µ-painter: embedded graphics and event system

This is a playground to figure out how to do a 2D graphics and event system (GES) on µ-controllers in a schmart™ way, i.e. fast on ARMs and yet efficient on AVRs.

This will focus on all layers of the graphics and event system process:

• memory access: either direct with FSMC, or (double-)buffered
• memory format: color depts, axis swapping, bit mappings
• acceleration: typical memory access operations optimized for format, like DMA2D support, fast line rendering
• renderers: using software renderer or external graphics card like FT8XX
• graphics context: transformations, context savings, etc.
• graphics api: with a small subset of SVG 2d api for resolution independence
• event system: something roughly similar to MicroUI from ESR but in C++

A full fledged GUI is not part of this playground, i.e. only GES, no Base Window System, no Window Manager, no UI Toolkit. Maybe later.

Have fun.

Implementation status

• C++14
• Pixel formats and colors:
  • many pixel formats with respective alpha formats. See Surfaces for renderings.
  • all operations from Porter and Duff's "Compositing Digital Images" implemented for all colors.
  • constexpr pixel color constants for compile-time casting to native color.
  • HTML 3.2 color constants.
• Pixel Buffer wrapper class.
• Surface class for applying pixel operations.
• Geometry:
  • classes for Point, Line, Size, Rectangle, Circle, Ellipse.
  • collision detection for combinations (some complex cases still missing).
  • unit tests for geometry classes.
• Math:
  • generic, constexpr and precision aware fixed_point_t class.
  • extensive unit tests for fixed_point_t.
• Renderer:
  • primitive rendering and filling.
    • Line.
    • Rect.
    • Circle.
    • Ellipse.
  • rectangular clipping not using guard band clipping (where possible).
  • anti-aliased rendering.
  • rendering unit tests.
• Simulation in Qt:
  • rendering into QImage with basic viewer.
  • native Qt project compiles with Qt 5.5 and statically linked xpcc library.
• working unit test harness from xpcc
• benchmarks of rendering
• optimization rendering

Example rendering in simulator showing RGB332 color format with clipped primitives: