screen metrics.
*/
QTextLayout::QTextLayout(const QString& text, const QFont &font, QPaintDevice *paintdevice)
{
    QFontPrivate *f = paintdevice ? QFont(font, paintdevice).d : font.d;
    d = new QTextEngine((text.isNull() ? (const QString&)QString::fromLatin1("") : text), f);
}

/*!
    \internal
    Constructs a text layout to lay out the given \a block.
*/
QTextLayout::QTextLayout(const QTextBlock &block)
{
    d = new QTextEngine();
    d->block = block;
}

/*!
    Destructs the layout.
*/
QTextLayout::~QTextLayout()
{
    if (!d->stackEngine)
        delete d;
}

/*!
    Sets the layout's font to the given \a font. The layout is
    invalidated and must be laid out again.

    \sa text()
*/
void QTextLayout::setFont(const QFont &font)
{
    d->fnt = font;
}

/*!
    Returns the current font that is used for the layout, or a default
    font if none is set.
*/
QFont QTextLayout::font() const
{
    return d->font();
}

/*!
    Sets the layout's text to the given \a string. The layout is
    invalidated and must be laid out again.

    \sa text()
*/
void QTextLayout::setText(const QString& string)
{
    d->invalidate();
    d->text = string;