Unit KambiPngUtils

Functions SO_Xxx return the version of used libpng library (taken by querying png_access_version_number). They raise ELibPngNotAvailable exception if libpng library was not available (not KambiPngInited) or if version of libpng library is incompatible with interface defined in KamiPng unit.

So these functions actually not only return version of libpng, they also check is libpng available (and has the proper version).

The three Integer functions should always match the first 3 components of SO_PNG_LIBPNG_VER_STRING.

Apply transformations in such a way that EVERY png format wil be converted to RGB 8bit depth, no fill, no alpha. So, paletted and grayscales must be converted, bytes got to have appriopriate order, alpha channel must be applied and then thrown out.

Apply transformation to convert EVERY png to RGBA 8 byte depth. So, paletted and grayscales must be converted, bytes got to have appriopriate order and alpha channel must be added (=1.0) if it is not already present in file.

png file has alpha info if it is has alpha channel (grayscale or rgb) or if it has tRNS chunk (for paletted image this stores alpha values for each palette color, for grayscale/rgb it determines one particular color to mean "transparent"). Function below checks it.