The 1.20 update made breaking changes to the way items are rendered in the GUI. I've been looking through the code (yarn 1.20+build.1) and I found the following things.

• Many methods were removed from ItemRenderer (including renderGuiItemIcon).
• The Fabric guide says that in many places DrawContext is now used instead of MatrixStack.
• net.minecraft.client.gui.hud.InGameHud.renderHotbarItem uses DrawContext.drawItemInSlot(TextRenderer, ItemStack, int, int) in 1.20 instead of what was used in 1.19.4 (ItemRenderer.renderGuiItemOverlay(MatrixStack, TextRenderer, ItemStack, int, int))`
  • Those two integers are called x and y in the 1.20 code, but the 1.19.4 appears to use the original parameter names (i and j).

If I figure out how to make the mixin work in 1.20 I will make a PR.

Thanks Adam, appreciate it.

I probably won't have a chance to review until after the 19th of June, so a PR would be amazing if you get the chance.

Resolved by #18.