@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(facing-mode-button) {
  /* The button responsible to change camera's facing mode */
}

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
noImage no-image	✓	Boolean	-	false	Defines 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	-	null	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.
cameraResolution camera-resolution1	✓	String	-	null	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	-	null	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	-	null	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	-	null	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.
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.
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.

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.

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.
facing-mode-button	Override the default facing mode button with your own. If facingMode is not supported in constrainable properties for the current MediaStreamTrack, the slot is hidden.
facing-mode-button-content	Override the default content of the facing mode button with your own content.
actions	Slot to add content inside the actions container element.
(default)	Un-named slot to add content inside the component.

Slots usage examples

Override the default buttons with your own elements

<capture-photo>
  <button slot="capture-button" type="button">
    Take picture
  </button>
  
  <a slot="facing-mode-button" href="#" role="button">
    Change camera
  </a>
</capture-photo>

Override just the content of the default buttons

<capture-photo>
  <span slot="capture-button-content">Take picture</span>
  
  <span slot="facing-mode-button-content">Change camera</span>
</capture-photo>

CSS Parts

Name	Description
video	The video element.
actions-container	The action buttons container element.
capture-button	The capture photo button.
facing-mode-button	The facing mode 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'
isSupported	Static	Returns true if MediaDevices.getUserMedia() is supported by the platform, otherwise returns false.	-
capture1	Prototype	Captures a photo using the element's properties.	-
getSupportedConstraints1	Prototype	Returns an object based on the MediaTrackSupportedConstraints dictionary, whose member fields each specify one of the constrainable properties the user agent understands. Read more...	-
getTrackCapabilities1	Prototype	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...	-
getTrackSettings1	Prototype	Returns a MediaTrackSettings object containing the current values of each of the constrainable properties for the current MediaStreamTrack. Read more...	-
startVideoStream1	Prototype	Starts the video stream. Use this method if you want to start the video stream manually, if you have previously stopped it using stopVideoStream().	-
stopVideoStream1	Prototype	Stops the video stream and releases the camera. Use this method if you want to stop the video stream manually.	-

¹ These 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.

License

The MIT License (MIT)

Changelog

v3.2.0 (2023-03-23)

• Add public methods startVideoStream() and stopVideoStream() to start and stop the video stream respectively.
• Add calculate-file-size attribute to optionally calculate the file size of the generated image and add it to the capture-photo:success event detail object.
• Update devDependencies.