QGraphicsSvgItem control size

Joel Bodenmann

Question
What's the proper way of setting a "scale offset" or "resize offset" when working with QGraphicsSvgItem to control how big the rendered SVG is in scene coordinates? My source SVG has a size/viewbox of 0, 0, 24, 24 and therefore the rendered SVG is only 24x24 in size - but I'd like it to be larger.
I started dicking around with retrieving the QSvgRenderer of the QGraphicsSvgItem using QGraphicsSvgItem::renderer() and then using QSvgRenderer::setViewBox() but that didn't lead me anywhere near what I am after as that just changes the viewbox of the resulted rendering.

Basically I am looking for something such as QGraphicsSvgItem::setScaleOffset() or QSvgRenderer::setSize().

Background
Currently I have a custom class named node that inherits from QGraphicsItem. Essentially it paints itself as a rectangle with rounded corners, drop shadow and an icon (in the top left corner of the item's rectangle).

So far I had a QIcon member in my node class and inside of node::paint() I use QIcon::paint() to paint the icon. This works great both in theory and practice.
The icon I am painting is an SVG image. But due to the current way of painting a QIcon it looks bad at any zoom level other than 100% as the rastered icon is being scaled when the user manipulates the zoom value.
To solve this issue, I removed my QIcon member and added a QGraphicsSvgItem child item to my node class.
I managed to get everything working (as in: The SVG is successfully being rendered as part of my node class). Also the scaling works as expected: I can zoom in an out and the icon now always looks great.

However, my issue is that the source SVG I have has a default view port of 0, 0, 24, 24. The resulting icon is too small in reference to my node rectangle. Therefore, I set out to find a way of how to manually add a scale factor to my SVG so that the rendered icon is larger relative to the node::boundingRect() while also keeping the already working zoom scaling stuff.

Unfortunately, I couldn't find a way of how to do this.

SGaist

Hi,

I don't know either but what about nuking the viewport before loading the file ?

Joel Bodenmann

@SGaist said in QGraphicsSvgItem control size:

I don't know either but what about nuking the viewport before loading the file ?

Could you elaborate a bit more what your suggestion consists of?

SGaist

SVG being XML, you could modify the view port as you see fit before loading it. But I may have misunderstood the issue at hand.

mrjj

Hi
If you open the SVG in say inkscape and change its page size (ViewBox) does it then
work as expected in your app ?

Im not sure i understand what the goal since QSvgRenderer::setViewBox() did change the rendered size for me with QIcon so are we looking for something else ?