setting an image backround(using qwt multi-axis)

[Uwe]

The SVG item tries to scale the content of the image according to its view box. When looking at the SVG it looks like the viewBox is a ~QRect( 9, 45, 9, 6 ), while I can see that other SVGs, that work as expected have a viewBox starting at 0, 0. So that might be a bug, that is related to this - I will have a look at it.

But a SVG can be translated easily into a QwtGraphic, so it makes sense to have a QwtPlotGraphicItem, that covers a lot more use cases and QwtPlotSvgItem could be removed then. Guess I will do this next time I'm working on the code.

As a side note: if your SVG image consists of these borders only it makes more sense to use one or several QPainterPaths instead of the SVG. A QPainterPath can be displayed as a QwtPlotShapeItem. The advantage of using a QPainterPath is, that you can set the colors, pen widths and filling, so that they fit to the background. When the boundaries are split into several painter paths you can also show/hide them Individually.

Uwe