From d6a72a5df5d01b024237ef1fbc4bebfd513541bc Mon Sep 17 00:00:00 2001
From: David Gustavsson <david.e.gustavsson@gmail.com>
Date: Tue, 2 Mar 2021 10:19:26 +0100
Subject: [PATCH] Add legend angle to pyplot

---
 src/backends/pyplot.jl | 63 +++++++++++++++---------------------------
 src/legend.jl          | 35 ++++++++++++++++++++++-
 2 files changed, 57 insertions(+), 41 deletions(-)

diff --git a/src/backends/pyplot.jl b/src/backends/pyplot.jl
index 83899620..d89ac3aa 100644
--- a/src/backends/pyplot.jl
+++ b/src/backends/pyplot.jl
@@ -492,11 +492,11 @@ function py_add_series(plt::Plot{PyPlotBackend}, series::Series)
                     y[rng], x[rng], z[rng]
                 else
                     y[rng], x[rng]
-                end        
+                end
             else
                 if RecipesPipeline.is3d(sp)
                     x[rng], y[rng], z[rng]
-                else 
+                else
                     x[rng], y[rng]
                 end
             end
@@ -1305,44 +1305,26 @@ end
 
 # -----------------------------------------------------------------
 
-py_legend_pos(pos::Symbol) = get(
-    (
-        right = "right",
-        left = "center left",
-        top = "upper center",
-        bottom = "lower center",
-        bottomleft = "lower left",
-        bottomright = "lower right",
-        topright = "upper right",
-        topleft = "upper left",
-        outerright = "center left",
-        outerleft = "right",
-        outertop = "lower center",
-        outerbottom = "upper center",
-        outerbottomleft = "lower right",
-        outerbottomright = "lower left",
-        outertopright = "upper left",
-        outertopleft = "upper right",
-    ),
-    pos,
-    "best",
-)
-py_legend_pos(pos) = "lower left"
+py_legend_pos(pos::Tuple{S,T}) where {S<:Real,T<:Real} = "lower left"
+
+function py_legend_pos(pos::Tuple{<:Real,Symbol})
+    (s,c) = sincosd(pos[1])
+    if pos[2] === :outer
+        s = -s
+        c = -c
+    end
+    yanchors = ["lower","center","upper"]
+    xanchors = ["left","center","right"]
+    return join([yanchors[legend_anchor_index(s)], xanchors[legend_anchor_index(c)]], ' ')
+end
+
+function py_legend_bbox(pos::Tuple{T,Symbol}) where T<:Real
+    if pos[2] === :outer
+        return legend_pos_from_angle(pos[1],-0.15,0.5,1.0,-0.15,0.5,1.0)
+    end
+    legend_pos_from_angle(pos[1],0.0,0.5,1.0,0.0,0.5,1.0)
+end
 
-py_legend_bbox(pos::Symbol) = get(
-    (
-        outerright = (1.0, 0.5, 0.0, 0.0),
-        outerleft = (-0.15, 0.5, 0.0, 0.0),
-        outertop = (0.5, 1.0, 0.0, 0.0),
-        outerbottom = (0.5, -0.15, 0.0, 0.0),
-        outerbottomleft = (-0.15, 0.0, 0.0, 0.0),
-        outerbottomright = (1.0, 0.0, 0.0, 0.0),
-        outertopright = (1.0, 1.0, 0.0, 0.0),
-        outertopleft = (-0.15, 1.0, 0.0, 0.0),
-    ),
-    pos,
-    (0.0, 0.0, 1.0, 1.0),
-)
 py_legend_bbox(pos) = pos
 
 function py_add_legend(plt::Plot, sp::Subplot, ax)
@@ -1388,6 +1370,7 @@ function py_add_legend(plt::Plot, sp::Subplot, ax)
 
         # if anything was added, call ax.legend and set the colors
         if !isempty(handles)
+            leg = legend_angle(leg)
             leg = ax."legend"(handles,
                 labels,
                 loc = py_legend_pos(leg),
@@ -1398,7 +1381,7 @@ function py_add_legend(plt::Plot, sp::Subplot, ax)
                 edgecolor = py_color(sp[:foreground_color_legend]),
                 framealpha = alpha(plot_color(sp[:background_color_legend])),
                 fancybox = false,  # makes the legend box square
-                borderpad=0.8      # to match GR legendbox
+                borderpad = 0.8      # to match GR legendbox
             )
             frame = leg."get_frame"()
             frame."set_linewidth"(py_thickness_scale(plt, 1))
diff --git a/src/legend.jl b/src/legend.jl
index bb1e0a46..0b996619 100644
--- a/src/legend.jl
+++ b/src/legend.jl
@@ -17,10 +17,43 @@ end
 
 
 """
-Split continuous range `[-1,1]` into an integer `[1,2,3]`
+Split continuous range `[-1,1]` evenly into an integer `[1,2,3]`
 """
 function legend_anchor_index(x)
     x<-1//3 && return 1
     x<1//3 && return 2
     return 3
 end
+
+"""
+Turn legend argument into a (theta, :inner) or (theta, :outer) tuple.
+For backends where legend position is given in normal coordinates (0,0) -- (1,1),
+so :topleft exactly corresponds to (45, :inner) etc.
+
+If `leg` is a (::Real,::Real) tuple, keep it as is.
+"""
+legend_angle(leg::Real) = (leg,:inner)
+legend_angle(leg::Tuple{S,T}) where {S<:Real,T<:Real} = leg
+legend_angle(leg::Tuple{S,Symbol}) where S<:Real = leg
+legend_angle(leg::Symbol) = get(
+                                (
+                                 topleft            =   (135,:inner),
+                                 top                =   (90, :inner),
+                                 topright           =   (45, :inner),
+                                 left               =   (180,:inner),
+                                 right              =   (0,  :inner),
+                                 bottomleft         =   (225,:inner),
+                                 bottom             =   (270,:inner),
+                                 bottomright        =   (315,:inner),
+                                 outertopleft       =   (135,:outer),
+                                 outertop           =   (90, :outer),
+                                 outertopright      =   (45, :outer),
+                                 outerleft          =   (180,:outer),
+                                 outerright         =   (0,  :outer),
+                                 outerbottomleft    =   (225,:outer),
+                                 outerbottom        =   (270,:outer),
+                                 outerbottomright   =   (315,:outer),
+                                ),
+                                leg,
+                                (45, :inner)
+                               )