swiper/core/update/updateProgress.js

Most modern mobile touch slider and framework with hardware accelerated transitions

import { elementIndex } from '../../shared/utils.js';
export default function updateProgress(translate) {
  const swiper = this;
  if (typeof translate === 'undefined') {
    const multiplier = swiper.rtlTranslate ? -1 : 1;
    // eslint-disable-next-line
    translate = swiper && swiper.translate && swiper.translate * multiplier || 0;
  }
  const params = swiper.params;
  const translatesDiff = swiper.maxTranslate() - swiper.minTranslate();
  let {
    progress,
    isBeginning,
    isEnd,
    progressLoop
  } = swiper;
  const wasBeginning = isBeginning;
  const wasEnd = isEnd;
  if (translatesDiff === 0) {
    progress = 0;
    isBeginning = true;
    isEnd = true;
  } else {
    progress = (translate - swiper.minTranslate()) / translatesDiff;
    const isBeginningRounded = Math.abs(translate - swiper.minTranslate()) < 1;
    const isEndRounded = Math.abs(translate - swiper.maxTranslate()) < 1;
    isBeginning = isBeginningRounded || progress <= 0;
    isEnd = isEndRounded || progress >= 1;
    if (isBeginningRounded) progress = 0;
    if (isEndRounded) progress = 1;
  }
  if (params.loop) {
    const firstSlideIndex = elementIndex(swiper.slides.filter(el => el.getAttribute('data-swiper-slide-index') === '0')[0]);
    const lastSlideIndex = elementIndex(swiper.slides.filter(el => el.getAttribute('data-swiper-slide-index') * 1 === swiper.slides.length - 1)[0]);
    const firstSlideTranslate = swiper.slidesGrid[firstSlideIndex];
    const lastSlideTranslate = swiper.slidesGrid[lastSlideIndex];
    const translateMax = swiper.slidesGrid[swiper.slidesGrid.length - 1];
    const translateAbs = Math.abs(translate);
    if (translateAbs >= firstSlideTranslate) {
      progressLoop = (translateAbs - firstSlideTranslate) / translateMax;
    } else {
      progressLoop = (translateAbs + translateMax - lastSlideTranslate) / translateMax;
    }
    if (progressLoop > 1) progressLoop -= 1;
  }
  Object.assign(swiper, {
    progress,
    progressLoop,
    isBeginning,
    isEnd
  });
  if (params.watchSlidesProgress || params.centeredSlides && params.autoHeight) swiper.updateSlidesProgress(translate);
  if (isBeginning && !wasBeginning) {
    swiper.emit('reachBeginning toEdge');
  }
  if (isEnd && !wasEnd) {
    swiper.emit('reachEnd toEdge');
  }
  if (wasBeginning && !isBeginning || wasEnd && !isEnd) {
    swiper.emit('fromEdge');
  }
  swiper.emit('progress', progress);
}