Help with programming using libcairo

[Kevin O'Gorman]

Well, color me embarrassed.  That was simple, and it worked, and I even
knew why as soon as I read it.  I didn't need -png, though.  The -static
was just one of my attempts to figure this out.


On Sat, May 18, 2013 at 5:29 PM, Tony Arnold
<tony.arnold at manchester.ac.uk>wrote:

> Kevin,
>
> On 17/05/13 16:15, Kevin O'Gorman wrote:
> > On Thu, May 16, 2013 at 2:50 PM, Tony Arnold
> > <tony.arnold at manchester.ac.uk <mailto:tony.arnold at manchester.ac.uk>>
> wrote:
> >
> >     Kevin,
> >
> >     On 16/05/13 22:35, Kevin O'Gorman wrote:
> >     > I'm trying to work with the tutorial at
> >     http://cairographics.org/tutorial/
> >     > but cannot get anything to compile and link.
> >     >
> >     > I entered their first example, and all of the cairo_* symbols show
> up
> >     > undefined in the link phase.
> >     >
> >     > I'm compiling the tutorial's simplest example, a hello.c program,
> >     using
> >     > gcc `pkg-config --cflags --libs cairo`  -static hello.c -o hello
> >     >
> >     > and it looks like the library's empty.  However, when I use nm(1)
> on
> >     > /usr/lib/i386-linux-gnu/cairo.so
> >     > I see those symbols. The nm utility does not seem to work on the
> .so
> >     > library, even after following symlinks.
> >     >
> >     > pkg-config --libs cairo
> >     > just emits "-lcairo"
> >     >
> >     > I've tried inserting -L /usr/lib/i36-linux-gnu/ to no avail.
> >     >
> >     > I'm not sure what else to try.
> >
> >     Can you post your example program somewhere?
> >
> >     Regards,
> >     Tony.
> >
> >
> > No need for a somewhere, it's so short.  It's from the tutorial
> >
> > #include <cairo.h>
> >
> > int
> > main (int argc, char *argv[])
> > {
> >         cairo_surface_t *surface =
> >             cairo_image_surface_create (CAIRO_FORMAT_ARGB32, 240, 80);
> >         cairo_t *cr =
> >             cairo_create (surface);
> >
> >         cairo_select_font_face (cr, "serif", CAIRO_FONT_SLANT_NORMAL,
> > CAIRO_FONT_WEIGHT_BOLD);
> >         cairo_set_font_size (cr, 32.0);
> >         cairo_set_source_rgb (cr, 0.0, 0.0, 1.0);
> >         cairo_move_to (cr, 10.0, 50.0);
> >         cairo_show_text (cr, "Hello, world");
> >
> >         cairo_destroy (cr);
> >         cairo_surface_write_to_png (surface, "hello.png");
> >         cairo_surface_destroy (surface);
> >         return 0;
> > }
> >
> > It compiles okay to a .o file.  I can't figure out how to link it.
>
> Sorry for delay in replying. Answer is simple. Put the name of the
> source file before the pkg-config bit opf your command, i.e.,
>
> gcc hello.c `pkg-config --cflags --libs cairo-png` -o hello
>
> I also changed '--libs cairo' to '--libs cairo-png'. Not sure if that is
> really needed.
>
> Also remove the -static option.
>
> HTH.
>
> Regards,
> Tony.
> --
> Tony Arnold,                        Tel: +44 (0) 161 275 6093
> Head of IT Security,                Fax: +44 (0) 705 344 3082
> University of Manchester,           Mob: +44 (0) 773 330 0039
> Manchester M13 9PL.                 Email: tony.arnold at manchester.ac.uk
>
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-- 
Kevin O'Gorman

programmer, n. an organism that transmutes caffeine into software.
Please consider the environment before printing this email.
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