looking for alternative drawing api

[magiruuvelvet]

Currently QtGui is used to draw the subtitle images from a text source using manual drawing with QPainter. I'm looking for Qt-free alternatives written in modern C++ (object oriented API, avoid "C-style C++"), optimally under a permissive license like MIT or BSD. The library optimally should support RGBA8888, exactly in that order, otherwise additional computing time must be wasted converting the color space to RGBA (alpha must be at last position). It must support alpha transparency.

The following features are absolutely mandatory for position calculation of the subtitle images:

• font support with correct font metrics to get the exact drawn glyph size (the size may differ before and after the drawing when stylings are applied, see QFontMetrics for details).
• api must report the size and position where text is drawn to move the coordinates correctly, especially for vertical text drawing and furigana placement

Optimally those would be nice:

• real text border (the current implementation is just brute force, because QPainter lacks some APIs)

The current implementation is a good starting point to understand those requirements. While this application still isn't stable yet, I want to preserve the output as much as possible (same in same out principle).