react/components/image/image.skeleton.tsx

import React from 'react'
import withDefaults from '../utils/with-defaults'
import useTheme from '../styles/use-theme'

interface Props {
  opacity: number
}

const defaultProps = {
  opacity: 0.5,
}

export type ImageSkeletonProps = Props & typeof defaultProps

const ImageSkeleton: React.FC<ImageSkeletonProps> = React.memo(({
  opacity, ...props
}) => {
  const theme = useTheme()
  return (
    <div className="skeleton" {...props}>
  
      <style jsx>{`
        .skeleton {
          position: absolute;
          top: 0;
          left: 0;
          right: 0;
          bottom: 0;
          width: 100%;
          height: 100%;
          background-image: linear-gradient(
            270deg,
            ${theme.palette.accents_1},
            ${theme.palette.accents_2},
            ${theme.palette.accents_2},
            ${theme.palette.accents_1});
          background-size: 400% 100%;
          animation: loading 3s ease-in-out infinite;
          opacity: ${opacity};
          transition: opacity 300ms ease-out;
        }
        
        @keyframes loading{
          0% {
            background-position: 200% 0;
          }
          to {
          background-position: -200% 0;
          }
        }
      `}</style>
      
    </div>
  )
})

export default withDefaults(ImageSkeleton, defaultProps)