Fix extra segment in eraseOpenCorners #1057
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In the process of porting this functionality to Rust, I've run into a funny issue: in some cases, after erasing corners, the outline generated here contained an extra duplicate point at the beginning. This error seems to be introduced only for contours where the last segment is a curve, and it is introduced early; even before we start processing, there is an extra segment in the segments list for these contours. This patch addresses this by changing the logic of closePath to not emit a final line segment if it would be a duplicate, but I'm not totally confident that this is the right approach.
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In the process of porting this functionality to Rust, I've run into a funny issue: in some cases, after erasing corners, the outline generated here contained an extra duplicate point at the beginning.
This error seems to be introduced only for contours where the last segment is a curve, and it is introduced early; even before we start processing, there is an extra segment in the segments list for these contours.
This patch addresses this by changing the logic of closePath to not emit a final line segment if it would be a duplicate, but I'm not totally confident that this is the right approach.
More detail: I believe that what is going on is an interaction between the logic for
closePathineraseOpenContoursand the logic in thePointToSegmentPenthat is writing into it. That pen is skipping the last LineTo segment in a closed path, trustingclosePathto handle it; but by always adding a lineTo inclosePathwe're inserting extra segments when the last segment wasn't a lineTo.Another note: this patch is causing a new fontmake failure on one crater font, based on a rounding issue; there's a case where the start/end points are off by an epsilon in one master and not the other, which leads us to add the extra segment in one case. I'm not sure how best I should check this case.. should I strictly be looking for epsilon difference, or would it be okay to check if the points are equal after otround?