scaling a GdkImage

[David Cooke <d j cooke lineone net>]

Hi,

I thought I should bring this to the attention of the gtk+ team, invite 
comments, and take the opportunity to put a question or two.

I'm just finishing porting a Win32 program to linux using gtk+ 1.2.  I'm 
proposing to release with the program a mini shared library which lumps 
together slight extensions to gdk and also gnome-print, just for use by the 
program.

The gdk stuff comprises a quick hack of code by Owen Taylor from the 
gdk-pixbuf library, providing a basic facility to scale a GdkImage.  I 
don't know anything about scaling, but it seems to work adequately for my 
purposes.

The program displays charts drawn directly to the screen using gdk drawing 
functions.  Under Win32, scaled-down versions of the charts are provided 
using the Window/Viewport scaling facility.  They can be larger than the 
screen, so need to be scrollable.  Under Linux, the chart is drawn to a 
pixmap, the pixels extracted to a GdkImage, this is scaled directly, and 
then drawn to the screen.

A couple of questions for the gtk+ team:

1  Why was this facility never provided in gdk 1.2 ?
2  Would it still be worth providing it in gdk 2 ?

I attach the code for anyone interested.

David J. Cooke

Attachment: libwt-gdkimage-x.c
Description: Text document