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.