Add new script hocr-cut for cutting a page

hocr-cut

@@ -0,0 +1,119 @@
+#!/usr/bin/env python
+
+from __future__ import print_function
+import argparse
+import os
+import re
+import sys
+
+from lxml import html
+from PIL import Image, ImageDraw
+
+
+def get_prop(node, name):
+    title = node.get('title')
+    if not title: return None
+    props = title.split(';')
+    for prop in props:
+        (key, args) = prop.split(None, 1)
+        if key == name: return args.strip('"')
+    return None
+
+
+def get_bbox(node):
+    bbox = get_prop(node, 'bbox')
+    if not bbox: return None
+    return tuple([int(x) for x in bbox.split()])
+
+
+parser = argparse.ArgumentParser(
+    description=
+    'Cut a page (horizontally) into two pages in the middle such that the most of the bounding boxes are separated nicely, e.g. cutting double pages or double columns'
+)
+parser.add_argument('file', nargs='?', default=sys.stdin)
+parser.add_argument('-d', '--debug', action="store_true")
+args = parser.parse_args()
+
+doc = html.parse(args.file)
+
+pages = doc.xpath("//*[@class='ocr_page']")
+
+for page in pages:
+
+    try:
+        filename = get_prop(page, 'image')
+        image = Image.open(filename)
+        debug_image = Image.open(filename)
+        dr = ImageDraw.Draw(debug_image)
+        image_found = True
+    except:
+        print("Warning: Image not found!")
+        args.debug = False
+        image_found = False
+
+    bbox = get_bbox(page)
+    middle = bbox[2] / 2
+
+    left_ends = []
+    right_starts = []
+    for line in doc.xpath("//*[@class='ocr_line']"):
+        b = get_bbox(line)
+        if (b[0] > middle):
+            pos = "right"
+        elif (b[2] < middle):
+            pos = "left"
+        elif (b[2] - middle > middle - b[1]):
+            pos = "right"
+        else:
+            pos = "left"
+        if (pos == "right"):
+            right_starts.append(b[0])
+            if (args.debug):
+                dr.rectangle(b, fill=32)
+        else:
+            left_ends.append(b[2])
+            if (args.debug):
+                dr.rectangle(b, fill=96)
+
+    left_ends.sort()
+    right_starts.sort()
+    n = len(left_ends)
+    m = len(right_starts)
+    middle_left = left_ends[n // 2]
+    middle_right = right_starts[m // 2]
+
+    middle = (middle_left + middle_right) / 2
+    print("Cutting at", middle)
+
+    if (image_found):
+
+        if filename[-4] == ".":
+            name = filename[:-3]
+            suffix = filename[-3:]
+        else:
+            name = filename
+            suffix = ""
+
+        if (args.debug):
+            dr.line(
+                (middle_left, 0, middle_left, debug_image.size[1]),
+                fill=64,
+                width=3)
+            dr.line(
+                (middle_right, 0, middle_right, debug_image.size[1]),
+                fill=64,
+                width=3)
+            dr.line(
+                (middle, 0, middle, debug_image.size[1]), fill=128, width=5)
+            debug_output = name + "cut." + suffix
+            debug_image.save(debug_output)
+            print("debug output is saved in", debug_output)
+
+        left = image.crop((0, 0, middle, image.size[1]))
+        left_name = name + "left." + suffix
+        left.save(left_name)
+        print("left page is saved in", left_name)
+        right = image.crop((middle, 0, image.size[0], image.size[1]))
+        right_name = name + "right." + suffix
+        right.save(right_name)
+        print("right page is saved in", right_name)