Barcode-reading system that obtains ranging data via targeting illumination

A barcode-reading system for a mobile device, the mobile device comprising a camera assembly and a white light source for providing illumination, the barcode-reading system comprising:

• a barcode-reading enhancement accessory securable to the mobile 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 mobile device, the optic system being configured to shape and filter the illumination from the white light source to project targeting illumination onto a target surface;
• calibration data that indicates a relationship between surface distance and at least one feature offset of the targeting illumination;
• and
• a barcode-reading application stored in memory of the mobile device, the barcode-reading application being executable by a processor of the mobile device to:
• determine a feature offset of the targeting illumination in an image that is captured by the camera assembly of the mobile device;
• determine an estimated surface distance based on the calibration data and the feature offset;
• and
• use the estimated surface distance to adjust at least one operating parameter of the mobile device.