enable alpha for Geom.rect (#1439)

docs/src/gallery/geometries.md

@@ -31,10 +31,10 @@ De = dataset("ggplot2","economics")
 De.Unemploy /= 10^3
 
 plot(De, x=:Date, y=:Unemploy, Geom.line,
-    layer(Dp, xmin=:Start, xmax=:End, Geom.vband, color=:Party),
+    layer(Dp, xmin=:Start, xmax=:End, Geom.vband, color=:Party, alpha=[0.6]),
     Scale.color_discrete_manual("deepskyblue", "lightcoral"),
     Coord.cartesian(xmin=Date("1965-01-01"), ymax=12),
-    Guide.xlabel("Time"), Guide.ylabel("Unemployment (x10³)"), Guide.colorkey(title=""),
+  Guide.xlabel("Time"), Guide.ylabel("Unemployment (x10³)"), Guide.colorkey(title=""),
     Theme(default_color="black", key_position=:top))
 ```
 
@@ -434,13 +434,16 @@ plot(x=[0, 1, 1, 2, 2, 3, 3, 2, 2, 1, 1, 0, 4, 5, 5, 4],
 ## [`Geom.rect`](@ref), [`Geom.rectbin`](@ref)
 
 ```@example
-using Gadfly, Colors, DataFrames, RDatasets
+using Gadfly, DataFrames
 set_default_plot_size(21cm, 8cm)
-theme1 = Theme(default_color=RGBA(0, 0.75, 1.0, 0.5))
-D = DataFrame(x=[0.5,1], y=[0.5,1], x1=[0,0.5], y1=[0,0.5], x2=[1,1.5], y2=[1,1.5])
-pa = plot(D, x=:x, y=:y, Geom.rectbin, theme1)
-pb = plot(D, xmin=:x1, ymin=:y1, xmax=:x2, ymax=:y2, Geom.rect, theme1)
-hstack(pa, pb)
+x1, y1, w1 = 0.5:10, rand(10), 0.09.+0.4*rand(10)
+D = DataFrame(x=x1, y=rand(x1, 10), y1=y1, x2=x1.+w1, y2=y1.+w1, c=0:9)
+p1 = plot(D, xmin=:x, ymin=:y1, xmax=:x2, ymax=:y2, color=[colorant"green"],
+    alpha=1:10, Geom.rect, Scale.alpha_discrete)
+p2 = plot(D, xmin=:x, ymin=:y1, xmax=:x2, ymax=:y2, color=:c, alpha=[0.7],
+    Geom.rect, Guide.ylabel(nothing))
+p3 = plot(D, x=:x, y=:y, color=:c, alpha=[0.5], Geom.rectbin, Scale.color_discrete)
+hstack(p1, p2, p3)
 ```
 
 ```@example

src/geom/rectbin.jl

@@ -50,7 +50,7 @@ end
 default_statistic(geom::RectangularBinGeometry) = geom.default_statistic
 
 element_aesthetics(::RectangularBinGeometry) =
-        [:x, :y, :xmin, :xmax, :ymin, :ymax, :color]
+        [:x, :y, :xmin, :xmax, :ymin, :ymax, :color, :alpha]
 
 # Render rectangular bin (e.g., heatmap) geometry.
 #
@@ -65,7 +65,8 @@ element_aesthetics(::RectangularBinGeometry) =
 function render(geom::RectangularBinGeometry, theme::Gadfly.Theme, aes::Gadfly.Aesthetics)
 
     default_aes = Gadfly.Aesthetics()
-    default_aes.color = discretize_make_ia(RGBA{Float32}[theme.default_color])
+    default_aes.color = RGBA{Float32}[theme.default_color]
+    default_aes.alpha = Float64[theme.alphas[1]]
     aes = inherit(aes, default_aes)
 
     Gadfly.assert_aesthetics_defined("RectangularBinGeometry", aes, :xmin, :xmax, :ymin, :ymax)
@@ -83,36 +84,37 @@ function render(geom::RectangularBinGeometry, theme::Gadfly.Theme, aes::Gadfly.A
     ywidths = [(y1 - y0)*cy - theme.bar_spacing
                for (y0, y1) in zip(aes.ymin, aes.ymax)]
 
-    if length(aes.color) == n
-        cs = aes.color
-    else
-        cs = Array{RGBA{Float32}}(undef, n)
-        for i in 1:n
-            cs[i] = aes.color[((i - 1) % length(aes.color)) + 1]
-        end
+    AT, CT = eltype(aes.alpha), eltype(aes.color)
+    aes_color = Vector{CT}(undef, n)
+    aes_alpha = Vector{Float64}(undef, n)
+    alphav = AT <: Int ? theme.alphas[aes.alpha] : aes.alpha
+    for (i, (_, c, a)) in enumerate(Compose.cyclezip(xmin, aes.color, alphav))
+        aes_color[i] = c
+        aes_alpha[i] = a
     end
 
     allvisible = true
-    for c in cs
+    for c in aes_color
         if c == nothing
             allvisible = false
             break
         end
     end
 
     if !allvisible
-        visibility = cs .!= nothing
-        cs = cs[visibility]
+        visibility = aes_color .!== nothing
+        aes_color = aes_color[visibility]
+        aes_alpha = aes_alpha[visibility]
         xmin = xmin[visibility]
-        xmax = xmax[visibility]
+        xwidths = xwidths[visibility]
         ymin = ymin[visibility]
-        ymax = ymax[visibility]
+        ywidths = ywidths[visibility]
     end
 
     return compose!(
         context(),
         rectangle(xmin, ymin, xwidths, ywidths, geom.tag),
-        fill(cs),
+        fill(aes_color), fillopacity(aes_alpha),
         stroke(nothing),
         svgclass("geometry"),
         svgattribute("shape-rendering", "crispEdges"))

test/testscripts/rectbin.jl

@@ -6,6 +6,6 @@ set_default_plot_size(6inch, 3inch)
 # plot(dataset("Zelig", "macro"), x="Year", y="Country", color="GDP", Geom.rectbin)
 
 D = DataFrame(x=[0.5,1], y=[0.5,1], x1=[0,0.5], y1=[0,0.5], x2=[1,1.5], y2=[1,1.5])
-pa = plot(D, x=:x, y=:y, Geom.rectbin)
-pb = plot(D, xmin=:x1, ymin=:y1, xmax=:x2, ymax=:y2, Geom.rect)
+pa = plot(D, x=:x, y=:y, alpha=[0.5], Geom.rectbin)
+pb = plot(D, xmin=:x1, ymin=:y1, xmax=:x2, ymax=:y2, alpha=[0.5], Geom.rect)
 hstack(pa,pb)