Add default widen=:auto, which matches default before 43e9a342

* If widen is a Bool, it always determines whether widening occurs.
* If widen is :auto (the defualt), widening occurs for appropriate
  seriestypes, unless lims were set manually

src/arg_desc.jl

@@ -178,6 +178,9 @@ const _arg_desc = KW(
 :minorgridlinewidth          => "Number. Width of the minor grid lines (in pixels)",
 :tick_direction              => "Symbol.  Direction of the ticks. `:in`, `:out` or `:none`",
 :showaxis                    => "Bool, Symbol or String.  Show the axis. `true`, `false`, `:show`, `:hide`, `:yes`, `:no`, `:x`, `:y`, `:z`, `:xy`, ..., `:all`, `:off`",
-:widen                       => "Bool. Widen the axis limits by a small factor to avoid cut-off markers and lines at the borders. Defaults to `true`.",
+:widen                       => """
+                                Bool or :auto. Widen the axis limits by a small factor to avoid cut-off markers and lines at the borders.
+                                Defaults to `:auto`, which widens unless limits were manually set.
+                                """,
 :draw_arrow                  => "Bool. Draw arrow at the end of the axis.",
 )

src/args.jl

@@ -476,7 +476,7 @@ const _axis_defaults = KW(
     :minorticks                  => false,
     :minorgrid                   => false,
     :showaxis                    => true,
-    :widen                       => true,
+    :widen                       => :auto,
     :draw_arrow                  => false,
 )
 

src/axes.jl

@@ -504,6 +504,11 @@ end
 const _widen_seriestypes = (:line, :path, :steppre, :stepmid, :steppost, :sticks, :scatter, :barbins, :barhist, :histogram, :scatterbins, :scatterhist, :stepbins, :stephist, :bins2d, :histogram2d, :bar, :shape, :path3d, :scatter3d)
 
 function default_should_widen(axis::Axis)
+    if axis[:widen] isa Bool
+        return axis[:widen]
+    end
+    # automatic behavior: widen if limits aren't specified and series type is appropriate
+    (is_2tuple(axis[:lims]) || axis[:lims] == :round) && return false
     for sp in axis.sps
         for series in series_list(sp)
             if series.plotattributes[:seriestype] in _widen_seriestypes
@@ -559,7 +564,7 @@ function axis_limits(sp, letter, should_widen = default_should_widen(sp[Symbol(l
         else
             amin, amax
         end
-    elseif should_widen && axis[:widen]
+    elseif should_widen
         widen(amin, amax, axis[:scale])
     elseif lims == :round
         round_limits(amin,amax)

test/test_axes.jl

@@ -35,6 +35,18 @@ end
 @testset "Axis limits" begin
     pl = plot(1:5, xlims=:symmetric, widen = false)
     @test Plots.xlims(pl) == (-5, 5)
+    
+    pl = plot(1:3)
+    @test Plots.xlims(pl) == Plots.widen(1,3)
+    
+    pl = plot(1:3, xlims=:round)
+    @test Plots.xlims(pl) == (1, 3)
+    
+    pl = plot(1:3, xlims=(1,5))
+    @test Plots.xlims(pl) == (1, 5)
+
+    pl = plot(1:3, xlims=(1,5), widen=true)
+    @test Plots.xlims(pl) == Plots.widen(1, 5)
 end
 
 @testset "3D Axis" begin