[webkit-dev] ImageDiff tool for gtk platform

Kalle Vahlman kalle.vahlman at gmail.com
Fri May 23 00:39:42 PDT 2008

2008/5/23 Mark Rowe <mrowe at apple.com>:
> On 22/05/2008, at 07:24, S Venkata Udai Kiran wrote:
>> Hi all,
>>  I was trying to understand how the Layout tests are being done in
>> Webkit. I  went through the perl code 'run-webkit-tests' and found that
>> the script is using a tool name ImageDiff
>> (WebKit/WebKitBuild/Release/Programs/ImageDiff) .But I could not 'find'
>> that tool in WebKit folder. As I understand that ImageDiff tool is
>> necessary to do a pixel level diff for test images generated.I am
>> looking at running individual tests using a small shell script rather
>> running all the tests at once. this will help me to know the underlying
>> things.  Please help.
> ImageDiff is currently only implemented for Mac and Windows.  It's not
> needed to run the standard regression tests.  Pixel test results will differ
> between platforms and software versions, so there is a lot of manual work
> involved in verifying results when bringing up pixel results on a new
> platform.  Focusing on text-only and render tree tests would provide much
> better bang for your buck than pixel test results.

That's very true. However, cairo aims at constant quality across
output targets and has a similar utility in it's testing suite to
verify that:


So assuming that the layout code produces identical output on all
platforms, testing cairo -backed platforms (gtk, win32...) for
pixel-perfectness might make sense.

Kalle Vahlman, zuh at iki.fi
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