Document CameraImageProvider

Makes it easier than looking up the Qt documentation online.

cura/CameraImageProvider.py

@@ -1,15 +1,26 @@
+# Copyright (c) 2018 Ultimaker B.V.
+# Cura is released under the terms of the LGPLv3 or higher.
+
 from PyQt5.QtGui import QImage
 from PyQt5.QtQuick import QQuickImageProvider
 from PyQt5.QtCore import QSize
 
 from UM.Application import Application
 
-
+##  Creates screenshots of the current scene.
 class CameraImageProvider(QQuickImageProvider):
     def __init__(self):
         super().__init__(QQuickImageProvider.Image)
 
     ##  Request a new image.
+    #
+    #   The image will be taken using the current camera position.
+    #   Only the actual objects in the scene will get rendered. Not the build
+    #   plate and such!
+    #   \param id The ID for the image to create. This is the requested image
+    #   source, with the "image:" scheme and provider identifier removed. It's
+    #   a Qt thing, they'll provide this parameter.
+    #   \param size The dimensions of the image to scale to.
     def requestImage(self, id, size):
         for output_device in Application.getInstance().getOutputDeviceManager().getOutputDevices():
             try: