custom implementation for pgfplotsx backend

src/args.jl

@@ -331,6 +331,7 @@ const _series_defaults = KW(
 
 const _plot_defaults = KW(
     :plot_title                  => "",
+    :plot_titleindex             => 0,
     :plot_titlefontsize          => 16,
     :plot_titlelocation          => :center,           # also :left or :right
     :plot_titlefontfamily        => :match,
@@ -1365,6 +1366,7 @@ const _match_map = KW(
     :colorbar_tickfontcolor   => :foreground_color_subplot,
     :plot_titlefontfamily     => :fontfamily,
     :plot_titlefontcolor      => :foreground_color,
+    :plot_titleindex             => 0,
     :tickfontcolor            => :foreground_color_text,
     :guidefontcolor           => :foreground_color_guide,
     :annotationfontfamily     => :fontfamily_subplot,

src/backends/pgfplotsx.jl

@@ -118,11 +118,24 @@ function (pgfx_plot::PGFPlotsXPlot)(plt::Plot{PGFPlotsXBackend})
         end
 
         for sp in plt.subplots
-            bb1 = sp.plotarea
             bb2 = bbox(sp)
+            dx, dy = bb2.x0
+            sp_width = width(bb2)
+            sp_height = height(bb2)
+            if sp[:subplot_index] == plt[:plot_titleindex]
+                x = dx + sp_width / 2 - 10mm # FIXME: get rid of magic constant
+                y = dy + sp_height / 2
+                @show width(bbox(plt.layout.grid[2]))
+                @show sp_width
+                pgfx_add_annotation!(the_plot, x, y, PlotText(plt[:plot_title], plottitlefont(plt)), pgfx_thickness_scaling(plt);
+                    cs = "",
+                    options = PGFPlotsX.Options("anchor" => "center")
+                )
+                continue
+            end
+
             sp_width = width(bb2)
             sp_height = height(bb2)
-            dx, dy = bb2.x0
             lpad = leftpad(sp) + sp[:left_margin]
             rpad = rightpad(sp) + sp[:right_margin]
             tpad = toppad(sp) + sp[:top_margin]
@@ -131,7 +144,6 @@ function (pgfx_plot::PGFPlotsXPlot)(plt::Plot{PGFPlotsXBackend})
             dy += tpad
             axis_height = sp_height - (tpad + bpad)
             axis_width = sp_width - (rpad + lpad)
-
             title_cstr = plot_color(sp[:titlefontcolor])
             title_a = alpha(title_cstr)
             title_loc = sp[:titlelocation]
@@ -999,24 +1011,27 @@ function pgfx_marker(plotattributes, i = 1)
     )
 end
 
-function pgfx_add_annotation!(o, x, y, val, thickness_scaling = 1)
+function pgfx_add_annotation!(o, x, y, val, thickness_scaling = 1; cs = "axis cs:", options = PGFPlotsX.Options())
     # Construct the style string.
     cstr = val.font.color
     a = alpha(cstr)
     push!(
         o,
-        [
+        join([
             "\\node",
+            sprint(PGFPlotsX.print_tex, merge(
                 PGFPlotsX.Options(
-                get((center = "", left = "right", right = "left"), val.font.halign, "") =>
+                    get((hcenter = "", left = "right", right = "left"), val.font.halign, "") =>
                         nothing,
                     "color" => cstr,
                     "draw opacity" => convert(Float16, a),
                     "rotate" => val.font.rotation,
                     "font" => pgfx_font(val.font.pointsize, thickness_scaling),
                 ),
-            " at (axis cs:$x, $y) {$(val.str)};",
+                options
-        ],
+            )),
+            string(" at (", cs, x, ",", y, ") {", val.str, "};"),
+        ]),
     )
 end
 

src/pipeline.jl

@@ -287,11 +287,6 @@ function _add_plot_title!(plt)
     if plot_title != ""
         the_layout = plt.layout
         vspan = plt[:plot_titlevspan]
-        if plt.backend isa PGFPlotsXBackend
-            # FIXME: we hit a 45pt height limit:
-            # https://github.com/pgf-tikz/pgfplots/blob/3bc2f42258fbfac9fe50b2978459da7e76fc046c/tex/generic/pgfplots/pgfplots.scaling.code.tex#L153
-            vspan = max(vspan, .16)
-        end
         plt.layout = grid(2, 1, heights=(vspan, 1 - vspan))
         plt.layout.grid[1, 1] = subplot = Subplot(plt.backend, parent=plt.layout[1, 1])
         plt.layout.grid[2, 1] = the_layout
@@ -302,6 +297,7 @@ function _add_plot_title!(plt)
         end
         plt[:force_minpad] = nothing, 0px, nothing, 0px
         subplot[:subplot_index] = last(plt.subplots)[:subplot_index] + 1
+        plt[:plot_titleindex] = subplot[:subplot_index]
         subplot[:framestyle] = :none
         subplot[:margin] = 0px
         push!(plt.subplots, subplot)