The color resolution is expected in bits 4-6 of the packed fields byte
of the logical screen descriptor (byte 10 of the GIF data stream),
according to the specification[1], section 18.
[1] <https://www.w3.org/Graphics/GIF/spec-gif89a.txt>
As seen in the gdImageRotateBicubicFixed() function the same setup
occurs but it uses signed integers, therefore we use also use
signed integers in gdImageRotateBilinear()
Moreover, these two functions have been removed upstream in
bd6d2e101f
therefore we should also mimic upstream and remove them...
Thanks to @cmb69 for pointing it out.
While `imagesetinterpolation()` is available as of PHP 5.5.0,
there is no according getter function, so users would have to track the
current interpolation method manually.
To remedy this, we introduce `imagegetinterpolation()` as thin wrapper
for `gdImageGetInterpolationMethod()` (which has been introduced with
libgd 2.1.1), and use `im->interpolation_id` as fallback for older
libgd. Since our bundled libgd does not yet have this function, we add
it.
We also simplify the recently introduced bug79068.phpt, where it is
sufficient to check that the interpolation method has not been changed.
This has been reported to upstream[1], but since ext/gd never calls
`gdTransformAffineCopy()` for a palette image, it is not a bug for PHP.
Therefore we apply the fix to master only.
[1] <https://github.com/libgd/libgd/issues/586>
Apparently, this has not been tested for a long time, and might be a
refactoring relict. Anyhow, we have to pass the context to
`GIFNextPixel` as well.
We add PHP bindings for libgd's features to read TGA files, which are
available as of libgd 2.1.0.
As PHP's bundled libgd doesn't yet include the respective features of the
external libgd, we add these.
Since TGA has no easily recognizable file signature, we don't add TGA
support for imagecreatefromstring() or getimagesize() and friends.
Changes to simplify managing libgd docs a bit:
- Move copyright statement and licensing info to common redistributable
bins file. All previous notices left intact and updated with the
upstream info.
- Remove unsynced and difficult to track README file compared to
upstream README.md file available at https://github.com/libgd/libgd
This filter is available as of libgd 2.1.0 which is our bare minimum for
external compilation of ext/gd.
The scatter filter works by iterating over all pixels in the image and
shifting them randomly based on two modifier (`plus` and `sub`) values:
dest_x = (int)(x + ((rand() % (plus - sub)) + sub));
dest_y = (int)(y + ((rand() % (plus - sub)) + sub));
Additionally the scatter filter also supports by only shifting pixels where
the current pixel being iterated is one or more colors, allowing the scatter
filter to only effect solid colors in part of an image.
Note, due to the nature of randomness and implementation, pixels who were
shifted ahead of iteration will be shifted once more and therefore the
bottom right of an image may contain a slight scatter effect due to this.
