Preserve workbook bookview attributes on update

Fix for issue PHPOffice#523.  When reading then writing
a Xlsx spreadsheet, preserve the workbook bookview attributes for
the spreadsheet, (e.g., the attribute that hides worksheet tabs.)
Beforehand, these attributes were always being set to fixed constants.

src/PhpSpreadsheet/Reader/Xlsx.php

@@ -1973,6 +1973,12 @@ public function load($pFilename)
                     }
 
                     if ((!$this->readDataOnly) || (!empty($this->loadSheetsOnly))) {
+                        if ($xmlWorkbook->bookViews->workbookView) {
+                            foreach ($xmlWorkbook->bookViews->workbookView->attributes() as $attr => $value) {
+                                $excel->setWorkbookViewAttribute((string) $attr, (string) $value);
+                            }
+                        }
+
                         // active sheet index
                         $activeTab = (int) ($xmlWorkbook->bookViews->workbookView['activeTab']); // refers to old sheet index
 

src/PhpSpreadsheet/Spreadsheet.php

@@ -123,6 +123,13 @@ class Spreadsheet
      */
     private $unparsedLoadedData = [];
 
+    /**
+     * workbookViewAttributes : null if workbook isn't Excel 2007 or doesn't have any workbook bookviews.
+     *
+     * @var null|array
+     */
+    private $workbookViewAttributes;
+
     /**
      * The workbook has macros ?
      *
@@ -1216,4 +1223,36 @@ public function getID()
     {
         return $this->uniqueID;
     }
+
+    /**
+     * Get a workbook bookview attribute.
+     *
+     * @param string $attr            Name of attribute to read
+     * @param null|string $default    Value to return if attribute doesn't exist
+     *
+     * @return string                 Value of attribute
+     */
+    public function getWorkbookViewAttribute($attr, $default = null)
+    {
+        if ($this->workbookViewAttributes && isset($this->workbookViewAttributes[$attr])) {
+            return $this->workbookViewAttributes[$attr];
+        }
+
+        return $default;
+    }
+
+    /**
+     * Set a workbook bookview attribute.
+     *
+     * @param string $attr            Name of attribute to set
+     * @param string $value           Value of the attribute
+     */
+    public function setWorkbookViewAttribute($attr, $value)
+    {
+        if ($this->workbookViewAttributes === null) {
+            $this->workbookViewAttributes = [];
+        }
+
+        $this->workbookViewAttributes[$attr] = $value;
+    }
 }

src/PhpSpreadsheet/Writer/Xlsx/Workbook.php

@@ -117,14 +117,38 @@ private function writeBookViews(XMLWriter $objWriter, Spreadsheet $spreadsheet)
         $objWriter->startElement('workbookView');
 
         $objWriter->writeAttribute('activeTab', $spreadsheet->getActiveSheetIndex());
-        $objWriter->writeAttribute('autoFilterDateGrouping', '1');
-        $objWriter->writeAttribute('firstSheet', '0');
-        $objWriter->writeAttribute('minimized', '0');
-        $objWriter->writeAttribute('showHorizontalScroll', '1');
-        $objWriter->writeAttribute('showSheetTabs', '1');
-        $objWriter->writeAttribute('showVerticalScroll', '1');
-        $objWriter->writeAttribute('tabRatio', '600');
-        $objWriter->writeAttribute('visibility', 'visible');
+        $objWriter->writeAttribute(
+            'autoFilterDateGrouping',
+            $spreadsheet->getWorkbookViewAttribute('autoFilterDateGrouping', '1')
+        );
+        $objWriter->writeAttribute(
+            'firstSheet',
+            $spreadsheet->getWorkbookViewAttribute('firstSheet', '0')
+        );
+        $objWriter->writeAttribute(
+            'minimized',
+            $spreadsheet->getWorkbookViewAttribute('minimized', '0')
+        );
+        $objWriter->writeAttribute(
+            'showHorizontalScroll',
+            $spreadsheet->getWorkbookViewAttribute('showHorizontalScroll', '1')
+        );
+        $objWriter->writeAttribute(
+            'showSheetTabs',
+            $spreadsheet->getWorkbookViewAttribute('showSheetTabs', '1')
+        );
+        $objWriter->writeAttribute(
+            'showVerticalScroll',
+            $spreadsheet->getWorkbookViewAttribute('showVerticalScroll', '1')
+        );
+        $objWriter->writeAttribute(
+            'tabRatio',
+            $spreadsheet->getWorkbookViewAttribute('tabRatio', '600')
+        );
+        $objWriter->writeAttribute(
+            'visibility',
+            $spreadsheet->getWorkbookViewAttribute('visibility', 'visible')
+        );
 
         $objWriter->endElement();
 

tests/PhpSpreadsheetTests/Writer/Xlsx/HiddenTabsTest.php

@@ -0,0 +1,32 @@
+<?php
+
+namespace PhpOffice\PhpSpreadsheetTests\Writer\Xlsx;
+
+use PhpOffice\PhpSpreadsheet\Settings;
+use PHPUnit\Framework\TestCase;
+
+class HiddenTabsTest extends TestCase
+{
+    /**
+     * Test that the worksheet tabs remain hidden when reading and writing a XLSX document
+     * with hidden worksheets tabs.
+     */
+    public function testUpdateWithHiddenTabs()
+    {
+        $sourceFilename = __DIR__ . '/../../../data/Writer/XLSX/hidden_tabs.xlsx';
+        Settings::setLibXmlLoaderOptions(null); // reset to default options
+        $reader = new \PhpOffice\PhpSpreadsheet\Reader\Xlsx();
+        $excel = $reader->load($sourceFilename);
+
+        $targetFilename = tempnam(sys_get_temp_dir(), 'tst');
+        $writer = new \PhpOffice\PhpSpreadsheet\Writer\Xlsx($excel);
+        $writer->save($targetFilename);
+
+        try {
+            $excel2 = $reader->load($targetFilename);
+            $this->assertEquals('0', $excel2->getWorkbookViewAttribute('showSheetTabs'));
+        } finally {
+            @unlink($targetFilename);
+        }
+    }
+}