Bar label alignment (#3177)

* Improve Barplot Label Alignment

* Barplot Label Alignment tests and NEWS.md

* Refactor calculate_bar_label_align with simpler code

---------

Co-authored-by: Matthijs Cox <matthijs.cox@asml.com>
Co-authored-by: Simon <sdanisch@protonmail.com>

NEWS.md

@@ -2,6 +2,7 @@
 
 ## master
 
+- Improved Barplot Label Alignment [#3160](https://github.com/MakieOrg/Makie.jl/issues/3160).
 - Fixed regression in determining axis limits [#3179](https://github.com/MakieOrg/Makie.jl/pull/3179)
 - Added a theme `theme_latexfonts` that uses the latex font family as default fonts [#3147](https://github.com/MakieOrg/Makie.jl/pull/3147).
 

src/basic_recipes/barplot.jl

@@ -80,6 +80,7 @@ $(ATTRIBUTES)
         label_font = theme(scene, :font),
         label_size = theme(scene, :fontsize),
         label_formatter = bar_label_formatter,
+        label_align = automatic,
         transparency = false
     )
 end
@@ -160,7 +161,28 @@ function stack_grouped_from_to(i_stack, y, grp)
     (from = from, to = to)
 end
 
-function text_attributes(values, in_y_direction, flip_labels_at, color_over_background, color_over_bar, label_offset)
+function calculate_bar_label_align(label_align, label_rotation::Real, in_y_direction::Bool, flip::Bool)
+    make_align(a::VecTypes{2, <:Real}) = Vec2f(a)
+    make_align(a::NTuple{2, Symbol}) = to_align(a)
+    make_align(a) = error("`label_align` needs to be of type NTuple{2, <:Real}, not of type $(typeof(a))")
+    if label_align == automatic
+        if flip
+            label_rotation += π
+        end
+        if !in_y_direction
+            label_rotation += π/2
+        end
+        s, c = sincos(label_rotation)
+        scale = 1 / max(abs(s), abs(c))
+        align = Vec2f(0.5 - 0.5scale * s, 0.5 - 0.5scale * c)
+        return align
+    else
+        return make_align(label_align)
+    end
+end
+
+function text_attributes(values, in_y_direction, flip_labels_at, color_over_background, color_over_bar,
+                         label_offset, label_rotation, label_align)
     aligns = Vec2f[]
     offsets = Vec2f[]
     text_colors = RGBAf[]
@@ -178,22 +200,27 @@ function text_attributes(values, in_y_direction, flip_labels_at, color_over_back
     end
 
     for (i, k) in enumerate(values)
-        # Plot text inside bar
-        if flip(k)
-            push!(aligns, swap(0.5, 1.0))
+
+        isflipped = flip(k)
+
+        push!(aligns, calculate_bar_label_align(label_align, label_rotation, in_y_direction, isflipped))
+
+        if isflipped
+            # plot text inside bar
             push!(offsets, swap(0, -label_offset))
             push!(text_colors, geti(color_over_bar, i))
         else
             # plot text next to bar
-            push!(aligns, swap(0.5, 0.0))
             push!(offsets, swap(0, label_offset))
             push!(text_colors, geti(color_over_background, i))
         end
     end
     return aligns, offsets, text_colors
 end
 
-function barplot_labels(xpositions, ypositions, bar_labels, in_y_direction, flip_labels_at, color_over_background, color_over_bar, label_formatter, label_offset)
+function barplot_labels(xpositions, ypositions, bar_labels, in_y_direction, flip_labels_at,
+                        color_over_background, color_over_bar, label_formatter, label_offset, label_rotation,
+                        label_align)
     if bar_labels isa Symbol && bar_labels in (:x, :y)
         bar_labels = map(xpositions, ypositions) do x, y
             if bar_labels === :x
@@ -205,7 +232,8 @@ function barplot_labels(xpositions, ypositions, bar_labels, in_y_direction, flip
     end
     if bar_labels isa AbstractVector
         if length(bar_labels) == length(xpositions)
-            attributes = text_attributes(ypositions, in_y_direction, flip_labels_at, color_over_background, color_over_bar, label_offset)
+            attributes = text_attributes(ypositions, in_y_direction, flip_labels_at, color_over_background,
+                                         color_over_bar, label_offset, label_rotation, label_align)
             label_pos = map(xpositions, ypositions, bar_labels) do x, y, l
                 return (string(l), in_y_direction ? Point2f(x, y) : Point2f(y, x))
             end
@@ -226,7 +254,7 @@ function Makie.plot!(p::BarPlot)
     label_colors = Observable(RGBAf[])
     function calculate_bars(xy, fillto, offset, transformation, width, dodge, n_dodge, gap, dodge_gap, stack,
                             dir, bar_labels, flip_labels_at, label_color, color_over_background,
-                            color_over_bar, label_formatter, label_offset)
+                            color_over_bar, label_formatter, label_offset, label_rotation, label_align)
 
         in_y_direction = get((y=true, x=false), dir) do
             error("Invalid direction $dir. Options are :x and :y.")
@@ -276,7 +304,7 @@ function Makie.plot!(p::BarPlot)
             obar = color_over_bar === automatic ? label_color : color_over_bar
             label_args = barplot_labels(x̂, y, bar_labels, in_y_direction,
                                         flip_labels_at, to_color(oback), to_color(obar),
-                                        label_formatter, label_offset)
+                                        label_formatter, label_offset, label_rotation, label_align)
             labels[], label_aligns[], label_offsets[], label_colors[] = label_args
         end
 
@@ -285,7 +313,7 @@ function Makie.plot!(p::BarPlot)
 
     bars = lift(calculate_bars, p, p[1], p.fillto, p.offset, p.transformation.transform_func, p.width, p.dodge, p.n_dodge, p.gap,
                 p.dodge_gap, p.stack, p.direction, p.bar_labels, p.flip_labels_at,
-                p.label_color, p.color_over_background, p.color_over_bar, p.label_formatter, p.label_offset)
+                p.label_color, p.color_over_background, p.color_over_bar, p.label_formatter, p.label_offset, p.label_rotation, p.label_align)
 
     poly!(
         p, bars, color = p.color, colormap = p.colormap, colorscale = p.colorscale, colorrange = p.colorrange,

test/barplot_labels.jl

@@ -0,0 +1,53 @@
+@testset "Barplot label align" begin
+    @testset "automatic" begin
+        # for more info see https://github.com/MakieOrg/Makie.jl/issues/3160
+        # below is the best square angles behavior for bar labels
+
+        al = Makie.automatic
+
+        y_dir, flip = false, false
+        @test Makie.calculate_bar_label_align(al, 0.0, y_dir, flip) ≈ Vec2f(0.0, 0.5)
+        @test Makie.calculate_bar_label_align(al, π, y_dir, flip) ≈ Vec2f(1.0, 0.5)
+        @test Makie.calculate_bar_label_align(al, π/2, y_dir, flip) ≈ Vec2f(0.5, 1.0)
+        @test Makie.calculate_bar_label_align(al, -π/2, y_dir, flip) ≈ Vec2f(0.5, 0.0)
+
+        y_dir, flip = true, false
+        @test Makie.calculate_bar_label_align(al, 0.0, y_dir, flip) ≈ Vec2f(0.5, 0.0)
+        @test Makie.calculate_bar_label_align(al, π, y_dir, flip) ≈ Vec2f(0.5, 1.0)
+        @test Makie.calculate_bar_label_align(al, π/2, y_dir, flip) ≈ Vec2f(0.0, 0.5)
+        @test Makie.calculate_bar_label_align(al, -π/2, y_dir, flip) ≈ Vec2f(1.0, 0.5)
+
+        y_dir, flip = false, true
+        @test Makie.calculate_bar_label_align(al, 0.0, y_dir, flip) ≈ Vec2f(1.0, 0.5)
+        @test Makie.calculate_bar_label_align(al, π, y_dir, flip) ≈ Vec2f(0.0, 0.5)
+        @test Makie.calculate_bar_label_align(al, π/2, y_dir, flip) ≈ Vec2f(0.5, 0.0)
+        @test Makie.calculate_bar_label_align(al, -π/2, y_dir, flip) ≈ Vec2f(0.5, 1.0)
+
+        y_dir, flip = true, true
+        @test Makie.calculate_bar_label_align(al, 0.0, y_dir, flip) ≈ Vec2f(0.5, 1.0)
+        @test Makie.calculate_bar_label_align(al, π, y_dir, flip) ≈ Vec2f(0.5, 0.0)
+        @test Makie.calculate_bar_label_align(al, π/2, y_dir, flip) ≈ Vec2f(1.0, 0.5)
+        @test Makie.calculate_bar_label_align(al, -π/2, y_dir, flip) ≈ Vec2f(0.0, 0.5)
+    end
+
+    @testset "manual" begin
+        input = 0.0, false, false
+        for align in (Vec2f(1.0, 0.5), Point2f(1.0, 0.5), (1.0, 0.5), (1, 0), (1.0, 0))
+            @test Makie.calculate_bar_label_align(align, input...) ≈ Vec2f(align)
+        end
+    end
+
+    @testset "symbols" begin
+        input = 0.0, false, false
+        @test Makie.calculate_bar_label_align((:center, :center), input...) ≈ Makie.calculate_bar_label_align((0.5, 0.5), input...)
+    end
+
+    @testset "error" begin
+        input = 0.0, false, false
+        for align in ("center", 0.5, ("center", "center"), (0.5, :center))
+            msg = "`label_align` needs to be of type NTuple{2, <:Real}, not of type $(typeof(align))"
+            @test_throws ErrorException(msg) Makie.calculate_bar_label_align(align, input...)
+        end
+    end
+
+end

test/runtests.jl

@@ -33,4 +33,5 @@ using Makie: volume
     include("text.jl")
     include("boundingboxes.jl")
     include("ray_casting.jl")
+    include("barplot_labels.jl")
 end