bpk-component-image

Backpack image component.

Installation

npm install bpk-component-image --save-dev

Usage

import React from 'react';
import BpkImage from 'bpk-component-image';
import { breakpointDesktop, breakpointTablet } from '@skyscanner/bpk-foundations-web/tokens/base.es6';

export default () => (
  <BpkImage
    altText="image description"
    aspectRatio={816 / 544}
    src="./path/to/image_1640.jpg"
  />
);

Accompanying HOCS

withLazyLoading

withLazyLoading is a HOC which adds an inView prop to components. This boolean prop can be used to determine if the component has been brought into view within a user's browser window. The BpkImage component will only load images if inView is true. Using this HOC can make pages load faster and prevent data being used to display images which are never seen by the user.

import BpkImage, { withLazyLoading, withLoadingBehavior } from 'bpk-component-image';
import { breakpointDesktop, breakpointTablet } from '@skyscanner/bpk-foundations-web/tokens/base.es6';

// Support for SSR
const documentIfExists = typeof window !== 'undefined' ? document : null;
// withLazyLoading will not use document when rendered server side so it's safe
// pass null.
const LazyLoadedImage = withLazyLoading(BpkImage, documentIfExists);

export default () => (
  <LazyLoadedImage
    altText="image description"
    aspectRatio={816 / 544}
    src="./path/to/image_1640.jpg"
  />
);

withLoadingBehavior

withLoadingBehavior is a HOC which provides loading state for BpkImage. This allows the component to have different behaviour before and after loading completes. When the loading prop is set true, a spinner will be displayed. When this changes to false, the spinner will fade away and the loaded image and content will fade into view.

import BpkImage, { BpkBackgroundImage, withLazyLoading, withLoadingBehavior } from 'bpk-component-image';
import { breakpointDesktop, breakpointTablet } from '@skyscanner/bpk-foundations-web/tokens/base.es6';

const FadingImage = withLoadingBehavior(BpkImage);
const FadingBackgroundImage = withLoadingBehavior(BpkBackgroundImage);

export default () => (
  <div>
    <FadingImage
      altText="image description"
      aspectRatio={816 / 544}
      src="./path/to/image_1640.jpg"
    />
    <FadingBackgroundImage
      altText="image description"
      aspectRatio={816 / 544}
      src="./path/to/image_1640.jpg"
      imageStyle={{
        backgroundRepeat: 'no-repeat',
        backgroundSize: 'cover',
        backgroundPosition: '50% 50%',
      }}
    />
  </div>
);

All together now

Combining withLazyLoading and withLoadingBehavior gives us a lazily loaded image that will show a spinner while the image loads.

import BpkImage, { withLazyLoading, withLoadingBehavior } from 'bpk-component-image';
import { breakpointDesktop, breakpointTablet } from '@skyscanner/bpk-foundations-web/tokens/base.es6';

const documentIfExists = typeof window !== 'undefined' ? document : null;
const FadingLazyLoadedImage = withLoadingBehavior(withLazyLoading(BpkImage, documentIfExists));

export default () => (
  <FadingLazyLoadedImage
    altText="image description"
    aspectRatio={816 / 544}
    src="./path/to/image_1640.jpg"
  />
);

Props

Property	PropType	Required	Default Value
altText	string	true	-
src	string	true	-
aspectRatio	number	true	-
borderRadiusStyle	oneOf(BORDER_RADIUS_STYLES)	false	BORDER_RADIUS_STYLES.none
className	string	false	null
inView	bool	false	true
loading	bool	false	false
onLoad	func	false	null
style	object	false	{}
suppressHydrationWarnings	bool	false	false

Note: The aspectRatio prop should be calculated as width/height of the original src image. It is used by the component to preserve space on screen while the image loads.

Note: All standard img attributes including srcSet are also supported.

BpkBackgroundImage

The background image component is useful for setting background images in CSS that can then contain other elements. It supports the same HOCs as BpkImage.

BpkBackgroundImage props

Property	PropType	Required	Default Value
src	string	true	-
aspectRatio	number	true	-
className	string	false	null
inView	bool	false	true
loading	bool	false	false
onLoad	func	false	null
style	object	false	{}
imageStyle	object	false	{}