vscroll/dist/esm5/classes/viewport.js

Virtual scroll engine

import { __read, __spreadArray } from "tslib";
import { Paddings } from './paddings';
import { Direction } from '../inputs/index';
var Viewport = /** @class */ (function () {
  function Viewport(settings, routines, state, logger) {
    this.settings = settings;
    this.routines = routines;
    this.state = state;
    this.logger = logger;
    this.paddings = new Paddings(this.routines, settings);
  }
  Viewport.prototype.reset = function (startIndex) {
    this.setOffset();
    this.paddings.reset(this.getSize(), startIndex, this.offset);
    this.scrollPosition = this.paddings.backward.size || 0;
    this.state.scroll.reset();
  };
  Viewport.prototype.setPosition = function (value) {
    var oldPosition = this.scrollPosition;
    if (oldPosition === value) {
      this.logger.log(function () { return ['setting scroll position at', value, '[cancelled]']; });
      return value;
    }
    this.routines.setScrollPosition(value);
    var position = this.scrollPosition;
    this.logger.log(function () { return __spreadArray([
      'setting scroll position at', position
    ], __read((position !== value ? ["(".concat(value, ")")] : [])), false); });
    return position;
  };
  Object.defineProperty(Viewport.prototype, "scrollPosition", {
    get: function () {
      return this.routines.getScrollPosition();
    },
    set: function (value) {
      this.setPosition(value);
    },
    enumerable: false,
    configurable: true
  });
  Viewport.prototype.getSize = function () {
    return this.routines.getViewportSize();
  };
  Viewport.prototype.getScrollableSize = function () {
    return this.routines.getScrollerSize();
  };
  Viewport.prototype.getMaxScrollPosition = function () {
    return this.getScrollableSize() - this.getSize();
  };
  Viewport.prototype.getBufferPadding = function () {
    return this.getSize() * this.settings.padding;
  };
  Viewport.prototype.getEdge = function (direction) {
    return this.routines.getViewportEdge(direction);
  };
  Viewport.prototype.setOffset = function () {
    this.offset = this.routines.getOffset();
  };
  Viewport.prototype.findItemElementById = function (id) {
    return this.routines.findItemElement(id);
  };
  Viewport.prototype.getEdgeVisibleItem = function (items, direction) {
    var bwd = direction === Direction.backward;
    var opposite = bwd ? Direction.forward : Direction.backward;
    var viewportEdge = this.getEdge(direction);
    var item, diff = 0;
    for (var i = bwd ? 0 : items.length - 1; bwd ? i <= items.length - 1 : i >= 0; i += bwd ? 1 : -1) {
      var itemEdge = this.routines.getEdge(items[i].element, opposite);
      diff = itemEdge - viewportEdge;
      if (bwd && diff > 0 || !bwd && diff < 0) {
        item = items[i];
        break;
      }
    }
    return { item: item, index: item ? item.$index : NaN, diff: diff };
  };
  return Viewport;
}());
export { Viewport };
//# sourceMappingURL=viewport.js.map