Greyscale bars/Display: Difference between revisions

=={{header|Julia}}==

<lang Julia>using Gtk, Cairo, ColorTypes

function generategrays(n, screenwidth)

horizontals = Vector{RGB}()

hwidth = Int(ceil(screenwidth/n))

for (i, x) in enumerate(00:Int(floor(0xff/(n-1))):0xff)

rgbgray = RGB(x/255, x/255, x/255)

for j in 1:hwidth

push!(horizontals, rgbgray)

end

end

horizontals

end

function drawline(ctx, p1, p2, color, width)

move_to(ctx, p1.x, p1.y)

set_source(ctx, color)

line_to(ctx, p2.x, p2.y)

set_line_width(ctx, width)

stroke(ctx)

end

const can = @GtkCanvas()

const win = GtkWindow(can, "Grayscale bars/Display", 400, 400)

fullscreen(win) # start full screen, then reduce to regular window in 5 seconds.

@guarded draw(can) do widget

ctx = getgc(can)

h = height(can)

w = width(can)

gpoints = generategrays(8, w)

for (i, x) in enumerate(0:w-1)

drawline(ctx, Point(x, 0.25*h), Point(x, 0), gpoints[i], 1)

end

gpoints = reverse(generategrays(16, w))

for (i, x) in enumerate(0:w-1)

drawline(ctx, Point(x, 0.5*h), Point(x, 0.25*h), gpoints[i], 1)

end

gpoints = generategrays(32, w)

for (i, x) in enumerate(0:w-1)

drawline(ctx, Point(x, 0.75*h), Point(x, 0.5*h), gpoints[i], 1)

end

gpoints = reverse(generategrays(64, w))

for (i, x) in enumerate(0:w-1)

drawline(ctx, Point(x, h), Point(x, 0.75*h), gpoints[i], 1)

end

end

show(can)

sleep(5)

unfullscreen(win)

const cond = Condition()

endit(w) = notify(cond)

signal_connect(endit, win, :destroy)

wait(cond)</lang>