Add PNG support. (#58)

It works perfectly, thanks for your submission @limonte

Author: Limon Monte

.gitignore

@@ -4,5 +4,5 @@ vendor/
 #composer.lock
 jobs/*.js
 
-demo/test.jpg
+demo/test.*
 test.php

README.md

@@ -60,9 +60,15 @@ You can also set the User Agent
 $screenCapture->setUserAgentString('Some User Agent String');
 ```
 
+And the resulted image format
+``` php
+// allowed formats are 'jpg' and 'png', default is 'jpg'.
+$screenCapture->setFormat('png');
+```
+
 And most importantly, save the result
 ``` php
-$fileLocation = '/some/dir/test.jpg';
+$fileLocation = '/some/dir/test.' . $screen->getFormat();
 $screen->save($fileLocation);
 ```
 

demo/index.html

@@ -118,6 +118,19 @@ <h2>Give it a test drive...</h2>
         <input type="text" name="bg-color" value="#ffffff" class="form-control color-picker" data-format="hex"/>
       </div>
 
+      <div class="form-group col-md-3">
+        <label for="bg-color">Format</label>
+        <div class="clearfix"></div>
+        <label class="radio-inline">
+          <input type="radio" name="format" value="jpg" checked/>
+          JPG
+        </label>
+        <label class="radio-inline">
+          <input type="radio" name="format" value="png"/>
+          PNG
+        </label>
+      </div>
+
       <div class="col-md-12">
         <button class="btn btn-default pull-right">Submit</button>
         <p class="lead pull-right">You may have to wait a little bit... &nbsp;</p>

demo/shot.php

@@ -34,10 +34,13 @@
     $screen->setBackgroundColor($_GET['bg-color']);
 }
 
-$fileLocation = 'test.jpg';
+if (isset($_GET['format'])) { // Format
+    $screen->setFormat($_GET['format']);
+}
+
+$fileLocation = 'test.' . $screen->getFormat();
 $screen->save($fileLocation);
 
-$type = 'image/jpeg';
-header('Content-Type:' . $type);
+header('Content-Type:' . $screen->getMimeType());
 header('Content-Length: ' . filesize($fileLocation));
 readfile($fileLocation);

src/Capture.php

@@ -56,6 +56,13 @@ class Capture
      */
     protected $backgroundColor = '#FFFFFF';
 
+    /**
+     * Image format
+     *
+     * @var string
+     */
+    protected $format = 'jpg';
+
     /**
      * User Agent String used on the page request
      *
@@ -260,6 +267,52 @@ public function setBackgroundColor($backgroundColor)
         return $this;
     }
 
+    /**
+     * Sets the image format
+     *
+     * @param string $format  'jpg' | 'png'
+     *
+     * @return Capture
+     */
+    public function setFormat($format)
+    {
+        $format = strtolower($format);
+        if (!in_array($format, ['jpg', 'png'])) {
+            throw new Exception(
+                "Invalid image format '{$format}'. " .
+                "Allowed formats are 'jpg' and 'png'"
+            );
+        }
+
+        $this->format = $format;
+
+        return $this;
+    }
+
+    /**
+     * Gets the image format
+     *
+     * @return string
+     */
+    public function getFormat()
+    {
+        return $this->format;
+    }
+
+    /**
+     * Gets the MIME type of resulted image
+     *
+     * @return string
+     */
+    public function getMimeType()
+    {
+        if ($this->format === 'png') {
+            return 'image/png';
+        }
+
+        return 'image/jpeg';
+    }
+
     /**
      * Sets the User Agent String to be used on the page request
      *