---
tags:
  - destiny/fleeting
  - topic/automation
  - topic/software
  - type/idea
title: Automating PDF Annotation
---
# Automating PDF Annotation

See [[portable-tools]] for valid dependencies.

## Clean Documents

### Page Rotation

Pages have a rotation value independent of appearance
which rotates the drawing reference grid.
This must be resolved before further processing.

Trivial coordinate-returning tools/functions
may use the non-rotation-adjusted values,
which are essentially useless for our purposes.

MuPDF and similar libraries provide functions
to return the "visual" (read _correct_) coordinates,
but it would be ideal to redraw content with the correct orientation.

## Extract Bluebeam Markups

Right now I'm exporting Bluebeam markups to csv before processing,
however if I converted to the code to extract the markups directly with MuPDF.Net
as I've managed before with itext, that could save a step.

### Bluebeam Revu Measure Hack

BlueBeam Revu does not give coordinates for count annotations,
even where count = 1.

Bluebeam's .bax is a annotation interchange format based on xml.

1. Export markups to .bax

    > [!menu]
    > Markups List > Markups > Export Markups

2. Edit markups

    Convert count annotations to polygons

    ```
    <TypeInternal>Bluebeam.PDF.Annotations.AnnotationPolygon</TypeInternal>
    ```

3. Delete all markups in the pdf

4. Import Markups from edited .bax file

    > [!menu]
    > Markups List > Markups > Import

## PDF Content Positional Tokenization

Recursively parse and consume pdf vector content.

> [!example]
> A span with text "GFCI" is consumed.
> (draw calls are removed from page content)
> A `gfci_label` token is created
> and encoded with the span's position.

> [!example]
> A `duplex_receptacle` token and a `gfci_label` token
> in close proximity are consumed
> creating a `duplex_gfci_receptacle` token
> which inherits the `duplex_receptacle`'s position.

## PDF Internals

```sh
$ mutool show file.pdf pages/1/Contents
```

```pdf
629 0 obj
<<
  /Filter /FlateDecode
  /Length 31375
>>
stream
q
0.12 0 0 0.12 0 0 cm
/R8 gs
/R9 gs
2 w
1 J
1 j
0 G
q
4217 3947 m
4217 3879 l
4467 3879 l
4467 3947 l
4455 3947 l
4455 3891 l
4230 3891 l
4230 3947 l
...
```