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feat: add ref support to Scanner component #143

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feat: add ref support to Scanner component #143

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91 changes: 40 additions & 51 deletions src/components/Scanner.tsx
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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
import React, { useState, useEffect, useRef, useMemo, ReactNode } from 'react';
import React, { useState, useEffect, useRef, useMemo, ReactNode, forwardRef } from 'react';

import type { BarcodeFormat } from 'barcode-detector';

Expand All @@ -8,14 +8,8 @@ import useScanner from '../hooks/useScanner';

import deepEqual from '../utilities/deepEqual';
import { defaultComponents, defaultConstraints, defaultStyles } from '../misc';
import {
IDetectedBarcode,
IPoint,
IScannerClassNames,
IScannerComponents,
IScannerStyles,
TrackFunction
} from '../types';
import { IDetectedBarcode, IPoint, IScannerClassNames, IScannerComponents, IScannerStyles, TrackFunction } from '../types';
import { mergeRefs } from '../utilities/mergeRefs';

export interface IScannerProps {
onScan: (detectedCodes: IDetectedBarcode[]) => void;
Expand Down Expand Up @@ -125,21 +119,8 @@ function onFound(detectedCodes: IDetectedBarcode[], videoEl?: HTMLVideoElement |
}
}

export function Scanner(props: IScannerProps) {
const {
onScan,
constraints,
formats = ['qr_code'],
paused = false,
components,
children,
styles,
classNames,
allowMultiple,
scanDelay,
onError,
sound
} = props;
export const Scanner = forwardRef<HTMLVideoElement, IScannerProps>((props, ref) => {
const { onScan, constraints, formats = ['qr_code'], paused = false, components, children, styles, classNames, allowMultiple, scanDelay, onError, sound } = props;

const videoRef = useRef<HTMLVideoElement>(null);
const pauseFrameRef = useRef<HTMLCanvasElement>(null);
Expand Down Expand Up @@ -284,12 +265,18 @@ export function Scanner(props: IScannerProps) {

return (
<div style={{ ...defaultStyles.container, ...styles?.container }} className={classNames?.container}>
<video ref={videoRef}
style={{
...defaultStyles.video, ...styles?.video,
visibility: paused ? 'hidden' : 'visible'
}}
className={classNames?.video} autoPlay muted playsInline />
<video
ref={mergeRefs(ref, videoRef)}
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Copilot AI Oct 18, 2025

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With the current mergeRefs signature (Array<RefObject | RefCallback ...>), videoRef (MutableRefObject<HTMLVideoElement | null>) is not assignable, producing a type error. This will be resolved by updating mergeRefs to accept React.Ref (or include MutableRefObject<T | null>) as suggested.

Copilot uses AI. Check for mistakes.

style={{
...defaultStyles.video,
...styles?.video,
visibility: paused ? 'hidden' : 'visible'
}}
className={classNames?.video}
autoPlay
muted
playsInline
/>
<canvas
ref={pauseFrameRef}
style={{
Expand All @@ -309,31 +296,31 @@ export function Scanner(props: IScannerProps) {
zoom={
mergedComponents.zoom && camera.settings.zoom
? {
value: camera.settings.zoom,
onChange: async (value) => {
const newConstraints = {
...constraintsCached,
advanced: [{ zoom: value }]
};

await camera.updateConstraints(newConstraints);
}
}
value: camera.settings.zoom,
onChange: async (value) => {
const newConstraints = {
...constraintsCached,
advanced: [{ zoom: value }]
};

await camera.updateConstraints(newConstraints);
}
}
: undefined
}
torch={
mergedComponents.torch
? {
status: camera.settings.torch ?? false,
toggle: async (value) => {
const newConstraints = {
...constraintsCached,
advanced: [{ torch: value }]
};

await camera.updateConstraints(newConstraints);
}
}
status: camera.settings.torch ?? false,
toggle: async (value) => {
const newConstraints = {
...constraintsCached,
advanced: [{ torch: value }]
};

await camera.updateConstraints(newConstraints);
}
}
: undefined
}
startScanning={async () => await onCameraChange()}
Expand All @@ -349,4 +336,6 @@ export function Scanner(props: IScannerProps) {
</div>
</div>
);
}
});

Scanner.displayName = 'Scanner';
18 changes: 18 additions & 0 deletions src/utilities/mergeRefs.ts
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Original file line number Diff line number Diff line change
@@ -0,0 +1,18 @@
import { RefCallback, RefObject } from 'react';

export function mergeRefs<T>(...refs: Array<RefObject<T> | RefCallback<T> | null | undefined>): RefCallback<T> {
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Copilot AI Oct 18, 2025

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The signature excludes MutableRefObject and uses RefObject, which makes passing useRef refs (e.g., MutableRefObject<HTMLVideoElement | null>) a type error. Switch to React.Ref (or include MutableRefObject<T | null>) so both object and callback refs are accepted.

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return (value) => {
for (const ref of refs) {
if (ref == null) {
continue;
}

if (typeof ref === 'function') {
ref(value);
continue;
}

(ref as RefObject<T | null>).current = value;
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Copilot AI Oct 18, 2025

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RefObject has a readonly current; assigning to .current here is a type error. Cast to MutableRefObject<T | null> (or narrow with an appropriate type guard) before assignment: (ref as MutableRefObject<T | null>).current = value.

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}
};
}