vscroll/dist/esm5/processes/render.js

Virtual scroll engine

import { __extends } from "tslib";
import { BaseProcessFactory, CommonProcess, ProcessStatus } from './misc/index';
var Render = /** @class */ (function (_super) {
  __extends(Render, _super);
  function Render() {
    return _super !== null && _super.apply(this, arguments) || this;
  }
  Render.run = function (scroller) {
    var workflow = scroller.workflow, state = scroller.state, viewport = scroller.viewport, routines = scroller.routines;
    var cycle = state.cycle, render = state.render, scroll = state.scroll, fetch = state.fetch;
    scroller.logger.stat('before new items render');
    if (scroll.positionBeforeAsync === null) {
      scroll.positionBeforeAsync = viewport.scrollPosition;
    }
    render.cancel = routines.render(function () {
      render.cancel = null;
      if (Render.doRender(scroller)) {
        workflow.call({
          process: Render.process,
          status: render.noSize ? ProcessStatus.done : ProcessStatus.next,
          payload: { process: cycle.initiator }
        });
      }
      else {
        workflow.call({
          process: Render.process,
          status: ProcessStatus.error,
          payload: { error: 'Can not associate item with element' }
        });
      }
    }, { items: fetch.items.map(function (i) { return i.get(); }) });
  };
  Render.doRender = function (scroller) {
    var state = scroller.state, viewport = scroller.viewport, buffer = scroller.buffer, logger = scroller.logger;
    var fetch = state.fetch, render = state.render;
    render.positionBefore = viewport.scrollPosition;
    if (!fetch.isCheck) {
      render.sizeBefore = viewport.getScrollableSize();
      if (!fetch.items.every(function (item) { return Render.processElement(scroller, item); })) {
        return false;
      }
    }
    buffer.checkDefaultSize();
    render.sizeAfter = viewport.getScrollableSize();
    logger.stat('after new items render');
    logger.log(function () { return (render.noSize ? 'viewport size has not been changed' : void 0); });
    return true;
  };
  Render.processElement = function (scroller, item) {
    var viewport = scroller.viewport, buffer = scroller.buffer;
    var element = viewport.findItemElementById(item.nodeId);
    if (!element) {
      return false;
    }
    item.element = element;
    item.makeVisible();
    item.setSize(buffer.getSizeByIndex(item.$index));
    buffer.cacheItem(item);
    return true;
  };
  return Render;
}(BaseProcessFactory(CommonProcess.render)));
export default Render;
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