Introduced with 5f8311f596
When using the Spacing stroke type, the exact spacing between brush
daubs becomes modified by the brush size. In the case of users using
a non default brush size curve with size pressure, we need to use the
evaluated pressure factor for the size, not the raw pressure value.
Additionally, this commit renames the parameters in a helper method
to more clearly differentiate between the two float parameters.
Pull Request: https://projects.blender.org/blender/blender/pulls/146054