miter
The current miter limit for the Canvas. If the current line join style is set to LineJoin.MITER then the miter limit is used to determine whether the lines should be joined with a bevel instead of a miter. Cairo divides the length of the miter by the line width. If the result is greater than the miter limit then the style is converted to a bevel.
As with the other stroke parameters the current line miter limit is examined by stroke, strokeExtents, and cairo_stroke_to_path, but doesn't have any effect during path construction. The default miter limit value is 10.0, which will convert joins with interior angles less than 11 degrees to bevels instead of miters. For reference a miter limit of 2.0 makes the miter cutoff at 60 degrees, and a miter limit of 1.414 makes the cutoff at 90 degrees.
A miter limit for a desired angle can be computed as: miter limit = 1/sin(angle/2)