Closest cross-platform alternative to Direct2D/DirectWrite?

What are some good cross-platform alternatives to Windows-specific 2D APIs? I'm looking for an API for rendering simple geometric objects as well as an API for rendering text with subpixel antialiasing (ClearType) and OpenType support, specifically support for hinting.

Solution

OpenGL is the defacto cross-platform graphics API. OpenGL supports the FreeType and OpenType libraries. Newer versions of FreeType (2.7+) have support for sub-pixel hinting similar to what DirectWrite offers.

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