Re: [AD] Multiple window icons

[Peter W. <nov...@gm...>]

On Sat, 13 Oct 2012 12:51:16 +0200, Elias Pschernig <in...@al...> wrote:
> On Sat, 13 Oct 2012 14:56:35 +1100
> Peter Wang <nov...@gm...> wrote:
> 
> > Hi,
> > 
> > Allegro doesn't support multiple window icons at the moment.
> > Here is a possibility:
> > 
> >     bool al_set_display_icons(ALLEGRO_DISPLAY *display,
> > 	int num_icons, ALLEGRO_BITMAP *icons[]);
> > 
> > where num_icons >= 1.
> > 
> > On some systems, Allegro may just pass converted but otherwise
> > unscaled images through to the window environment, and let it choose
> > the appropriate one for whatever context (taskbar, alt-tab selector,
> > etc.)
> > 
> > On other systems, Allegro may use an exact size bitmap if possible or
> > upscale the next smallest bitmap to the size required by the
> > environment.  I assume scaling up is preferable to scaling down at
> > icon resolutions.
> > 
> > How does that sound?
> > 
> 
> I think scaling down works best. All our icons were made by scaling
> down a 512x512 pixel bitmap (and I think in many cases Apple just
> scales down that bitmap themselves - but not sure).

It depends on the resolutions and the scaling algorithm.

al_set_display_icon scaling down a 32x32 icon to 16x16 can make for an
incomprehensible mess: it just drops 3/4 pixels after all.  On the other
hand scaling up the 16x16 icon to 32x32 gains nothing, but loses nothing
either.

> And I don't know anything about Window icons, so if on some platform
> multiple sizes make sense, that function sounds good.

Windows supports at least two sizes, and X11 supports multiple
(run xprop and click on Firefox or Chrome, for example).

Peter