How to set BackGround Image for the plot

[metow]

Is there a way to set a background image for my plot.
I'm preparing a demo version for my program , and I want to write "Demo Version" at the background of the plot.
If setting a background image is not possible ( which I couldn't find) , is there something else I can do?
Thanks for any kinds of help

[Uwe]

You can assign a brush with an image to the palette of the canvas, but better implement a small plot item for your background text:

class Watermark: public QwtPlotItem
{
public:
    Watermark()
    {
        setZ(0.0);
    }
 
    virtual int rtti() const
    {
        return QwtPlotItem::Rtti_PlotUserItem + 123;
    }
 
    virtual void draw(QPainter *painter,
        const QwtScaleMap &, const QwtScaleMap &,
        const QRect &rect) const
    {
        QwtPainter::fillRect(painter, rect, ...);
        QwtPainter::drawText(painter, rect, ...);
    }
};

class Watermark: public QwtPlotItem
{
public:
    Watermark()
    {
        setZ(0.0);
    }

    virtual int rtti() const
    {
        return QwtPlotItem::Rtti_PlotUserItem + 123;
    }

    virtual void draw(QPainter *painter,
        const QwtScaleMap &, const QwtScaleMap &,
        const QRect &rect) const
    {
        QwtPainter::fillRect(painter, rect, ...);
        QwtPainter::drawText(painter, rect, ...);
    }
};

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Uwe

[wagmare]

QPixmap pixmap("jughead-jones_large.png");
QWidget w;
QPalette p = w.palette();
p.setBrush(QPalette::Base, pixmap);
w.setPalette(p);

[rakkar]

You can assign a brush with an image to the palette of the canvas, but better implement a small plot item for your background text:

class Watermark: public QwtPlotItem
{
public:
    Watermark()
    {
        setZ(0.0);
    }
 
    virtual int rtti() const
    {
        return QwtPlotItem::Rtti_PlotUserItem + 123;
    }
 
    virtual void draw(QPainter *painter,
        const QwtScaleMap &, const QwtScaleMap &,
        const QRect &rect) const
    {
        QwtPainter::fillRect(painter, rect, ...);
        QwtPainter::drawText(painter, rect, ...);
    }
};

class Watermark: public QwtPlotItem
{
public:
    Watermark()
    {
        setZ(0.0);
    }

    virtual int rtti() const
    {
        return QwtPlotItem::Rtti_PlotUserItem + 123;
    }

    virtual void draw(QPainter *painter,
        const QwtScaleMap &, const QwtScaleMap &,
        const QRect &rect) const
    {
        QwtPainter::fillRect(painter, rect, ...);
        QwtPainter::drawText(painter, rect, ...);
    }
};

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Uwe

This works, but the texture tiles. How can I get it to stretch instead of tile?