Question

I want to create a window using GTK 3 under linux (fedora 12) and draw on it a simple rectangle using cairo-gl backend, for this I want to create a cairo-gl surface. How can I do this, can anybody help me with a sample code.

Thanks in advance.

RC7

Answer 1

Well, first of all you need to make sure your cairo version has gl support. I m not sure the version in Fedora 12 has it. You may have to compile your own cairo.

Then you need to look at cairo-gl.h: http://cgit.freedesktop.org/cairo/tree/src/cairo-gl.h

This file has a nice comment explaining that first you need to create a cairo_device using your gl context and then pass it to cairo_gl_surface_create().

This file from the cairo test suite contains an example of a gl surface: http://cgit.freedesktop.org/cairo/tree/test/gl-surface-source.c

Notice that it is a .c file that includes another .c file: http://cgit.freedesktop.org/cairo/tree/test/set-source.c

The test suite is full of cairo programming examples. Use it! :)

I m not sure how you do GL using GTK3, but in the worst case, you can use GDK to get X11 s Display and Window IDs, then you use standard glx calls: http://developer.gnome.org/gdk3/stable/gdk3-X-Window-System-Interaction.html

And to use cairo with GTK3, you need to look at this: http://developer.gnome.org/gdk3/stable/gdk3-Cairo-Interaction.html And this: http://zetcode.com/tutorials/cairographicstutorial/

I gave you a bunch of Lego bricks. Now you need to assemble them. (Or maybe someone with more time will do it and write a better answer here?)

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