swiper/src/components/controller/controller.js

Most modern mobile touch slider and framework with hardware accelerated transitions

/* eslint no-bitwise: ["error", { "allow": [">>"] }] */
import Swiper from '../core/core-class';
import Utils from '../../utils/utils';

const Controller = {
  LinearSpline: function LinearSpline(x, y) {
    const binarySearch = (function search() {
      let maxIndex;
      let minIndex;
      let guess;
      return (array, val) => {
        minIndex = -1;
        maxIndex = array.length;
        while (maxIndex - minIndex > 1) {
          guess = maxIndex + minIndex >> 1;
          if (array[guess] <= val) {
            minIndex = guess;
          } else {
            maxIndex = guess;
          }
        }
        return maxIndex;
      };
    }());
    this.x = x;
    this.y = y;
    this.lastIndex = x.length - 1;
    // Given an x value (x2), return the expected y2 value:
    // (x1,y1) is the known point before given value,
    // (x3,y3) is the known point after given value.
    let i1;
    let i3;

    this.interpolate = function interpolate(x2) {
      if (!x2) return 0;

      // Get the indexes of x1 and x3 (the array indexes before and after given x2):
      i3 = binarySearch(this.x, x2);
      i1 = i3 - 1;

      // We have our indexes i1 & i3, so we can calculate already:
      // y2 := ((x2−x1) × (y3−y1)) ÷ (x3−x1) + y1
      return (((x2 - this.x[i1]) * (this.y[i3] - this.y[i1])) / (this.x[i3] - this.x[i1])) + this.y[i1];
    };
    return this;
  },
  // xxx: for now i will just save one spline function to to
  getInterpolateFunction(c) {
    const swiper = this;
    if (!swiper.controller.spline) {
      swiper.controller.spline = swiper.params.loop
        ? new Controller.LinearSpline(swiper.slidesGrid, c.slidesGrid)
        : new Controller.LinearSpline(swiper.snapGrid, c.snapGrid);
    }
  },
  setTranslate(setTranslate, byController) {
    const swiper = this;
    const controlled = swiper.controller.control;
    let multiplier;
    let controlledTranslate;
    function setControlledTranslate(c) {
      // this will create an Interpolate function based on the snapGrids
      // x is the Grid of the scrolled scroller and y will be the controlled scroller
      // it makes sense to create this only once and recall it for the interpolation
      // the function does a lot of value caching for performance
      const translate = swiper.rtlTranslate ? -swiper.translate : swiper.translate;
      if (swiper.params.controller.by === 'slide') {
        swiper.controller.getInterpolateFunction(c);
        // i am not sure why the values have to be multiplicated this way, tried to invert the snapGrid
        // but it did not work out
        controlledTranslate = -swiper.controller.spline.interpolate(-translate);
      }

      if (!controlledTranslate || swiper.params.controller.by === 'container') {
        multiplier = (c.maxTranslate() - c.minTranslate()) / (swiper.maxTranslate() - swiper.minTranslate());
        controlledTranslate = ((translate - swiper.minTranslate()) * multiplier) + c.minTranslate();
      }

      if (swiper.params.controller.inverse) {
        controlledTranslate = c.maxTranslate() - controlledTranslate;
      }
      c.updateProgress(controlledTranslate);
      c.setTranslate(controlledTranslate, swiper);
      c.updateActiveIndex();
      c.updateSlidesClasses();
    }
    if (Array.isArray(controlled)) {
      for (let i = 0; i < controlled.length; i += 1) {
        if (controlled[i] !== byController && controlled[i] instanceof Swiper) {
          setControlledTranslate(controlled[i]);
        }
      }
    } else if (controlled instanceof Swiper && byController !== controlled) {
      setControlledTranslate(controlled);
    }
  },
  setTransition(duration, byController) {
    const swiper = this;
    const controlled = swiper.controller.control;
    let i;
    function setControlledTransition(c) {
      c.setTransition(duration, swiper);
      if (duration !== 0) {
        c.transitionStart();
        if (c.params.autoHeight) {
          Utils.nextTick(() => {
            c.updateAutoHeight();
          });
        }
        c.$wrapperEl.transitionEnd(() => {
          if (!controlled) return;
          if (c.params.loop && swiper.params.controller.by === 'slide') {
            c.loopFix();
          }
          c.transitionEnd();
        });
      }
    }
    if (Array.isArray(controlled)) {
      for (i = 0; i < controlled.length; i += 1) {
        if (controlled[i] !== byController && controlled[i] instanceof Swiper) {
          setControlledTransition(controlled[i]);
        }
      }
    } else if (controlled instanceof Swiper && byController !== controlled) {
      setControlledTransition(controlled);
    }
  },
};
export default {
  name: 'controller',
  params: {
    controller: {
      control: undefined,
      inverse: false,
      by: 'slide', // or 'container'
    },
  },
  create() {
    const swiper = this;
    Utils.extend(swiper, {
      controller: {
        control: swiper.params.controller.control,
        getInterpolateFunction: Controller.getInterpolateFunction.bind(swiper),
        setTranslate: Controller.setTranslate.bind(swiper),
        setTransition: Controller.setTransition.bind(swiper),
      },
    });
  },
  on: {
    update() {
      const swiper = this;
      if (!swiper.controller.control) return;
      if (swiper.controller.spline) {
        swiper.controller.spline = undefined;
        delete swiper.controller.spline;
      }
    },
    resize() {
      const swiper = this;
      if (!swiper.controller.control) return;
      if (swiper.controller.spline) {
        swiper.controller.spline = undefined;
        delete swiper.controller.spline;
      }
    },
    observerUpdate() {
      const swiper = this;
      if (!swiper.controller.control) return;
      if (swiper.controller.spline) {
        swiper.controller.spline = undefined;
        delete swiper.controller.spline;
      }
    },
    setTranslate(translate, byController) {
      const swiper = this;
      if (!swiper.controller.control) return;
      swiper.controller.setTranslate(translate, byController);
    },
    setTransition(duration, byController) {
      const swiper = this;
      if (!swiper.controller.control) return;
      swiper.controller.setTransition(duration, byController);
    },
  },
};