Claw & Bitmaps

Claw & Bitmaps

[Cornel Arnet]

Hi,

well, Claw works now, but I can't find out how to use bitmap operations like
Get_Size, Set_Pixel,..
there's always this parameter On_Canvas of type Root_Canvas_Type'Class,
which is defined not visible. So how can I use it? (examples would be great)

Thanks
Cornel

Re: Claw & Bitmaps

[tmoran]

>there's always this parameter On_Canvas of type Root_Canvas_Type'Class,
  You don't just draw things in Windows.  You have to wait to be asked.
Create a window type, overiding When_Draw, then open a window of that
type.  Your When_Draw routine will be called whenever the window needs
to be drawn.  Notice the Basic_Canvas_Type'class parameter.  That's what
you pass, along with your bitmap, to Copy_To_Canvas to actually make the
bitmap show up on the CRT.  Similarly for Set_Pixel.  Think of the
window as glass, and the canvas as the actual surface behind the glass
that has the picture.

Re: Claw & Bitmaps

[tmoran]

"Cornel Arnet" <cornel.arnet@epfl.ch> said:
>well, Claw works now, but I can't find out how to use bitmap operations like
  Look at http://members.home.net/twmoran/H1.htm  (note the capital H).
An early, incomplete, testing version of the html Claw docs is currently there.
It does include some stuff for Claw.Bitmaps

Re: Claw & Bitmaps

[Randy Brukardt]

Cornel Arnet wrote in message <976mph$l2m$1@bw107zhb.bluewin.ch>...
>Hi,
>
>well, Claw works now, but I can't find out how to use bitmap operations
like
>Get_Size, Set_Pixel,..
>there's always this parameter On_Canvas of type Root_Canvas_Type'Class,
>which is defined not visible. So how can I use it? (examples would be
great)


You have to create a canvas of some type before you can draw in it.
You'll find the canvas types in the family of Claw.Canvas packages
(Claw.Canvas.Window, Claw.Canvas.Paint, etc.). But you may want to
follow Tom's advice and wait for Windows to call you with a canvas
before doing anything.

            Randy.



>
>Thanks
>Cornel
>
>