@georapbox/capture-photo-element

<capture-photo>

A custom element that implements the MediaDevices.getUserMedia() method of the MediaDevices interface to capture a photo in the browser.

API documentation • Demo

Install

$ npm install --save @georapbox/capture-photo-element

Usage

Script

import { CapturePhoto } from './node_modules/@georapbox/capture-photo-element/dist/capture-photo.js';

// Manually define the element.
CapturePhoto.defineCustomElement();

Alternatively, you can import the automatically defined custom element.

import './node_modules/@georapbox/capture-photo-element/dist/capture-photo-defined.js';

Markup

<capture-photo facing-mode="environment" camera-resolution="320x240"></capture-photo>

Style

By default, the component is style-free to remain as less opinionated as possible. However, you can style the various elements of the component using the ::part() CSS pseudo-elements provided for this purpose. Below are demonstrated all available parts for styling.

capture-photo::part(video) {
  /* The video element */
}

capture-photo::part(actions-container) {
  /* Actions container element - where actions buttons are placed */
}

capture-photo::part(capture-button) {
  /* The button responsible to take picture */
}

capture-photo::part(output-container) {
  /* Output container - where the final output photo is placed */  
}

capture-photo::part(output-image) {
  /* The generated photo */
}

API

Properties

Name	Reflects	Type	Required	Default	Description
autoPlay auto-play	✓	Boolean	-	false	Determines if the video stream should start playing automatically when the component is connected to the DOM. If set to false, you can start the video stream manually using startVideoStream() method.
noImage no-image	✓	Boolean	-	false	Determines if the generated image is added in DOM. Use it if you don't need to display the generated image or if you need to display it somewhere else in DOM.
facingMode facing-mode1	✓	String	-	"environment"	The preferred camera to be used if the camera hardware supports more than one (mostly for mobile devices). Available values: "user" and "environment" for the front and the rear camera respectively. Note that this property might not have any effect if you have called startVideoStream() method with a specific video input device as argument because the camera hardware might not support changing the facing mode.
cameraResolution camera-resolution1	✓	String	-	""	Defines the ideal camera resolution constraint. It must be of the format [width]x[height], eg 640x480. The browser will try to honour this, but may return other resolutions if an exact match is not available. You can access the min & max supported values for width and height, using getTrackCapabilities().width and getTrackCapabilities().height respectively.
pan1	✓	Number	-	0	Defines the camera's pan level if supported by the camera hardware. You can access the min & max supported values for pan level, using getTrackCapabilities().pan.
tilt1	✓	Number	-	0	Defines the camera's tilt level if supported by the camera hardware. You can access the min & max supported values for tilt level, using getTrackCapabilities().tilt.
zoom1	✓	Number	-	1	Defines the camera's zoom level if supported by the camera hardware. You can access the min & max supported values for zoom level, using getTrackCapabilities().zoom.
torch1	✓	Boolean	-	false	Determines if the camera's fill light should be turned on if supported by the camera hardware. This works only when facingMode is set to environment or the selected video input device supports it. You can access the supported values for torch, using getTrackCapabilities().torch. NOTE: The support for this feature is known to be limited and heavily dependent on the device, browser, and operating system.
calculateFileSize calculate-file-size	✓	Boolean	-	false	Indicates if the component should calculate the file size of the generated image. If set to true the file size (in bytes) will be included in the event detail object when the capture-photo:success event is fired. The reason for not calculating the file size by default is that it might be an "expensive" operation, especially for large images, therefore it is recommended to set this property to true only if you need the file size.
loading	✓	Boolean	-	false	Readonly. Indicates if the component is ready for interaction. It is used internally but is also exposed as a readonly property for purposes such as styling, etc.

¹ Changing any of these properties/attributes may not always guarantee the desired result, because they all depend on the camera hardware support. For example, zoom=3 might not result to the camera to zoom if the camera hardware does not support zooming. Using getTrackCapabilities() and getTrackSettings() can prove helpful to check the campera hardware support.

[!IMPORTANT] Changing the facingMode and cameraResolution, properties or equivalent after the video stream has started will not have any effect. You need to stop the video stream and start it again with the new properties. This is to avoid unnecessary camera hardware operations.

Slots

Name	Description
capture-button	Override the default capture photo button with your own.
capture-button-content	Override the default content of the capture photo button with your own content.
actions	Slot to add content inside the actions container element. Useful for adding custom actions, such as a button to switch camera facing mode, or zoom in/out buttons.
(default)	Un-named slot to add content inside the component.

CSS Parts

Name	Description
video	The video element.
actions-container	The container element for custom actions.
capture-button	The capture photo button.
output-container	The output container element.
output-image	The output image element.

Methods

Name	Type	Description	Arguments
defineCustomElement	Static	Defines/registers the custom element with the name provided. If no name is provided, the default name is used. The method checks if the element is already defined, hence will skip trying to redefine it.	[elementName='capture-photo']
getVideoInputDevices	Static	Returns a promise that resolves with an array of MediaDeviceInfo objects representing the available video input devices. Make sure to call this method after permission is granted to access the camera.	-
isSupported	Static	Returns true if MediaDevices.getUserMedia() is supported by the platform, otherwise returns false.	-
capture	Instance	Captures a photo using the element's properties.	-
getSupportedConstraints	Instance	Returns an object based on the MediaTrackSupportedConstraints dictionary, whose member fields each specify one of the constrainable properties the user agent understands. Read more...	-
getTrackCapabilities	Instance	Returns a MediaTrackCapabilities object which specifies the values or range of values which each constrainable property, based upon the platform and user agent. Read more...	-
getTrackSettings	Instance	Returns a MediaTrackSettings object containing the current values of each of the constrainable properties for the current MediaStreamTrack. Read more...	-
startVideoStream	Instance	Starts the video stream. Use this method to start the video stream manually, if autoPlay is set to false or if you want to restart the video stream after it has been previously stopped by calling stopVideoStream() method. If videoInputId is provided and the camera hardware supports it, the video stream will start using the specified video input device. You can get the available video input devices using getVideoInputDevices() static method.	[videoInputId]
restartVideoStream	Instance	Same as startVideoStream() method but first stops the video stream if it is already playing.	[videoInputId]
stopVideoStream	Instance	Stops the video stream and releases the camera. Use this method if you want to stop the video stream manually.	-

[!IMPORTANT] Instance methods are only available after the component has been defined. To ensure the component is defined, you can use whenDefined method of the CustomElementRegistry interface, eg customElements.whenDefined('capture-photo').then(() => { /* call methods here */ });

Events

Name	Description	Event Detail
capture-photo:video-play	Emitted when camera's video stream starts playing. It is triggered during initial load, or when facing mode or camera resolution mode change are requested.	{ video: HTMLVideoElement }
capture-photo:success	Emitted when a photo is captured successfully.	{ dataURI: string, width: number, height: number, size?: number }
capture-photo:error	Emitted when an error occurs. An error might occur because camera permission is denied, a photo cannot be captured for any reason, the video stream cannot start for any reason, etc.	{ error: DOMException }

Changelog

For API updates and breaking changes, check the CHANGELOG.

Development setup

Prerequisites

The project requires Node.js and npm to be installed on your environment. Preferrably, use nvm Node Version Manager and use the version of Node.js specified in the .nvmrc file by running nvm use.

Install dependencies

Install the project dependencies by running the following command.

npm install

Build for development

Watch for changes and start a development server by running the following command.

npm start

Linting

Lint the code by running the following command.

npm run lint

Testing

Run the tests by running any of the following commands.

npm test
npm run test:watch # watch mode

Build for production

Create a production build by running the following command.

npm run build

License

The MIT License (MIT)

Changelog

v5.0.0 (2024-10-16)

Breaking Changes

• Change default value of facingMode property from "user" to "environment", to be as much consistent as possible with the default camera facing mode of most mobile devices.
• Remove the facing-mode-button slot and button to toggle the camera facing mode in favor of consistence with other camera properties thad don't have a dedicated button, such as camera-resolution, torch, pan, tilt and zoom.
• Changing the facingMode and cameraResolution, properties or equivalent attributes after the video stream has started will not have any effect. You need to restart the video stream with the new properties. This is to avoid unnecessary camera hardware operations.

Other Changes

• Add static method getVideoInputDevices() to get the list of available video input devices.
• Support passing a deviceInputId as argument to the startVideoStream() method to start the video stream with a specific video input device.
• Add instance method restartVideoStream() to restart the video stream with the current properties.