Merge pull request #9 from wnielson/master

Added screenshot support

chromote/__init__.py

@@ -8,6 +8,7 @@
 https://chromedevtools.github.io/devtools-protocol/1-2
 """
 
+import base64
 import json
 import requests
 import websocket
@@ -77,6 +78,24 @@ def evaluate(self, javascript):
         """
         return self._send({"method": "Runtime.evaluate", "params": {"expression": javascript}})
 
+    def screenshot(self, format='png', quality=85, fromSurface=False):
+        """
+        Take a screenshot of the page
+        """
+        args = {
+            "method": "Page.captureScreenshot",
+            "params": {
+                "format":      format,
+                "quality":     quality,
+                "fromSurface": fromSurface
+            }
+        }
+        result = self._send(args)
+        data = json.loads(result)
+        if data.has_key('error'):
+            raise ValueError(data['error']['data'])
+        return base64.b64decode(data.get('result',{}).get('data', ''))
+
     def __str__(self):
         return '%s - %s' % (self.title, self.url)