LineReader.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
###################################################
# by Maciej Kamiński Politechnika Wrocławska
# Under GPL 3 and  MIT licence
#
__author__ = 'Maciej Kamiński Politechnika Wrocławska'

import matplotlib.pyplot as plt
import matplotlib.image as mpimg
import argparse
import numpy as np


parser=argparse.ArgumentParser(description="Helps determine point coordinates in scanned chart")
parser.add_argument('-xfs','--x_figure_size', type=int, help='Window width in inches',default=12)
parser.add_argument('-yfs','--y_figure_size', type=int, help='Window height in inches',default=8)
parser.add_argument('maxx', type=int, help='Max X point - (0,X) coordinated')
parser.add_argument('maxy', type=int, help='Max Y point - (Y,0) coordinated')
parser.add_argument('input', type=str, help='Input image filename')
parser.add_argument('output', type=str, help='Output CSV filename')

args=parser.parse_args()


def onclick(event):

    global point_zero
    global point_xmax
    global point_ymax
    global points

    if not point_zero:
        event.canvas.figure.suptitle("Select X max Point", fontsize=14, fontweight='bold')
        point_zero=(event.xdata, event.ydata)
        event.canvas.draw()

    elif not point_xmax:
        event.canvas.figure.suptitle("Select Y max Point", fontsize=14, fontweight='bold')
        point_xmax=(event.xdata, event.ydata)
        event.canvas.draw()

    elif not point_ymax:
        event.canvas.figure.suptitle("Select First Point", fontsize=14, fontweight='bold')
        point_ymax=(event.xdata, event.ydata)
        event.canvas.draw()

    else:
        event.canvas.figure.suptitle("Select Next Point", fontsize=14, fontweight='bold')
        points.append((event.xdata, event.ydata))
        event.canvas.draw()
        with open(args.output,"a") as file:
            zero=complex(*point_zero)
            xmax=complex(*point_xmax)
            ymax=complex(*point_ymax)
            point=complex(*points[-1])
            x=xmax-zero
            y=ymax-zero
            p=point-zero
            xversor=x/args.maxx
            yversor=y/args.maxy
            a=np.array([
                [xversor.real,yversor.real],
                [xversor.imag,yversor.imag]
            ])
            b=np.array([p.real,p.imag])

            h=np.linalg.solve(a,b)
            print(h)
            print("{:.2f}, {:.2f}".format(round(h[0],2),round(h[1],2)),file=file)

def onZoom(event):
    # get the current x and y limits
    base_scale=1.8
    global ax
    cur_xlim = ax.get_xlim()
    cur_ylim = ax.get_ylim()
    # get middle
    xdata = event.xdata # get event x location
    ydata = event.ydata # get event y location

    x_l=xdata-cur_xlim[0]
    x_r=cur_xlim[1]-xdata
    y_d=ydata-cur_ylim[0]
    y_u=cur_ylim[1]-ydata


    if event.button == 'up':
        # deal with zoom in
        scale_factor = 1/base_scale
    elif event.button == 'down':
        # deal with zoom out
        scale_factor = base_scale
    else:
        # deal with something that should never happen
        scale_factor = 1
        print(event.button)
    # set new limits
    x_l*=scale_factor
    x_r*=scale_factor
    y_d*=scale_factor
    y_u*=scale_factor

    new_min_x_limit=xdata - x_l
    new_max_x_limit=xdata + x_r
    new_min_y_limit=ydata - y_d
    new_max_y_limit=ydata + y_u

    if x_l+x_r>1 or y_u+y_d>1:
        new_min_x_limit=0
        new_max_x_limit=1
        new_min_y_limit=0
        new_max_y_limit=1

    if new_min_x_limit<=0:
        new_max_x_limit+=(0-new_min_x_limit)
        new_min_x_limit=0

    if new_max_x_limit>=1:
        new_min_x_limit-=(new_max_x_limit-1)
        new_max_x_limit=1

    if new_min_y_limit<=0:
        new_max_y_limit+=(0-new_min_y_limit)
        new_min_y_limit=0

    if new_max_y_limit>=1:
        new_min_y_limit-=(new_max_y_limit-1)
        new_max_y_limit=1

    ax.set_xlim([new_min_x_limit,new_max_x_limit])
    ax.set_ylim([new_min_y_limit,new_max_y_limit])
    plt.draw() # force re-draw


def main():
    global point_zero
    global point_xmax
    global point_ymax
    global points
    global ax

    point_zero=None
    point_xmax=None
    point_ymax=None
    points=[]
    image=mpimg.imread(args.input)
    fig, ax = plt.subplots(figsize=(args.x_figure_size,args.y_figure_size))
    fig.suptitle("Select zero point", fontsize=14, fontweight='bold')
    fig.canvas.mpl_connect('button_press_event', onclick)
    fig.canvas.mpl_connect('scroll_event',onZoom)
    plt.imshow(image,zorder=0,extent=[0.0,1.0,0.0,1.0],aspect='auto')
    ax.xaxis.set_visible(False)
    ax.yaxis.set_visible(False)
    plt.tight_layout(pad=0)
    plt.show()

main()