list-with-headers-layout.js

import ShelfFirst from 'layout-bin-packer/shelf-first';

export default class ListWithHeaders
{
  constructor(content, width) {
    this.content = content;
    this.width = width;
    this.bin = new ShelfFirst(content, width);
    var bin = this.bin;
    bin.length = function() {
      return content.get('length');
    };
    bin.widthAtIndex = function() {
      return width;
    };
    bin.heightAtIndex = function(index) {
      if (this.content.objectAt(index).group) {
        return 37;
      }
      return 49;
    };
  }

  contentSize(clientSize) {
    return {
      width: clientSize.width,
      height: this.bin.height()
    };
  }

  indexAt(offsetX, offsetY, width, height) {
    return this.bin.visibleStartingIndex(offsetY, width, height);
  }

  positionAt(index, width /*,height*/) {
    var position = this.bin.position(index, width);
    return position;
  }

  widthAt() {
    return this.width;
  }

  heightAt(index) {
    return this.bin.heightAtIndex(index);
  }

  count(offsetX, offsetY, width, height) {
    return this.bin.numberVisibleWithin(offsetY, width, height, true);
  }
}