QRCodeScanner

Scan QR codes and other barcodes with the first-party ruflet_qrcode_scanner Flet extension, backed by mobile_scanner.

Enable it and rebuild the client:

# ruflet.yaml
extensions:
  - qrcode_scanner

Ruflet adds camera declarations automatically. To customize the Apple usage message, declare the camera service:

# services.yaml
services:
  - camera:
      description: Scan QR codes and product barcodes.

Example

Ruflet.run do |page|
  result = text(value: "Point the camera at a code")

  scanner = qrcode_scanner(
    expand: true,
    formats: %i[qr_code data_matrix],
    detection_speed: :no_duplicates,
    on_detect: ->(event) {
      page.update(result, value: event.value.to_s)
    },
    on_error: ->(event) {
      page.update(result, value: event.data["message"].to_s)
    }
  )

  page.add(column(controls: [scanner, result]))
end

Scanner properties

• auto_start — start after mounting (default true).
• auto_zoom — automatically zoom toward a detected code (default false; Android only).
• camera_facing — :back or :front (default :back).
• detection_speed — :normal, :no_duplicates, or :unrestricted (default :normal).
• detection_timeout — normal-mode interval in milliseconds (default 250).
• fit — preview box fit (default :cover).
• formats — formats to detect; an empty array means all supported formats.
• invert_image — detect white-on-black codes (default false; Android only).
• return_image — include a base64 capture in detection events (default false; Android, iOS, and macOS).
• scan_window — { left:, top:, right:, bottom: } or { x:, y:, width:, height: }.
• tap_to_focus — enable focus by tapping the preview (default false).
• torch_enabled — start with the torch enabled (default false).
• zoom_scale — optional initial zoom using the normalized 0.0–1.0 range.

It is unset by default, preserving the camera's normal 1x zoom. 1.0 means maximum zoom, not 1x.

Supported format names are all, unknown, aztec, codabar, code_39, code_93, code_128, data_bar, data_bar_expanded, data_bar_limited, data_matrix, ean_8, ean_13, itf_2_of_5, itf_2_of_5_with_checksum, itf_14, maxi_code, micro_qr_code, pdf_417, qr_code, upc_a, and upc_e.

Layout properties

align, animate_align, animate_margin, animate_offset, animate_opacity, animate_position, animate_rotation, animate_scale, animate_size, aspect_ratio, badge, bottom, col, data, disabled, expand, expand_loose, height, key, left, margin, offset, opacity, right, rotate, rtl, scale, size_change_interval, tooltip, top, visible, and width.

Events

• on_detect — event.value is the first raw value. event.data["barcodes"]

contains all results with raw_value, display_value, format, type, and optional corners. event.data["image"] is present when return_image is enabled and the platform supplies a frame.

• on_error — exposes event.data["message"], event.data["type"], and an

optional stack_trace.

• on_animation_end and on_size_change — inherited layout events.

Methods

After mounting, call start, stop, switch_camera, toggle_torch, set_zoom_scale(value), or reset_zoom_scale. Each accepts timeout: 10 and on_result:; the callback receives (result, error).

The extension supports Android, iOS, macOS, and web. Linux and Windows are not supported. Web camera access requires a secure context.