fix #78

[yakir12]

This PR drammatically improves on performance for ellipse drawing:

using Revise
using BenchmarkTools
using ImageDraw 
import ColorTypes: RGB, N0f8

img = rand(RGB{N0f8}, 1000, 1000)
c = CirclePointRadius(Point(500, 500), 400)
f() = draw!(img, c)
@benchmark f()

before this PR:

BenchmarkTools.Trial: 1875 samples with 1 evaluation.
 Range (min … max):  2.258 ms …   5.262 ms  ┊ GC (min … max): 0.00% … 0.00%
 Time  (median):     2.499 ms               ┊ GC (median):    0.00%
 Time  (mean ± σ):   2.600 ms ± 292.306 μs  ┊ GC (mean ± σ):  0.00% ± 0.00%

       ▅██▆▂▁                                                  
  ▂▃▄▇▇███████▆▇▅▆▇██▆▅▄▃▃▃▃▃▃▃▂▂▁▂▂▂▂▂▃▃▃▃▃▃▃▂▂▂▂▂▃▃▂▂▂▂▁▁▂▂ ▃
  2.26 ms         Histogram: frequency by time        3.63 ms <

 Memory estimate: 3.66 MiB, allocs estimate: 22.

After this PR:

BenchmarkTools.Trial: 8135 samples with 1 evaluation.
 Range (min … max):  594.081 μs …  1.619 ms  ┊ GC (min … max): 0.00% … 0.00%
 Time  (median):     609.660 μs              ┊ GC (median):    0.00%
 Time  (mean ± σ):   612.257 μs ± 26.233 μs  ┊ GC (mean ± σ):  0.00% ± 0.00%

               █        ▁                                       
  ▂▂▂▂▁▁▂▂▃▃▂▃▃█▄▄▄▇▆▅▅▄█▄▄▄▄▄▃▃▃▃▃▃▃▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂ ▃
  594 μs          Histogram: frequency by time          643 μs <

 Memory estimate: 0 bytes, allocs estimate: 0.

[yakir12]

Does anyone have time to review this? The code change is pretty small and the improvement is substantial, to put it in relative terms 😛

[ashwanirathee]

Hey yakir, please format it correctly, otherwise it looks good to me

[yakir12]

oh wow, I was really confused cause it looked fine in vim but off when I printed it out. Apparently some of the spaces here are tabs, which I think is discouraged (precisely for this reason).

[mkitti]

Thanks... but I think you used two spaces. The rest of the package uses four.

[yakir12]

Right, fixed it now.

[mkitti]

Looks good to me. The indenting looks a bit strange from my phone though.

[yakir12]

This file contained tab-spaces so I replaced them with (2) spaces, hope that doesn't go against the style guide of ImageDraw...