QwtPlotMarker On the Center of the Plot

[ken123]

I am trying to have to two labels in the middle of the QwtPlot.
ie: plot
|--------------------------------------|
| |
| top center label |
| |
| label 2 |
| |
|--------------------------------------|
How can I do that? Thanks.

[Uwe]

Implement a new type of plot item ( derive from QwtPlotItem ). In YourItem::draw use QPainter ::drawText centered to the canvasRect.

Uwe

[ken123]

I am a bit confused. When do I call this new myItem::draw method or how do I call this method, like override a new drawCanvas method for myQwtPlot? Thanks.

[Uwe]

Something like this:

class TextItem: public QwtPlotItem
{
public:
    void setText( const QString &text )
    {
        m_text = text;
    }
 
    virtual void draw( QPainter *painter,
        const QwtScaleMap &, const QwtScaleMap &,
        const QRectF &canvasRect ) const
    {
        painter->drawText( canvasRect, Qt::AlignCenter, m_text );
    }
 
private:
    QString m_text;
};

class TextItem: public QwtPlotItem
{
public:
    void setText( const QString &text )
    {
        m_text = text;
    }

    virtual void draw( QPainter *painter,
        const QwtScaleMap &, const QwtScaleMap &,
        const QRectF &canvasRect ) const
    {
        painter->drawText( canvasRect, Qt::AlignCenter, m_text );
    }

private:
    QString m_text;
};

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Attach this item to your plot like a curve and the draw method will be part of the plot image composition.

Uwe