Qt Reference Documentation

- Qt 4.8
- ALL VERSIONS

- A
- A
- A
- Print

# highlighter.cpp Example File

richtext/syntaxhighlighter/highlighter.cpp

     /****************************************************************************
     **
     ** Copyright (C) 2015 The Qt Company Ltd.
     ** Contact: http://www.qt.io/licensing/
     **
     ** This file is part of the examples of the Qt Toolkit.
     **
     ** $QT_BEGIN_LICENSE:BSD$
     ** You may use this file under the terms of the BSD license as follows:
     **
     ** "Redistribution and use in source and binary forms, with or without
     ** modification, are permitted provided that the following conditions are
     ** met:
     **   * Redistributions of source code must retain the above copyright
     **     notice, this list of conditions and the following disclaimer.
     **   * Redistributions in binary form must reproduce the above copyright
     **     notice, this list of conditions and the following disclaimer in
     **     the documentation and/or other materials provided with the
     **     distribution.
     **   * Neither the name of The Qt Company Ltd nor the names of its
     **     contributors may be used to endorse or promote products derived
     **     from this software without specific prior written permission.
     **
     **
     ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     ** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
     **
     ** $QT_END_LICENSE$
     **
     ****************************************************************************/

     #include <QtGui>

     #include "highlighter.h"

     Highlighter::Highlighter(QTextDocument *parent)
         : QSyntaxHighlighter(parent)
     {
         HighlightingRule rule;

         keywordFormat.setForeground(Qt::darkBlue);
         keywordFormat.setFontWeight(QFont::Bold);
         QStringList keywordPatterns;
         keywordPatterns << "\\bchar\\b" << "\\bclass\\b" << "\\bconst\\b"
                         << "\\bdouble\\b" << "\\benum\\b" << "\\bexplicit\\b"
                         << "\\bfriend\\b" << "\\binline\\b" << "\\bint\\b"
                         << "\\blong\\b" << "\\bnamespace\\b" << "\\boperator\\b"
                         << "\\bprivate\\b" << "\\bprotected\\b" << "\\bpublic\\b"
                         << "\\bshort\\b" << "\\bsignals\\b" << "\\bsigned\\b"
                         << "\\bslots\\b" << "\\bstatic\\b" << "\\bstruct\\b"
                         << "\\btemplate\\b" << "\\btypedef\\b" << "\\btypename\\b"
                         << "\\bunion\\b" << "\\bunsigned\\b" << "\\bvirtual\\b"
                         << "\\bvoid\\b" << "\\bvolatile\\b";
         foreach (const QString &pattern, keywordPatterns) {
             rule.pattern = QRegExp(pattern);
             rule.format = keywordFormat;
             highlightingRules.append(rule);
         }

         classFormat.setFontWeight(QFont::Bold);
         classFormat.setForeground(Qt::darkMagenta);
         rule.pattern = QRegExp("\\bQ[A-Za-z]+\\b");
         rule.format = classFormat;
         highlightingRules.append(rule);

         singleLineCommentFormat.setForeground(Qt::red);
         rule.pattern = QRegExp("//[^\n]*");
         rule.format = singleLineCommentFormat;
         highlightingRules.append(rule);

         multiLineCommentFormat.setForeground(Qt::red);

         quotationFormat.setForeground(Qt::darkGreen);
         rule.pattern = QRegExp("\".*\"");
         rule.format = quotationFormat;
         highlightingRules.append(rule);

         functionFormat.setFontItalic(true);
         functionFormat.setForeground(Qt::blue);
         rule.pattern = QRegExp("\\b[A-Za-z0-9_]+(?=\\()");
         rule.format = functionFormat;
         highlightingRules.append(rule);

         commentStartExpression = QRegExp("/\\*");
         commentEndExpression = QRegExp("\\*/");
     }

     void Highlighter::highlightBlock(const QString &text)
     {
         foreach (const HighlightingRule &rule, highlightingRules) {
             QRegExp expression(rule.pattern);
             int index = expression.indexIn(text);
             while (index >= 0) {
                 int length = expression.matchedLength();
                 setFormat(index, length, rule.format);
                 index = expression.indexIn(text, index + length);
             }
         }
         setCurrentBlockState(0);

         int startIndex = 0;
         if (previousBlockState() != 1)
             startIndex = commentStartExpression.indexIn(text);

         while (startIndex >= 0) {
             int endIndex = commentEndExpression.indexIn(text, startIndex);
             int commentLength;
             if (endIndex == -1) {
                 setCurrentBlockState(1);
                 commentLength = text.length() - startIndex;
             } else {
                 commentLength = endIndex - startIndex
                                 + commentEndExpression.matchedLength();
             }
             setFormat(startIndex, commentLength, multiLineCommentFormat);
             startIndex = commentStartExpression.indexIn(text, startIndex + commentLength);
         }
     }