Added JPG exporter for a single paged PDF

src/Jpg.php

@@ -0,0 +1,46 @@
+<?php
+
+namespace ThreeWS\PdfTools;
+
+use ThreeWS\PdfTools\Exceptions\OpenOutputException;
+use ThreeWS\PdfTools\Exceptions\OpenPDFException;
+use ThreeWS\PdfTools\Exceptions\OtherException;
+use ThreeWS\PdfTools\Exceptions\PDFPermissionException;
+
+class Jpg
+{
+    protected $file;
+    protected $quality;
+    protected $progressive;
+
+    public function __construct($file, $quality = '60', $progressive = 'y')
+    {
+        $this->file = $file;
+        $this->quality = $quality;
+        $this->progressive = $progressive;
+    }
+
+    public function convert()
+    {
+        exec("pdftocairo -jpeg -jpegopt quality=$this->quality,progressive=$this->progressive -singlefile $this->file $this->file", $output, $returnVar);
+
+        switch ($returnVar) {
+            case 1:
+                throw new OpenPDFException("Error opening PDF file: {$this->file}.");
+                break;
+            case 2:
+                throw new OpenOutputException();
+                break;
+            case 3:
+                throw new PDFPermissionException();
+                break;
+            case 99:
+                throw new OtherException();
+                break;
+            default:
+                break;
+        }
+
+        return $returnVar;
+    }
+}