I'm implementing a language for robot development in Minecraft and I want to add syntax highlighting to my language. This could be accomplished tediously by drawing each syntactic element with proper spacing, but I would prefer to just draw one string (or a string per visible line) with multiple colors in one string. This is possible to do with chat messages, but can it accomplished when drawing strings directly?

If you look at GuiNewChat#drawChat (which renders the recent chat messages), you'll see that it renders each line by calling ITextComponent#getFormattedText to get the text with formatting codes and then FontRenderer#drawStringWithShadow to render the text. FontRenderer is responsible for interpreting the formatting codes and rendering each character with the appropriate colour and style.

 

The vanilla FontRenderer only supports the colours and styles of the TextFormatting enum, you'd need to implement custom colours yourself.