Question: How to move selected code right/left using Tab/Shift+Tab? about richtextfx HOT 3 CLOSED

// Pattern to see if a line starts with a tab or 1-4 spaces
var tabOrSpacePattern = Pattern.compile( "^(\t| {1,4})" );

codeArea.addEventFilter( KeyEvent.KEY_PRESSED, KE ->
{
    if ( KE.getCode() == KeyCode.TAB )
    {
        var selection = codeArea.getSelection();
        var startParagraph = codeArea.offsetToPosition( selection.getStart(), Bias.Backward ).getMajor();
        var endParagraph = codeArea.offsetToPosition( selection.getEnd(), Bias.Forward ).getMajor();

        if ( startParagraph != endParagraph ) // is it a multi-line selection
        {
            var mc = codeArea.createMultiChange(); // group the changes into one for undo/redo
            IntConsumer tabAction; // takes paragraph number p as a parameter

            if ( ! KE.isShiftDown() ) tabAction = p -> mc.insertText( p, 0, "\t" );
            else tabAction = p -> // remove tabs/spaces if present
            {
                var match = tabOrSpacePattern.matcher( codeArea.getText( p, 0, p, 4 ) );
                if ( match.find() ) mc.deleteText( p, 0, p, match.group().length() );
            };

            for ( var p = startParagraph; p <= endParagraph; p++ )
            {
                if ( codeArea.getParagraph( p ).length() > 0 )
                {
                    tabAction.accept( p );
                }
            }

            mc.commit();

            // Reselect the original selection for further tab actions
            var endLength = codeArea.getParagraph( endParagraph ).length();
            codeArea.selectRange( startParagraph, 0, endParagraph, endLength );

            KE.consume();
        }
    }
} );