skip annotations for plot title subplot (#5104)

Co-authored-by: t-bltg <tf.bltg@gmail.com>

Author: InfiniteChai

PlotsBase/src/Plots.jl

@@ -247,6 +247,10 @@ function _update_subplot_attrs(
 
     # grab those args which apply to this subplot
     for k ∈ keys(_subplot_defaults)
+        # We don't apply annotations to the plot-title sub-plot
+        if k == :annotations && get(plt.attr, :plot_titleindex, 0) == subplot_index
+            continue
+        end
         PlotsBase.slice_arg!(plotattributes_in, sp.attr, k, subplot_index, remove_pair)
     end
 

PlotsBase/test/test_components.jl

@@ -187,6 +187,66 @@ end
             annotate!(pl, loc, string(loc))
         end
     end
+
+    let p = scatter([4], [4], plot_title = "x", xlims = (0, 10), ylims = (0, 10))
+        for sp ∈ p.subplots
+            @test sp[:annotations] == []
+        end
+        annotate!(4, 4, "4")
+
+        for (i, sp) ∈ enumerate(p.subplots)
+            if i == p.attr[:plot_titleindex]
+                @test sp[:annotations] == []
+            else
+                @test length(sp[:annotations]) == 1
+                @test sp[:annotations][1][1] == 4
+                @test sp[:annotations][1][2] == 4
+                @test sp[:annotations][1][3].str == "4"
+            end
+        end
+    end
+
+    let p = scatter(
+            [4],
+            [4],
+            plot_title = "x",
+            xlims = (0, 10),
+            ylims = (0, 10),
+            annotations = (4, 4, "4"),
+        )
+        for (i, sp) ∈ enumerate(p.subplots)
+            if i == p.attr[:plot_titleindex]
+                @test sp[:annotations] == []
+            else
+                @test length(sp[:annotations]) == 1
+                @test sp[:annotations][1][1] == 4
+                @test sp[:annotations][1][2] == 4
+                @test sp[:annotations][1][3].str == "4"
+            end
+        end
+    end
+
+    let p = plot(
+            scatter([4], [4], xlims = (0, 10), ylims = (0, 10)),
+            scatter([4], [4], xlims = (0, 10), ylims = (0, 10)),
+            plot_title = "x",
+        )
+        for sp ∈ p.subplots
+            @test sp[:annotations] == []
+        end
+        annotate!(4, 4, "4")
+
+        for (i, sp) ∈ enumerate(p.subplots)
+            if i == p.attr[:plot_titleindex]
+                @test sp[:annotations] == []
+            else
+                @test length(sp[:annotations]) == 1
+                @test sp[:annotations][1][1] == 4
+                @test sp[:annotations][1][2] == 4
+                @test sp[:annotations][1][3].str == "4"
+            end
+        end
+    end
 end
 
 @testset "Fonts" begin