When animating through a variable font's design space on a 1x screen, the glyphs look like they are jumping from pixel to pixel.
This is because of sub pixel quantization. In particular, when passing true to CGContextSetShouldSubpixelQuantizeFonts(), there are fewer places within a pixel that a glyph can lie, so cache hit rates are higher (and vice-versa). When performing a variable font animation, there are not enough places within a pixel that a glyph can lie, so the glyphs appear to jump from pixel to pixel.
Created attachment 292439 [details]
Comment on attachment 292439 [details]
I don' think we should do this now, but we might want to try to figure something out in future. This patch will blow the glyph cache if a variation font is used as body text.
Created attachment 302464 [details]
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