Spiral
#!/usr/bin/env python
# [SNIPPET_NAME: Spiral]
# [SNIPPET_CATEGORIES: Cairo]
# [SNIPPET_DESCRIPTION: Generate a spiral]
# [SNIPPET_DOCS: http://www.tortall.net/mu/wiki/CairoTutorial]
# [SNIPPET_LICENSE: MPL]
import cairo
import os
WIDTH, HEIGHT = 600, 600
def draw_spiral (ctx, width, height):
wd = .02 * width
hd = .02 * height
width -= 2
height -= 2
ctx.move_to (width + 1, 1-hd)
for i in range(9):
ctx.rel_line_to (0, height - hd * (2 * i - 1))
ctx.rel_line_to (- (width - wd * (2 *i)), 0)
ctx.rel_line_to (0, - (height - hd * (2*i)))
ctx.rel_line_to (width - wd * (2 * i + 1), 0)
ctx.set_source_rgb (0, 0, 1)
ctx.stroke()
surface = cairo.ImageSurface (cairo.FORMAT_ARGB32, WIDTH, HEIGHT)
ctx = cairo.Context(surface)
ctx.set_source_rgb (1, 1, 1)
ctx.set_operator (cairo.OPERATOR_SOURCE)
ctx.paint()
draw_spiral (ctx, WIDTH, HEIGHT)
# the output is written to your home directory
surface.write_to_png(os.path.expanduser("~") + '/spiral.png')