import { Filter } from '../types/filter.type' ; import { normalizeAngle } from '../utils/filter.utils' ; export const hueRotate = ( context , rotation = '0deg' ) => { const amount = normalizeAngle ( rotation ) ; if ( amount <= 0 ) { return context ; } const { height , width } = context . canvas ; const imageData = context . getImageData ( 0 , 0 , width , height ) ; const { data } = imageData ; const h = ( amount % 1 + 1 ) % 1 ; const th = h * 3 ; const thr = Math . floor ( th ) ; const d = th - thr ; const b = 1 - d ; let ma , mb , mc ; let md , me , mf ; let mg , mh , mi ; switch ( thr ) { case 0 : ma = b ; mb = 0 ; mc = d ; md = d ; me = b ; mf = 0 ; mg = 0 ; mh = d ; mi = b ; break ; case 1 : ma = 0 ; mb = d ; mc = b ; md = b ; me = 0 ; mf = d ; mg = d ; mh = b ; mi = 0 ; break ; case 2 : ma = d ; mb = b ; mc = 0 ; md = 0 ; me = d ; mf = b ; mg = b ; mh = 0 ; mi = d ; break ; } let place = 0 ; for ( let y = 0 ; y < height ; ++ y ) { for ( let x = 0 ; x < width ; ++ x ) { place = 4 * ( y * width + x ) ; const ir = data [ place + 0 ] ; const ig = data [ place + 1 ] ; const ib = data [ place + 2 ] ; data [ place + 0 ] = Math . floor ( ma * ir + mb * ig + mc * ib ) ; data [ place + 1 ] = Math . floor ( md * ir + me * ig + mf * ib ) ; data [ place + 2 ] = Math . floor ( mg * ir + mh * ig + mi * ib ) ; } } context . putImageData ( imageData , 0 , 0 ) ; return context ; } ;