switch GIF save to frame at a time
And make a new colormap if the frame average changes. This keeps memory use low, even for very large GIFs, though is somewhat slower.
See https://github.com/libvips/libvips/pull/2445
only include source files in make dist for libnsgif and module/
we were just including the whole directory, which stopped the derived
files (eg. the .la archives) from being rebuilt on other platforms
By default, a dynamically loadable module is built for *magick (i.e.
`--with-magick=module`) when:
* ImageMagick or GraphicsMagick is found;
* GModule is supported (`gmodule_supported` pkg-config variable).
This can be overridden on the command line with:
* `--without-magick` - to disable *magick usage;
* `--with-magick[=yes]` - to restore the previous behavior;
* `--disable-modules` - to disable the build of dynamic modules.
By default, a dynamically loadable module is built for poppler (i.e.
`--with-poppler=module`) when:
* poppler is found;
* GModule is supported (`gmodule_supported` pkg-config variable).
This can be overridden on the command line with:
* `--without-poppler` - to disable poppler usage;
* `--with-poppler[=yes]` - to restore the previous behavior;
* `--disable-modules` - to disable the build of dynamic modules.
By default, a dynamically loadable module is built for libheif (i.e.
`--with-heif=module`) when:
* libheif is found;
* GModule is supported (`gmodule_supported` pkg-config variable).
This can be overridden on the command line with:
* `--without-heif` - to disable libheif usage;
* `--with-heif[=yes]` - to restore the previous behavior;
* `--disable-modules` - to disable the build of dynamic modules.
By default, a dynamically loadable module is built for OpenSlide (i.e.
`--with-openslide=module`) when:
* OpenSlide is found;
* GModule is supported (`gmodule_supported` pkg-config variable).
This can be overridden on the command line with:
* `--without-openslide` - to disable OpenSlide usage;
* `--with-openslide[=yes]` - to restore the previous behavior;
* `--disable-modules` - to disable the build of dynamic modules.