Re: need raster image examples

[John Cupitt ng-london org uk]

Wolfgang Rupprecht wrote:
 > I need to find a way to efficiently display a small subsection of a
 > very large (50 megapixel or more) 8-bit graymap.

Hi Wolfgang,

You have lots of choices.

The lowest level is gdk_draw_grey_image(): this paints a section of a
large image onto a section of the screen. It's very quick (fast enough
to use for video applications). gtk+1.2.x/gtk/testrgb.c has example
code. If your image is in a file, you can just mmap() it, then paint
directly from disc to screen (and beat xv by quite a margin). I do this
for >1GB files with no problems.

The gdk-pixbuf library is much higher level. This is going to be the
standard gtk thing for 2.0. It can paint sections of images in any
format to any device, with some simple transformations on the way (crop,
zoom etc).

There are also some image view widgets people have done that you can
just drop into your program. I've not used any, so I shan't try to make
a recommendation.

John




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