Bitmap/Midpoint circle algorithm: Difference between revisions

=={{header|Julia}}==

{{works with|Julia|0.6}}

<lang julia>function drawcircle!(img::Matrix{T}, col::T, x0::Int, y0::Int, radius::Int) where T

x = radius - 1

y = 0

δx = δy = 1

er = δx - (radius << 1)

s = x + y

while x ≥ y

for opx in (+, -), opy in (+, -), el in (x, y)

@inbounds img[opx(x0, el) + 1, opy(y0, s - el) + 1] = col

end

if er ≤ 0

y += 1

er += δy

δy += 2

end

if er > 0

x -= 1

δx += 2

er += (-radius << 1) + δx

end

s = x + y

end

return img

end

# Test

using Images

img = fill(Gray(255.0), 25, 25);

drawcircle!(img, Gray(0.0), 12, 12, 12)</lang>