On Thu, 6 Sep 2018 at 11:40, Emmanuele Bassi via gtk-devel-list
<gtk-devel-list@gnome.org> wrote:
> On Wed, 5 Sep 2018 at 19:25, Magnus Bergman <magnus.berg...@snisurset.net> 
> wrote:
>> Gegl is great for image editing. But not as much for simple viewing.
> This is debatable. If I'm viewing a 4000x4000 RGB image on a hidpi display 
> I'm already pushing gdk-pixbuf and cairo to their limits because of the 
> scaling factor applied to the window — not only the buffer gets loaded 
> uncompressed to allow for zooming, but the image viewer needs to render a 
> CPU-scaled down copy of the image.

It doesn't have to be gegl, of course, you could use any image
processing library to load and scale down the images. I made a tiny
image viewer based on libvips:


It's 300 lines, but does multi-threaded, asynchronous painting of many
image formats. It can display gigapixel images on very modest
hardware, and it should be quick.

There's a more complete image viewer here:


That adds most of the usual navigation stuff, though it's not quite
done, I must get back to it. The image display part is a widget you
could easily cut out and paste into other applications. It's in C, but
libvips is a GObject-based library, so it'd be easy to write in any

Here it is displaying a 18k x 8k 16-bit TIFF:


That image takes about 8s to load on this laptop. Here it is
displaying a 120k x 100k pixel ndpi slide image:


That image loads instantly, since ndpi supports random access and
vipsdisp can just load the parts it needs to paint the screen.

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