### GVAR–9: IUP, again

The font for this test case has one axis, TEST, that runs from –1.0 to 1.0 with default 0.0. It has one glyph, A, which contains 4 square contours, all identical apart from their x position. The top edge of each contour contains 5 points, with 3 extra points spaced evenly between the top-left and top-right points. It has one gvar variation tuple, value 1 on axis TEST. This tuple only moves points that lie on the top of each contour. Note that in each contour moved by the gvar tuple, there are TWO runs of interpolated points. Thus: contour #0 has points 0–6; contour #1 has points 7–13; contour #2 has points 14–20; contour #3 has points 21–27.
If your implementation is correct, you should see four square contours for values of TEST ≤ 0. As the value increases towards +1.0, the first, third and fourth contour should look increasingly distorted.
An early version of Apple’s CoreText library had a bug which prevented the third contour from getting interpolated at TEST = +0.944444; see Radar bug 31935412. An early version of FreeType had a different problem; see FreeType bug 50832. For fontkit, see fontkit bug 182. Finally, see also the OpenType-Layout mailing list archives of November 2018.

| –1.0 | –0.5 | ±0.0 | +0.5 | +0.6 | +0.7 | +0.8 | +0.9 | +0.944444 | +1.0
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