qtextdocument.cpp

奇趣公司比较新的qt/emd版本

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#include "qtextdocument.h"
#include <qtextformat.h>
#include "qtextdocumentlayout_p.h"
#include "qtextdocumentfragment.h"
#include "qtextdocumentfragment_p.h"
#include "qtexttable.h"
#include "qtextlist.h"
#include <qdebug.h>
#include <qregexp.h>
#include <qvarlengtharray.h>
#include <qtextcodec.h>
#include "qtexthtmlparser_p.h"
#include "qpainter.h"
#include "qprinter.h"
#include "qtextedit.h"
#include "qtextcontrol_p.h"

#include "qtextdocument_p.h"

#include <limits.h>

/*!
    Returns true if the string \a text is likely to be rich text;
    otherwise returns false.

    This function uses a fast and therefore simple heuristic. It
    mainly checks whether there is something that looks like a tag
    before the first line break. Although the result may be correct
    for common cases, there is no guarantee.

    This function is defined in the \c <QTextDocument> header file.
*/
bool Qt::mightBeRichText(const QString& text)
{
    if (text.isEmpty())
        return false;
    int start = 0;

    while (start < text.length() && text.at(start).isSpace())
        ++start;

    // skip a leading <?xml ... ?> as for example with xhtml
    if (text.mid(start, 5) == QLatin1String("<?xml")) {
        while (start < text.length()) {
            if (text.at(start) == QLatin1Char('?')
                && start + 2 < text.length()
                && text.at(start + 1) == QLatin1Char('>')) {
                start += 2;
                break;
            }
            ++start;
        }

        while (start < text.length() && text.at(start).isSpace())
            ++start;
    }

    if (text.mid(start, 5).toLower() == QLatin1String("<!doc"))
        return true;
    int open = start;
    while (open < text.length() && text.at(open) != QLatin1Char('<')
            && text.at(open) != QLatin1Char('\n')) {
        if (text.at(open) == QLatin1Char('&') &&  text.mid(open+1,3) == QLatin1String("lt;"))
            return true; // support desperate attempt of user to see <...>
        ++open;
    }
    if (open < text.length() && text.at(open) == QLatin1Char('<')) {
        const int close = text.indexOf(QLatin1Char('>'), open);
        if (close > -1) {
            QString tag;
            for (int i = open+1; i < close; ++i) {
                if (text[i].isDigit() || text[i].isLetter())
                    tag += text[i];
                else if (!tag.isEmpty() && text[i].isSpace())
                    break;
                else if (!text[i].isSpace() && (!tag.isEmpty() || text[i] != QLatin1Char('!')))
                    return false; // that's not a tag
            }
            return QTextHtmlParser::lookupElement(tag.toLower()) != -1;
        }
    }
    return false;
}

/*!
    Converts the plain text string \a plain to a HTML string with
    HTML metacharacters \c{<}, \c{>}, and \c{&} replaced by HTML
    entities.

    Example:

    \code
        QString plain = "#include <QtCore>"
        QString html = Qt::escape(plain);
        // html == "#include &lt;QtCore&gt;"
    \endcode

    This function is defined in the \c <QTextDocument> header file.

    \sa convertFromPlainText(), mightBeRichText()
*/
QString Qt::escape(const QString& plain)
{
    QString rich;
    rich.reserve(int(plain.length() * 1.1));
    for (int i = 0; i < plain.length(); ++i) {
        if (plain.at(i) == QLatin1Char('<'))
            rich += QLatin1String("&lt;");
        else if (plain.at(i) == QLatin1Char('>'))
            rich += QLatin1String("&gt;");
        else if (plain.at(i) == QLatin1Char('&'))
            rich += QLatin1String("&amp;");
        else
            rich += plain.at(i);
    }
    return rich;
}

/*!
    \fn QString Qt::convertFromPlainText(const QString &plain, WhiteSpaceMode mode)

    Converts the plain text string \a plain to an HTML-formatted
    paragraph while preserving most of its look.

    \a mode defines how whitespace is handled.

    This function is defined in the \c <QTextDocument> header file.

    \sa escape(), mightBeRichText()
*/
QString Qt::convertFromPlainText(const QString &plain, Qt::WhiteSpaceMode mode)
{
    int col = 0;
    QString rich;
    rich += QLatin1String("<p>");
    for (int i = 0; i < plain.length(); ++i) {
        if (plain[i] == QLatin1Char('\n')){
            int c = 1;
            while (i+1 < plain.length() && plain[i+1] == QLatin1Char('\n')) {
                i++;
                c++;
            }
            if (c == 1)
                rich += QLatin1String("<br>\n");
            else {
                rich += QLatin1String("</p>\n");
                while (--c > 1)
                    rich += QLatin1String("<br>\n");
                rich += QLatin1String("<p>");
            }
            col = 0;
        } else {
            if (mode == Qt::WhiteSpacePre && plain[i] == QLatin1Char('\t')){
                rich += QChar(0x00a0U);
                ++col;
                while (col % 8) {
                    rich += QChar(0x00a0U);
                    ++col;
                }
            }
            else if (mode == Qt::WhiteSpacePre && plain[i].isSpace())
                rich += QChar(0x00a0U);
            else if (plain[i] == QLatin1Char('<'))
                rich += QLatin1String("&lt;");
            else if (plain[i] == QLatin1Char('>'))
                rich += QLatin1String("&gt;");
            else if (plain[i] == QLatin1Char('&'))
                rich += QLatin1String("&amp;");
            else
                rich += plain[i];
            ++col;
        }
    }
    if (col != 0)
        rich += QLatin1String("</p>");
    return rich;
}

#ifndef QT_NO_TEXTCODEC
/*!
    \internal

    This function is defined in the \c <QTextDocument> header file.
*/
QTextCodec *Qt::codecForHtml(const QByteArray &ba)
{
    return QTextCodec::codecForHtml(ba);
}
#endif

/*!
    \class QTextDocument qtextdocument.h
    \brief The QTextDocument class holds formatted text that can be
    viewed and edited using a QTextEdit.

    \ingroup text
    \mainclass

    QTextDocument is a container for structured rich text documents, providing
    support for styled text and various types of document elements, such as
    lists, tables, frames, and images.
    They can be created for use in a QTextEdit, or used independently.

    Each document element is described by an associated format object. Each
    format object is treated as a unique object by QTextDocuments, and can be
    passed to objectForFormat() to obtain the document element that it is
    applied to.

    A QTextDocument can be edited programmatically using a QTextCursor, and
    its contents can be examined by traversing the document structure. The
    entire document structure is stored as a hierarchy of document elements
    beneath the root frame, found with the rootFrame() function. Alternatively,
    if you just want to iterate over the textual contents of the document you
    can use begin(), end(), and findBlock() to retrieve text blocks that you
    can examine and iterate over.

    The layout of a document is determined by the documentLayout();
    you can create your own QAbstractTextDocumentLayout subclass and
    set it using setDocumentLayout() if you want to use your own
    layout logic. The document's title can be obtained by calling the
    documentTitle() function.

    The toPlainText() and toHtml() convenience functions allow you to retrieve the
    contents of the document as plain text and HTML.
    The document's text can be searched using the find() functions.

    Undo/redo of operations performed on the document can be controlled using
    the setUndoRedoEnabled() function. The undo/redo system can be controlled
    by an editor widget through the undo() and redo() slots; the document also
    provides contentsChanged(), undoAvailable(), and redoAvailable() signals
    that inform connected editor widgets about the state of the undo/redo
    system.

    \sa QTextCursor QTextEdit \link richtext.html Rich Text Processing\endlink
*/

/*!
    \property QTextDocument::defaultFont
    \brief the default font used to display the document's text
*/

/*!
    \property QTextDocument::defaultTextOption
    \brief the default text option will be set on all \l{QTextLayout}s in the document.

    When \l{QTextBlock}s are created, the defaultTextOption is set on their
    QTextLayout. This allows setting global properties for the document such as the
    default word wrap mode. 
 */

/*!
    Constructs an empty QTextDocument with the given \a parent.
*/
QTextDocument::QTextDocument(QObject *parent)
    : QObject(*new QTextDocumentPrivate, parent)
{
    Q_D(QTextDocument);
    d->init();
}

/*!
    Constructs a QTextDocument containing the plain (unformatted) \a text
    specified, and with the given \a parent.
*/
QTextDocument::QTextDocument(const QString &text, QObject *parent)
    : QObject(*new QTextDocumentPrivate, parent)
{
    Q_D(QTextDocument);
    d->init();
    QTextCursor(this).insertText(text);
}

/*!
    \internal
*/
QTextDocument::QTextDocument(QTextDocumentPrivate &dd, QObject *parent)
    : QObject(dd, parent)
{
    Q_D(QTextDocument);
    d->init();
}

/*!
    Destroys the document.
*/
QTextDocument::~QTextDocument()
{
}


/*!
  Creates a new QTextDocument that is a copy of this text document. \a
  parent is the parent of the returned text document.
*/
QTextDocument *QTextDocument::clone(QObject *parent) const
{
    Q_D(const QTextDocument);
    QTextDocument *doc = new QTextDocument(parent);
    QTextCursor(doc).insertFragment(QTextDocumentFragment(this));
    doc->rootFrame()->setFrameFormat(rootFrame()->frameFormat());
    QTextDocumentPrivate *priv = doc->d_func();
    priv->title = d->title;
    priv->pageSize = d->pageSize;
    priv->defaultTextOption = d->defaultTextOption;
    priv->setDefaultFont(d->defaultFont());
    priv->resources = d->resources;
    priv->defaultStyleSheet = d->defaultStyleSheet;
    priv->parsedDefaultStyleSheet = d->parsedDefaultStyleSheet;
    return doc;
}

/*!
    Returns true if the document is empty; otherwise returns false.
*/
bool QTextDocument::isEmpty() const
{
    Q_D(const QTextDocument);
    /* because if we're empty we still have one single paragraph as
     * one single fragment */
    return d->length() <= 1;
}

/*!
  Clears the document.
*/
void QTextDocument::clear()
{
    Q_D(QTextDocument);
    d->clear();
    d->resources.clear();
}

/*!
    \since 4.2

    Undoes the last editing operation on the document if undo is
    available. The provided \a cursor is positioned at the end of the
    location where the edition operation was undone.

    See the \l {Overview of Qt's Undo Framework}{Qt Undo Framework}
    documentation for details.

    \sa undoAvailable(), isUndoRedoEnabled()
*/
void QTextDocument::undo(QTextCursor *cursor)
{
    Q_D(QTextDocument);
    const int pos = d->undoRedo(true);
    if (cursor && pos >= 0) {
        *cursor = QTextCursor(this);
        cursor->setPosition(pos);
    }
}

/*!
    \since 4.2
    Redoes the last editing operation on the document if \link
    QTextDocument::isRedoAvailable() redo is available\endlink.

    The provided \a cursor is positioned at the end of the location where
    the edition operation was redone.
*/
void QTextDocument::redo(QTextCursor *cursor)
{
    Q_D(QTextDocument);
    const int pos = d->undoRedo(false);
    if (cursor && pos >= 0) {
        *cursor = QTextCursor(this);
        cursor->setPosition(pos);
    }
}

/*!
    \overload

*/
void QTextDocument::undo()
{
    Q_D(QTextDocument);
    d->undoRedo(true);
}

/*!
    \overload
    Redoes the last editing operation on the document if \link
    QTextDocument::isRedoAvailable() redo is available\endlink.