Workspace orbtk_tinyskia

Rendering is a key component of the toolkit. Everybody is expecting state of the art presentation of implemented widgets. User interaction that will result in layout and entity changes inside the GUI should be updated as soon as possible. A comfortable user experience is mainly influenced by fast rendering tasks. New rendering of layouts should only take place, if constraint changes will need to do so. Entities and their attributes will only require new rendering if a user interaction changes their state to be dirty.

Lets summarize the main goals of OrbTk rendering infrastructure:

  • API encapsulated access to all renderer functions

    This design decision is taken to keep freedom for further development of OrbTk when it comes to support different renderers. We are able to support

    • different versions of a given renderer
    • support different renderer for different target platforms

  • 2D rendering

    We need a fast and complete implementation of all rendering functions that are supported in the OrbTk toolkit. The following summary is a list of tiny-skia provided functions:

    • Pixmaps
    • Canvas
    • Path
    • geometry primitives
    • Blending modes
    • Path filling
    • Anti-aliased Path filling
    • Path stroking
    • Path hairline stroking
    • Anti-aliased Path hairline stroking
    • Stroke dashing
    • Gradients (linear and radial)
    • Pixmaps blending (image on image rendering)
    • Patterns
    • Fill rect
    • Stroke rect
    • Rectangular clipping
    • Clipping
    • Anti-aliased clipping
    • Analytical anti-aliased Path filling
    • Dithering
    • Blending modes

We are looking forward to a Rust native ecosystem that handles text rendering. This is a complex task and by the time of writing a complete library addressing this issue isn’t available. The Rust community has developed building blocks, like

  • Font parser: ttf-parser.
  • Text shaper: rustybuzz or all-sorts.
  • Font database: fontdb (supporting a font fallback mechanism).

The missing peace, beside the glue code to use the components inside orbtk_tinyskia is a high-quality glyph rasterization library. Preferably it will offer a FreeType level of quality. ab_glyph_rasterizer or fontdue might evolve to fill this gap.