A belated thanks for this. It works nicely and I am able to use it as a
starting point for my project.
>
> > > I'm interested in having a cairo window as a member of a=20
> > group. the cairo example in the test directory has the cairo=20
> > window as the main window. Since the constructor has only=20
> > width and height arguments, i don't see a way to put it in a group.
> >=20
> >=20
> > To be honest, when I want a cairo "subwindow" I don't=20
> > generally use the "native" fltk cairo hooks - they were added=20
> > after a lot of my codebase was written, so I have a heap of=20
> > code that already did it differently anyway...
>
> Coffe-break, so here's a simple demo of this approach, in the hope that
> it may be useful...
>
>
> -------------------
> /*
> * Demo of a simple cairo_box in a (nested) group
> */
> #include <FL/Fl.H>
> #include <FL/Fl_Group.H>
> #include <FL/Fl_Double_Window.H>
> #include <FL/Fl_Box.H>
> #include <FL/x.H>
> #include <FL/fl_draw.H>
> #include <FL/Fl_Button.H>
>
> #include <cairo.h>
>
> #ifdef WIN32
> # include <cairo-win32.h>
> #elif defined (__APPLE__)
> # include <cairo-quartz.h>
> #else
> # include <cairo-xlib.h>
> #endif
>
> Fl_Double_Window *main_win=3D(Fl_Double_Window *)0;
> Fl_Group *outer_group=3D(Fl_Group *)0;
> Fl_Group *inner_grp1=3D(Fl_Group *)0;
> Fl_Group *inner_grp2=3D(Fl_Group *)0;
> Fl_Group *inner_grp3=3D(Fl_Group *)0;
>
> /*************************************************************/
> class cairo_box : public Fl_Box {
> void draw(void); // draw method
> cairo_surface_t *surface;
> cairo_t *cairo_context;
> float rr, gg, bb, aa;
> void set_cairo_cxt(int wo, int ho);
> public:
> // constructor
> cairo_box(int x, int y, int w, int h) : Fl_Box(x,y,w,h) {
> surface =3D NULL; cairo_context =3D NULL;
> rr =3D gg =3D bb =3D aa =3D 0.0;}
>
> void set_rgb(float RR, float GG, float BB, float AA)
> {rr =3D RR; gg =3D GG; bb =3D BB; aa =3D AA;}
> };
> /*************************************************************/
> void cairo_box::set_cairo_cxt(int wo, int ho) {
> #ifdef WIN32
> #warning win32 mode
> /* Get a Cairo surface for the current DC */
> HDC dc =3D fl_gc; /* Exported by fltk */
> surface =3D cairo_win32_surface_create(dc);
> #elif defined (__APPLE__)
> #warning Apple Quartz mode
> /* Get a Cairo surface for the current CG context */
> CGContext *ctx =3D fl_gc;
> surface =3D cairo_quartz_surface_create_for_cg_context(ctx, wo,
> ho);
> #else
> #warning X windows mode
> /* Get a Cairo surface for the current display */
> surface =3D cairo_xlib_surface_create(fl_display, fl_window,
> fl_visual->visual, wo, ho);
> #endif
> /* Store the cairo context */
> cairo_context =3D cairo_create(surface);
>
> /* All Cairo co-ordinates are shifted by 0.5 pixels to correct
> anti-aliasing */
> cairo_translate(cairo_context, 0.5, 0.5);
> }
> /*************************************************************/
> void cairo_box::draw(void) {
> int xo =3D x(); // origin is current window position for Fl_Box
> int yo =3D y();
> int wo =3D w();
> int ho =3D h();
>
> /* draw the base widget */
> fl_push_no_clip(); /* remove any clipping region set by the
> expose events... */
> fl_push_clip(xo, yo, wo, ho); /* reset local clipping */
>
> fl_color(FL_CYAN);
> fl_rectf(xo, yo, wo, ho);
> // set cairo context
> set_cairo_cxt(wo, ho);
> // draw a triangle pointing upwards
> int x1, y1, x2, y2, x3, y3;
> x1 =3D xo + wo/2; y1 =3D yo;
> x2 =3D xo + wo; y2 =3D yo + ho;
> x3 =3D xo; y3 =3D y2;
> cairo_set_source_rgba(cairo_context, rr, gg, bb, aa);
> cairo_new_path(cairo_context);
> cairo_move_to(cairo_context, x1, y1);
> cairo_line_to(cairo_context, x2, y2);
> cairo_line_to(cairo_context, x3, y3);
> cairo_line_to(cairo_context, x1, y1);
> cairo_fill(cairo_context);
> // release the cairo context
> cairo_destroy(cairo_context);
> cairo_surface_destroy(surface);
> cairo_context =3D NULL;
>
> fl_pop_clip(); // remove the local clip region
> fl_pop_clip(); // remove the "no_clip" region
> } // draw method
>
> /*************************************************************/
> cairo_box *cairo1=3D(cairo_box *)0;
> cairo_box *cairo2=3D(cairo_box *)0;
> cairo_box *cairo3=3D(cairo_box *)0;
> /*************************************************************/
> static void cb_Quit(Fl_Button*, void*) {
> main_win->hide();
> }
>
> /*************************************************************/
> int main(int argc, char **argv) {
> main_win =3D new Fl_Double_Window(500, 500);
> main_win->begin();
>
> Fl_Button* o =3D new Fl_Button(430, 460, 60, 30, "Quit");
> o->box(FL_THIN_UP_BOX);
> o->callback((Fl_Callback*)cb_Quit);
>
> outer_group =3D new Fl_Group(5, 5, 490, 450);
> outer_group->begin();
>
> inner_grp1 =3D new Fl_Group(5, 5, 160, 450);
> inner_grp1->begin();
> cairo1 =3D new cairo_box(7, 7, 156, 446);
> cairo1->box(FL_FLAT_BOX);
> cairo1->set_rgb(1.0,0,0,0.7);
> inner_grp1->end();
> inner_grp1->box(FL_DOWN_BOX);
>
> inner_grp2 =3D new Fl_Group(165, 5, 160, 450);
> inner_grp2->begin();
> cairo2 =3D new cairo_box(167, 7, 156, 446);
> cairo2->box(FL_FLAT_BOX);
> cairo2->set_rgb(0,1.0,0,0.9);
> inner_grp2->end();
> inner_grp2->box(FL_DOWN_BOX);
>
> inner_grp3 =3D new Fl_Group(325, 5, 170, 450);
> inner_grp3->begin();
> cairo3 =3D new cairo_box(327, 7, 166, 446);
> cairo3->box(FL_FLAT_BOX);
> cairo3->set_rgb(0,0,1.0, 0.3);
> inner_grp3->end();
> inner_grp3->box(FL_DOWN_BOX);
>
> outer_group->end();
> // outer_group->resizable(inner_grp2);
>
> main_win->end();
> main_win->resizable(cairo1);
> main_win->label("Cairo Box Test");
> main_win->show(argc, argv);
>
> return Fl::run();
> }
> /* end of file */
>
>
>
>
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