DocScanner Pro
A Flutter document scanner that keeps image processing off the UI thread.
- Designer and developer
- 2026
What it is
Scan pages with a guided camera, crop and straighten them, apply document filters and export to PDF, PNG or JPEG through the phone's native share and save sheets. It runs on iOS and Android.
The problem
Cropping, rotating and filtering full-resolution photos on a phone stalls the interface if it runs on the UI thread, and scanned documents are sensitive files that must not leak.
Architecture
Requests flow left to right. Hover a component for its role.
- Camera and batch capture client
- Flutter UI service
- Background isolates worker, crop, rotate, filters, thumbnails
- Crop and edge adjuster service, 8 handles, 10-step undo
- Sandboxed storage data, canonical-path checks
- Native share and save external, PDF, PNG, JPEG, AirPrint
Key decisions
Nothing heavy on the UI thread
Cropping, rotation, filtering, thumbnails and format conversion run on background isolates. Filter previews are computed in parallel on 150 px thumbnails.
Treat scans as sensitive
Every read, write and share is checked against a canonical directory, Android backups are disabled, and release builds are shrunk and obfuscated.
Highlights
- Batch capture assembles multi-page PDFs as you scan.
- Five filters, including a high-contrast black and white mode tuned for text.
- Exports to Files, iCloud Drive, Google Drive, AirDrop or straight to a printer.
Stack
Screens
