We currently have support for interpolating CGFloat, CGPoint, and CGSize. We should add a method for CGRect as well.

Currently vivliostyle-ui/test/ files are old (so removed from travis CI vivliostyle/vivliostyle-ui@b965cd2) and need to be updated and reenabled auto test.

Unfortunately for TightenText, Safari rounds font sizes to whole pixels as soon as it crosses the half-pixel boundary. This leads to a significant jump in how wide the text is, and also potentially means the resulting text is smaller than the developer's desired minFontSize (if, say, they want it to be 0.97 ems, and that results in a font size of 15.49px, Safari will render 15px text).

Some

Be able to convert small images (like 150x150) to pixels could be used to reduce a lot of effort in manually producing shapes, boosting productivity. There are a lot of libraries in Python that could help in this task, like Pillow.