class QgsDiagram
{
%TypeHeaderCode
#include <qgsdiagram.h>
%End
  public:
    virtual ~QgsDiagram();
    /**Draws the diagram at the given position (in pixel coordinates)*/
    virtual void renderDiagram( const QgsAttributes& att, QgsRenderContext& c, const QgsDiagramSettings& s, const QPointF& position ) = 0;
    virtual QString diagramName() const = 0;
    /**Returns the size in map units the diagram will use to render.*/
    virtual QSizeF diagramSize( const QgsAttributes& attributes, const QgsRenderContext& c, const QgsDiagramSettings& s ) = 0;
    /**Returns the size in map units the diagram will use to render. Interpolate size*/
    virtual QSizeF diagramSize( const QgsAttributes& attributes, const QgsRenderContext& c, const QgsDiagramSettings& s, const QgsDiagramInterpolationSettings& is ) = 0;

  protected:
    /** Changes the pen width to match the current settings and rendering context
     *  @param pen The pen to modify
     *  @param s   The settings that specify the pen width
     *  @param c   The rendering specifying the proper scale units for pixel conversion
     */
    void setPenWidth( QPen& pen, const QgsDiagramSettings& s, const QgsRenderContext& c );

    /** Calculates a size to match the current settings and rendering context
     *  @param size The size to convert
     *  @param s    The settings that specify the size type
     *  @param c    The rendering specifying the proper scale units for pixel conversion
     *
     *  @return The converted size for rendering
     */
    QSizeF sizePainterUnits( const QSizeF& size, const QgsDiagramSettings& s, const QgsRenderContext& c );

    /** Calculates a length to match the current settings and rendering context
     *  @param l    The length to convert
     *  @param s    Unused
     *  @param c    The rendering specifying the proper scale units for pixel conversion
     *
     *  @return The converted length for rendering
     */
    float sizePainterUnits( float l, const QgsDiagramSettings& s, const QgsRenderContext& c );

    /** Calculates a size to match the current settings and rendering context
     *  @param s    The settings that contain the font size and size type
     *  @param c    The rendering specifying the proper scale units for pixel conversion
     *
     *  @return The properly scaled font for rendering
     */
    QFont scaledFont( const QgsDiagramSettings& s, const QgsRenderContext& c );
};