blob: 92963f6bfe59d33c978fb0aab8d6a8bf0af7c08a [file] [log] [blame]
# Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
import logging
import os
import time
from autotest_lib.client.bin import utils
from autotest_lib.client.common_lib import error
from autotest_lib.client.common_lib.cros import chrome
from import graphics_utils
from autotest_lib.client.cros.image_comparison import pdiff_image_comparer
def get_percent_difference(file1, file2):
Performs pixel comparison of two files, given by their paths |file1|
and |file2| using terminal tool 'perceptualdiff' and returns percentage
difference of the total file size.
@param file1: path to image
@param file2: path to secondary image
@return: percentage difference of total file size.
@raise ValueError: if image dimensions are not the same
@raise OSError: if file does not exist or cannot be opened.
# Using pdiff image comparer to compare the two images. This class
# invokes the terminal tool perceptualdiff.
pdi = pdiff_image_comparer.PdiffImageComparer()
diff_bytes =, file2)[0]
return round(100. * diff_bytes / os.path.getsize(file1))
class graphics_VTSwitch(graphics_utils.GraphicsTest):
Verify that VT switching works.
version = 2
_WAIT = 5
# TODO( Need to handle more than one display screen.
def run_once(self,
# Check for chromebook type devices
if not utils.get_board_type() == 'CHROMEBOOK':
raise error.TestNAError('DUT is not Chromebook. Test Skipped.')
self._num_errors = 0
keyvals = {}
# Make sure we start in VT1.
with chrome.Chrome():
# wait for Chrome to start before taking screenshot
# Take screenshot of browser.
vt1_screenshot = self._take_current_vt_screenshot(1)
keyvals['num_iterations'] = num_iterations
# Go to VT2 and take a screenshot.
vt2_screenshot = self._take_current_vt_screenshot(2)
# Make sure VT1 and VT2 are sufficiently different.
diff = get_percent_difference(vt1_screenshot, vt2_screenshot)
keyvals['percent_initial_VT1_VT2_difference'] = diff
if not diff >= difference_percent_threshold:
self._num_errors += 1
logging.error('VT1 and VT2 screenshots only differ by ' + \
'%d %%: %s vs %s' %
(diff, vt1_screenshot, vt2_screenshot))
num_identical_vt1_screenshots = 0
num_identical_vt2_screenshots = 0
max_vt1_difference_percent = 0
max_vt2_difference_percent = 0
# Repeatedly switch between VT1 and VT2.
for iteration in xrange(num_iterations):'Iteration #%d', iteration)
# Go to VT1 and take a screenshot.
current_vt1_screenshot = self._take_current_vt_screenshot(1)
# Make sure the current VT1 screenshot is the same as (or similar
# to) the original login screen screenshot.
diff = get_percent_difference(vt1_screenshot,
if not diff < similarity_percent_threshold:
max_vt1_difference_percent = \
max(diff, max_vt1_difference_percent)
self._num_errors += 1
logging.error('VT1 screenshots differ by %d %%: %s vs %s',
diff, vt1_screenshot,
num_identical_vt1_screenshots += 1
# Go to VT2 and take a screenshot.
current_vt2_screenshot = self._take_current_vt_screenshot(2)
# Make sure the current VT2 screenshot is the same as (or
# similar to) the first VT2 screenshot.
diff = get_percent_difference(vt2_screenshot,
if not diff <= similarity_percent_threshold:
max_vt2_difference_percent = \
max(diff, max_vt2_difference_percent)
self._num_errors += 1
'VT2 screenshots differ by %d %%: %s vs %s',
diff, vt2_screenshot, current_vt2_screenshot)
num_identical_vt2_screenshots += 1
keyvals['percent_VT1_screenshot_max_difference'] = \
keyvals['percent_VT2_screenshot_max_difference'] = \
keyvals['num_identical_vt1_screenshots'] = num_identical_vt1_screenshots
keyvals['num_identical_vt2_screenshots'] = num_identical_vt2_screenshots
if self._num_errors > 0:
raise error.TestFail('Failed: saw %d VT switching errors.' %
def _take_current_vt_screenshot(self, current_vt):
Captures a screenshot of the current VT screen in PNG format.
@param current_vt: desired vt for screenshot.
@returns the path of the screenshot file.
return graphics_utils.take_screenshot(self.resultsdir,
'graphics_VTSwitch_VT%d' % current_vt)
def cleanup(self):
# Return to VT1 when done. Ideally, the screen should already be in VT1
# but the test might fail and terminate while in VT2.
super(graphics_VTSwitch, self).cleanup()