From 1df5f97a5b2c9ca65ea3aca065394bcc1a42349d Mon Sep 17 00:00:00 2001
From: Alexander Kurilo <alex@kurilo.me>
Date: Mon, 17 Oct 2016 00:56:18 +0300
Subject: [PATCH] Require GD for saving images in xls

GD is implicitly required for saving images anyway, this exception when
it's not loaded simply gives more information on what to do if the
execution flow reaches a places that depends on a function from GD.
---
 src/PhpSpreadsheet/Writer/Xls.php | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/PhpSpreadsheet/Writer/Xls.php b/src/PhpSpreadsheet/Writer/Xls.php
index 1ca89211..d60a415c 100644
--- a/src/PhpSpreadsheet/Writer/Xls.php
+++ b/src/PhpSpreadsheet/Writer/Xls.php
@@ -454,6 +454,9 @@ class Xls extends BaseWriter implements IWriter
         // the BSE's (all the images)
         foreach ($this->spreadsheet->getAllsheets() as $sheet) {
             foreach ($sheet->getDrawingCollection() as $drawing) {
+                if (!extension_loaded('gd')) {
+                    throw new \RuntimeException('Saving images in xls requires gd extension');
+                }
                 if ($drawing instanceof \PhpOffice\PhpSpreadsheet\Worksheet\Drawing) {
                     $filename = $drawing->getPath();