Support keyword arguments for font attributes

src/components.jl

@@ -258,24 +258,22 @@ end
 
 """
     font(args...)
-
-Create a Font from an unordered list of features. 
-
+Create a Font from a list of features. Values may be specified either as
+arguments (which are distinguished by type/value) or as keyword arguments.
 # Arguments
-
 - `family`: AbstractString. "serif" or "sans-serif" or "monospace" 
 - `pointsize`: Integer. Size of font in points
 - `halign`: Symbol. Horizontal alignment (:hcenter, :left, or :right)
 - `valign`: Symbol. Vertical aligment (:vcenter, :top, or :bottom)
 - `rotation`: Real. Angle of rotation for text in degrees (use a non-integer type)
 - `color`: Colorant or Symbol
-
 # Examples 
 ```julia-repl
-julia> text("sans-serif",8,:hcenter,45.0,:blue)
+julia> font(8)
+julia> font(family="serif",halign=:center,rotation=45.0)
 ```
 """
-function font(args...)
+function font(args...;kw...)
 
   # defaults
   family = "sans-serif"
@@ -319,6 +317,32 @@ function font(args...)
     end
   end
 
+  for symbol in keys(kw)
+    if symbol == :family
+      family = kw[:family]
+    elseif symbol == :pointsize
+      pointsize = kw[:pointsize]
+    elseif symbol == :halign
+      halign = kw[:halign]
+      if halign == :center
+        halign = :hcenter
+      end
+      @assert halign in (:hcenter, :left, :right)
+    elseif symbol == :valign
+      valign = kw[:valign]
+      if valign == :center
+        valign = :vcenter
+      end
+      @assert valign in (:vcenter, :top, :bottom)
+    elseif symbol == :rotation
+      rotation = kw[:rotation]
+    elseif symbol == :color
+      color = parse(Colorant, kw[:color])
+    else
+      @warn("Unused font kwarg: $symbol")
+    end
+  end
+
   Font(family, pointsize, halign, valign, rotation, color)
 end
 
@@ -362,15 +386,16 @@ end
 PlotText(str) = PlotText(string(str), font())
 
 """
-    text(string, args...)
+    text(string, args...; kw...)
 
-Create a PlotText object wrapping a string with font info, for plot annotations
+Create a PlotText object wrapping a string with font info, for plot annotations. 
+`args` and `kw` are passed to `font`. 
 """
 text(t::PlotText) = t
 text(t::PlotText, font::Font) = PlotText(t.str, font)
 text(str::AbstractString, f::Font) = PlotText(str, f)
-function text(str, args...)
-  PlotText(string(str), font(args...))
+function text(str, args...;kw...)
+  PlotText(string(str), font(args...;kw...))
 end
 
 Base.length(t::PlotText) = length(t.str)