[py] Adding full page screenshot feature for Firefox (#7182)

Geckodriver allows to make full page screenshots since version 0.24.0.
This commit makes use of that feature.

py/selenium/webdriver/firefox/remote_connection.py

@@ -32,3 +32,5 @@ def __init__(self, remote_server_addr, keep_alive=True):
             ("POST", "/session/$sessionId/moz/addon/install")
         self._commands["UNINSTALL_ADDON"] = \
             ("POST", "/session/$sessionId/moz/addon/uninstall")
+        self._commands["FULL_PAGE_SCREENSHOT"] = \
+            ("GET", "/session/$sessionId/moz/screenshot/full")

py/selenium/webdriver/firefox/webdriver.py

@@ -19,6 +19,7 @@
 except NameError:  # Python 3.x
     basestring = str
 
+import base64
 import shutil
 import warnings
 from contextlib import contextmanager
@@ -257,3 +258,71 @@ def uninstall_addon(self, identifier):
                 driver.uninstall_addon('addon@foo.com')
         """
         self.execute("UNINSTALL_ADDON", {"id": identifier})
+
+    def get_full_page_screenshot_as_file(self, filename):
+        """
+        Saves a full document screenshot of the current window to a PNG image file. Returns
+           False if there is any IOError, else returns True. Use full paths in
+           your filename.
+
+        :Args:
+         - filename: The full path you wish to save your screenshot to. This
+           should end with a `.png` extension.
+
+        :Usage:
+            ::
+
+                driver.get_full_page_screenshot_as_file('/Screenshots/foo.png')
+        """
+        if not filename.lower().endswith('.png'):
+            warnings.warn("name used for saved screenshot does not match file "
+                          "type. It should end with a `.png` extension", UserWarning)
+        png = self.get_full_page_screenshot_as_png()
+        try:
+            with open(filename, 'wb') as f:
+                f.write(png)
+        except IOError:
+            return False
+        finally:
+            del png
+        return True
+
+    def save_full_page_screenshot(self, filename):
+        """
+        Saves a full document screenshot of the current window to a PNG image file. Returns
+           False if there is any IOError, else returns True. Use full paths in
+           your filename.
+
+        :Args:
+         - filename: The full path you wish to save your screenshot to. This
+           should end with a `.png` extension.
+
+        :Usage:
+            ::
+
+                driver.save_full_page_screenshot('/Screenshots/foo.png')
+        """
+        return self.get_full_page_screenshot_as_file(filename)
+
+    def get_full_page_screenshot_as_png(self):
+        """
+        Gets the full document screenshot of the current window as a binary data.
+
+        :Usage:
+            ::
+
+                driver.get_full_page_screenshot_as_png()
+        """
+        return base64.b64decode(self.get_full_page_screenshot_as_base64().encode('ascii'))
+
+    def get_full_page_screenshot_as_base64(self):
+        """
+        Gets the full document screenshot of the current window as a base64 encoded string
+           which is useful in embedded images in HTML.
+
+        :Usage:
+            ::
+
+                driver.get_full_page_screenshot_as_base64()
+        """
+        return self.execute("FULL_PAGE_SCREENSHOT")['value']

py/test/selenium/webdriver/firefox/ff_takes_full_page_screenshots_tests.py

@@ -0,0 +1,31 @@
+# Licensed to the Software Freedom Conservancy (SFC) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The SFC licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+import base64
+import imghdr
+
+
+def test_get_full_page_screenshot_as_base64(driver, pages):
+    pages.load("simpleTest.html")
+    result = base64.b64decode(driver.get_full_page_screenshot_as_base64())
+    assert imghdr.what('', result) == 'png'
+
+
+def test_get_full_page_screenshot_as_png(driver, pages):
+    pages.load("simpleTest.html")
+    result = driver.get_full_page_screenshot_as_png()
+    assert imghdr.what('', result) == 'png'