Added a GUI theme selector in preferences and a new class for handling GUI changes.

Added a new feature for editing style sheets and variable colors and see immediately the result.
Made Qwt plots (and items) stylable.
Added icons, improved styling possibilities of QMinimizePanel, fixed minor bugs in RicThemeColorEditorFeature.

ApplicationCode/UserInterface/RiuQssSyntaxHighlighter.cpp

@@ -0,0 +1,185 @@
+/////////////////////////////////////////////////////////////////////////////////
+//
+//  Copyright (C) 2020 Equinor ASA
+//
+//  ResInsight is free software: you can redistribute it and/or modify
+//  it under the terms of the GNU General Public License as published by
+//  the Free Software Foundation, either version 3 of the License, or
+//  (at your option) any later version.
+//
+//  ResInsight is distributed in the hope that it will be useful, but WITHOUT ANY
+//  WARRANTY; without even the implied warranty of MERCHANTABILITY or
+//  FITNESS FOR A PARTICULAR PURPOSE.
+//
+//  See the GNU General Public License at <http://www.gnu.org/licenses/gpl.html>
+//  for more details.
+//
+/////////////////////////////////////////////////////////////////////////////////
+
+#include "RiuQssSyntaxHighlighter.h"
+
+#include <QRegularExpression>
+
+//--------------------------------------------------------------------------------------------------
+///
+//--------------------------------------------------------------------------------------------------
+QssSyntaxHighligter::QssSyntaxHighligter( QTextDocument* parent )
+    : QSyntaxHighlighter( parent )
+{
+}
+
+//--------------------------------------------------------------------------------------------------
+///
+//--------------------------------------------------------------------------------------------------
+void QssSyntaxHighligter::highlightBlock( const QString& text )
+{
+    QTextCharFormat variableFormat;
+    variableFormat.setFontWeight( QFont::Bold );
+    variableFormat.setForeground( QColor( "#e20a48" ) );
+
+    QTextCharFormat commentFormat;
+    commentFormat.setFontWeight( QFont::Normal );
+    commentFormat.setForeground( QColor( "#4e9041" ) );
+
+    QTextCharFormat classFormat;
+    classFormat.setFontWeight( QFont::Bold );
+    classFormat.setForeground( QColor( "#fc8f00" ) );
+
+    QTextCharFormat handleFormat;
+    handleFormat.setFontWeight( QFont::Bold );
+    handleFormat.setForeground( QColor( "#e20a48" ) );
+
+    QTextCharFormat modifierFormat;
+    modifierFormat.setFontWeight( QFont::Normal );
+    modifierFormat.setForeground( QColor( "#e20a48" ) );
+
+    // Block states:
+    // -1 - none
+    // 1 - inside class
+    // 2 - inside function
+    // 3 - inside multiline comment
+
+    QRegularExpression classStartExpression    = QRegularExpression( QString( "\\{" ) );
+    QRegularExpression classEndExpression      = QRegularExpression( QString( "\\}" ) );
+    QRegularExpression functionStartExpression = QRegularExpression( QString( "\\(" ) );
+    QRegularExpression functionEndExpression   = QRegularExpression( QString( "\\)" ) );
+    QRegularExpression commentStartExpression  = QRegularExpression( QString( "/\\*" ) );
+    QRegularExpression commentEndExpression    = QRegularExpression( QString( "\\*/" ) );
+
+    setCurrentBlockState( -1 );
+
+    auto parseClass = [this, text]( int startIndex, int length ) {
+        QTextCharFormat propertyFormat;
+        propertyFormat.setFontWeight( QFont::Bold );
+
+        QTextCharFormat valueFormat;
+        valueFormat.setFontWeight( QFont::Normal );
+        valueFormat.setForeground( QColor( "#0d98ce" ) );
+
+        QTextCharFormat functionFormat;
+        functionFormat.setFontWeight( QFont::Bold );
+        functionFormat.setForeground( QColor( "#dd1bc1" ) );
+
+        QRegularExpression expression =
+            QRegularExpression( "\\s*([a-zA-Z0-9_-]+)[ \\t]*:\\s*([a-zA-Z0-9_-]+\\()?([\\$#\\[\\]:\\.,a-zA-Z0-9-_ "
+                                "]+)(\\))?[ \\t]*;" );
+        QRegularExpressionMatchIterator j = expression.globalMatch( text );
+        while ( j.hasNext() )
+        {
+            QRegularExpressionMatch matchClass = j.next();
+            setFormat( startIndex + matchClass.capturedStart( 1 ), matchClass.capturedLength( 1 ), propertyFormat );
+            setFormat( startIndex + matchClass.capturedStart( 2 ), matchClass.capturedLength( 2 ), functionFormat );
+            setFormat( startIndex + matchClass.capturedStart( 3 ), matchClass.capturedLength( 3 ), valueFormat );
+            setFormat( startIndex + matchClass.capturedStart( 4 ), matchClass.capturedLength( 4 ), functionFormat );
+        }
+    };
+
+    if ( previousBlockState() == -1 )
+    {
+        QRegularExpression expression = QRegularExpression( "([a-zA-z0-9_-]+)(::[a-zA-Z0-9_-]+)?(:[a-zA-Z0-9_-]+)?" );
+        QRegularExpressionMatchIterator i = expression.globalMatch( text );
+        while ( i.hasNext() )
+        {
+            QRegularExpressionMatch matchClass = i.next();
+            setFormat( matchClass.capturedStart( 1 ), matchClass.capturedLength( 1 ), classFormat );
+            setFormat( matchClass.capturedStart( 2 ), matchClass.capturedLength( 2 ), handleFormat );
+            setFormat( matchClass.capturedStart( 3 ), matchClass.capturedLength( 3 ), modifierFormat );
+        }
+
+        int startIndex = text.indexOf( classStartExpression );
+        while ( startIndex >= 0 )
+        {
+            QRegularExpressionMatch match       = classEndExpression.match( text, startIndex );
+            int                     endIndex    = match.capturedStart();
+            int                     classLength = 0;
+            if ( endIndex == -1 )
+            {
+                setCurrentBlockState( 1 );
+                classLength = text.length() - startIndex;
+            }
+            else
+            {
+                classLength = endIndex - startIndex + match.capturedLength();
+            }
+            parseClass( startIndex, classLength );
+            startIndex = text.indexOf( classStartExpression, startIndex + classLength );
+        }
+    }
+    if ( previousBlockState() == 1 )
+    {
+        int startIndex = 0;
+        while ( startIndex >= 0 )
+        {
+            QRegularExpressionMatch match       = classEndExpression.match( text, startIndex );
+            int                     endIndex    = match.capturedStart();
+            int                     classLength = 0;
+            if ( endIndex == -1 )
+            {
+                setCurrentBlockState( 1 );
+                classLength = text.length() - startIndex;
+            }
+            else
+            {
+                classLength = endIndex - startIndex + match.capturedLength();
+            }
+            parseClass( startIndex, classLength );
+            startIndex = text.indexOf( classStartExpression, startIndex + classLength );
+        }
+    }
+
+    QRegularExpression              expression( "\\$[a-zA-z0-9_]+" );
+    QRegularExpressionMatchIterator i = expression.globalMatch( text );
+    while ( i.hasNext() )
+    {
+        QRegularExpressionMatch match = i.next();
+        setFormat( match.capturedStart(), match.capturedLength(), variableFormat );
+    }
+
+    expression = QRegularExpression( "\\/\\/(.*)" );
+    i          = expression.globalMatch( text );
+    while ( i.hasNext() )
+    {
+        QRegularExpressionMatch match = i.next();
+        setFormat( match.capturedStart(), match.capturedLength(), commentFormat );
+    }
+
+    int startIndex = 0;
+    if ( previousBlockState() != 2 ) startIndex = text.indexOf( commentStartExpression );
+    while ( startIndex >= 0 )
+    {
+        QRegularExpressionMatch match         = commentEndExpression.match( text, startIndex );
+        int                     endIndex      = match.capturedStart();
+        int                     commentLength = 0;
+        if ( endIndex == -1 )
+        {
+            setCurrentBlockState( 2 );
+            commentLength = text.length() - startIndex;
+        }
+        else
+        {
+            commentLength = endIndex - startIndex + match.capturedLength();
+        }
+        setFormat( startIndex, commentLength, commentFormat );
+        startIndex = text.indexOf( commentStartExpression, startIndex + commentLength );
+    }
+}