Glad I could help. It took me a long, long time (~3 days working on it
nearly non-stop) to figure that one out.
Since it actually is pretty useful, perhaps I should get around to adding it
to some documentation... Anyone agree?
We'll see how much free time I'll get in the next week.
--Chris Wilson
On Tue, Aug 12, 2008 at 9:45 AM, John Hobbs <[EMAIL PROTECTED]> wrote:
> That works brilliantly. Thank you very much. I never would have
> gotten to that one on my own, don't understand the internals enough.
> :-)
>
> - John Hobbs
>
> [EMAIL PROTECTED]
>
> On Tue, Aug 12, 2008 at 12:15 AM, Chris Wilson
> <[EMAIL PROTECTED]> wrote:
> > Here is the method I successfully use:
> >
> > I have a class called daViewMap which is derived from Gtk::DrawingArea
> > I use a Cairo::ImageSurface to import a 2-D array into an useful image
> form
> > for Cairo.
> >
> > class daViewMap : public Gtk::DrawingArea
> > {
> > public:
> > Cairo::RefPtr<Cairo::ImageSurface> viewSurface;
> > Cairo::RefPtr<Cairo::Context> myCr;
> > };
> >
> > daViewMap::daViewMap() :
> > {
> > viewSurface = Cairo::ImageSurface::create(&viewMap[0][0],
> > Cairo::FORMAT_A8, VIEW_MAP_X, VIEW_MAP_Y, VIEW_MAP_X );
> > myCr = Cairo::Context::create(viewSurface);
> > }
> >
> > I perform all the cairo-based drawing using the context daViewMap->myCr
> > and then extract the image via a button callback:
> >
> > void exportImage(std::string filename)
> > {
> > Glib::RefPtr<Gdk::Window> win2 = daViewMap->get_window();
> > if (win2)
> > {
> > Glib::RefPtr<Gdk::Drawable> dra2 =
> > Glib::RefPtr<Gdk::Window>::cast_dynamic(win2);
> > Glib::RefPtr<Gdk::Pixbuf> img2 = Gdk::Pixbuf::create(dra2 ,0
> ,0
> > ,daViewMap->get_allocation().get_width(),
> > daViewMap->get_allocation().get_height());
> > img2->save(filename,Glib::ustring("png"));
> > }
> > }
> >
> > Note the use of a Pixbuf to extract the image from the drawing area's
> space,
> > and then we use that to save it out to a file.
> >
> > Hope that makes sense...
> > Chris Wilson
> >
> > On Mon, Aug 11, 2008 at 5:48 PM, John Hobbs <[EMAIL PROTECTED]>
> wrote:
> >>
> >> Hello, I apologize if this is off-topic as it deals a lot with Cairo,
> >> I feel it is a borderline thing. Please feel free to send me packing
> >> to somewhere else if I'm wrong on that point :-)
> >>
> >> I'm trying to load an image into a DrawingArea, then put lines on it
> >> with Cairo and get that back out. Is this possible or do I need to go
> >> figure out something with GC and Drawable?
> >>
> >> Here's the guts of the procedure so far, sorry it's big but I don't
> >> know how to trim it down and keep it understandable.
> >>
> >> ---------------------------------------------
> >> class ExampleWindow : public Gtk::Window {
> >>
> >> public:
> >> ExampleWindow (std::string path) {
> >> imagePB = Gdk::Pixbuf::create_from_file(path);
> >>
> >>
>
> drawOnMe.signal_expose_event().connect(sigc::mem_fun(*this,&ExampleWindow::on_da_expose_event));
> >> add(drawOnMe);
> >> show_all();
> >> }
> >>
> >> private:
> >> Gtk::DrawingArea drawOnMe;
> >> Glib::RefPtr<Gdk::Pixbuf> imagePB;
> >>
> >> bool on_da_expose_event (GdkEventExpose * event) {
> >> std::cout << "Expose Event" << std::endl;
> >> Glib::RefPtr<Gdk::Window> window =
> >> drawOnMe.get_window();
> >> Cairo::RefPtr<Cairo::Context> context =
> >> window->create_cairo_context();
> >> Cairo::RefPtr<Cairo::ImageSurface> image_surface
> =
> >> Cairo::ImageSurface::create (Cairo::FORMAT_RGB24,
> >> imagePB->get_width(), imagePB->get_height());
> >> Cairo::RefPtr<Cairo::Context> image_context =
> >> Cairo::Context::create(image_surface);
> >>
> >> Gdk::Cairo::set_source_pixbuf (image_context,
> >> imagePB, 0.0, 0.0);
> >> image_context->paint();
> >>
> >> context->set_source(image_surface, 0.0, 0.0);
> >> context->paint();
> >>
> >> context->set_line_width(5.0);
> >> context->set_source_rgb(0.8, 0.0, 0.0);
> >> context->move_to(10,20);
> >> context->line_to(100, 200);
> >> context->stroke();
> >>
> >> return false;
> >> }
> >> };
> >> ---------------------------------------------
> >>
> >> I tried getting a surface from that context after the stroke() call
> >> and then a write to PNG:
> >>
> >> Cairo::RefPtr<Cairo::Surface> sfc = context->get_target();
> >> sfc->write_to_png("please_work.png");
> >>
> >> That just crashed on an expose event and I didn't bother to debug. I
> >> have the feeling I've gone wrong in my understanding of Cairo.
> >>
> >> So I guess what it boils down to is I'm curious if there is an easier
> >> path by using something in Gtkmm (which I chased my tail for a long
> >> time trying to find something) or if there is a way to get that drawn
> >> data back out of there.
> >>
> >> Thanks for any and all help :-)
> >>
> >> - John Hobbs
> >>
> >> [EMAIL PROTECTED]
> >> _______________________________________________
> >> gtkmm-list mailing list
> >> [email protected]
> >> http://mail.gnome.org/mailman/listinfo/gtkmm-list
> >
> >
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