Blurry Text on Windows with Non-HDPI Displays (Linux is ok)

Hi,

On Windows, Gtk will by default use

  • the platform’s font renderer (i.e. DirectWrite or GDI)
  • the system font (i.e. “Segoe UI 9”)

But due to technical reasons, Gtk4 doesn’t support RGB subpixel aliasing, but only grayscale. This is an issue, because:

  • DirectWrite doesn’t handle grayscale subpixels as good as RGB ones
  • The Segoe font is optimized for RGB aliasing, and renders weird in grayscale

There are several options to improve rendering:

  • disable DirectWrite in Pango, like they do in msys2 (see patches)
  • use another font renderer, like fontconfig, by setting the environment variable PANGOCAIRO_BACKEND=fc
  • use another font than Segoe

I detailed some days ago my personal font config on Windows, you may want to have a look.