Add support for font antialiasing

[dgolub]

One major feature that's present in System.Drawing but missing in ImageSharp is rendering text with antialiasing. I have some code on my web site for rendering county route shields that looks like this:

FontFamily family = SystemFonts.Get("Arial");
Font smallFont = family.CreateFont(3);
TextOptions smallTextOptions = new(smallFont) {
    Dpi = 96,
    HorizontalAlignment = HorizontalAlignment.Center,
    Origin = new Point(x, y),
    WrappingLength = 42
};
Color smallTextColor = Color.FromRgb(0xF7, 0xD1, 0x17);
image.Mutate(ctx => ctx.DrawText(smallTextOptions, "COUNTY", smallTextColor));

Due to the small 3-point font size, this leads to the text appearing pixelated as in the attached image. I did not have this issue with System.Drawing when I enabled ClearType, but as far as I can tell, there's no equivalent in ImageSharp as the moment.

[JimBobSquarePants]

I think you're mixing AntiAliasing with Hinting.

Antialias is turned on by default.
https://docs.sixlabors.com/api/ImageSharp/SixLabors.ImageSharp.GraphicsOptions.html#SixLabors_ImageSharp_GraphicsOptions_Antialias

Hinting is turned off by default (because it's experimental)
https://docs.sixlabors.com/api/Fonts/SixLabors.Fonts.TextOptions.html#SixLabors_Fonts_TextOptions_ApplyHinting

[dgolub]

No, that doesn't seem to make a difference. I turned on ApplyHinting, and it still appears pixelated.

[JimBobSquarePants]

Like I said. Experimental....

Hinting is..... Hard. I'd love to learn a lot more about how FreeType does hinting but I find their code difficult to parse so would love some community help to improve matters.

[JimBobSquarePants]

Managed to make a fairly large improvement to the hinter (not pushed currently). I'll need to look at the drawing library next to figure out LCD ratserization to include the color anti aliasing System.Drawing uses. That's where a big improvement would come.

Hinting - Y direction only

Hinting - X & Y

[dgolub]

Awesome! That definitely looks like a major improvement. Looking forward to the upgrade!