Hi, Juan José

On Tue, Mar 31, 2020 at 10:03 AM Juan José García-Ripoll <
juanjose.garciaripoll@gmail.com> wrote:

> I have build GDI+ as a built-in back-end with which to compile Emacs. An
> Emacs built with GDI+ requires UTF-16 support and thus will not run on
> Windows 98, but it will run on Windows XP on later. GDI+ support is
> optional because it can be selected at build time, not because it can be
> chosen at compilation time.

Assuming you mean "not because it can be chosen at run time", ok, but then
the
(not really) "official" builds of Emacs for Windows will either not use
GDI+, or
it'll be necessary to provide GDI+ and non-GDI+ builds. We still want to
support
Windows 9X.

> WIC and Direct2D are Windows' now standard display components, providing
> support for accelerated GPU-based processing. WIC can act as a canvas
> for rendering other components and would allow for a more up-to-date
> capability in terms of image processing.

Well, then it would be perhaps a worthy goal for (GDI+ builds of) Emacs to
detect
WIC at run-time and use it instead.

> > I mean, if as Eli suggests you're going to dynamically check for GDI+
> > support and revert back to the current API in Windows 9X,...
>
> Neither of us said this. It is a compilation parameter.

Eli said:

> We cannot do this at compile time, because we still try supporting
> ancient Windows versions where GDI+ is not available.  Moreover, I
> think it's good to let users have the ability to decide dynamically
> which image display capability they want.  It certainly makes sense to
> do that initially, while the GDI+ way is being tested in all kinds of
> real-life use cases.
> So all the compile-time tests will have to be rewritten as run-time
> tests, and we should provide variables to force Emacs use/not use
> GDI+, perhaps at image format granularity, and expose those variables
> to Lisp, so users could control that.

Did I misunderstand him?