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MAINT: Increase readability of text extraction code (#3091)
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@j-t-1
j-t-1 authored Jan 30, 2025
1 parent 8b3a786 commit d67e807
Showing 1 changed file with 22 additions and 31 deletions.
53 changes: 22 additions & 31 deletions pypdf/_page.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1840,6 +1840,7 @@ def _extract_text(
str, float, Union[str, Dict[int, str]], Dict[str, str], DictionaryObject
],
] = {}

try:
objr = obj
while NameObject(PG.RESOURCES) not in objr:
Expand All @@ -1852,6 +1853,7 @@ def _extract_text(
# No resources means no text is possible (no font); we consider the
# file as not damaged, no need to check for TJ or Tj
return ""

if "/Font" in resources_dict:
for f in cast(DictionaryObject, resources_dict["/Font"]):
cmaps[f] = build_char_map(f, space_width, obj)
Expand All @@ -1863,6 +1865,7 @@ def _extract_text(
"NotInitialized",
None,
) # (encoding, CMAP, font resource name, font)

try:
content = (
obj[content_key].get_object() if isinstance(content_key, str) else obj
Expand Down Expand Up @@ -1891,11 +1894,12 @@ def _extract_text(
space_scale = 1.0
_space_width: float = 500.0 # will be set correctly at first Tf
_actual_str_size: Dict[str, float] = {
"str_widths": 0.0, "space_width": 0.0, "str_height": 0.0} # will be set to string length calculation result
"str_widths": 0.0, "space_width": 0.0, "str_height": 0.0
} # will be set to string length calculation result
TL = 0.0
font_size = 12.0 # init just in case of

def compute_strwidths(str_widths: float) -> float:
def compute_str_widths(str_widths: float) -> float:
return str_widths / 1000

def process_operation(operator: bytes, operands: List[Any]) -> None:
Expand Down Expand Up @@ -1955,15 +1959,8 @@ def process_operation(operator: bytes, operands: List[Any]) -> None:
visitor_text(text, memo_cm, memo_tm, cmap[3], font_size)
text = ""
cm_matrix = mult(
[
float(operands[0]),
float(operands[1]),
float(operands[2]),
float(operands[3]),
float(operands[4]),
float(operands[5]),
],
cm_matrix,
[float(operand) for operand in operands[:6]],
cm_matrix
)
memo_cm = cm_matrix.copy()
memo_tm = tm_matrix.copy()
Expand Down Expand Up @@ -2023,19 +2020,12 @@ def process_operation(operator: bytes, operands: List[Any]) -> None:
ty = float(operands[1])
tm_matrix[4] += tx * tm_matrix[0] + ty * tm_matrix[2]
tm_matrix[5] += tx * tm_matrix[1] + ty * tm_matrix[3]
str_widths = compute_strwidths(_actual_str_size["str_widths"])
str_widths = compute_str_widths(_actual_str_size["str_widths"])
_actual_str_size["str_widths"] = 0.0
elif operator == b"Tm":
check_crlf_space = True
tm_matrix = [
float(operands[0]),
float(operands[1]),
float(operands[2]),
float(operands[3]),
float(operands[4]),
float(operands[5]),
]
str_widths = compute_strwidths(_actual_str_size["str_widths"])
tm_matrix = [float(operand) for operand in operands[:6]]
str_widths = compute_str_widths(_actual_str_size["str_widths"])
_actual_str_size["str_widths"] = 0.0
elif operator == b"T*":
check_crlf_space = True
Expand All @@ -2046,7 +2036,7 @@ def process_operation(operator: bytes, operands: List[Any]) -> None:
text,
operands,
cm_matrix,
tm_matrix, # text matrix
tm_matrix,
cmap,
orientations,
font_size,
Expand All @@ -2057,6 +2047,7 @@ def process_operation(operator: bytes, operands: List[Any]) -> None:
)
else:
return None

if check_crlf_space:
try:
text, output, cm_prev, tm_prev = crlf_space_check(
Expand All @@ -2070,7 +2061,7 @@ def process_operation(operator: bytes, operands: List[Any]) -> None:
font_size,
visitor_text,
str_widths,
compute_strwidths(_actual_str_size["space_width"]),
compute_str_widths(_actual_str_size["space_width"]),
_actual_str_size["str_height"]
)
if text == "":
Expand All @@ -2082,7 +2073,7 @@ def process_operation(operator: bytes, operands: List[Any]) -> None:
for operands, operator in content.operations:
if visitor_operand_before is not None:
visitor_operand_before(operator, operands, cm_matrix, tm_matrix)
# Multiple operators are defined in here
# Multiple operators are handled here
if operator == b"'":
process_operation(b"T*", [])
process_operation(b"Tj", operands)
Expand All @@ -2091,9 +2082,6 @@ def process_operation(operator: bytes, operands: List[Any]) -> None:
process_operation(b"Tc", [operands[1]])
process_operation(b"T*", [])
process_operation(b"Tj", operands[2:])
elif operator == b"TD":
process_operation(b"TL", [-operands[1]])
process_operation(b"Td", operands)
elif operator == b"TJ":
# The space width may be smaller than the font width, so the width should be 95%.
_confirm_space_width = _space_width * 0.95
Expand All @@ -2102,11 +2090,14 @@ def process_operation(operator: bytes, operands: List[Any]) -> None:
if isinstance(op, (str, bytes)):
process_operation(b"Tj", [op])
if isinstance(op, (int, float, NumberObject, FloatObject)) and (
(abs(float(op)) >= _confirm_space_width)
and (len(text) > 0)
and (text[-1] != " ")
abs(float(op)) >= _confirm_space_width
and text
and text[-1] != " "
):
process_operation(b"Tj", [" "])
elif operator == b"TD":
process_operation(b"TL", [-operands[1]])
process_operation(b"Td", operands)
elif operator == b"Do":
output += text
if visitor_text is not None:
Expand Down Expand Up @@ -2157,7 +2148,7 @@ def process_operation(operator: bytes, operands: List[Any]) -> None:
process_operation(operator, operands)
if visitor_operand_after is not None:
visitor_operand_after(operator, operands, cm_matrix, tm_matrix)
output += text # just in case of
output += text # just in case
if text != "" and visitor_text is not None:
visitor_text(text, memo_cm, memo_tm, cmap[3], font_size)
return output
Expand Down

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