react-virtualized
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React components for efficiently rendering large, scrollable lists and tabular data
82 lines (81 loc) • 3.26 kB
JavaScript
import _slicedToArray from "@babel/runtime/helpers/slicedToArray";
import _classCallCheck from "@babel/runtime/helpers/classCallCheck";
import _createClass from "@babel/runtime/helpers/createClass";
import _defineProperty from "@babel/runtime/helpers/defineProperty";
import createIntervalTree from '../vendor/intervalTree';
/*:: type RenderCallback = (index: number, left: number, top: number) => void;*/
// Position cache requirements:
// O(log(n)) lookup of cells to render for a given viewport size
// O(1) lookup of shortest measured column (so we know when to enter phase 1)
var PositionCache = /*#__PURE__*/function () {
function PositionCache() {
_classCallCheck(this, PositionCache);
// Tracks the height of each column
_defineProperty(this, "_columnSizeMap", {});
// Store tops and bottoms of each cell for fast intersection lookup.
_defineProperty(this, "_intervalTree", createIntervalTree());
// Maps cell index to x coordinates for quick lookup.
_defineProperty(this, "_leftMap", {});
}
return _createClass(PositionCache, [{
key: "estimateTotalHeight",
value: function estimateTotalHeight(cellCount /*: number*/, columnCount /*: number*/, defaultCellHeight /*: number*/) /*: number*/{
var unmeasuredCellCount = cellCount - this.count;
return this.tallestColumnSize + Math.ceil(unmeasuredCellCount / columnCount) * defaultCellHeight;
}
// Render all cells visible within the viewport range defined.
}, {
key: "range",
value: function range(scrollTop /*: number*/, clientHeight /*: number*/, renderCallback /*: RenderCallback*/) /*: void*/{
var _this = this;
this._intervalTree.queryInterval(scrollTop, scrollTop + clientHeight, function (_ref) {
var _ref2 = _slicedToArray(_ref, 3),
top = _ref2[0],
_ = _ref2[1],
index = _ref2[2];
return renderCallback(index, _this._leftMap[index], top);
});
}
}, {
key: "setPosition",
value: function setPosition(index /*: number*/, left /*: number*/, top /*: number*/, height /*: number*/) /*: void*/{
this._intervalTree.insert([top, top + height, index]);
this._leftMap[index] = left;
var columnSizeMap = this._columnSizeMap;
var columnHeight = columnSizeMap[left];
if (columnHeight === undefined) {
columnSizeMap[left] = top + height;
} else {
columnSizeMap[left] = Math.max(columnHeight, top + height);
}
}
}, {
key: "count",
get: function get() /*: number*/{
return this._intervalTree.count;
}
}, {
key: "shortestColumnSize",
get: function get() /*: number*/{
var columnSizeMap = this._columnSizeMap;
var size = 0;
for (var i in columnSizeMap) {
var height = columnSizeMap[(i /*: any*/)];
size = size === 0 ? height : Math.min(size, height);
}
return size;
}
}, {
key: "tallestColumnSize",
get: function get() /*: number*/{
var columnSizeMap = this._columnSizeMap;
var size = 0;
for (var i in columnSizeMap) {
var height = columnSizeMap[(i /*: any*/)];
size = Math.max(size, height);
}
return size;
}
}]);
}();
export { PositionCache as default };