PNG support

Hi
First of all thanks for all the replies before and now my video and audio
are fine.

I want to enable PNG support. I could get jpeg working fine by dynamic
loading. I see that png library check is failing for me

**checking for png.h… yes
**checking for png_create_read_struct in -lpng… no
**configure: WARNING: *** Unable to find PNG library (
http://www.libpng.org/pub/png/libpng.html)
**configure: WARNING: PNG image loading disabled

So I forced *ac_cv_lib_png_png_create_read_struct=yes in the make file
thinking that this shd help as I have already installed libpng12.so

lrwxrwxrwx 1 root root 11 Jun 3 2008 libpng.so ->
libpng12.so
lrwxrwxrwx 1 root root 18 Jun 3 2008 libpng12.so ->
libpng12.
so.0.16.0
lrwxrwxrwx 1 root root 18 Jun 3 2008 libpng12.so.0 ->
libpng1
2.so.0.16.0
-rwxr-xr-x 1 root root 223816 Jun 3 2008 libpng12.so.0.16.0

But the application gives an error
***Couldn’t load /etc/CandyBar.png: Failed loading libpng.so.3: File not
found

What is the difference between libpng12 and libpng libraries. I was
thinking that libpng12 uses libz as core and there is no other dependency.

Thanks
Sanu Mathews

Sanu Mathews wrote:

Hi
First of all thanks for all the replies before and now my video and
audio are fine.

I want to enable PNG support. I could get jpeg working fine by dynamic
loading. I see that png library check is failing for me

**checking for png.h… yes
**checking for png_create_read_struct in -lpng… no
**configure: WARNING: *** Unable to find PNG library
(http://www.libpng.org/pub/png/libpng.html)
**configure: WARNING: PNG image loading disabled

So I forced *ac_cv_lib_png_png_create_read_struct=yes in the make
file thinking that this shd help as I have already installed libpng12.so

You’ve installed the libraries, which means it’ll run if you throw a
precompiled binary on your system. However, from how I read your post
you’ve not installed the header files, which are needed at compilation
time for your code and the compiler to ‘know’ how to interact with said
libraries. In a very rough explanation.

Typically on Linux and similar systems, if you’re installing stuff from
packages, you’ll have something like a libpng-devel to install to give
you those headers.

Alternatively, if you’ve installed from source, and the library and
headers are there, it’s likely that your code is looking for the headers
in one place, when they’re totally in another. Check your
Makefile/configure options to ensure that you’re pointing stuff to the
right directory to pick up the headers and libraries.

It’s a bit late, and I’m probably off the mark and rambling a little.
Saw your post, thought I might be able to give some tips to help. Hope
it does, and apologies if it doesn’t.

All the best!

First read this:

http://tldp.org/HOWTO/Program-Library-HOWTO/introduction.html

Then, you will understand that the you’re missing libpng.so.3. Exactly
WHY is not entirely clear.

The version of libpng provided by my system includes both libpng12.so.0
and libpng.so.3.

Because libpng have decided not to follow the conventional naming format
for their libraries, it is clear as mud as to what is going on - is
libpng.so.3 the compatibility library or is it the current version (this
is one of my pet hates…)?

The rather cryptic libpng documentation indicates that the 'current’
version is libpng12.so, so the program you’re trying to run was linked
against an older version. Your distro may have a libpng-old or
libpng-compat library that needs installing.

Eddy

Sanu Mathews wrote:> Hi

First of all thanks for all the replies before and now my video and
audio are fine.

I want to enable PNG support. I could get jpeg working fine by dynamic
loading. I see that png library check is failing for me

**checking for png.h… yes
**checking for png_create_read_struct in -lpng… no
**configure: WARNING: *** Unable to find PNG library
(http://www.libpng.org/pub/png/libpng.html)
**configure: WARNING: PNG image loading disabled

So I forced *ac_cv_lib_png_png_create_read_struct=yes in the make
file thinking that this shd help as I have already installed libpng12.so

lrwxrwxrwx 1 root root 11 Jun 3 2008 libpng.so ->
libpng12.so
lrwxrwxrwx 1 root root 18 Jun 3 2008 libpng12.so ->
libpng12.
so.0.16.0
lrwxrwxrwx 1 root root 18 Jun 3 2008 libpng12.so.0 ->
libpng1
2.so.0.16.0
-rwxr-xr-x 1 root root 223816 Jun 3 2008 libpng12.so.0.16.0

But the application gives an error
***Couldn’t load /etc/CandyBar.png: Failed loading libpng.so.3: File not
found

What is the difference between libpng12 and libpng libraries. I was
thinking that libpng12 uses libz as core and there is no other dependency.

Thanks
Sanu Mathews



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Eddy Cullen wrote:

First read this:

http://tldp.org/HOWTO/Program-Library-HOWTO/introduction.html

Then, you will understand that the you’re missing libpng.so.3. Exactly
WHY is not entirely clear.

The version of libpng provided by my system includes both libpng12.so.0
and libpng.so.3.

Because libpng have decided not to follow the conventional naming format
for their libraries, it is clear as mud as to what is going on - is
libpng.so.3 the compatibility library or is it the current version (this
is one of my pet hates…)?

The rather cryptic libpng documentation indicates that the 'current’
version is libpng12.so, so the program you’re trying to run was linked
against an older version. Your distro may have a libpng-old or
libpng-compat library that needs installing.

Eddy

Heya Ed,
Ah yes, I’d totally forgotten about the libpng craziness. Been … too
long, since I had to deal with it directly. Thanks for the reminder, adn
apologies to the list for what was more than likely a pointless post :slight_smile:

Pete.

Wouldn’t worry about it - we’ve all made pointless posts or participated
in flame wars at one time or another :slight_smile:

Eddy

Peter Lawler wrote:> Eddy Cullen wrote:

First read this:

http://tldp.org/HOWTO/Program-Library-HOWTO/introduction.html

Then, you will understand that the you’re missing libpng.so.3. Exactly
WHY is not entirely clear.

The version of libpng provided by my system includes both
libpng12.so.0 and libpng.so.3.

Because libpng have decided not to follow the conventional naming
format for their libraries, it is clear as mud as to what is going on

  • is libpng.so.3 the compatibility library or is it the current
    version (this is one of my pet hates…)?

The rather cryptic libpng documentation indicates that the 'current’
version is libpng12.so, so the program you’re trying to run was linked
against an older version. Your distro may have a libpng-old or
libpng-compat library that needs installing.

Eddy

Heya Ed,
Ah yes, I’d totally forgotten about the libpng craziness. Been … too
long, since I had to deal with it directly. Thanks for the reminder, adn
apologies to the list for what was more than likely a pointless post :slight_smile:

Pete.


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