QTextEdit with different text colors (Qt / C++)

The ONLY thing that worked for me was html.

Code snippet follows.

QString line = "contains some text from somewhere ..."
    :
    :
QTextCursor cursor = ui->messages->textCursor();
QString alertHtml = "<font color=\"DeepPink\">";
QString notifyHtml = "<font color=\"Lime\">";
QString infoHtml = "<font color=\"Aqua\">";
QString endHtml = "</font><br>";

switch(level)
{
    case msg_alert: line = alertHtml % line; break;
    case msg_notify: line = notifyHtml % line; break;
    case msg_info: line = infoHtml % line; break;
    default: line = infoHtml % line; break;
}

line = line % endHtml;
ui->messages->insertHtml(line);
cursor.movePosition(QTextCursor::End);
ui->messages->setTextCursor(cursor);

Link to doc

A few quotes:

QTextEdit is an advanced WYSIWYG viewer/editor supporting rich text formatting using HTML-style tags. It is optimized to handle large documents and to respond quickly to user input.

.

The text edit can load both plain text and HTML files (a subset of HTML 3.2 and 4).

.

QTextEdit can display a large HTML subset, including tables and images.

This means mostly deprecated tags and as such does not include any current CSS, so I turned to this:

// save    
int fw = ui->textEdit->fontWeight();
QColor tc = ui->textEdit->textColor();
// append
ui->textEdit->setFontWeight( QFont::DemiBold );
ui->textEdit->setTextColor( QColor( "red" ) );
ui->textEdit->append( entry );
// restore
ui->textEdit->setFontWeight( fw );
ui->textEdit->setTextColor( tc );

Just a quick addition: an alternative to generating the html yourself, if you're populating the text box programatically, is to use textEdit->setTextColor(QColor&). You can create the QColor object yourself, or use one of the predefined colours in the Qt namespace (Qt::black, Qt::red, etc). It will apply the specified colour to any text you add, until it is called again with a different one.

Use text formated as HTML, for example:

textEdit->setHtml(text);

where text, is a HTML formated text, contains with colored lines and etc.