QT有问！进来没奖

//![cursorPositionChanged]
//![extraAreaPaintEvent_0]
voidCodeEditor::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]