[Caml-list] Lablgtk3 & Cairo & drawing area

[Caml-list] Lablgtk3 & Cairo & drawing area

[Philippe Strauss]

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.


--
I thought I caught you stealing from my cuckoo mind
        -- The House Of Love

Re: [Caml-list] Lablgtk3 & Cairo & drawing area

[Philippe Strauss]

It seems « Gdk.Cairo.create » is what I was looking for.

> Le 15 janv. 2021 à 14:21, Philippe Strauss <philippe@strauss-engineering.ch> a écrit :
> 
> 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.
> 
> 
> --
> I thought I caught you stealing from my cuckoo mind
>        -- The House Of Love
> 
> 

--
if you lie on the ground in somebody’s arms
you'll probably swallow some of their history
        -- Suzanne Vega