ENH: Improve space setting for text extraction (#922)

MartinThoma · pubpub-zz · web-flow · commit c008b0f44821 · 2022-05-29T14:14:07.000+02:00
Full credit to pubpub-zz who introduced this change in #881 Co-authored-by: pubpub-zz <4083478+pubpub-zz@users.noreply.github.com>
diff --git a/PyPDF2/_page.py b/PyPDF2/_page.py
@@ -1080,34 +1080,64 @@ def extract_text(self, Tj_sep: str = "", TJ_sep: str = "") -> str:
         # Note: we check all strings are TextStringObjects.  ByteStringObjects
         # are strings where the byte->string encoding was unknown, so adding
         # them to the text here would be gibberish.
+
+        space_scale = 1.0
+
         for operands, operator in content.operations:
-            if operator == b_("Tj"):
+            if operator == b_("Tf"):  # text font
+                pass
+            elif operator == b_("Tfs"):  # text font size
+                pass
+            elif operator == b_("Tc"):  # character spacing
+                # See '5.2.1 Character Spacing'
+                pass
+            elif operator == b_("Tw"):  # word spacing
+                # See '5.2.2 Word Spacing'
+                space_scale = 1.0 + float(operands[0])
+            elif operator == b_("Th"):  # horizontal scaling
+                # See '5.2.3 Horizontal Scaling'
+                pass
+            elif operator == b_("Tl"):  # leading
+                # See '5.2.4 Leading'
+                pass
+            elif operator == b_("Tmode"):  # text rendering mode
+                # See '5.2.5 Text Rendering Mode'
+                pass
+            elif operator == b_("Trise"):  # text rise
+                # See '5.2.6 Text Rise'
+                pass
+            elif operator == b_("Tj"):
+                # See 'TABLE 5.6 Text-showing operators'
                 _text = operands[0]
                 if isinstance(_text, TextStringObject):
                     text += Tj_sep
                     text += _text
                     text += "\n"
             elif operator == b_("T*"):
+                # See 'TABLE 5.5 Text-positioning operators'
                 text += "\n"
             elif operator == b_("'"):
+                # See 'TABLE 5.6 Text-showing operators'
                 text += "\n"
                 _text = operands[0]
                 if isinstance(_text, TextStringObject):
                     text += operands[0]
             elif operator == b_('"'):
+                # See 'TABLE 5.6 Text-showing operators'
                 _text = operands[2]
                 if isinstance(_text, TextStringObject):
                     text += "\n"
                     text += _text
             elif operator == b_("TJ"):
+                # See 'TABLE 5.6 Text-showing operators'
                 for i in operands[0]:
                     if isinstance(i, TextStringObject):
                         text += TJ_sep
                         text += i
-                    elif isinstance(i, NumberObject):
+                    elif isinstance(i, (NumberObject, FloatObject)):
                         # a positive value decreases and the negative value increases
                         # space
-                        if int(i) < 0:
+                        if int(i) < -space_scale * 250:
                             if len(text) == 0 or text[-1] != " ":
                                 text += " "
                         else:
diff --git a/resources/crazyones.txt b/resources/crazyones.txt
@@ -1,18 +1,18 @@
 The Crazy Ones
 October 14, 1998
-Heres to the crazy ones. The mis˝ts. The reb els. The troublemakers.
-The round p egs in the square holes.
+Heres to the crazy ones. The mis˝ts. The rebels. The troublemakers.
+The round pegs in the square holes.
 The ones who see things di˙erently. Theyre not fond of rules. And
-they have no resp ect for the status quo. You can quote them,
+they have no respect for the status quo. You can quote them,
 disagree with them, glorify or vilify them.
-Ab out the only thing you cant do is ignore them. Because they change
+About the only thing you cant do is ignore them. Because they change
 things. They invent. They imagine. They heal. They explore. They
 create. They inspire. They push the human race forward.
-Mayb e they have to b e crazy.
+Maybe they have to be crazy.
 How else can you stare at an empty canvas and see a work of art? Or
-sit in silence and hear a song thats never b een written? Or gaze at
-a red planet and see a lab oratory on wheels?
-We make to ols for these kinds of p eople.
+sit in silence and hear a song thats never been written? Or gaze at
+a red planet and see a laboratory on wheels?
+We make tools for these kinds of people.
 While some see them as the crazy ones, we see genius. Because the
-p eople who are crazy enough to think they can change the world,
+people who are crazy enough to think they can change the world,
 are the ones who do.
