153 lines
6.0 KiB
Python
153 lines
6.0 KiB
Python
import json
|
|
import sys
|
|
|
|
from pypdf import PdfReader
|
|
|
|
|
|
# Extracts data for the fillable form fields in a PDF and outputs JSON that
|
|
# Claude uses to fill the fields. See forms.md.
|
|
|
|
|
|
# This matches the format used by PdfReader `get_fields` and `update_page_form_field_values` methods.
|
|
def get_full_annotation_field_id(annotation):
|
|
components = []
|
|
while annotation:
|
|
field_name = annotation.get('/T')
|
|
if field_name:
|
|
components.append(field_name)
|
|
annotation = annotation.get('/Parent')
|
|
return ".".join(reversed(components)) if components else None
|
|
|
|
|
|
def make_field_dict(field, field_id):
|
|
field_dict = {"field_id": field_id}
|
|
ft = field.get('/FT')
|
|
if ft == "/Tx":
|
|
field_dict["type"] = "text"
|
|
elif ft == "/Btn":
|
|
field_dict["type"] = "checkbox" # radio groups handled separately
|
|
states = field.get("/_States_", [])
|
|
if len(states) == 2:
|
|
# "/Off" seems to always be the unchecked value, as suggested by
|
|
# https://opensource.adobe.com/dc-acrobat-sdk-docs/standards/pdfstandards/pdf/PDF32000_2008.pdf#page=448
|
|
# It can be either first or second in the "/_States_" list.
|
|
if "/Off" in states:
|
|
field_dict["checked_value"] = states[0] if states[0] != "/Off" else states[1]
|
|
field_dict["unchecked_value"] = "/Off"
|
|
else:
|
|
print(f"Unexpected state values for checkbox `${field_id}`. Its checked and unchecked values may not be correct; if you're trying to check it, visually verify the results.")
|
|
field_dict["checked_value"] = states[0]
|
|
field_dict["unchecked_value"] = states[1]
|
|
elif ft == "/Ch":
|
|
field_dict["type"] = "choice"
|
|
states = field.get("/_States_", [])
|
|
field_dict["choice_options"] = [{
|
|
"value": state[0],
|
|
"text": state[1],
|
|
} for state in states]
|
|
else:
|
|
field_dict["type"] = f"unknown ({ft})"
|
|
return field_dict
|
|
|
|
|
|
# Returns a list of fillable PDF fields:
|
|
# [
|
|
# {
|
|
# "field_id": "name",
|
|
# "page": 1,
|
|
# "type": ("text", "checkbox", "radio_group", or "choice")
|
|
# // Per-type additional fields described in forms.md
|
|
# },
|
|
# ]
|
|
def get_field_info(reader: PdfReader):
|
|
fields = reader.get_fields()
|
|
|
|
field_info_by_id = {}
|
|
possible_radio_names = set()
|
|
|
|
for field_id, field in fields.items():
|
|
# Skip if this is a container field with children, except that it might be
|
|
# a parent group for radio button options.
|
|
if field.get("/Kids"):
|
|
if field.get("/FT") == "/Btn":
|
|
possible_radio_names.add(field_id)
|
|
continue
|
|
field_info_by_id[field_id] = make_field_dict(field, field_id)
|
|
|
|
# Bounding rects are stored in annotations in page objects.
|
|
|
|
# Radio button options have a separate annotation for each choice;
|
|
# all choices have the same field name.
|
|
# See https://westhealth.github.io/exploring-fillable-forms-with-pdfrw.html
|
|
radio_fields_by_id = {}
|
|
|
|
for page_index, page in enumerate(reader.pages):
|
|
annotations = page.get('/Annots', [])
|
|
for ann in annotations:
|
|
field_id = get_full_annotation_field_id(ann)
|
|
if field_id in field_info_by_id:
|
|
field_info_by_id[field_id]["page"] = page_index + 1
|
|
field_info_by_id[field_id]["rect"] = ann.get('/Rect')
|
|
elif field_id in possible_radio_names:
|
|
try:
|
|
# ann['/AP']['/N'] should have two items. One of them is '/Off',
|
|
# the other is the active value.
|
|
on_values = [v for v in ann["/AP"]["/N"] if v != "/Off"]
|
|
except KeyError:
|
|
continue
|
|
if len(on_values) == 1:
|
|
rect = ann.get("/Rect")
|
|
if field_id not in radio_fields_by_id:
|
|
radio_fields_by_id[field_id] = {
|
|
"field_id": field_id,
|
|
"type": "radio_group",
|
|
"page": page_index + 1,
|
|
"radio_options": [],
|
|
}
|
|
# Note: at least on macOS 15.7, Preview.app doesn't show selected
|
|
# radio buttons correctly. (It does if you remove the leading slash
|
|
# from the value, but that causes them not to appear correctly in
|
|
# Chrome/Firefox/Acrobat/etc).
|
|
radio_fields_by_id[field_id]["radio_options"].append({
|
|
"value": on_values[0],
|
|
"rect": rect,
|
|
})
|
|
|
|
# Some PDFs have form field definitions without corresponding annotations,
|
|
# so we can't tell where they are. Ignore these fields for now.
|
|
fields_with_location = []
|
|
for field_info in field_info_by_id.values():
|
|
if "page" in field_info:
|
|
fields_with_location.append(field_info)
|
|
else:
|
|
print(f"Unable to determine location for field id: {field_info.get('field_id')}, ignoring")
|
|
|
|
# Sort by page number, then Y position (flipped in PDF coordinate system), then X.
|
|
def sort_key(f):
|
|
if "radio_options" in f:
|
|
rect = f["radio_options"][0]["rect"] or [0, 0, 0, 0]
|
|
else:
|
|
rect = f.get("rect") or [0, 0, 0, 0]
|
|
adjusted_position = [-rect[1], rect[0]]
|
|
return [f.get("page"), adjusted_position]
|
|
|
|
sorted_fields = fields_with_location + list(radio_fields_by_id.values())
|
|
sorted_fields.sort(key=sort_key)
|
|
|
|
return sorted_fields
|
|
|
|
|
|
def write_field_info(pdf_path: str, json_output_path: str):
|
|
reader = PdfReader(pdf_path)
|
|
field_info = get_field_info(reader)
|
|
with open(json_output_path, "w") as f:
|
|
json.dump(field_info, f, indent=2)
|
|
print(f"Wrote {len(field_info)} fields to {json_output_path}")
|
|
|
|
|
|
if __name__ == "__main__":
|
|
if len(sys.argv) != 3:
|
|
print("Usage: extract_form_field_info.py [input pdf] [output json]")
|
|
sys.exit(1)
|
|
write_field_info(sys.argv[1], sys.argv[2])
|