105 lines
2.4 KiB
Markdown
105 lines
2.4 KiB
Markdown
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# rsnaps
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Capture a raw snap stream (scans or pictures) through a locally running webapp.
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*rsnaps* is a simple webapp for local deployment on a machine with access to
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one or more scanner devices, or cameras with Canon CHDK.
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Users can start scan jobs and the scanned images will be put into
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a local directory with a serial number in the name.
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Users can see the list of previously scanned images and redo previous scans.
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The scanned images are stored in PNG format and few metadata are added to them:
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* the name of the operator doing the scan
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* the ID of the unit/batch of material that is being scanned
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* the date and time of the scan
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* the device used for scanning
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Limitations:
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* no concurrency: only one instance of rsnaps can run on a machine
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* A4 (181x256)
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## Prerequisites
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Debian Linux with these packages installed
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* python3-sane
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* python3-aiohttp
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* python3-aiohttp-jinja2
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```
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apt install sane python3-sane python3-aiohttp python3-aiohttp-jinja2
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```
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### PDF creation
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Install jbig2 from https://github.com/agl/jbig2enc
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(cf. https://ocrmypdf.readthedocs.io/en/latest/jbig2.html).
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You'll need these dependencies: TODO
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Note: For jbig2 compression architecture amd64 is required.
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### OCR
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`apt install pngquant ocrmypdf`
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and required tesseract language packages, e.g. `tesseract-ocr-eng`, `tesseract-ocr-deu`, ...
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### Page rotationa
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`apt install imagemagick`
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## Setup
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### User and software
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```
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adduser --disabled-login --home /srv/rsnaps --ingroup scanner
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su - rsnaps
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git clone _______TODO_________ repo
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... TODO
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```
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### systemd integration
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Put a systemd service unit in `/etc/systemd/system/rsnaps.service`:
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```
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[Unit]
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Description=rsnaps local sanning service
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[Service]
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Type=
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ExecStart=
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[Install]
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WantedBy=multi-user.target
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```
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```
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systemctl daemon-reload
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systemctl enable rsnaps.service
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systemctl start rsnaps.service
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```
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## Development
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Useful resources:
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* [python-sane docs](https://python-sane.readthedocs.io/en/latest/)
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* [example.py](https://github.com/python-pillow/Sane/blob/main/example.py)
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* [python-sane source](https://github.com/python-pillow/Sane/)
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* [SANE standard](https://sane-project.gitlab.io/standard/)
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## TODO
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* handle timeout of subprocess calls
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* lazy image loading:
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https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API
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https://css-tricks.com/the-complete-guide-to-lazy-loading-images/
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https://web.dev/lazy-loading-images/
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https://developer.mozilla.org/en-US/docs/Web/Performance/Lazy_loading
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