QPlainTextEdit and anchors

[bear101]

Hi

I'm using a QPlainTextEdit for text chat and would like to highlight URLs. I do this by subclassing QSyntaxHighlighter and call setFormat() like this:

class UrlSyntaxHighlighter : public QSyntaxHighlighter
...
    void highlightBlock(const QString& text)
    {
        QString pattern = "(http://[^ ]+)";
        QRegExp expression(pattern);
        int index = text.indexOf(expression);
        while (index >= 0) {
            int length = expression.matchedLength();
            QTextCharFormat myClassFormat = format(index);
            myClassFormat.setFontUnderline(true);
            myClassFormat.setForeground(Qt::blue);
            myClassFormat.setAnchor(true);
            myClassFormat.setAnchorHref(expression.cap(1));
            myClassFormat.setAnchorName(expression.cap(1));
            setFormat(index, length, myClassFormat);
            index = text.indexOf(expression, index + length);
        }
    }

class UrlSyntaxHighlighter : public QSyntaxHighlighter
...
    void highlightBlock(const QString& text)
    {
        QString pattern = "(http://[^ ]+)";
        QRegExp expression(pattern);
        int index = text.indexOf(expression);
        while (index >= 0) {
            int length = expression.matchedLength();
            QTextCharFormat myClassFormat = format(index);
            myClassFormat.setFontUnderline(true);
            myClassFormat.setForeground(Qt::blue);
            myClassFormat.setAnchor(true);
            myClassFormat.setAnchorHref(expression.cap(1));
            myClassFormat.setAnchorName(expression.cap(1));
            setFormat(index, length, myClassFormat);
            index = text.indexOf(expression, index + length);
        }
    }

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In my QPlainTextEdit I'm then overriding mouseMoveEvent(.) to change the mouse cursor when the anchor is hovered. However, when I access the QTextCursor using QPlainTextEdit::cursorForPosition(.) and extract the QTextCharFormat there is no anchor set on the text. Anyone know why?

Btw, I know I can use QTextEdit instead which has better support for anchors but I try and keep memory low and I don't need all the fancy picture-stuff. Also I'm aware that the regex isn't entirely correct.

-- Bjoern

[fullmetalcoder]

does the highlighting even show up? did you enable mouse tracking? could you also post the code of your mouseMoveEvent?

[bear101]

Hi

I've solved it in a rather cumbersome way where I use cursorForPosition() to manually sweep each QTextBlock for a URL.

Here is basically what I do:

QString ChatTextEdit::currentUrl(QMouseEvent* e) const
{
    QTextDocument* doc = document();
 
    int cursor_pos = cursorForPosition(e->pos()).position();
    QTextBlock block = doc->findBlock(cursor_pos);
    int block_pos = block.position();
 
    QString text = block.text();
 
    QVector<int> url_index, url_length;
    QStringList urls;
 
    int index = 0;
    QString url;
    do
    {
        int length = 0;
        url = urlFound(text, index, length);
        if(url.size())
        {
            url_index.push_back(index);
            url_length.push_back(length);
            urls.push_back(url);
        }
        index += length;
    }
    while(url.size());
 
    url.clear();
 
    for(int i=0;i<url_index.size();i++)
    {
        if(cursor_pos >= block_pos+url_index[i] &&
           cursor_pos < block_pos+url_index[i]+url_length[i])
        {
           url = urls[i];
           break;
        }
    }
 
    return url;
}

QString ChatTextEdit::currentUrl(QMouseEvent* e) const
{
    QTextDocument* doc = document();

    int cursor_pos = cursorForPosition(e->pos()).position();
    QTextBlock block = doc->findBlock(cursor_pos);
    int block_pos = block.position();

    QString text = block.text();

    QVector<int> url_index, url_length;
    QStringList urls;

    int index = 0;
    QString url;
    do
    {
        int length = 0;
        url = urlFound(text, index, length);
        if(url.size())
        {
            url_index.push_back(index);
            url_length.push_back(length);
            urls.push_back(url);
        }
        index += length;
    }
    while(url.size());

    url.clear();

    for(int i=0;i<url_index.size();i++)
    {
        if(cursor_pos >= block_pos+url_index[i] &&
           cursor_pos < block_pos+url_index[i]+url_length[i])
        {
           url = urls[i];
           break;
        }
    }

    return url;
}

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-- Bjoern