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#!/usr/bin/env python3
# Author: L. Tattrie
# Purpose: svgwrite examples
# Created: 2012/5/31
# Copyright (C) 2012, L. Tattrie
# License: LGPL
# Python version 2.7
import math, sys
import svgwrite
from svgwrite import rgb
#
# http://www.w3.org/TR/SVG11/types.html#ColorKeywords
# Note both grey and gray are valide but only color not colour is valid.
#
PROGNAME = sys.argv[0].rstrip('.py')
def create_svg(name):
WIDTH = 900
HEIGHT = 900
FONT_SIZE = 20
COMPLETE_SIZE = 800 # size of the whole set of triangles.
TRIANGLES_PER_SIDE = 50 # How many triangles there will be per side. integer.
TRIHEIGHT = math.sqrt(3) / 2
title1 = name + ': Example of creating your own colors.'
start = ((WIDTH - COMPLETE_SIZE)/2, (HEIGHT - COMPLETE_SIZE)/2) # center triangle
#tri_color = ((255, 0, 0), (0, 255, 0), (0, 0, 255))
#tri_color = ((128, 0, 0), (0, 128, 0), (0, 0, 128))
tri_color = ((20, 128, 30), (10, 0, 50), (0, 0, 128))
dwg = svgwrite.Drawing(name, (WIDTH, HEIGHT), debug=True)
def draw_triangle(insert, size, fill, rotate=None):
x, y = insert
points = [insert, (x + size, y), ((x + size / 2), (y + size * TRIHEIGHT))]
triangle = dwg.add(dwg.polygon(points, fill=fill, stroke='none'))
if rotate:
triangle.rotate(rotate, center=insert)
def nfrange(fstart, fstop, n):
# n = number of points
delta = (fstop - fstart) / n
return [ fstart + delta * i for i in range(n) ]
# Background will be dark but not black so the background does not overwhelm the colors.
dwg.add(dwg.rect(insert=(0, 0), size=('100%', '100%'), fill='grey'))
# Give the name of the example and a title.
y = FONT_SIZE + 5
dwg.add(dwg.text(title1, insert=(0, y),
font_family="serif", font_size=FONT_SIZE, fill='white'))
tri_size = COMPLETE_SIZE / TRIANGLES_PER_SIDE
tri_height = tri_size * TRIHEIGHT
ratio_side = nfrange(0.0, 1.0, TRIANGLES_PER_SIDE)
for i in range(TRIANGLES_PER_SIDE, 0, -1):
# The number of triangle in the row is the sum of the point up and the point down
# triangles.
num_tri_in_row = 2 * i - 1
num_tri_drawn_in_row = 0
# Calculate color
start_color = [int(tri_color[0][k] * ratio_side[i-1] +
tri_color[2][k] * (1 - ratio_side[i-1])) for k in range(3)]
end_color = [int(tri_color[1][k] * ratio_side[i-1] +
tri_color[2][k] * (1 -ratio_side[i-1])) for k in range(3)]
# calculate ratios of the two ending colors.
ratio_row = nfrange(0.0, 1.0, num_tri_in_row) if num_tri_in_row > 1 else [0.5]
for j in range(i):
x = start[0] + (j + ((TRIANGLES_PER_SIDE - i) / 2)) * tri_size
y = start[1] + (TRIANGLES_PER_SIDE - i) * tri_height
# Calculate color
new_color = [int(start_color[k] * (1 - ratio_row[num_tri_drawn_in_row ]) +
end_color[k] * ratio_row[num_tri_drawn_in_row]) for k in range(3)]
draw_triangle((x, y), tri_size, rgb(*new_color))
num_tri_drawn_in_row += 1
if j != (i - 1):
# The on screen point up triangles have one fewer per row.
x += tri_size
# Calculate color
new_color = [int(start_color[k] * (1 - ratio_row[num_tri_drawn_in_row ]) +
end_color[k] * ratio_row[num_tri_drawn_in_row]) for k in range(3)]
draw_triangle((x, y), tri_size, rgb(*new_color), rotate=60)
num_tri_drawn_in_row += 1
dwg.save()
if __name__ == '__main__':
create_svg(PROGNAME + '.svg')
# vim: expandtab shiftwidth=4 tabstop=8 softtabstop=4 textwidth=99
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