Added documentation about the barcode scanner

docs/usage/scanner.md

@@ -0,0 +1,51 @@
+---
+title: Barcode Scanner
+layout: default
+parent: Usage
+---
+
+# Barcode scanner
+
+When the user has the correct permission there will be a barcode scanner button in the navbar.
+On this page you can either input a barcode code by hand, use an external barcode scanner, or use your devices camera to
+scan a barcode.
+
+In info mode (when the "Info" toggle is enabled) you can scan a barcode and Part-DB will parse it and show information 
+about it.
+
+Without info mode, the barcode will directly redirect you to the corresponding page.
+
+### Barcode matching
+
+When you scan a barcode, Part-DB will try to match it to an existing part, part lot or storage location first.
+For Part-DB generated barcodes, it will use the internal ID of a part.  Alternatively you can also scan a barcode that contains the part's IPN.
+
+You can set a GTIN/EAN code in the part properties and Part-DB will open the part page when you scan the corresponding GTIN/EAN barcode.
+
+On a part lot you can under "Advanced" set a user barcode, that will redirect you to the part lot page when scanned. This allows to reuse
+arbitrary existing barcodes that already exist on the part lots (for example, from the manufacturer) and link them to the part lot in Part-DB.
+
+Part-DB can also parse various distributor barcodes (for example from Digikey and Mouser) and will try to redirect you to the corresponding
+part page based on the distributor part number in the barcode.
+
+### Part creation from barcodes
+For certain barcodes Part-DB can automatically create a new part, when it cannot find a matching part.
+Part-DB will try to retrieve the part information from an information provider and redirects you to the part creation page 
+with the retrieved information pre-filled.
+
+## Using an external barcode scanner
+
+Part-DB supports the use of external barcode scanners that emulate keyboard input. To use a barcode scanner with Part-DB,
+simply connect the scanner to your computer and scan a barcode while the cursor is in a text field in Part-DB.
+The scanned barcode will be entered into the text field as if you had typed it on the keyboard.
+
+In scanner fields, it will also try to insert special non-printable characters the scanner send via Alt + key combinations.
+This is required for EIGP114 datamatrix codes.
+
+### Automatically redirect on barcode scanning
+
+If you configure your barcode scanner to send a <SOH> (Start of heading, 0x01) non-printable character at the beginning
+of the scanned barcode, Part-DB will automatically scan the barcode that comes afterward (and is ended with an enter key)
+and redirects you to the corresponding page.
+This allows you to quickly scan a barcode from anywhere in Part-DB without the need to first open the scanner page.
+If an input field is focused, the barcode will be entered into the field as usual and no redirection will happen.