我有一个 qtquick 项目，其中包含一个 main.qml 和一个 EaDrawArea，它继承自 QQuickPaintedItem，并且可以从 main.qml 访问。qml 中有一个 Slider，它绑定到 EaDrawArea 的m_scale（3 到 100），我还设置了一个世界变换矩阵
（m_rate、0.0、0.0、
  0.0、-m_rate、0.0、
  512.0、384.0、1.0），
m_rate是 EaDrawArea 的成员，它是 1024/20。下面是 main.qml：
Window {
    width: 1200
    height: 1000
    visible: true
    title: qsTr("Hello World")

    DrawingArea {
        id: drawarea
        focus: trues
        fillColor: "#dddddd"
        width: 1024
        height: 768
        anchors.left: parent.left
        anchors.leftMargin: 10
        anchors.top: parent.top
        anchors.topMargin: 10

        MouseArea {
            anchors.fill: parent
            onPressed: {
                drawarea.focus = true
                mouse.accepted = false
            }
        }
    }

    Slider {
        id: scalevalue
        height: 50
        anchors.bottom: parent.bottom
        anchors.horizontalCenter: parent.horizontalCenter
        width: parent.width-10
        anchors.margins: 5
        value: 3.0
        stepSize: 1.0
        minimumValue: 3.0
        maximumValue: 100.0
        onValueChanged: {
            drawarea.setScaleValue(scalevalue.value)
        }
    }
}
构造函数, mousePressEvent 和paint函数如下：
EaDrawArea::EaDrawArea(QQuickItem *parent) {
    m_scale = 3;
    m_rate = 1024.0 / 20.0;
    m_x=0;
    m_y=0;
    m_x1 = 0;
    m_y1 = 0;
    setAcceptedMouseButtons(Qt::AllButtons);
    setAcceptHoverEvents(true);
}

void EaDrawArea::mousePressEvent(QMouseEvent *event)
{
    m_x = (event->x() - 512.0) / m_rate; // 512 is half of the canvas width (1024 / 2)
    m_y = -(event->y() - 384.0) / m_rate; // 384 is half of the canvas height (768 / 2)
    m_x1 = m_x * m_rate / m_scale;
    m_y1 = m_y * m_rate / m_scale;
    this->update(); // Trigger a repaint to draw at the new coordinates
}

void EaDrawArea::paint(QPainter* painter) {
    painter->setRenderHint(QPainter::Antialiasing, true);

    QTransform trans;

    trans.setMatrix(m_rate, 0.0, 0.0,
                    0.0, -m_rate, 0.0,
                    512.0, 384.0, 1.0);
    painter->resetTransform();
    painter->setWorldTransform(trans);

    painter->save();
    QPen redPen(Qt::red);
    redPen.setWidth(1);
    redPen.setCosmetic(true);
    painter->setPen(redPen);

    QRectF rect(m_x1, m_y1, 10, 5);
    QPointF center = rect.center();
    //1. painter->translate(center);
    painter->scale(m_scale/m_rate, m_scale/m_rate);
    //2. painter->translate(-center);
    painter->drawRect(rect);
    painter->restore();
}
我想在鼠标光标处绘制一个红色矩形，更重要的是从矩形的中心缩放。如果我在 paint 函数中注释掉上面的两行，缩放有效但不从中心开始。如果我取消注释上面的两行，缩放将从中心开始，但矩形不会在鼠标光标处呈现，为什么？如何解决（在光标处渲染并从矩形中心缩放）？有偿100元解决。
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