Quick and dirty square cropper

cropper.py

import cv2
import os
import numpy as np

import sys

print("""
Pass a folder of images as a prameter:

script.py Z:\\somefolder\\somewhere

Space for next image.
Mousewheel for resizing the box
Click to capture the hilighted square

images are saved into \\outdir\\

""")


if len(sys.argv)<2:
    print('Pass in a source folder as a parameter')
    exit()

source_folder = sys.argv[-1]

if not os.path.isdir(source_folder):
    print('source_folder', source_folder, 'does not exist.')
    exit()

print('source_folder', source_folder)

files = []
for f in os.listdir(source_folder):
    files.append(os.path.join(source_folder, f))

cv2.namedWindow("imageWindow", cv2.WND_PROP_FULLSCREEN)
cv2.setWindowProperty("imageWindow",cv2.WND_PROP_FULLSCREEN,cv2.WINDOW_FULLSCREEN)


lastx, lasty = 0, 0
dim = 512
grabNow = False


def on_mouse(event, x, y, buttons, param):
    global lastx, lasty, dim, grabNow
    lastx, lasty = (x, y)

    if event == cv2.EVENT_MOUSEWHEEL:
        if buttons > 0:
            dim += 10
        elif buttons < 0:
            dim -= 10

        dim = max(10,dim)
    elif event == cv2.EVENT_LBUTTONDOWN:
        grabNow = True


cv2.setMouseCallback('imageWindow', on_mouse)

n = 0
font = cv2.FONT_HERSHEY_SIMPLEX
for f in files:
    im = cv2.imread(f)
    if im is None:
        continue

    rect = cv2.getWindowImageRect('imageWindow')
    _, _, w, h = rect

    old_size = im.shape[:2]
    target_size = min(w, h)

    ratio = float(target_size)/max(old_size)

    new_size = tuple([int(x*ratio) for x in old_size])

    im = cv2.resize(im, (new_size[1], new_size[0]))

    delta_w = w - new_size[1]
    delta_h = h - new_size[0]
    top, bottom = delta_h//2, delta_h-(delta_h//2)
    left, right = delta_w//2, delta_w-(delta_w//2)

    color = [0, 0, 0]

    padded_im = cv2.copyMakeBorder(im, top, bottom, left, right, cv2.BORDER_CONSTANT, value=color)

    k = 0
    lastsave=None

    while 1:
        fg = padded_im.copy()
        colour = (255, 255, 255)
        if dim == 512:
            colour = (0, 255, 0)
        elif dim < 512:
            colour = (0, 0, 255)

        if lastsave is not None:
            fg = cv2.putText(fg, 'Saved:{}'.format(lastsave), (0, 11), font, 0.4, (0, 0, 0), 2, cv2.LINE_AA)
            fg = cv2.putText(fg, 'Saved:{}'.format(lastsave), (0, 11), font, 0.4, (255, 255, 255), 1, cv2.LINE_AA)

        fg = cv2.rectangle(fg, (lastx-(dim//2), lasty-(dim//2)), (lastx+(dim//2), lasty+(dim//2)), colour, 1)

        if grabNow:
            os.path.exists('outdir') or os.mkdir('outdir')
            fn = os.path.basename(f)
            outfile = os.path.join('outdir', '{}_{}_out.png'.format(fn, n))
            cv2.imwrite(outfile, padded_im[lasty-(dim//2):lasty+(dim//2), lastx-(dim//2):lastx+(dim//2), :])
            lastsave = outfile
            n += 1
            grabNow = False

        cv2.imshow('imageWindow', fg)

        k = cv2.waitKey(1)
        if k != -1:
            break
    if k == ord('q'):
        break