support "showZeros" setting in Excel advanced worksheet options (#1199)

* support "showZeros" setting in Excel advanced worksheet options

* add changelog entry

* change isShowZeros to getShowZeros

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 ### Added
 
 - Implementation of IFNA() logical function
+- Support "showZeros" worksheet option to change how Excel shows and handles "null" values returned from a calculation
 
 ### Fixed
 

src/PhpSpreadsheet/Calculation/Calculation.php

@@ -2813,7 +2813,7 @@ class Calculation
         }
         self::$returnArrayAsType = $returnArrayAsType;
 
-        if ($result === null) {
+        if ($result === null && $pCell->getWorksheet()->getSheetView()->getShowZeros()) {
             return 0;
         } elseif ((is_float($result)) && ((is_nan($result)) || (is_infinite($result)))) {
             return Functions::NAN();

src/PhpSpreadsheet/Reader/Xlsx/SheetViews.php

@@ -24,6 +24,7 @@ class SheetViews extends BaseParserClass
         $this->gridLines();
         $this->headers();
         $this->direction();
+        $this->showZeros();
 
         if (isset($this->sheetViewXml->pane)) {
             $this->pane();
@@ -92,6 +93,15 @@ class SheetViews extends BaseParserClass
         }
     }
 
+    private function showZeros()
+    {
+        if (isset($this->sheetViewXml['showZeros'])) {
+            $this->worksheet->getSheetView()->setShowZeros(
+                self::boolean((string) $this->sheetViewXml['showZeros'])
+            );
+        }
+    }
+
     private function pane()
     {
         $xSplit = 0;

src/PhpSpreadsheet/Worksheet/SheetView.php

@@ -35,6 +35,16 @@ class SheetView
      */
     private $zoomScaleNormal = 100;
 
+    /**
+     * ShowZeros.
+     *
+     * If true, "null" values from a calculation will be shown as "0". This is the default Excel behaviour and can be changed
+     * with the advanced worksheet option "Show a zero in cells that have zero value"
+     *
+     * @var bool
+     */
+    private $showZeros = true;
+
     /**
      * View.
      *
@@ -115,6 +125,24 @@ class SheetView
         return $this;
     }
 
+    /**
+     * Set ShowZeroes setting.
+     *
+     * @param bool $pValue
+     */
+    public function setShowZeros($pValue)
+    {
+        $this->showZeros = $pValue;
+    }
+
+    /**
+     * @return bool
+     */
+    public function getShowZeros()
+    {
+        return $this->showZeros;
+    }
+
     /**
      * Get View.
      *

src/PhpSpreadsheet/Writer/Xlsx/Worksheet.php

@@ -221,6 +221,11 @@ class Worksheet extends WriterPart
             $objWriter->writeAttribute('zoomScaleNormal', $pSheet->getSheetView()->getZoomScaleNormal());
         }
 
+        // Show zeros (Excel also writes this attribute only if set to false)
+        if ($pSheet->getSheetView()->getShowZeros() === false) {
+            $objWriter->writeAttribute('showZeros', 0);
+        }
+
         // View Layout Type
         if ($pSheet->getSheetView()->getView() !== SheetView::SHEETVIEW_NORMAL) {
             $objWriter->writeAttribute('view', $pSheet->getSheetView()->getView());