fix gradient in theme

src/themes.jl

@@ -1,68 +1,8 @@
 
-# const _invisible = RGBA(0,0,0,0)
-#
-# const _themes = KW(
-#     :default => KW(
-#         :bg         => :white,
-#         :bglegend   => :match,
-#         :bginside   => :match,
-#         :bgoutside  => :match,
-#         :fg         => :auto,
-#         :fglegend   => :match,
-#         :fggrid     => :match,
-#         :fgaxis     => :match,
-#         :fgtext     => :match,
-#         :fgborder   => :match,
-#         :fgguide    => :match,
-#     )
-# )
-
-# function add_theme(sym::Symbol, theme::KW)
-#     _themes[sym] = theme
-# end
-#
-# # add a new theme, using an existing theme as the base
-# function add_theme(sym::Symbol;
-#                    base      = :default,  # start with this theme
-#                    bg        = _themes[base][:bg],
-#                    bglegend  = _themes[base][:bglegend],
-#                    bginside  = _themes[base][:bginside],
-#                    bgoutside = _themes[base][:bgoutside],
-#                    fg        = _themes[base][:fg],
-#                    fglegend  = _themes[base][:fglegend],
-#                    fggrid    = _themes[base][:fggrid],
-#                    fgaxis    = _themes[base][:fgaxis],
-#                    fgtext    = _themes[base][:fgtext],
-#                    fgborder  = _themes[base][:fgborder],
-#                    fgguide   = _themes[base][:fgguide],
-#                    kw...)
-#     _themes[sym] = merge(KW(
-#         :bg => bg,
-#         :bglegend  => bglegend,
-#         :bginside  => bginside,
-#         :bgoutside => bgoutside,
-#         :fg        => fg,
-#         :fglegend  => fglegend,
-#         :fggrid    => fggrid,
-#         :fgaxis    => fgaxis,
-#         :fgtext    => fgtext,
-#         :fgborder  => fgborder,
-#         :fgguide   => fgguide,
-#     ), KW(kw))
-# end
-#
-# add_theme(:ggplot2,
-#     bglegend = :lightgray,
-#     bginside = :lightgray,
-#     fg       = :black,
-#     fggrid   = :white,
-#     fgborder = _invisible,
-#     fgaxis   = _invisible
-# )
-
 function theme(s::Symbol; kw...)
     # reset?
     if s == :none || s == :default
+        PlotUtils._default_gradient[] = :inferno
         default(;
             bg        = :white,
             bglegend  = :match,
@@ -80,8 +20,11 @@ function theme(s::Symbol; kw...)
         return
     end
 
+    # update the default gradient and other defaults
     thm = PlotThemes._themes[s]
-    PlotUtils._default_gradient[] = s
+    if thm.gradient != nothing
+        PlotUtils._default_gradient[] = s
+    end
     default(;
         bg       = thm.bg_secondary,
         bginside = thm.bg_primary,