line-x-at-y

Arguments: point1 point2 y

Returns the x coordinate where a line has a particular y coordinate, or nil for a horizontal line.

The first two arguments are position objects that specify any two distinct points on the line. The last argument is a real number for the y coordinate. The returned value is a real number or nil.

As usual, position objects should contain integers. See make-position. See also line-x-at-y-x-y and line-y-at-x.

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Created 2019.8.20.