bug#73730: 31.0.50; Support for color fonts on MS-Windows

[Cecilio Pardo]

On 10/10/2024 15:08, Eli Zaretskii wrote:

> IOW, how about just modifying the few methods of the HarfBuzz font
> driver when DirectWrite is available, and otherwise leaving the
> HarfBuzz font driver be the one which supports this?  With Uniscribe
> we had legacy support issues (Windows 9X etc.), but there's no such
> problem with HarfBuzz vs DirectWrite, so adding yet another font
> driver which needs to coexist with the others is a complexity I'd like
> to avoid.  In my mental model, we just use DirectWrite for low-level
> drawing of font glyphs, and otherwise we still keep the HarfBuzz font
> driver.  Does that make sense?

Yes. I'll rewrite it like that.

> > +  hr = dwrite_factory->lpVtbl->
> > +    CreateCustomRenderingParams (dwrite_factory,
> > +                                def->lpVtbl->GetGamma(def),
> > +                                def->lpVtbl->GetEnhancedContrast(def),
> > +                                def->lpVtbl->GetClearTypeLevel(def),
> > +                                def->lpVtbl->GetPixelGeometry(def),
> > +                                DWRITE_RENDERING_MODE_GDI_CLASSIC,
> > +                                &rendering_params);
>
> Are there some options for the rendering here that we perhaps need to
> discuss?  E.g., is DWRITE_RENDERING_MODE_GDI_CLASSIC the only
> reasonable choice?

This gives poor quality, we will definitely use something else. But in 
my tests other methods gave fractional widths for glyphs, so I took this 
one for the first version.