recenter to center-of-mass origin before rotation

Author: thchr

src/NetworkLayout.jl

@@ -214,7 +214,7 @@ macro addcall(expr::Expr)
     @assert typedef isa Expr &&
             typedef.head === :<: &&
             typedef.args[2] isa Expr && # supertype
-            typedef.args[2].args[1] ∈ [:AbstractLayout, :IterativeLayout] "Macro musst be used on subtype of AbstractLayout"
+            typedef.args[2].args[1] ∈ [:AbstractLayout, :IterativeLayout] "Macro must be used on subtype of AbstractLayout"
 
     if typedef.args[1] isa Symbol # no type parameters
         name = typedef.args[1]

src/align.jl

@@ -5,6 +5,7 @@ export Align
     
 Align the vertex positions of `inner_layout` so that the principal axis of the resulting
 layout makes an `angle` with the **x**-axis.
+Also automatically centers the layout origin to its center of mass (average node position).
 
 Only supports two-dimensional inner layouts.
 """
@@ -40,7 +41,7 @@ function layout(algo::Align{Ptype, <:AbstractLayout{2, Ptype}}, adj_matrix::Abst
     s, c = sincos(-axis_angle + algo.angle)
     R = @SMatrix [c -s; s c] # [cos(θ) -sin(θ); sin(θ) cos(θ)]
     for (i, r) in enumerate(rs)
-        rs[i] = Point2{Ptype}(R * r) :: Point2{Ptype}
+        rs[i] = Point2{Ptype}(R * (r-centerofmass)) :: Point2{Ptype}
     end
 
     return rs