How to change color of border and font in an inline text / freetext annotation in a pdf document?

Question

I'm writing a python script to change color of text and borders of inline annotations inserted with okular into a pdf document.

This script instead of changing only text and border seems change the entire annotation red (full filled red rectangle shows up instead).

Is this supported at all? I realize how complex pdf format is, but I hoped that this simple change won't require anything unusual.

sample inline text annotation in pdf as produced by okular:

11533   │ 229·13·obj␍␊
11534   │ <>·>>·>>·stream␍␊
11535   │ q␊
11536   │ []·0·d␊
11537   │ 2.00·w␊
11538   │ 0.00000·0.00000·0.00000·RG␊
11539   │ 1.00·1.00·230.79·26.17·re␊
11540   │ 0.21569·0.18824·1.00000·rg␊
11541   │ B␊
11542   │ 4.00·4.00·224.79·20.17·re·W·n␊
11543   │ 0.00000·0.00000·0.00000·rg␊
11544   │ BT·1·0·0·1·4.00·24.17·Tm␊
11545   │ /popplerfont·10.00·Tf␊
11546   │ 0.00·-10.00·Td␊
11547   │ (\000e\000r\000g\000r\000g\000h\000r\000e\000h\000r\000h\000e\000h)·Tj␊
11548   │ ET·Q␊
11549   │ ␍␊
11550   │ endstream␍␊
11551   │ ␍␊
11552   │ endobj␍␊
11553   │ 230·0·obj␍␊
11554   │ <·/Contents··/NM·(okular-{a598c121-968e-4134-8fa3-b6d17caa86f2})·/CreationDate·(D:20241117102025Z␀································)·/F·20·/C·[0.2156862766·0.1882352978·1·]·/CA·1·/Border·[0·0·2·]·/Q·0·/IT·/FreeText·/P·2·0·R·/AP·<>·/AS·/N·>>·␍␊
11555   │ endobj␍␊
11556   │ 231·0·obj␍␊
11557   │ <>·>>·>>·stream␍␊
11558   │ q␊
11559   │ []·0·d␊
11560   │ 2.00·w␊
11561   │ 0.00000·0.00000·0.00000·RG␊
11562   │ 1.00·1.00·0.03·7.38·re␊
11563   │ 0.21569·0.18824·1.00000·rg␊
11564   │ B␊
11565   │ 4.00·4.00·-5.97·1.38·re·W·n␊
11566   │ 0.00000·0.00000·0.00000·rg␊
11567   │ BT·1·0·0·1·4.00·5.38·Tm␊
11568   │ /popplerfont·10.00·Tf␊
11569   │ 0.00·-10.00·Td␊
11570   │ ()·Tj␊
11571   │ ET·Q␊
11572   │ ␍␊
11573   │ endstream␍␊
11574   │ ␍␊
11575   │ endobj␍␊
11576   │ xref␍␊

and here converted to qpdf format:

40687   │ 0183013890·00000·n·␊
40688   │ 0185638157·00000·n·␊
40689   │ trailer·<<␊
40690   │ ··/Info·2·0·R␊
40691   │ ··/Root·1·0·R␊
40692   │ ··/Size·372␊
40693   │ ··/ID·[]␊
40694   │ >>␊
40695   │ startxref␊
40696   │ 185638183␊
40697   │ %%EOF␊
40698   │ 1·0·obj␍␊
40699   │ <>·␍␊
40700   │ endobj␍␊
40701   │ 4·0·obj␍␊
40702   │ <>·/ProcSet·73·0·R·/XObject·<>·>>·/Type·/Page·/Annots·378·0·R·>>·␍␊
40703   │ endobj␍␊
40704   │ 372·0·obj␍␊
40705   │ <·/Contents··/NM·(okular-{c67d430b-37dd-4ba6-85c6-45a45db4e512})·/CreationDate·(D:20241117100143Z␀································)·/F·20·/C·[0.2156862766·0.1882352978·1·]·/CA·1·/Border·[0·0·2·]·/Q·0·/IT·/FreeText·/P·4·0·R·/AP·<>·/AS·/N·>>·␍␊
40706   │ endobj␍␊
40707   │ 373·0·obj␍␊
40708   │ <>·>>·>>·␍␊
40709   │ endobj␍␊
40710   │ 374·0·obj␍␊
40711   │ <>·stream␍␊

#!/usr/bin/env python3

import sys
import pikepdf
from pikepdf import Name
import re

def change_annotation_font_and_border_to_red(input_path):
    output_path = input_path.replace(".pdf", "-output.pdf")

    # Open the PDF file
    with pikepdf.open(input_path) as pdf:
        for page_number, page in enumerate(pdf.pages, start=1):
            # Check if the page has annotations
            if "/Annots" in page:
                print(f"Page {page_number} contains annotations:")
                # Iterate over each annotation in the /Annots array
                for annot in page["/Annots"]:
                    print(f"  - Annotation detected: {annot}")

                    # Set the border color to red (RGB)
                    annot[Name("/C")] = pikepdf.Array([1, 0, 0])  # RGB for red border

                    # Update the default appearance string (/DA) to set text color to red
                    if "/DA" in annot:
                        da_str = str(annot[Name("/DA")])
                        print(f"    Original /DA: {da_str}")
                        # Remove any existing color settings in the DA string
                        da_str = re.sub(r"(\d+\.?\d*\s){1,3}[rg]", "", da_str)
                        # Append red color setting for text color
                        da_str = da_str.strip() + " 1 0 0 rg"
                        annot[Name("/DA")] = da_str
                        print(f"    Updated /DA: {annot[Name('/DA')]}")

                    # Remove the appearance stream to apply changes if present
                    if "/AP" in annot:
                        del annot[Name("/AP")]
                        print("    Removed /AP to force appearance regeneration")

        # Save the modified PDF with '-output.pdf' suffix
        pdf.save(output_path)
        print(f"Font and border color changed to red. Saved as: {output_path}")

if __name__ == "__main__":
    if len(sys.argv) != 2:
        print("Usage: python change_annotation_font_and_border_to_red.py ")
    else:
        input_path = sys.argv[1]
        change_annotation_font_and_border_to_red(input_path)

How to change color of border and font in an inline text / freetext annotation in a pdf document?

Answers (1)

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