Enlarge bounding box by the largest stroke width.

[paulkaplan]

Resolves

What Github issue does this resolve (please include link)?

Fixes #175

Proposed Changes

Describe what this Pull Request does

Enlarge the bounding box that is read from the DOM method getBBox() which doesn't take into account the strokes by the largest found stroke width. As mentioned in the code comment, this may have false positives, as in it may enlarge an SVG viewbox that didn't need it (if, for example, the largest shape was a fill, not a stroke). But it will always make the viewbox large enough to include the strokes, which seems like an ok trade-off.

Reason for Changes

Explain why these changes should be made

Clipping of SVG's, which is impacting project rendering and also messes with the upcoming speech bubble rendering.

Test Coverage

Please show how you have added tests to cover your changes

None.

/cc @tmickel since it looks like a lot of this code was yours.

[fsih]

Should it be sufficient to enlarge by 1/2 the largest stroke width?

[paulkaplan]

@fsih good catch! done in
ab4046b

[cwillisf]

I'm OK with this for now but I expect we'll want to refine it later. I can imagine situations where this could go really wrong -- for example, if there's a thin border around some content which uses a very large stroke width.