代码之家 › 专栏 › 技术社区 › Toloka

Qpainter绘制图像边界不透明

qpixmap qt6 qgraphicsitem pyqt qt

0

Toloka · 技术社区 · 2 年前

我做了一个习惯 QGraphicsItem 我正在压倒 paint 用于绘制图像的函数 ghost.png ,一个具有复杂边界的角色,可以通过单击移动降低 / 上面的 / 左边 / 正确的 图像的一侧。

我知道这是因为 boundingRect ,我将其设置得更大,因为我需要绘制其他内容,例如:文本、健康栏等。。。

我怎样才能保留更大的 boundingrect 并且还限制图像仅在点击图像时移动。

我的班级:

class DrawImage : public QGraphicsItem
{
public:
    DrawImage();

protected:
    QRectF boundingRect() const override;
    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) override;
};

我的定义:

DrawImage::DrawImage()
{
    setFlag(ItemIsMovable);
}

QRectF DrawImage::boundingRect() const
{
    return QRectF(0, 0, 100, 200);
}

void DrawImage::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
    auto ghost = QImage(":ghost.png");
    painter->drawImage(QRect(0, 0, 100, 100), ghost);
}

0 回复 | 直到 2 年前

1

2

user17726418 Shajeen Ahamed 2 年前

musicamante 说:

覆盖[QGraphicsItem::] shape .

以下是如何使 QGraphicsPixmapItem 仅当点击其时可移动 pixmap ,并拥有 boundingRect 围绕它:

class DrawImage : public QGraphicsItem
{
public:
    DrawImage()
    {
        setFlag(ItemIsMovable);
    }

protected:
    QRectF boundingRect() const override
    {
        return QRectF(0, 0, 100, 200);
    }

    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget) override
    {
        auto greenBall = QPixmap(":green.svg");
        QRect rect = boundingRect().toRect();

        //You can adjust where your pixmap is drawn
        //I chose the upper part of the bounding rect
        rect.adjust(0,0,0,-rect.height()/2);
        painter->drawPixmap(rect, greenBall);

        //I'm drawing the full bounding rect just to make it visible
        painter->setPen(Qt::green);
        painter->drawRect(boundingRect());
    }

    QPainterPath shape() const
    {
        //this is where you sepecify which area of your object allows the user to move it when clicked
        auto greenBall = QPixmap(":green.svg");
        QRect rect = boundingRect().toRect();
        
        //Make sure it is the same area where you're drawing your pixmap
        rect.adjust(0,0,0,-rect.height()/2);
        QPainterPath path;
        //add it as the shape you want, I chose an ellipse for the green circle
        path.addEllipse(rect);
        return path;
    }
};

结果如下:

有关更多详细信息,请参阅源代码:

QGraphicsItem QGraphicsPixmapItemPrivate: updateShape()