Use standard CMake variables in the install target.
Reformulate comments and error messages.
Move all CMake keywords in front of their arguments.
Fix indentation.
Add the CMake option PNG_EXECUTABLES (on by default) in order to
allow or disallow the building of non-essential executable programs
associated with libpng.
Contributed-by: Alex Gaynor <alex.gaynor@gmail.com>
Contributed-by: Cosmin Truta <ctruta@gmail.com>
Signed-off-by: Cosmin Truta <ctruta@gmail.com>
When building with Emscripten, linkage to libm is neither required
nor working. As find_library will fail, M_LIBRARY will be set to
NOTFOUND and the build would fail later. The build works just fine
without libm linkage.
Although CMake version 3.0.2 was previously required, the policies
CMP0053 and CMP0054, introduced only in CMake version 3.1 and used
in this CMakeLists file, can have surprising effects under an older
CMake version.
Simplify the CMakeLists file by setting the global policy version
to 3.1, and remove the specific policy settings.
As an added bonus, remove the vestigial workarounds for all ancient
CMake versions.
Only use libm on Unix and Unix-like systems, except for Apple (where
it's unnecessary), and BeOS and Haiku (where it's unavailable).
Avoid searching for libm at explicit locations. They may be incorrect,
especially for cross-platform builds.
NEON support is provided by filter_neon.S which is currently not build
by cmake causing an error when linking with libpng16.so.16.32.0:
[ 97%] Linking C executable pngstest
libpng16.so.16.32.0: undefined reference to `png_read_filter_row_avg4_neon'
libpng16.so.16.32.0: undefined reference to `png_read_filter_row_paeth3_neon'
libpng16.so.16.32.0: undefined reference to `png_read_filter_row_up_neon'
libpng16.so.16.32.0: undefined reference to `png_read_filter_row_avg3_neon'
libpng16.so.16.32.0: undefined reference to `png_read_filter_row_paeth4_neon'
libpng16.so.16.32.0: undefined reference to `png_read_filter_row_sub4_neon'
libpng16.so.16.32.0: undefined reference to `png_read_filter_row_sub3_neon'
