On 31 Oct 2011, at 21:33, David Allen wrote:
> I'm interested in having a cairo window as a member of a group. the cairo
> example in the test directory has the cairo window as the main window. Since
> the constructor has only width and height arguments, i don't see a way to put
> it in a group.
To be honest, when I want a cairo "subwindow" I don't generally use the
"native" fltk cairo hooks - they were added after a lot of my codebase was
written, so I have a heap of code that already did it differently anyway...
So, what I do is derive my own widget from Fl_Box, then in the draw() method of
that box, I do something like (paraphrasing wildly...)
At the top of the draw method, make sure I have a valid cairo surface and
context to draw into, something like...
#ifdef WIN32
/* Get a Cairo surface for the current DC */
HDC dc = fl_gc; /* Exported by fltk */
surface = cairo_win32_surface_create(dc);
#else
# ifdef __APPLE__
# ifdef __APPLE_QUARTZ__
/* Get a Cairo surface for the current CG context */
CGContext *ctx = (CGContext *)fl_gc;
surface = cairo_quartz_surface_create_for_cg_context(ctx, (int)w,
(int)h);
# else
/* Fatal compile time error */
# error Apple quartz platform not defined
# endif
# else
/* Get a Cairo surface for the current display */
surface = cairo_xlib_surface_create(fl_display, fl_window,
fl_visual->visual, (int)w, (int)h);
# endif
#endif
/* Store the cairo context */
cairo_context = cairo_create(context->surface);
/* All Cairo co-ordinates are shifted by 0.5 pixels for anti-aliasing */
#ifndef __APPLE__ // Apple Quartz does not need the offset nudge
cairo_translate(cairo_context, 0.5, 0.5);
#endif
And at that point I have a usable cairo state I can draw into... "normal" cairo
drawing follows...
Then I dispose of the context like...
/* Destroy the Cairo surface */
cairo_destroy(cairo_context);
cairo_surface_destroy(surface);
And that pretty much seems to work.
Since the widget derives from Fl_Box, embedding it into an Fl_Group is
straightforward...
Any use?
HTH,
--
Ian
_______________________________________________
fltk mailing list
[email protected]
http://lists.easysw.com/mailman/listinfo/fltk
