1 files changed, 118 insertions, 0 deletions
diff --git a/Tools/Scripts/webkitpy/port/image_diff.py b/Tools/Scripts/webkitpy/port/image_diff.py
new file mode 100644
index 000000000..4f1b059b4
--- /dev/null
+++ b/Tools/Scripts/webkitpy/port/image_diff.py
@@ -0,0 +1,118 @@
+# Copyright (C) 2010 Google Inc. All rights reserved.
+# Copyright (C) 2010 Gabor Rapcsanyi <rgabor@inf.u-szeged.hu>, University of Szeged
+# Copyright (C) 2011, 2012 Apple Inc. All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the Google name nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+"""WebKit implementations of the Port interface."""
+
+import logging
+import re
+import time
+
+from webkitpy.port import server_process
+
+
+_log = logging.getLogger(__name__)
+
+
+class ImageDiffer(object):
+    def __init__(self, port):
+        self._port = port
+        self._tolerance = None
+        self._process = None
+
+    def diff_image(self, expected_contents, actual_contents, tolerance):
+        if tolerance != self._tolerance:
+            self.stop()
+        try:
+            assert(expected_contents)
+            assert(actual_contents)
+            assert(tolerance is not None)
+
+            if not self._process:
+                self._start(tolerance)
+            # Note that although we are handed 'old', 'new', ImageDiff wants 'new', 'old'.
+            self._process.write('Content-Length: %d\n%sContent-Length: %d\n%s' % (
+                len(actual_contents), actual_contents,
+                len(expected_contents), expected_contents))
+            return self._read()
+        except IOError as exception:
+            return (None, 0, "Failed to compute an image diff: %s" % str(exception))
+
+    def _start(self, tolerance):
+        command = [self._port._path_to_image_diff(), '--tolerance', str(tolerance)]
+        environment = self._port.setup_environ_for_server('ImageDiff')
+        self._process = self._port._server_process_constructor(self._port, 'ImageDiff', command, environment)
+        self._process.start()
+        self._tolerance = tolerance
+
+    def _read(self):
+        deadline = time.time() + 2.0
+        output = None
+        output_image = ""
+
+        while not self._process.timed_out and not self._process.has_crashed():
+            output = self._process.read_stdout_line(deadline)
+            if self._process.timed_out or self._process.has_crashed() or not output:
+                break
+
+            if output.startswith('diff'):  # This is the last line ImageDiff prints.
+                break
+
+            if output.startswith('Content-Length'):
+                m = re.match('Content-Length: (\d+)', output)
+                content_length = int(m.group(1))
+                output_image = self._process.read_stdout(deadline, content_length)
+                output = self._process.read_stdout_line(deadline)
+                break
+
+        stderr = self._process.pop_all_buffered_stderr()
+        err_str = ''
+        if stderr:
+            err_str += "ImageDiff produced stderr output:\n" + stderr
+        if self._process.timed_out:
+            err_str += "ImageDiff timed out\n"
+        if self._process.has_crashed():
+            err_str += "ImageDiff crashed\n"
+
+        # FIXME: There is no need to shut down the ImageDiff server after every diff.
+        self._process.stop()
+
+        diff_percent = 0
+        if output and output.startswith('diff'):
+            m = re.match('diff: (.+)% (passed|failed)', output)
+            if m.group(2) == 'passed':
+                return (None, 0, None)
+            diff_percent = float(m.group(1))
+
+        return (output_image, diff_percent, err_str or None)
+
+    def stop(self):
+        if self._process:
+            self._process.stop()
+            self._process = None