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Glyph Blaster

WIP C++11 Port

Justifications.

  • Standard smart pointers that will make the memory management of resources less error prone.
  • can drop dependency on uthash and utlist, and use standard collections
  • lamdas provide a better mechanism for rendering hooks then c function ptrs.
  • all of my personal projects are in C++, C linkage is not important to me.
  • shared lib version of library is also not important to me.
  • Interop with other languages is not important to me.

Design questions

Should Context be a singleton? YES. simplifies things, i can sort this out later if necessary.

Architecture Diagram

Image

The Context holds a weak collection of all gyphs ever created. Each Text object holds a collection of glyphs it is activly using.

Features

  • Pluggable render function, to integrate into existing engines.
  • Uses HarfBuzz for glyph shaping for ligatures & arabic languages.
  • FreeType is used for rasterization, after shaping.
  • Manages glyph bitmaps in a tightly packed set of OpenGL textures.
  • utf8 support
  • rtl language support (arabic & hebrew)

Dependencies

  • FreeType2
  • HarfBuzz-0.9 (optional)

Implementation Notes

  • When cache is full, glyphs will use a fallback texture, which is 1/2 alpha.
  • When glyph is not present in the font, the replacement character is used. �
  • Bidi text is not supported, it makes word-wrapping a pain.
  • I still don't know how slow a full repack is. Benchmark it.
  • I'm not sure if the interface is very good.
    • Text's are not mutable, they must be destroyed and re-created.
    • No metrics available.
    • The metrics should be good enough to perform custom word-wrapping, bidi, underline & html styles at a higher level.

TODO:

Dependency Build Tasks

  • Bundle harf-buzz, to make building easier

Implementation Tasks

  • Split MakeGlyphQuadRuns into two parts.
    • Build metrics/do word wrapping.
    • Build quads from metrics.
  • Group quads that share the same texture into a single mesh.
  • Add metrics function to text.
  • Add ability to set pen position.
  • Test support of LCD subpixel decimated RGB using shader and GL_COLOR_MASK
  • Enable sRGB aware blending, during rendering. (if available) provide a sample renderer
  • Justify-Vertical: top, center, bottom
  • Justify: Scale to fit
  • currently two fonts with different pt sizes will have two copies of the same FreeType font. resources should be shared.
  • add glyph bitmap-padding option, necessary for scaled or non-screen aligned text.
  • Currently mipmapping on glyph texture is disabled.
  • bidi
  • Better SDL test prog.
  • Add pluggable texture creation & subload functions, for Direct3D renderers.