Detect properly the libpng so that inkscape can build against 1.4.x and further too

[Fridrich]

Inkscape would not detect correctly libpng 1.4.x. The attached patch is fixing it.

[Christoph Buchner (bilderbuchi)]

So, is this the only bug still blocking a 0.48.2 release? https://launchpad.net/inkscape/+milestone/0.48.2

[Jeff Kowalczyk (jfkw)]

Adding my note here (also (I can't search currently, Launchpad timeouts) instead of opening a new bug:

On Gentoo Linux ~amd64, I have libpng version 1.2.46 1.4.8 1.5.5 installed in their respective slots, e.g. Google Chrome depends on libpng-1.2. Inkscape was building OK with libpng-1.4, but on 2011-09-18 when libpng-1.5 was first added to my system, Inkscape subsequently tries to build against 1.5, but fails with the following error:

  CXX helper/png-write.o
x86_64-pc-linux-gnu-g++ -DHAVE_CONFIG_H -I. -I.. -I/usr/include/freetype2 -fopenmp -I/usr/include/ImageMagick -I/usr/inc
lude/libwpg-0.2 -I/usr/include/libwpd-0.9 -I/usr/include/poppler -pthread -I/usr/include/poppler/glib -I/usr/include/pop
pler -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -I/usr/include/cairo -I/usr/include/gtk-2.0 -I/usr/lib64/gtk-2.0/inc
lude -I/usr/include/gdk-pixbuf-2.0 -I/usr/include/pixman-1 -I/usr/include/freetype2 -I/usr/include/libpng15 -I/usr/include/libd
rm -I/usr/include/pango-1.0 -DPOTRACE=\"potrace\" -pthread -I/usr/include/glib-2.0 -I/usr/lib64/glib-2.0/include -I/usr/inclu
de/gtk-2.0 -I/usr/lib64/gtk-2.0/include -I/usr/include/atk-1.0 -I/usr/include/cairo -I/usr/include/gdk-pixbuf-2.0 -I/usr/includ
e/pango-1.0 -I/usr/include/pixman-1 -I/usr/include/freetype2 -I/usr/include/libpng15 -I/usr/include/libdrm -I/usr/include/libxm
l2 -I/usr/include/sigc++-2.0 -I/usr/lib64/sigc++-2.0/include -I/usr/include/gtkspell-2.0 -I/usr/include/glibmm-2.4 -I/usr/lib64
/glibmm-2.4/include -I/usr/include/giomm-2.4 -I/usr/lib64/giomm-2.4/include -I/usr/include/gdkmm-2.4 -I/usr/lib64/gdkmm-2.4/inc
lude -I/usr/include/pangomm-1.4 -I/usr/lib64/pangomm-1.4/include -I/usr/include/cairomm-1.0 -I/usr/lib64/cairomm-1.0/include -I
/usr/include/gtkmm-2.4 -I/usr/lib64/gtkmm-2.4/include -I/usr/include/atkmm-1.6 -I/usr/include/gtk-unix-print-2.0 -I../cxxtest
  -I./bind/javainc -I./bind/javainc/linux -I./extension/dbus -Werror=format-security -Wall -Wformat -Wformat-security -W -D_F
ORTIFY_SOURCE=2 -Wpointer-arith -Wcast-align -Wsign-compare -Woverloaded-virtual -Wswitch -Wno-unused-parameter -march=core2
-O2 -pipe -fno-strict-aliasing -fopenmp -c -o helper/png-write.o helper/png-write.cpp
helper/png-write.cpp: In function ‘bool sp_png_write_rgba_striped(SPDocument*, const gchar*, long unsigned int, long unsigned i
nt, double, double, int (*)(const guchar**, void**, int, int, void*), void*)’:
helper/png-write.cpp:169:9: error: invalid use of incomplete type ‘struct png_struct’
/usr/include/libpng15/png.h:830:16: error: forward declaration of ‘struct png_struct’

[su_v (suv-lp)]

@Jeff Kowalczyk - build failure with libpng 1.5 (due to stricter type checking) is tracked in
- Bug #721029 “inkscape fails to build against libpng 1.5”
 <https://bugs.launchpad.net/inkscape/+bug/721029>

[Alex Valavanis (valavanisalex)]

It would be neater to just use pkg-config as suggested in bug #261410. That will give us easy access to the library version. We can then write conditional builds (as we do with Gtk+) wherever there is an API compatibility break.

[Alex Valavanis (valavanisalex)]

Fix committed in lp:inkscape r12152. We now just use pkg-config rather than unreliable manual check.