Support page margin in mPDF

Fixes #750
Fixes #751

CHANGELOG.md

@@ -15,6 +15,7 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 - Fix print area parser for XLSX reader - [#734](https://github.com/PHPOffice/PhpSpreadsheet/pull/734)
 - Support overriding `DefaultValueBinder::dataTypeForValue()` without overriding `DefaultValueBinder::bindValue()` - [#735](https://github.com/PHPOffice/PhpSpreadsheet/pull/735)
 - Mpdf export can exceed pcre.backtrack_limit - [#637](https://github.com/PHPOffice/PhpSpreadsheet/issues/637)
+- Support page margin in mPDF - [#750](https://github.com/PHPOffice/PhpSpreadsheet/issues/750)
 
 ## [1.5.0] - 2018-10-21
 

src/PhpSpreadsheet/Writer/Pdf/Mpdf.php

@@ -70,7 +70,13 @@ public function save($pFilename)
         $ortmp = $orientation;
         $pdf->_setPageSize(strtoupper($paperSize), $ortmp);
         $pdf->DefOrientation = $orientation;
-        $pdf->AddPage($orientation);
+        $pdf->AddPageByArray([
+            'orientation' => $orientation,
+            'margin-left' => $this->inchesToMm($this->spreadsheet->getActiveSheet()->getPageMargins()->getLeft()),
+            'margin-right' => $this->inchesToMm($this->spreadsheet->getActiveSheet()->getPageMargins()->getRight()),
+            'margin-top' => $this->inchesToMm($this->spreadsheet->getActiveSheet()->getPageMargins()->getTop()),
+            'margin-bottom' => $this->inchesToMm($this->spreadsheet->getActiveSheet()->getPageMargins()->getBottom()),
+        ]);
 
         //  Document info
         $pdf->SetTitle($this->spreadsheet->getProperties()->getTitle());
@@ -91,4 +97,16 @@ public function save($pFilename)
 
         parent::restoreStateAfterSave($fileHandle);
     }
+
+    /**
+     * Convert inches to mm.
+     *
+     * @param float $inches
+     *
+     * @return float
+     */
+    private function inchesToMm($inches)
+    {
+        return $inches * 25.4;
+    }
 }