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>
Passing `NULL` as `gdTransformAffineGetImage()`'s `src_area` is fine,
but in this case there's no need to calculate the `rect`, and since
`pRect` has already been initialized to `NULL`, we can remove the whole
else branch.
* PHP-7.4:
Call zend_unregister_ini_entries() when unload extension loaded through dl() without MSHUTDOWN callback. Extensions with MSHUTDOWN should use UNREGISTER_INI_ENTRIES().
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.
That parameter is mostly useless in practise, and likely has been
directly ported from the underlying `gdImagePolygon()` and friends,
which require that parameter since the number of elements of the point
array would otherwise be unknown. Typical usages of `imagepolygon()`,
`imageopenpolygon()` and `imagefilledpolygon()` pass `count($points)/2`
or hard-code this value as literal. Since explicitly specifying this
parameter is annoying and error-prone, we offer the possibility to omit
it, in which case the `$points` array must have an even number of
elements, and the number of points is calculated as `count($points)/2`.
We actually have to check `$num_points` instead of `2*count($points)`,
because the latter may be greater than the former, but not all elements
of `$points` are guaranteed to be used. This allowed to pass arrays
with excess elements to draw polygons with less than three vertices.
While the current implementation of `gdImagePolygon()` and friends
would allow us to draw monogons and digons, we don't allow that
anymore, because the respective drawing primitives work slightly
different (e.g. drawing lines support anti-aliasing, but drawing
general polygons does not).
To minimize the BC break, we do not fix this longstanding issue for PHP
7, but target PHP 8 only.
Raise a ValueError instead of a plain Error when calling imagecreate()
or imagecreatetruecolor() with too big or small values for the width or
height arguments.
