Ensure that the list of shared formulae is maintained while chunk-reading Xlsx Files (#1680)

* Ensure that the list of shared formulae is maintained while chunk-reading Xlsx files

Author: Mark Baker

CHANGELOG.md

@@ -25,7 +25,7 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 
 ### Fixed
 
-- Nothing.
+- Ensure that the list of shared formulae is maintained when an xlsx file is chunked with readFilter[Issue #169](https://github.com/PHPOffice/PhpSpreadsheet/issues/1669).
 
 ## 1.15.0 - 2020-10-11
 

src/PhpSpreadsheet/Reader/Xlsx.php

@@ -661,6 +661,9 @@ public function load($pFilename)
                                             $coordinates = Coordinate::coordinateFromString($r);
 
                                             if (!$this->getReadFilter()->readCell($coordinates[0], (int) $coordinates[1], $docSheet->getTitle())) {
+                                                if (isset($c->f)) {
+                                                    $this->castToFormula($c, $r, $cellDataType, $value, $calculatedValue, $sharedFormulas, 'castToError');
+                                                }
                                                 ++$rowIndex;
 
                                                 continue;