A picture is worth a thousand message digests

The bundled GD test suites makes heavy use of md5() to verify the result
of drawing operations. This leads to fragile tests (even a slight c

A picture is worth a thousand message digests

The bundled GD test suites makes heavy use of md5() to verify the result
of drawing operations. This leads to fragile tests (even a slight change
in a PNG header would cause failure, and of course there is the
possibility of collisions), and even worse, eventual test failures are
rather unrevealing.

Therefore we replace all md5() verification with a simplistic
test_image_equals_file(), which is basically a simplified port of libgd's
gdTestImageCompareToFile(), adapted to the needs of PHPTs.

In the long run better tests helpers should be introduced (see also
<http://news.php.net/php.internals/94081>), but for now this solution
is preferable over the former.

(cherry picked from commit 24f9e96792518ec2a75f26b1eb2471dd7694f2b7)

show more ...

Skip tests that are supposed to fail due to bugs in old external libgd

Make tests a little more resilient

PNG allows identical images to be stored differently what makes nearly all
tests checking the MD5 hash of the PNG representation fail with external

Make tests a little more resilient

PNG allows identical images to be stored differently what makes nearly all
tests checking the MD5 hash of the PNG representation fail with external
libgd. For now, we use the GD format instead, which doesn't allow for such
differences.

Of course, this md5() checking should be replaced by a image diffing feature
in the long run.

show more ...

Fix #43828: broken transparency of imagearc for truecolor in blendingmode

No pixel of a filled arc must ever be drawn multiple times. Otherwise we get
artifacts regarding transparency. T

Fix #43828: broken transparency of imagearc for truecolor in blendingmode

No pixel of a filled arc must ever be drawn multiple times. Otherwise we get
artifacts regarding transparency. That happens with the current
implementation of gdImageFilledArc() unless gdChord or gdNoFill are set.
When gdPie is set, however, the filled arc is drawn in wedges, which are
polygons of three points, and so some overlap is natural.

To resolve the issue, we stick with the current algorithm of calculating the
wedges, but instead of drawing each polygon separately, we put the relevant
points in a large array, and draw a single polygon. That also is supposed to
improve the performance considerably.

Note that this modification will change the results when gdImageSetStyle()
or gdImageSetBrush() are used, but we believe that this modification is also
an improvement in this regard, even though it still might not make much
sense to use these functions with gdImageFilledArc().

The respective fix for libgd is
<https://github.com/libgd/libgd/commit/e7e20d6>.

show more ...