技術標籤：qtc++ui設計

Qt中mouseMoveEvent(QmouseEvent *event)使用探討

在學習網路教程過程中，嘗試使用Qpainter製作一個塗鴉板，需要使用QmouseEvent ，按照教程，塗鴉板不能繪製曲線，只能繪製直線。這裡做一些總結。
教程連結：http://shouce.jb51.net/qt-beginning/21.html

依據連結的教程所述，mouseMoveEvent實現如上，除錯是後面加的，程式碼中判斷語句沒有執行進來
ui中關於mouseTracking的設定如上(本例中不需要勾選)
問題確認：
1）ui設計介面勾選mouseTracking或者程式碼設定setMouseTracking(true);後，不需要按下滑鼠左鍵，移動滑鼠即可捕捉滑鼠移動事件

void Dialog::paintEvent(QPaintEvent *event)
{
    Q_UNUSED
 
(event);

    QPainter pp(&pix);
    pp.drawLine(lastpoint / scale, endpoint / scale);
    lastpoint = endpoint;
    QPainter painter(this);
    painter.scale(scale, scale);
    painter.drawPixmap(0, 0, pix);
}

void Dialog::mousePressEvent(QMouseEvent *event)
{
    lastpress_button = event->button
 
();
    if (event->button() == Qt::LeftButton) {
        lastpoint = event->pos();
        qDebug() << "mousePressEvent pos:" << event->pos() << endl;
    }
}

void Dialog::mouseMoveEvent(QMouseEvent *event)
{
    qDebug() << "mouseMoveEvent  pos:" << event->pos() << endl;
    qDebug() << "event->button():" << event->button() << endl;
    if (lastpress_button & Qt::LeftButton) {
        endpoint = event->pos();
        qDebug() << "mouseMoveEvent LeftButtonpress pos:" << event->pos() << endl;
        update();
    }
}

void Dialog::mouseReleaseEvent(QMouseEvent *event)
{
    if (event->button() == Qt::LeftButton) {
        endpoint = event->pos();
        qDebug() << "mouseReleaseEvent pos:" << event->pos() << endl;
        update();
    }
}

void Dialog::wheelEvent(QWheelEvent *event)
{
    if (event->delta() > 0) {    //滾輪向上滾
        scale *= 1.25;
    } else if (event->delta() < 0) {
        scale /= 1.25;
    }
    update();
}