src/img2pdf.py

@@ -22,17 +22,7 @@ import sys
 import os
 import zlib
 import argparse
-from PIL import Image, TiffImagePlugin, GifImagePlugin
-
-if hasattr(GifImagePlugin, "LoadingStrategy"):
-    # Pillow 9.0.0 started emitting all frames but the first as RGB instead of
-    # P to make sure that more than 256 colors can be represented. But palette
-    # images compress far better than RGB images in PDF so we instruct Pillow
-    # to only emit RGB frames if the palette differs and return P otherwise.
-    # This works since Pillow 9.1.0.
-    GifImagePlugin.LOADING_STRATEGY = (
-        GifImagePlugin.LoadingStrategy.RGB_AFTER_DIFFERENT_PALETTE_ONLY
-    )
+from PIL import Image, TiffImagePlugin
 
 # TiffImagePlugin.DEBUG = True
 from PIL.ExifTags import TAGS
@@ -101,10 +91,7 @@ ImageFormat = Enum("ImageFormat", "JPEG JPEG2000 CCITTGroup4 PNG GIF TIFF MPO ot
 
 PageMode = Enum("PageMode", "none outlines thumbs")
 
-PageLayout = Enum(
-    "PageLayout",
-    "single onecolumn twocolumnright twocolumnleft twopageright twopageleft",
-)
+PageLayout = Enum("PageLayout", "single onecolumn twocolumnright twocolumnleft twopageright twopageleft")
 
 Magnification = Enum("Magnification", "fit fith fitbh")
 
@@ -402,28 +389,6 @@ class ExifOrientationError(Exception):
     pass
 
 
-# temporary change the attribute of an object using a context manager
-class temp_attr:
-    def __init__(self, obj, field, value):
-        self.obj = obj
-        self.field = field
-        self.value = value
-
-    def __enter__(self):
-        self.exists = False
-        if hasattr(self.obj, self.field):
-            self.exists = True
-            self.old_value = getattr(self.obj, self.field)
-        print(f"setting {self.obj}.{self.field} = {self.value}")
-        setattr(self.obj, self.field, self.value)
-
-    def __exit__(self, exctype, excinst, exctb):
-        if self.exists:
-            setattr(self.obj, self.field, self.old_value)
-        else:
-            delattr(self.obj, self.field)
-
-
 # without pdfrw this function is a no-op
 def my_convert_load(string):
     return string
@@ -1141,17 +1106,9 @@ class pdfdoc(object):
                 [initial_page, PdfName.XYZ, NullObject, NullObject, 0]
             )
 
-        # The /OpenAction array must contain the page as an indirect object.
-        # This changed some time after 4.2.0 and on or before 5.0.0 and current
-        # versions require to use .obj or otherwise we get:
-        #   TypeError: Can't convert ObjectHelper (or subclass) to Object
-        #   implicitly. Use .obj to get access the underlying object.
-        # See https://github.com/pikepdf/pikepdf/issues/313 for details.
+        # the /OpenAction array must contain the page as an indirect object
         if self.engine == Engine.pikepdf:
-            if isinstance(initial_page, pikepdf.Page):
-                initial_page = self.writer.make_indirect(initial_page.obj)
-            else:
-                initial_page = self.writer.make_indirect(initial_page)
+            initial_page = self.writer.make_indirect(initial_page)
 
         if self.magnification == Magnification.fit:
             catalog[PdfName.OpenAction] = PdfArray([initial_page, PdfName.Fit])
@@ -1453,29 +1410,27 @@ def transcode_monochrome(imgdata):
     # into putting everything into a single strip. Thanks to Andrew Murray for
     # the hack.
     #
-    # Since version 8.4.0 Pillow allows us to modify the strip size explicitly
-    tmp_strip_size = (imgdata.size[0] + 7) // 8 * imgdata.size[1]
-    if hasattr(TiffImagePlugin, "STRIP_SIZE"):
-        # we are using Pillow 8.4.0 or later
-        with temp_attr(TiffImagePlugin, "STRIP_SIZE", tmp_strip_size):
-            im.save(newimgio, format="TIFF", compression="group4")
-    else:
-        # only needed for Pillow 8.3.x but works for versions before that as
-        # well
-        pillow__getitem__ = TiffImagePlugin.ImageFileDirectory_v2.__getitem__
+    # This can be dropped once this gets merged:
+    # https://github.com/python-pillow/Pillow/pull/5744
+    pillow__getitem__ = TiffImagePlugin.ImageFileDirectory_v2.__getitem__
 
-        def __getitem__(self, tag):
-            overrides = {
-                TiffImagePlugin.ROWSPERSTRIP: imgdata.size[1],
-                TiffImagePlugin.STRIPBYTECOUNTS: [tmp_strip_size],
-                TiffImagePlugin.STRIPOFFSETS: [0],
-            }
-            return overrides.get(tag, pillow__getitem__(self, tag))
+    def __getitem__(self, tag):
+        overrides = {
+            TiffImagePlugin.ROWSPERSTRIP: imgdata.size[1],
+            TiffImagePlugin.STRIPBYTECOUNTS: [
+                (imgdata.size[0] + 7) // 8 * imgdata.size[1]
+            ],
+            TiffImagePlugin.STRIPOFFSETS: [0],
+        }
+        return overrides.get(tag, pillow__getitem__(self, tag))
 
-        with temp_attr(
-            TiffImagePlugin.ImageFileDirectory_v2, "__getitem__", __getitem__
-        ):
-            im.save(newimgio, format="TIFF", compression="group4")
+    # use try/finally to make sure that __getitem__ is reset even if save()
+    # raises an exception
+    try:
+        TiffImagePlugin.ImageFileDirectory_v2.__getitem__ = __getitem__
+        im.save(newimgio, format="TIFF", compression="group4")
+    finally:
+        TiffImagePlugin.ImageFileDirectory_v2.__getitem__ = pillow__getitem__
 
     # Open new image in memory
     newimgio.seek(0)