What underlying graphics library for text output Sublime Text is using?

Question

I noticed that Sublime Text has much better rendering for some fonts and sizes than Scintilla based editors. How is that achieved? Is there some famous text renderer underneath it or they developed their own?

Answer 1

Sublime Text uses highly tuned settings over platform-specific libraries to render text. It has actually used several different libraries throughout the years. I couldn't find any specifics for OSX, but there are some details for Windows/Linux in the forums and release notes.

In ST3 build 3034, it is noted that the graphics rendering engine was "ported to Skia from Cairo". However, it is not clear if there was custom text rendering being done, or if it is just for UI elements.

Sublime Text 1

I can't find a good reference for version 1, but through bits and pieces of forum conversations, it looks like it may have been a custom rendering engine written on top of OpenGL. Other forum posts point out that all future rendering would be pure software as there was a lot of cross-platform issues caused by GPU rendering.

The best quote I could find was this:

Sublime Text 2 uses software rendering only. Ultimately, it caused too many compatibility issues in 1.x, and with going cross platform for version 2, that would only have increased. Nonetheless, I'll talk about Sublime Text 1.x for a bit.

The basic text rendering itself was fairly standard: textured quads are drawn to the screen, one per character. However, there are a few details worth noting:
* Characters are buffered, and sorted by color, to reduce state changes.
* Most OpenGL applications will have a single channel texture for the characters, and blend the desired color on top. Sublime Text uses RGB textures, with the text pre-composed with the correct foreground and background color. This takes more memory, but allows ClearType to be used, which is important for a text editor.

Sublime Text 2 (release notes)

Windows uses GDI, with an option added in build 2081 to use DirectWrite instead.

In build 2170, Pango was added as the rendering on Linux to improve support for cjk text.

Sublime Text 3 (release notes)

DirectWrite replaced GDI as the default renderer on Windows in build 3127, unless you are using the fonts Consolas or Courier New. GDI was kept as a rendering option in the settings.