|  | Home · Examples

# Code for Code Editor Example

    /****************************************************************************
    **
    ** Copyright (C) 1992-2008 Nokia. All rights reserved.
    **
    ** This file is part of Qt Jambi.
    **
    ** * Commercial Usage
    * Licensees holding valid Qt Commercial licenses may use this file in
    * accordance with the Qt Commercial License Agreement provided with the
    * Software or, alternatively, in accordance with the terms contained in
    * a written agreement between you and Nokia.
    *
    *
    * GNU General Public License Usage
    * Alternatively, this file may be used under the terms of the GNU
    * General Public License versions 2.0 or 3.0 as published by the Free
    * Software Foundation and appearing in the file LICENSE.GPL included in
    * the packaging of this file.  Please review the following information
    * to ensure GNU General Public Licensing requirements will be met:
    * http://www.fsf.org/licensing/licenses/info/GPLv2.html and
    * http://www.gnu.org/copyleft/gpl.html.  In addition, as a special
    * exception, Nokia gives you certain additional rights. These rights
    * are described in the Nokia Qt GPL Exception version 1.2, included in
    * the file GPL_EXCEPTION.txt in this package.
    *
    * Qt for Windows(R) Licensees
    * As a special exception, Nokia, as the sole copyright holder for Qt
    * Designer, grants users of the Qt/Eclipse Integration plug-in the
    * right for the Qt/Eclipse Integration to link to functionality
    * provided by Qt Designer and its related libraries.
    *
    *
    * If you are unsure which license is appropriate for your use, please
    * contact the sales department at qt-sales@nokia.com.

    **
    ** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
    ** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
    **
    ****************************************************************************/

    package com.trolltech.examples;

    import com.trolltech.qt.*;
    import com.trolltech.qt.core.*;
    import com.trolltech.qt.gui.*;

    import java.util.*;

    @QtJambiExample(name = "Code Editor")
    public class CodeEditor extends QPlainTextEdit
    {

        public CodeEditor()
        {
            lineNumberArea = new LineNumberArea(this);

            blockCountChanged.connect(this, "updateLineNumberAreaWidth(Integer)");
            updateRequest.connect(this, "updateLineNumberArea(QRect,Integer)");
            cursorPositionChanged.connect(this, "highlightCurrentLine()");

            updateLineNumberAreaWidth(0);
            highlightCurrentLine();

            setWindowTitle("Code Editor Example");
            setWindowIcon(new QIcon("classpath:com/trolltech/images/qt-logo.png"));
        }

        public int lineNumberAreaWidth()
        {
            int digits = 1;
            int max = Math.max(1, blockCount());
            while (max >= 10) {
                max /= 10;
                ++digits;
            }

            int space = 3 + fontMetrics().width('9') * digits;

            return space;
        }

        public void updateLineNumberAreaWidth(Integer newBlockCount)
        {
            setViewportMargins(lineNumberAreaWidth(), 0, 0, 0);
        }

        public void updateLineNumberArea(QRect rect, Integer dy)
        {
            if (dy > 0)
                lineNumberArea.scroll(0, dy);
            else
                lineNumberArea.update(0, rect.y(), lineNumberArea.width(),
                                      rect.height());

            if (rect.contains(viewport().rect()))
                updateLineNumberAreaWidth(0);
        }

        @Override
        protected void resizeEvent(QResizeEvent e)
        {
            super.resizeEvent(e);

            QRect cr = contentsRect();
            lineNumberArea.setGeometry(new QRect(cr.left(), cr.top(),
                                       lineNumberAreaWidth(), cr.height()));
        }

        private void highlightCurrentLine()
        {
            List<QTextEdit_ExtraSelection> extraSelections =
                new Vector<QTextEdit_ExtraSelection>();

            if (!isReadOnly()) {
                QTextEdit_ExtraSelection selection =
                    new QTextEdit_ExtraSelection();

                QColor lineColor = QColor.yellow.lighter(160);

                QTextCharFormat format = selection.format();
                format.setBackground(new QBrush(lineColor));
                format.setProperty(QTextFormat.Property.FullWidthSelection.value(), new Boolean(true));
                selection.setFormat(format);
                QTextCursor cursor = textCursor();
                cursor.clearSelection();
                selection.setCursor(cursor);
                extraSelections.add(selection);
            }

            setExtraSelections(extraSelections);
        }

        public void lineNumberAreaPaintEvent(QPaintEvent event)
        {
            QPainter painter = new QPainter(lineNumberArea);
            painter.setPen(new QPen(QColor.black));
            painter.fillRect(event.rect(), new QBrush(QColor.lightGray));

            QTextBlock block = firstVisibleBlock();
            int blockNumber = block.blockNumber();
            int top = (int) blockBoundingGeometry(block).translated(contentOffset()).top();
            int bottom = top + (int) blockBoundingRect(block).height();

            while (block.isValid() && top <= event.rect().bottom()) {
                if (block.isVisible() && bottom >= event.rect().top()) {
                    String number = String.valueOf(blockNumber + 1);
                    painter.drawText(0, top, lineNumberArea.width(), fontMetrics().height(),
                                    Qt.AlignmentFlag.AlignRight.value(), number);
                }

                block = block.next();
                top = bottom;
                bottom = top + (int) blockBoundingRect(block).height();
                ++blockNumber;
            }
        }

        private static class LineNumberArea extends QWidget
        {
            public LineNumberArea(CodeEditor editor)
            {
                codeEditor = editor;
                setParent(codeEditor);
            }

            @Override
            public QSize sizeHint()
            {
                return new QSize(codeEditor.lineNumberAreaWidth(), 0);
            }

            @Override
            protected void paintEvent(QPaintEvent event)
            {
                codeEditor.lineNumberAreaPaintEvent(event);
            }

            private CodeEditor codeEditor;
        }

        private LineNumberArea lineNumberArea;

        public static void main(String args[])
        {
            QApplication.initialize(args);

            new CodeEditor().show();

            QApplication.exec();
        }
    }