[Caml-list] Lablgtk3 & Cairo & drawing area

[Philippe Strauss <philippe@strauss-engineering.ch>]

Hello ocaml users,

Using previously lablgtk2, I was using Cairo_gtk to get a Cairo context from a gdkwindow:

cairo_ctx <- Some (Cairo_gtk.create (self #area) #misc #window) ;

Now I want to definitively switch to Lablgtk3. Using the following:

cairo_ctx <- Some (Cairo.create (self #area) #misc #window) ;

I get this build error:

————8<--------
- build straightliner/plwrap plot2d.cmx
+ ocamlfind ocamlopt -package lablgtk3,cairo2,plplot,plcairo,react,batteries,logs,logs-ppx -warn-error -a -thread -inline 10 -I . -I /Users/philippe/mysrc/sp_base.ml -I sigproc -I /Users/philippe/mysrc/zfilters -I plwrap -I /Users/philippe/mysrc/sp_base.ml -c plot2d.ml
File "plot2d.ml", line 132, characters 44-70:
132 |             cairo_ctx <- Some (Cairo.create (self #area) #misc #window) ;
                                                  ^^^^^^^^^^^^^^^^^^^^^^^^^^
Error: This expression has type Gdk.window = [ `gdkwindow ] Gobject.obj
       but an expression was expected of type Cairo.Surface.t
————8<--------

How do I get from a gdkwindow to a Cairo surface.t, or more generally, what is wrong with my code?

TIA, Philippe.


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