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Date: Wed, 22 Sep 2004 09:21:59 +0200
From: =?iso-8859-1?q?Jens_Axel_S=F8gaard?= <usenet@soegaard.net>
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Subject: Re: Displaying bitmaps
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Dennis Dunn wrote:

> I'm using PLT Scheme to do some image processing.  I would like to=20
> display an image file but the viewport graphics module doesn't seem to=20
> have an easy way to do this.
>=20
> I see that there is a method to draw an image in a viewport but the=20
> viewport must be the proper size first.  I need to know the resolution=20
> of the image file before I can create a viewport big enough to draw into.

If you just want to see the image, then you can use the repl as in
<http://schemecookbook.org/Cookbook/GUIRecipeImagesInTheInteractionWindow>.
Otherwise make a bitmap (search for bitmap% in the HelpDesk) and then
call the methods get-height and get-depth to find the size.

> The MrEd module has a bitmap% class that would seem to do what I need,=20
> that is I can load an image file into the bitmap% object without knowing=
=20
>  the resolution of the image.  However, I haven't been able to figure=20
> out how to display the bitmap% object.

> I could load the image file into the bitmap% object and do all of my=20
> processing on the bitmap device context if only I could display the=20
> bitmap%.  Or I could do all of my processing on a viewport (or pixmap)=20
> if I could easily load the file into the viewport.

The function update-view is an example of how to do this:
     <http://schemecookbook.org/view/Cookbook/GUIRecipeAnimation>.
First one gets a drawing context from the canvas, and then
the method draw-bitmap of the drawing context is called with the
bitmap as one of it's arguments.

--=20
Jens Axel S=F8gaard

]