From 1e9691a7c08a0863f30c13137b7802a1046028cb Mon Sep 17 00:00:00 2001
From: hhaensel <31985040+hhaensel@users.noreply.github.com>
Date: Thu, 21 May 2020 12:32:25 +0200
Subject: [PATCH] Add support for mathjax (latex) and extra_plot_kwargs in
 plotly backend (#2719)

* support mathjax header in plotly backend

* support extra_plot_kwargs in plotly backend

* correct local file parameter to `file:///`

* corrections proposed by @BeastyBlacksmith

* include extra_kwargs for subplots

* don't merge subplot extra_kwargs

Co-authored-by: Helmut Haensel <M136270@eu.merckgroup.com>
Co-authored-by: Simon Christ <SimonChrist@gmx.de>
---
 src/backends/plotly.jl | 11 ++++++++---
 src/utils.jl           |  5 +++++
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/src/backends/plotly.jl b/src/backends/plotly.jl
index 6839dc4e..0d39c424 100644
--- a/src/backends/plotly.jl
+++ b/src/backends/plotly.jl
@@ -336,7 +336,7 @@ function plotly_layout(plt::Plot)
         plotattributes_out[:hovermode] = "none"
     end
 
-    plotattributes_out
+    plotattributes_out = recursive_merge(plotattributes_out, plt.attr[:extra_plot_kwargs])
 end
 
 function plotly_layout_json(plt::Plot)
@@ -810,9 +810,14 @@ html_body(plt::Plot{PlotlyBackend}) = plotly_html_body(plt)
 const ijulia_initialized = Ref(false)
 
 function plotly_html_head(plt::Plot)
-    local_file = ("file://" * plotly_local_file_path)
+    local_file = ("file:///" * plotly_local_file_path)
     plotly =
         use_local_dependencies[] ? local_file : "https://cdn.plot.ly/plotly-latest.min.js"
+
+    include_mathjax = get(plt[:extra_plot_kwargs], :include_mathjax, "")
+    mathjax_file = include_mathjax != "cdn" ? ("file://" * include_mathjax) : "https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.7/MathJax.js?config=TeX-MML-AM_CHTML"
+    mathjax_head = include_mathjax == "" ? "" : "<script src=\"$mathjax_file\"></script>\n\t\t"
+
     if isijulia() && !ijulia_initialized[]
         # using requirejs seems to be key to load a js depency in IJulia!
         # https://requirejs.org/docs/start.html
@@ -826,7 +831,7 @@ function plotly_html_head(plt::Plot)
         """)
         ijulia_initialized[] = true
     end
-    return "<script src=$(repr(plotly))></script>"
+    return "$mathjax_head<script src=$(repr(plotly))></script>"
 end
 
 function plotly_html_body(plt, style = nothing)
diff --git a/src/utils.jl b/src/utils.jl
index d24ed3a7..5bc022d4 100644
--- a/src/utils.jl
+++ b/src/utils.jl
@@ -302,6 +302,11 @@ Base.convert(::Type{Vector{T}}, rng::AbstractRange{S}) where {T<:Real,S<:Real} =
 
 Base.merge(a::AbstractVector, b::AbstractVector) = sort(unique(vcat(a,b)))
 
+# recursively merge kw-dicts, e.g. for merging extra_kwargs / extra_plot_kwargs in plotly)
+recursive_merge(x::AbstractDict...) = merge(recursive_merge, x...)
+# if values are not AbstractDicts, take the last definition (as does merge)
+recursive_merge(x...) = x[end]
+
 nanpush!(a::AbstractVector, b) = (push!(a, NaN); push!(a, b))
 nanappend!(a::AbstractVector, b) = (push!(a, NaN); append!(a, b))