Libspng Versions Save

Bugfixes

• Fixed return value in example.c for valid images
• Fixed MSVC build with miniz (Matthew Albrecht)
• Fixed argument types for spng__zalloc()
• Fixed some signedness warnings

Changes

Changes to the default behavior were made for libpng compatibility:

• Ignore tRNS chunks for grayscale alpha / truecolor alpha images - #118
• Do not check the text field of tEXt, zTXt chunks - #123

This release is backward compatible.

New

• Progressive image decode support, added new functions:

  • spng_decode_scanline() - Decodes a single scanline
  • spng_decode_row() - Decodes and deinterlaces a scanline
  • spng_get_row_info() - Get current scanline, row information

• Added support for reading tEXt, iTXt, zTXt and iCCP color profile chunks, all standard chunks are supported in this release.

• Added support for building with miniz, spng.c/h and miniz.c/h can be used together without additional dependencies

• Added output format SPNG_FMT_PNG, it represents the PNG's format in host-endian (thanks to Matthew Stadelman for initial implementation)

• Added output format SPNG_FMT_RAW, it represents the PNG's format in big-endian (Matthew Stadelman)

• Added output format SPNG_FMT_RGB8, conversion is supported from any color type and bit depth

• Added grayscale output formats SPNG_FMT_G8, SPNG_FMT_GA8 and SPNG_FMT_GA16, in this release conversion is only supported from a subset of grayscale and bit depth combinations, see documentation for details

• Added support for decoding from a FILE* with spng_set_png_file()

• Added SPNG_CTX_IGNORE_ADLER32 context flag to ignore checksums in DEFLATE streams

• Added enums for filter types and interlace method

• Added Meson option use_miniz and compiler option SPNG_USE_MINIZ for building with miniz

• Added Meson option benchmarks to run benchmarks provided by spngt, this requires Git LFS.

• Added Meson option static_zlib to link the static version of zlib

• Multiversioned defilter_up() function (enabled for GCC + glibc)

Changes

• spng_decode_image() takes a void* for the output buffer (was unsigned char*)

• Reaching chunk size- or cache limits is now handled as an out-of-memory error

• Out-of-range palette indices are handled as black opaque pixels when decoding, this matches libpng's default behavior

• PNG image row length and output row length is now limited to 2^32-1 (UINT32_MAX)

Bugfixes

• Fixed an IDAT streaming bug (Mathieu Mallet)
• Fixed CMake install issues
• Fixed bKGD handling and a testsuite issue on big-endian
• Fixed setting of PLTE presence bit (Matthew Stadelman)
• Added missing error condition for indexed images without a palette
• Fixed zlib constness warnings
• Fixed ordering checks for tRNS, hIST and bKGD chunks

Known issues

• Decoding to SPNG_FMT_G8, SPNG_FMT_GA8 and SPNG_FMT_GA16 output formats is not supported for all PNG color type and bit depth combinations, see documentation for details
• Gamma correction is not implemented for SPNG_FMT_PNG, SPNG_FMT_G8, SPNG_FMT_GA8 and SPNG_FMT_GA16
• spng_crc_set_action() is partially implemented, SPNG_CRC_DISCARD has no effect

This is a release candidate, the API may change for the stable release! Share your feedback on the API here or on Gitter!

• Documentation
• Remaining issues

UPDATE: This release is broken, use https://github.com/randy408/libspng/commit/a0b7323558e0f45e899cd7b5f8ddde2e18c9709e for testing progressive decode functionality with SPNG_FMT_PNG.

New features:

• Progressive image decode support, added new functions:
  • spng_decode_scanline() - decodes a single scanline
  • spng_decode_row() - decodes and deinterlaces a scanline
  • spng_get_row_info() - get scanline/row info including the filter type
• New output format SPNG_FMT_RGB8, conversion is supported from any color type and bit depth
• New output format SPNG_FMT_PNG, this always matches the PNG's format in host-endian
• Added support for decoding from a FILE* via spng_set_png_file()
• Added SPNG_CTX_IGNORE_ADLER32 context flag to ignore checksums in DEFLATE streams
• Enums for filter types, interlace method
• New Meson option benchmarks to run benchmarks provided by spngt, this requires Git LFS.
• New Meson option to link the static version of zlib: static_zlib
• Multiversioned defilter_up() function (enabled for GCC + glibc)

Documentation:

• Added notes on build optimization level
• Added section on decoding arbitrary files

Bugfixes:

• Fixed an IDAT streaming bug (Mathieu Mallet)
• Fixed CMake install issues
• Fixed bKGD handling and a testsuite issue on big-endian (Robert-André Mauchin)
• Fixed setting of PLTE presence bit (Matthew Stadelman)
• Added missing error condition for indexed images without a palette
• Fixed zlib constness warnings
• Fixed ordering checks for tRNS, hIST and bKGD chunks