Allow band to pass the alpha attribute to its mesh

CHANGELOG.md

@@ -5,6 +5,7 @@
 - Fixed bugs with format strings and add new features by switching to Format.jl [#3633](https://github.com/MakieOrg/Makie.jl/pull/3633).
 - Fixed an issue where CairoMakie would unnecessarily rasterize polygons [#3605](https://github.com/MakieOrg/Makie.jl/pull/3605).
 - Added `PointBased` conversion trait to `scatterlines` recipe [#3603](https://github.com/MakieOrg/Makie.jl/pull/3603).
+- Fixed `band` not passing the `alpha` keyword to its mesh [#3612](https://github.com/MakieOrg/Makie.jl/pull/3612)
 
 ## [0.20.7] - 2024-02-04
 

CairoMakie/src/overrides.jl

@@ -41,9 +41,29 @@ function draw_poly(scene::Scene, screen::Screen, poly, points, color, model, str
  draw_poly_as_mesh(scene, screen, poly)
 end
 
-function draw_poly(scene::Scene, screen::Screen, poly, points::Vector{<:Point2})
- color = to_cairo_color(poly.color[], poly)
+"""
+ _retrieve_poly_calculated_colors(poly::Makie.Poly)
+
+Polygon colors are passed down to the internal `mesh` and `lines` 
+plots which do the computation correctly, so we need to retrieve 
+them from there, since `poly` doesn't define a [`Makie.calculated_attributes!`](@ref) method!
+"""
+function _retrieve_poly_calculated_colors(poly::Makie.Poly)
+ color = if haskey(poly.plots[1].attributes, :calculated_colors)
+ to_cairo_color(poly.plots[1].calculated_colors[], poly)
+ else
+ to_cairo_color(poly.color[], poly)
+ end
  strokecolor = to_cairo_color(poly.strokecolor[], poly)
+ # if haskey(poly.plots[2].attributes, :calculated_colors)
+ # to_cairo_color(poly.plots[2].calculated_colors[], poly)
+ # else
+ # to_cairo_color(poly.strokecolor[], poly)
+ # end
+ return (color, strokecolor)
+end
+function draw_poly(scene::Scene, screen::Screen, poly, points::Vector{<:Point2})
+ color, strokecolor = _retrieve_poly_calculated_colors(poly)
  strokestyle = Makie.convert_attribute(poly.linestyle[], key"linestyle"())
  draw_poly(scene, screen, poly, points, color, poly.model[], strokecolor, strokestyle, poly.strokewidth[])
 end
@@ -69,8 +89,7 @@ function draw_poly(scene::Scene, screen::Screen, poly, points::Vector{<:Point2},
 end
 
 function draw_poly(scene::Scene, screen::Screen, poly, points_list::Vector{<:Vector{<:Point2}})
- color = to_cairo_color(poly.color[], poly)
- strokecolor = to_cairo_color(poly.strokecolor[], poly)
+ color, strokecolor = _retrieve_poly_calculated_colors(poly)
  strokestyle = Makie.convert_attribute(poly.linestyle[], key"linestyle"())
 
  broadcast_foreach(points_list, color,
@@ -87,7 +106,7 @@ function draw_poly(scene::Scene, screen::Screen, poly, shapes::Vector{<:Union{Re
  space = to_value(get(poly, :space, :data))
  projected_shapes = project_shape.(Ref(poly), space, shapes, Ref(model))
 
- color = to_cairo_color(poly.color[], poly)
+ color, strokecolor = _retrieve_poly_calculated_colors(poly)
 
  linestyle = Makie.convert_attribute(poly.linestyle[], key"linestyle"())
  if isnothing(linestyle)
@@ -97,7 +116,7 @@ function draw_poly(scene::Scene, screen::Screen, poly, shapes::Vector{<:Union{Re
  else
  error("Wrong type for linestyle: $(poly.linestyle[]).")
  end
- strokecolor = to_cairo_color(poly.strokecolor[], poly)
+
  broadcast_foreach(projected_shapes, color, strokecolor, poly.strokewidth[]) do shape, c, sc, sw
  create_shape_path!(screen.context, shape)
  set_source(screen.context, c)
@@ -165,8 +184,7 @@ function draw_poly(scene::Scene, screen::Screen, poly, polygons::AbstractArray{<
  space = to_value(get(poly, :space, :data))
  projected_polys = project_polygon.(Ref(poly), space, polygons, Ref(model))
 
- color = to_cairo_color(poly.color[], poly)
- strokecolor = to_cairo_color(poly.strokecolor[], poly)
+ color, strokecolor = _retrieve_poly_calculated_colors(poly)
  strokestyle = Makie.convert_attribute(poly.linestyle[], key"linestyle"())
 
  broadcast_foreach(projected_polys, color, strokecolor, strokestyle, poly.strokewidth[]) do po, c, sc, ss, sw
@@ -185,8 +203,8 @@ function draw_poly(scene::Scene, screen::Screen, poly, polygons::AbstractArray{<
  space = to_value(get(poly, :space, :data))
  projected_polys = project_multipolygon.(Ref(poly), space, polygons, Ref(model))
 
- color = to_cairo_color(poly.color[], poly)
- strokecolor = to_cairo_color(poly.strokecolor[], poly)
+ color, strokecolor = _retrieve_poly_calculated_colors(poly)
+
  strokestyle = Makie.convert_attribute(poly.linestyle[], key"linestyle"())
  broadcast_foreach(projected_polys, color, strokecolor, strokestyle, poly.strokewidth[]) do mpo, c, sc, ss, sw
  for po in mpo.polygons
@@ -211,9 +229,14 @@ end
 
 function draw_plot(scene::Scene, screen::Screen,
  band::Band{<:Tuple{<:AbstractVector{<:Point2},<:AbstractVector{<:Point2}}})
-
- if !(band.color[] isa AbstractArray)
- color = to_cairo_color(band.color[], band)
+
+ # Similarly to what we do in `poly`, we retrieve the 
+ # calculated colors from the internal `mesh` plot of `band`.
+ # See the `_retrieve_poly_calculated_colors` function for more details.
+ band_color = band.plots[1].calculated_colors[]
+
+ if !(band_color isa AbstractArray)
+ color = to_cairo_color(band_color, band)
  upperpoints = band[1][]
  lowerpoints = band[2][]
  points = vcat(lowerpoints, reverse(upperpoints))
@@ -252,7 +275,7 @@ end
 function draw_plot(scene::Scene, screen::Screen, tric::Tricontourf)
 
  pol = only(tric.plots)::Poly
- colornumbers = pol.color[]
+ colornumbers = pol.plots[1].calculated_colors[] # just as in `poly`, we retrieve the calculated colors from the internal `mesh` plot.
  colors = to_cairo_color(colornumbers, pol)
  polygons = pol[1][]
  model = pol.model[]

ReferenceTests/src/tests/examples2d.jl

@@ -1392,3 +1392,11 @@ end
  ylims!(ax, 0, 1)
  fig
 end
+
+@reference_test "transparency in band (#3356)" begin
+ f = Figure()
+ ax = Axis(f[1, 1])
+ band!(ax, 1:10, 1:10, 2:11)
+ band!(ax, reverse(1:10), 1:10, 2:11, alpha = 0.5)
+ f
+end