react-virtualized/dist/commonjs/Masonry/createCellPositioner.js

React components for efficiently rendering large, scrollable lists and tabular data

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = createCellPositioner;

var _Masonry = require('./Masonry');

function createCellPositioner(_ref) {
  var cellMeasurerCache = _ref.cellMeasurerCache,
      columnCount = _ref.columnCount,
      columnWidth = _ref.columnWidth,
      _ref$spacer = _ref.spacer,
      spacer = _ref$spacer === undefined ? 0 : _ref$spacer;

  var columnHeights = void 0;

  initOrResetDerivedValues();

  function cellPositioner(index) {
    // Find the shortest column and use it.
    var columnIndex = 0;
    for (var i = 1; i < columnHeights.length; i++) {
      if (columnHeights[i] < columnHeights[columnIndex]) {
        columnIndex = i;
      }
    }

    var left = columnIndex * (columnWidth + spacer);
    var top = columnHeights[columnIndex] || 0;

    columnHeights[columnIndex] = top + cellMeasurerCache.getHeight(index) + spacer;

    return {
      left: left,
      top: top
    };
  }

  function initOrResetDerivedValues() {
    // Track the height of each column.
    // Layout algorithm below always inserts into the shortest column.
    columnHeights = [];
    for (var i = 0; i < columnCount; i++) {
      columnHeights[i] = 0;
    }
  }

  function reset(params) {
    columnCount = params.columnCount;
    columnWidth = params.columnWidth;
    spacer = params.spacer;

    initOrResetDerivedValues();
  }

  cellPositioner.reset = reset;

  return cellPositioner;
}