Problem rendering custom QwtPlotLegendItem

[LoranM]

Hi everyone,

I want to have a QwtPlotLegendItem fully positionable, not only with Qt::Alignment and setMargins.
So, in the legends example, I modified the class Legend like this:

class LegendItem: public QwtPlotLegendItem
{
    QPoint m_pos;
public:
    LegendItem()
    {
        setRenderHint( QwtPlotItem::RenderAntialiased );
        QColor color( Qt::white );
        setTextPen( color );
#if 1
        setBorderPen( color );
 
        QColor c( Qt::gray );
        c.setAlpha( 200 );
 
        setBackgroundBrush( c );
 
#endif
        setPosition(QPoint(0,25));
    }
    virtual QRect geometry(const QRectF &canvasRect) const {
        QRect rect = QwtPlotLegendItem::geometry( canvasRect );
        rect.moveTopLeft( m_pos );
        return rect;
    }
    void setPosition(const QPoint &pos){
        m_pos = pos;
        itemChanged();
    }
};

class LegendItem: public QwtPlotLegendItem
{
    QPoint m_pos;
public:
    LegendItem()
    {
        setRenderHint( QwtPlotItem::RenderAntialiased );
        QColor color( Qt::white );
        setTextPen( color );
#if 1
        setBorderPen( color );

        QColor c( Qt::gray );
        c.setAlpha( 200 );

        setBackgroundBrush( c );

#endif
        setPosition(QPoint(0,25));
    }
    virtual QRect geometry(const QRectF &canvasRect) const {
        QRect rect = QwtPlotLegendItem::geometry( canvasRect );
        rect.moveTopLeft( m_pos );
        return rect;
    }
    void setPosition(const QPoint &pos){
        m_pos = pos;
        itemChanged();
    }
};

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It works fine on the plot, the legend top left corner is at position (0,25) of the canvas, but when I export in a pdf file using QwtPlotRenderer, then the position of the legend is not correct (see the attached file), it is shifted by I don't know how much in the left and top direction. What am I doing wrong here?

Thank you for your help

[Uwe]

m_pos is used as an absolute offset from (0, 0), but it needs to be relative to canvasRect.topLeft().

When drawing to screen canvasRect is the contentsRect() of the canvas ( rect() without margins ), but when using QwtPlotRenderer it is a rectangle somewhere inside a layout for the complete plot.

Uwe

[LoranM]

Thank you Uwe,

Here is the modified code in LegendItem class:

virtual QRect geometry( const QRectF &canvasRect ) const
{
    QRect rect = QwtPlotLegendItem::geometry( canvasRect );
    rect.moveTopLeft( m_pos + canvasRect.topLeft().toPoint());
    return rect;
}

virtual QRect geometry( const QRectF &canvasRect ) const
{
    QRect rect = QwtPlotLegendItem::geometry( canvasRect );
    rect.moveTopLeft( m_pos + canvasRect.topLeft().toPoint());
    return rect;
}

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