Line Length#

Our examples so far have been too simplistic, what happens if the start and end points do not fit nicely into the length of the pattern, linspace will be unphased and produce an array of floating values, which after converting to integers will not coincide with the sizes required. If a user feeds in a pattern it is of secondary importance that the line finishes exactly at the end point. What should concern us is that the dashes and gaps are accurate, so ensure that the correct information is fed into the linspace functions.

Change the end position so that the dash gap pattern finishes at the highest multiple of the pattern length that fits into the pattern length. With an eye on orientation, make this so it suits any angle:

theta = atan2(y1 - y0, x1 - x0)

if line_length % dash_gap_length != 0:
    factor = line_length//dash_gap_length
    line_length = factor * dash_gap_length
    x1 = int(x0 + line_length * cos(theta) + 0.5)
    y1 = int(y0 + line_length * sin(theta) + 0.5)

Once the above changes are made run the script with an end position of say (30, 90). It should fit into the old framework.

import sys
sys.path.append('../dims')

from PIL import Image, ImageDraw, ImageFont
from math import dist, atan2, sin, cos
from numpy import linspace, concatenate, int_
from DimLinesPIL import angled_text, dims, int_up

def line_dashed(dr, start_pos, end_pos, dash=(5,5), width = 1, fill='black'):
    # create dashed lines in PIL

    # unpack tuples
    x0, y0 = start_pos
    x1, y1 = end_pos
    dash0, dash1 = dash
    dash2 = dash0 - 1
    theta = atan2(y1 - y0, x1 - x0)

    # sort out lengths
    dash_gap_length = sum(dash)
    line_length = dist(start_pos, end_pos)

    # adjust length to suit start and end positions if required
    if line_length % dash_gap_length != 0:
        factor = line_length//dash_gap_length # + 1
        line_length = factor * dash_gap_length
        x1 = int_up(x0 + line_length * cos(theta))
        y1 = int_up(y0 + line_length * sin(theta))

    # inclusive number of dashes and gaps
    dash_amount = int_up(line_length / dash_gap_length) + 1


    start_arr = linspace((x0, y0), (x1, y1), dash_amount)
    end_arr = linspace((x0, y0 + dash2), (x1, y1 + dash2), dash_amount)

    both_arr = concatenate([start_arr, end_arr], axis=0)

    fin_arr = int_(both_arr[both_arr[:, 1].argsort()])

    nr_lines = len(fin_arr)

    [dr.line([tuple(fin_arr[n]), tuple(fin_arr[n+1])], width=1, fill=fill)
            for n in range(0, nr_lines, 2)]

if __name__ == "__main__":
    Font = ImageFont.truetype('consola.ttf', 12)

    arr =[(30, 10),
    (30, 24),
    (30, 40),
    (30, 54),
    (30, 70),
    (30, 84)]

    nr_lines = len(arr)

    dash =(15, 15)

    start_pos = (30, 10)
    end_pos = (30, 90)

    w, h = 100, 100
    image = Image.new('RGB', (w,h), '#FFFFDD')
    draw = ImageDraw.Draw(image)

    # wide, height = Font.getsize('(30, 84)')
    unused1, unused2, wide, height = Font.getbbox('(30, 84)')


    for i in range(nr_lines):
        angled_text(image, (arr[i][0] + 10 + wide//2, arr[i][1]),text=str(arr[i]),
                angle=0, fill='black', font=Font)

    for j in range(nr_lines - 1):
        dims(image, draw, arr[j], arr[j+1], (8, 2), text='15', font=Font, fill='lightgreen',
                textorient='horizontal')


    line_dashed(draw, start_pos, end_pos, dash=dash, width = 1, fill='black')

    image.show()

Line Length#

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