Add some improvements

[amotl]

Dear @Czaki,

thanks for your excellent work building upon @cgohlke's imagecodecs here. Coming from pypa/cibuildwheel#568 (comment) ff. (thanks again!), I wanted to leave a note here in order to come back to this later.

I took a quick look at these images, specifically the 32-bit variant bokota/imagecodecs_i686 in comparison to the bokota/imagecodecs_64 variant, and found that even more libraries are installed than those you listed. Let me write down a short summary about my findings.

Installed libraries

• find / -iname '*hdf5*' shows that libhdf5 is installed within both image variants.
• find / -iname '*lzo*' shows that liblzo is installed within bokota/imagecodecs_64, but not within bokota/imagecodecs_i686.
• find / -iname '*blosc*' shows that libblosc is not installed into standard system locations.

Using yum

Regarding yum croaking, as outlined at pypa/cibuildwheel#568 (comment), I have been able to fix it ad hoc by adjusting /etc/yum.repos.d/CentOS-Base.repo like [1]

baseurl=https://vault.centos.org/6.10/os/$basearch/
baseurl=https://vault.centos.org/6.10/updates/$basearch/
baseurl=https://vault.centos.org/6.10/extras/$basearch/
baseurl=https://vault.centos.org/6.10/centosplus/$basearch/
baseurl=https://vault.centos.org/6.10/contrib/$basearch/

With kind regards,
Andreas.

[1] https://forums.cpanel.net/threads/yumrepo-error-and-cannot-find-valid-baseurl.682465/

[Czaki]

In this project all libraries are installed in:
/opt/imagecodecs/build_utils/libs_build/lib

but C_INCLUDE_PATH and LD_LIBRARY_PATH are modified. I decide to do this way to use the same scripts inside docker and for userspace installation. I'm not sure how Docker COPY work and if I could use it to install in standard location.

imagecodecs_build/build_utils/build_libraries.sh

Lines 4 to 6 in 674131f

	DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
	PATH="/usr/local/opt/gettext/bin:$PATH"
	build_dir=${DIR}/libs_build

I do some refactor of Dockerfile to use multistage build and got a reduction of image size.
You may try 2021.2.1 version of image.

[amotl]

C_INCLUDE_PATH and LD_LIBRARY_PATH are modified.

So it will do no harm even when installed within non-standard locations, right? Thanks for clarifying!

[Czaki]

So it will do no harm even when installed within non-standard locations, right? Thanks for clarifying!

My experience show that it not harm. It also allow to use other version than installed in system.