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2010-05-25T14:21:06Z

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==Code editor==

<source lang="cpp">
/****************************************************************************
**
** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** 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 Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 2.1 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 2.1 requirements
** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
**
** In addition, as a special exception, Nokia gives you certain additional
** rights. These rights are described in the Nokia Qt LGPL Exception
** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 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 the GNU General Public License version 3.0 requirements will be
** met: http://www.gnu.org/copyleft/gpl.html.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
#ifndef CODEEDITOR_H
#define CODEEDITOR_H
#include <QPlainTextEdit>
#include <QObject>
QT_BEGIN_NAMESPACE
class QPaintEvent;
class QResizeEvent;
class QSize;
class QWidget;
QT_END_NAMESPACE
class LineNumberArea;
//![codeeditordefinition]
class CodeEditor : public QPlainTextEdit
{
Q_OBJECT
public:
CodeEditor(QWidget *parent = 0);
void lineNumberAreaPaintEvent(QPaintEvent *event);
int lineNumberAreaWidth();
protected:
void resizeEvent(QResizeEvent *event);
private slots:
void updateLineNumberAreaWidth(int newBlockCount);
void highlightCurrentLine();
void updateLineNumberArea(const QRect &, int);
private:
QWidget *lineNumberArea;
};
//![codeeditordefinition]
//![extraarea]
class LineNumberArea : public QWidget
{
public:
LineNumberArea(CodeEditor *editor) : QWidget(editor) {
codeEditor = editor;
}
QSize sizeHint() const {
return QSize(codeEditor->lineNumberAreaWidth(), 0);
}
protected:
void paintEvent(QPaintEvent *event) {
codeEditor->lineNumberAreaPaintEvent(event);
}
private:
CodeEditor *codeEditor;
};
//![extraarea]
#endif

#include <QtGui>
#include "codeeditor.h"
//![constructor]
CodeEditor::CodeEditor(QWidget *parent) : QPlainTextEdit(parent)
{
lineNumberArea = new LineNumberArea(this);
connect(this, SIGNAL(blockCountChanged(int)), this, SLOT(updateLineNumberAreaWidth(int)));
connect(this, SIGNAL(updateRequest(const QRect &, int)), this, SLOT(updateLineNumberArea(const QRect &, int)));
connect(this, SIGNAL(cursorPositionChanged()), this, SLOT(highlightCurrentLine()));
updateLineNumberAreaWidth(0);
highlightCurrentLine();
}
//![constructor]
//![extraAreaWidth]
int CodeEditor::lineNumberAreaWidth()
{
int digits = 1;
int max = qMax(1, blockCount());
while (max >= 10) {
max /= 10;
++digits;
}
int space = 3 + fontMetrics().width(QLatin1Char("9")) * digits;
return space;
}
//![extraAreaWidth]
//![slotUpdateExtraAreaWidth]
void CodeEditor::updateLineNumberAreaWidth(int /* newBlockCount */)
{
setViewportMargins(lineNumberAreaWidth(), 0, 0, 0);
}
//![slotUpdateExtraAreaWidth]
//![slotUpdateRequest]
void CodeEditor::updateLineNumberArea(const QRect &rect, int dy)
{
if (dy)
lineNumberArea->scroll(0, dy);
else
lineNumberArea->update(0, rect.y(), lineNumberArea->width(), rect.height());
if (rect.contains(viewport()->rect()))
updateLineNumberAreaWidth(0);
}
//![slotUpdateRequest]
//![resizeEvent]
void CodeEditor::resizeEvent(QResizeEvent *e)
{
QPlainTextEdit::resizeEvent(e);
QRect cr = contentsRect();
lineNumberArea->setGeometry(QRect(cr.left(), cr.top(), lineNumberAreaWidth(), cr.height()));
}
//![resizeEvent]
//![cursorPositionChanged]
void CodeEditor::highlightCurrentLine()
{
QList<QTextEdit::ExtraSelection> extraSelections;
if (!isReadOnly()) {
QTextEdit::ExtraSelection selection;

QColor lineColor = QColor(Qt::yellow).lighter(160);
selection.format.setBackground(lineColor);
selection.format.setProperty(QTextFormat::FullWidthSelection, true);
selection.cursor = textCursor();
selection.cursor.clearSelection();
extraSelections.append(selection);
}
setExtraSelections(extraSelections);
}
//![cursorPositionChanged]
//![extraAreaPaintEvent_0]
void CodeEditor::lineNumberAreaPaintEvent(QPaintEvent *event)
{
QPainter painter(lineNumberArea);
painter.fillRect(event->rect(), Qt::lightGray);
//![extraAreaPaintEvent_0]
//![extraAreaPaintEvent_1]
QTextBlock block = firstVisibleBlock();
int blockNumber = block.blockNumber();
int top = (int) blockBoundingGeometry(block).translated(contentOffset()).top();
int bottom = top + (int) blockBoundingRect(block).height();
//![extraAreaPaintEvent_1]
//![extraAreaPaintEvent_2]
while (block.isValid() && top <= event->rect().bottom()) {
if (block.isVisible() && bottom >= event->rect().top()) {
QString number = QString::number(blockNumber + 1);
painter.setPen(Qt::black);
painter.drawText(0, top, lineNumberArea->width(), fontMetrics().height(),
Qt::AlignRight, number);
}
block = block.next();
top = bottom;
bottom = top + (int) blockBoundingRect(block).height();
++blockNumber;
}
}
//![extraAreaPaintEvent_2]

#include <QtGui>
#include "codeeditor.h"
int main(int argv, char **args)
{
QApplication app(argv, args);
CodeEditor editor;
editor.setWindowTitle(QObject::tr("Code Editor Example"));
editor.show();
return app.exec();
}

</source>

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