CLI(renderer/pageobjects): slightly improve code style

src/pypdfium2/_cli/_parsers.py

@@ -3,8 +3,9 @@
 
 import os
 import sys
-import argparse
 import logging
+import argparse
+import itertools
 from pathlib import Path
 import pypdfium2._helpers as pdfium
 import pypdfium2.internal as pdfium_i
@@ -91,6 +92,21 @@ def get_input(args, init_forms=False, **kwargs):
     return pdf
 
 
+# dummy more_itertools.peekable().__bool__ alternative
+
+def _postpeek_generator(value, iterator):
+    yield value
+    yield from iterator
+
+def iterator_hasvalue(iterator):
+    try:
+        first_value = next(iterator)
+    except StopIteration:
+        return False, None
+    else:
+        return True, _postpeek_generator(first_value, iterator)
+
+
 if sys.version_info >= (3, 9):
     from argparse import BooleanOptionalAction
 

src/pypdfium2/_cli/pageobjects.py

@@ -3,7 +3,6 @@
 
 # TODO test-confirm filter and info params
 
-from itertools import chain
 from collections import OrderedDict
 import pypdfium2._helpers as pdfium
 import pypdfium2.internal as pdfium_i
@@ -13,6 +12,7 @@
     add_n_digits,
     get_input,
     round_list,
+    iterator_hasvalue,
 )
 
 
@@ -83,17 +83,13 @@ def main(args):
     for i in args.pages:
 
         page = pdf[i]
-        obj_searcher = page.get_objects(args.filter, max_depth=args.max_depth)
-        # note, more_itertools.peekable() could handle this more elegantly
-        try:
-            first_obj = next(obj_searcher)
-        except StopIteration:
-            continue
+        hasvalue, obj_searcher = iterator_hasvalue( page.get_objects(args.filter, max_depth=args.max_depth) )
+        if not hasvalue: continue
 
         print(f"# Page {i+1}")
         count = 0
 
-        for obj in chain([first_obj], obj_searcher):
+        for obj in obj_searcher:
 
             pad_0 = "    " * obj.level
             pad_1 = pad_0 + "    "

src/pypdfium2/_cli/render.py

@@ -17,6 +17,7 @@
 from pypdfium2._cli._parsers import (
     add_input, get_input,
     setup_logging,
+    iterator_hasvalue,
     BooleanOptionalAction,
 )
 
@@ -288,37 +289,26 @@ def _saving_hook(self, out_path, bitmap, page, postproc_kwargs):
     @classmethod
     def postprocess(cls, src_image, bitmap, page, invert_lightness, exclude_images):
         dst_image = src_image
-
         if invert_lightness:
-
             if bitmap.format == pdfium_c.FPDFBitmap_Gray:
                 dst_image = ~src_image
             else:
-
-                if bitmap.rev_byteorder:
-                    convert_to = cv2.COLOR_RGB2HLS
-                    convert_from = cv2.COLOR_HLS2RGB
-                else:
-                    convert_to = cv2.COLOR_BGR2HLS
-                    convert_from = cv2.COLOR_HLS2BGR
-
+                convert_to, convert_from = (cv2.COLOR_RGB2HLS, cv2.COLOR_HLS2RGB) if bitmap.rev_byteorder else (cv2.COLOR_BGR2HLS, cv2.COLOR_HLS2BGR)
                 dst_image = cv2.cvtColor(dst_image, convert_to)
                 h, l, s = cv2.split(dst_image)
                 l = ~l
                 dst_image = cv2.merge([h, l, s])
                 dst_image = cv2.cvtColor(dst_image, convert_from)
-
             if exclude_images:
-                assert bitmap.format != pdfium_c.FPDFBitmap_BGRx, "Not sure how to paste with mask on {RGB,BGR}X image using cv2"
+                assert bitmap.format != pdfium_c.FPDFBitmap_BGRx, "Not sure how to paste with mask on {RGB,BGR}X image using cv2"  # FIXME?
                 posconv = bitmap.get_posconv(page)
-                image_objs = list(page.get_objects([pdfium_c.FPDF_PAGEOBJ_IMAGE], max_depth=1))
-                if len(image_objs) > 0:
+                have_images, obj_searcher = iterator_hasvalue( page.get_objects([pdfium_c.FPDF_PAGEOBJ_IMAGE], max_depth=1) )
+                if have_images:
                     mask = np.zeros((bitmap.height, bitmap.width, 1), np.uint8)
-                    for obj in image_objs:
+                    for obj in obj_searcher:
                         qpoints = np.array([posconv.to_bitmap(x, y) for x, y in obj.get_quad_points()], np.int32)
                         cv2.fillPoly(mask, [qpoints], 1)
                     dst_image = cv2.copyTo(src_image, mask=mask, dst=dst_image)
-
         return dst_image