Barcode-reading system that obtains ranging data via targeting illumination

A barcode-reading system for a computing device, the computing device comprising a camera assembly and a white light source for illuminating a target, the barcode-reading system comprising:

• a barcode-reading enhancement accessory securable to the computing device, the barcode-reading enhancement accessory comprising an optic system that is positionable within a field of illumination of the white light source when the barcode-reading enhancement accessory is secured to the computing device, the optic system being configured to shape a targeting illumination projected by the white light source;
• and
• a barcode-reading application stored in memory of the computing device, the barcode-reading application being executable by a processor of the computing device to:
• determine a feature offset of the targeting illumination in an image that is captured by the camera assembly of the computing device;
• and
• based on the determined feature offset, adjust one or more operating parameters of the computing device.