[QScintilla] Using QsciLexerCustom

[Chris Packham]

On Wed, Jan 13, 2010 at 1:12 PM, Baz Walter <bazwal at ftml.net> wrote:
> Chris Packham wrote:
>>
>> Hi,
>>
>> Is there an example somewhere using the QsciLexerCustom class?
>
> there's a thread here which may be some help to you:
>
> http://www.riverbankcomputing.com/pipermail/pyqt/2009-July/023655.html
>

Thanks for the link that got me started. For completeness here's my
initial C++ version. Its probably buggy but you get the idea.

> cat mylexer.h

#ifndef MYLEXER_H
#define MYLEXER_H

#include <QObject>
#include <qscilexercustom.h>

class QsciStyle;

class MyLexer : public QsciLexerCustom {
        Q_OBJECT

public:
        enum {
                Default = 0,
                Comment = 1,
                MaxStyle
        };

        MyLexer(QObject *parent = 0);
        ~MyLexer();
        const char *language() const;
        QString description(int) const;
        void styleText(int start, int end);
        QColor defaultColor(int);
        QFont  defaultFont(int);
        QColor defaultPaper(int);

private:
        QsciStyle getStyle(int);
};

#endif

> cat mylexer.cpp

#include <QDebug>
#include <QColor>
#include <QFont>
#include <qsciscintilla.h>
#include <qscistyle.h>
#include "mylexer.h"

MyLexer::MyLexer(QObject *parent)
        : QsciLexerCustom(parent)
{
        qDebug() << __FUNCTION__;
}

MyLexer::~MyLexer()
{
        qDebug() << __FUNCTION__;
}

const char* MyLexer::language() const
{
        return "AsciiDoc";
}

QString MyLexer::description(int style) const
{
        switch(style){
        case Default:
                return "Default";
        case Comment:
                return "Comment";
        }

        return QString();
}

void MyLexer::styleText(int start, int end)
{
        QString source;
        int i;

        qDebug() << __FUNCTION__
                << "start =" << start
                << " end =" << end;

        if (!editor())
                return;

        char *chars = (char *) malloc (end - start);
        editor()->SendScintilla(QsciScintilla::SCI_GETTEXTRANGE,
start, end, chars);
        source = QString(chars);
        free(chars);

        qDebug() << "source =" << source;

        startStyling(start, 0x1f);
        QStringList list = source.split("\n");
        for (i = 0; i < list.size(); i++) {
                QString line = list.at(i);
                int len = line.size();
                int style;
                qDebug() << "line =" << line;

                if (line.startsWith("//")) {
                        style = Comment;
                } else {
                        style = Default;
                }
                qDebug() << "Styling " << len << "bytes " << description(style);
                setStyling(len, getStyle(style));
                // newline character was consumed in split so...
                setStyling(1, getStyle(Default));
        }
}

QColor MyLexer::defaultColor(int style)
{
        switch(style){
        case Default:
                return QColor(0xe0, 0x0, 0x0);
        case Comment:
                return QColor(0x0, 0xe0, 0x0);
        }
        return QsciLexer::defaultColor(style);
}

QFont  MyLexer::defaultFont(int style)
{
        return QFont("Courier New", 10);
}

QColor MyLexer::defaultPaper(int style)
{
        return QsciLexer::defaultPaper(style);
}

QsciStyle MyLexer::getStyle(int style)
{
        if (style < MaxStyle) {
                return QsciStyle(style, description(style), defaultColor(style),
                        defaultPaper(style), defaultFont(style));
        } else {
                return QsciStyle(style);
        }
}