Re: GDI+ take 3

[Alan Third <alan@idiocy.org>]

On Tue, Apr 21, 2020 at 09:35:05AM +0200, Juan José García-Ripoll wrote:
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Also, do you have any suggestions how to fix this?  Perhaps we should first
> > create the images and cache them, and only then start the animation?  Some
> > other ideas?
> 
> That is one option. I am not sure about the logic on caching, and whether it
> warrants that all frames would be kept in memory.
> 
> Other than that, one might have to reconsider the current mechanism how images
> are built. In all platforms, when using giflib, images cleared various times
> and built using PUT_PIXEL. I think this is behind the slowdown compared to
> GDI+.
> 
> To make an informed decision, it would be appropriate to know what happens on
> other platforms. In OSX it seems that loading of gifs is fast enough that, like
> GDI+, no fix would be required. What about Xwindows / Cairo? Does it vary much?
> I do not have machines to gather this information

Loading of gifs on macOS may be fast enough because the image library
does its own caching, so may not be regenerating the images from
scratch each time.

XWindows (and I think Cairo) uses giflib exclusively, so shouldn’t
perform substantially different from either Windows or macOS when
using giflib instead of the native image library.

I agree with you, though, that fixing this particular performance
problem would require us to rethink how we load and cache images.

-- 
Alan Third