Title location and alignment

src/backends/gr.jl

@@ -1814,17 +1814,36 @@ function gr_add_title(sp, viewport_plotarea, viewport_subplot)
         gr_set_font(titlefont(sp), sp)
         loc = sp[:titlelocation]
         if loc === :left
-            xpos = viewport_plotarea[1]
-            halign = GR.TEXT_HALIGN_LEFT
+            xpos, ypos = viewport_plotarea[1], viewport_subplot[4]
+            halign, valign = GR.TEXT_HALIGN_LEFT, GR.TEXT_VALIGN_TOP
+        elseif loc === :center
+            xpos, ypos = +(viewport_plotarea[1:2]...) / 2, viewport_subplot[4]
+            halign, valign = GR.TEXT_HALIGN_CENTER, GR.TEXT_VALIGN_TOP
         elseif loc === :right
-            xpos = viewport_plotarea[2]
-            halign = GR.TEXT_HALIGN_RIGHT
+            xpos, ypos = viewport_plotarea[2], viewport_subplot[4]
+            halign, valign = GR.TEXT_HALIGN_RIGHT, GR.TEXT_VALIGN_TOP
         else
-            xpos = gr_view_xcenter(viewport_plotarea)
-            halign = GR.TEXT_HALIGN_CENTER
+            xpos = gr_view_xposition(viewport_plotarea, loc[1])
+            ypos = gr_view_yposition(viewport_plotarea, loc[2])
+            halign = sp[:titlefonthalign]
+            valign = sp[:titlefontvalign]
+            if halign == :left
+                halign = GR.TEXT_HALIGN_LEFT
+            elseif halign == :hcenter || halign == :center
+                halign = GR.TEXT_HALIGN_CENTER
+            elseif halign == :right
+                halign = GR.TEXT_HALIGN_RIGHT
+            end
+            if valign == :top
+                valign = GR.TEXT_VALIGN_TOP
+            elseif valign == :vcenter || valign == :center
+                valign = GR.TEXT_VALIGN_HALF
+            elseif valign == :bottom
+                valign = GR.TEXT_VALIGN_BOTTOM
+            end
         end
-        GR.settextalign(halign, GR.TEXT_VALIGN_TOP)
-        gr_text(xpos, viewport_subplot[4], sp[:title])
+        GR.settextalign(halign, valign)
+        gr_text(xpos, ypos, sp[:title])
         GR.restorestate()
     end
 end

src/backends/pgfplotsx.jl

@@ -138,6 +138,14 @@ function (pgfx_plot::PGFPlotsXPlot)(plt::Plot{PGFPlotsXBackend})
             title_cstr = plot_color(sp[:titlefontcolor])
             bgc_inside = plot_color(sp[:background_color_inside])
             update_clims(sp)
+            title_halign = sp[:titlefonthalign]
+            if title_halign === :left
+                title_halign = "left"
+            elseif title_halign === :hcenter || title_halign === :center
+                title_halign = "center"
+            elseif title_halign === :right
+                title_halign = "right"
+            end
             axis_opt = Options(
                 "point meta max" => get_clims(sp)[2],
                 "point meta min" => get_clims(sp)[1],
@@ -150,6 +158,7 @@ function (pgfx_plot::PGFPlotsXPlot)(plt::Plot{PGFPlotsXBackend})
                     "color" => title_cstr,
                     "draw opacity" => alpha(title_cstr),
                     "rotate" => sp[:titlefontrotation],
+                    "align" => title_halign,
                 ),
                 "legend style" => pgfx_get_legend_style(sp),
                 "axis background/.style" =>

src/backends/plotly.jl

@@ -219,20 +219,28 @@ function plotly_layout(plt::Plot)
     for sp in plt.subplots
         spidx = multiple_subplots ? sp[:subplot_index] : ""
         x_idx, y_idx = multiple_subplots ? plotly_link_indicies(plt, sp) : ("", "")
-        # add an annotation for the title... positioned horizontally relative to plotarea,
-        # but vertically just below the top of the subplot bounding box
+
+        # add an annotation for the title
         if sp[:title] != ""
             bb = plotarea(sp)
             tpos = sp[:titlelocation]
-            xmm = if tpos === :left
-                left(bb)
+            if tpos === :left
+                xmm, ymm = left(bb), top(bbox(sp))
+                halign, valign = :left, :top
+            elseif tpos === :center
+                xmm, ymm = 0.5 * (left(bb) + right(bb)), top(bbox(sp))
+                halign, valign = :hcenter, :top
             elseif tpos === :right
-                right(bb)
+                xmm, ymm = right(bb), top(bbox(sp))
+                halign, valign = :right, :top
             else
-                0.5 * (left(bb) + right(bb))
+                xmm = left(bb) + tpos[1]*width(bb)
+                # inverting to make consistent with GR
+                ymm = bottom(bb) - tpos[2]*height(bb)
+                halign, valign = sp[:titlefonthalign], sp[:titlefontvalign]
             end
-            titlex, titley = xy_mm_to_pcts(xmm, top(bbox(sp)), w * px, h * px)
-            title_font = font(titlefont(sp), :top)
+            titlex, titley = xy_mm_to_pcts(xmm, ymm, w * px, h * px)
+            title_font = font(titlefont(sp), halign=halign, valign=valign)
             push!(
                 plotattributes_out[:annotations],
                 plotly_annotation_dict(titlex, titley, text(sp[:title], title_font)),