kc3-lang/libpng/scripts/cmake/PNGCheckLibconf.cmake

Branch - branch -libpng16libpng17

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• Hash : 23bdc7a6
  Author :
  Date : 2025-04-28T20:44:53
  

  build: Add the CMake build option `PNG_LIBCONF_HEADER`
  
  Running the pnglibconf scripts (script/*.awk) is not always possible.
  An AWK interpreter is not always guaranteed to be available; and even
  if it is, there are limitations when making cross-platform libpng
  builds, especially when the differences between the host platform and
  the target platform are significant. For example:
   * Building for the Windows (MinGW) target on a Unix development host;
   * Building for the iOS target on a macOS development host;
   * Building for the Android target on any development host.
  
  In such scenarios, a preconfigured (i.e. prebuilt) pnglibconf.h file,
  either taken from the libpng source tree or provided by the user who
  wants to make a custom libpng build, becomes a necessity.
  
  In this commit we introduce the build option `PNG_LIBCONF_HEADER` in
  order to address this specific use case.
  
  We also specify a version range (3.14...4.0) for the minimum required
  CMake program, to future-proof the CMake build for just a little bit
  longer.
  
  Signed-off-by: Cosmin Truta <ctruta@gmail.com>
  

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• scripts/cmake/PNGCheckLibconf.cmake

• # PNGConfig.cmake
  # Utility functions for configuring and building libpng
  
  # Copyright (c) 2025 Cosmin Truta
  #
  # Use, modification and distribution are subject to
  # the same licensing terms and conditions as libpng.
  # Please see the copyright notice in png.h or visit
  # http://libpng.org/pub/png/src/libpng-LICENSE.txt
  #
  # SPDX-License-Identifier: libpng-2.0
  
  # Check libconf file (pnglibconf.h.* or *.dfa):
  # png_check_libconf([HEADER <file>] [DFA_XTRA <file>])
  function(png_check_libconf)
    set(options)
    set(oneValueArgs HEADER DFA_XTRA)
    set(multiValueArgs)
  
    cmake_parse_arguments(_CHK "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
  
    if(_CHK_HEADER AND _CHK_DFA_XTRA)
      message(FATAL_ERROR "png_check_libconf: Mutually-exclusive arguments: HEADER and DFA_XTRA")
    endif()
  
    if(_CHK_HEADER)
      if(EXISTS "${_CHK_HEADER}")
        if("x${_CHK_HEADER}" STREQUAL "x${PNG_LIBCONF_HEADER_PREBUILT}")
          message(STATUS "Using standard libconf header: ${_CHK_HEADER}")
        else()
          message(STATUS "Using custom libconf header: ${_CHK_HEADER}")
        endif()
      else()
        message(SEND_ERROR "Could not find libconf header: ${_CHK_HEADER}")
      endif()
    else()
      if("x${_CHK_DFA_XTRA}" STREQUAL "x")
        message(STATUS "Creating standard configuration")
      elseif(EXISTS "${_CHK_DFA_XTRA}")
        message(STATUS "Creating custom configuration with DFA_XTRA file: ${_CHK_DFA_XTRA}")
      else()
        message(SEND_ERROR "Could not find DFA_XTRA file: ${_CHK_DFA_XTRA}")
      endif()
    endif()
  endfunction()
  

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