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#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(QRect,int)), this, SLOT(updateLineNumberArea(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]