gfx_glyph

Fast GPU cached text rendering using gfx-rs & rusttype.

Makes use of three kinds of caching to optimise frame performance.

• Caching of glyph positioning output to avoid repeated cost of identical text rendering on sequential frames.
• Caches draw calculations to avoid repeated cost of identical text rendering on sequential frames.
• GPU cache logic to dynamically maintain a GPU texture of rendered glyphs.

extern crate gfx_glyph;
use gfx_glyph::{Section, GlyphBrushBuilder};

let arial: &[u8] = include_bytes!("examples/Arial Unicode.ttf");
let mut glyph_brush = GlyphBrushBuilder::using_font(arial)
    .build(gfx_factory.clone());

let section = Section {
    text: "Hello gfx_glyph",
    ..Section::default() // color, position, etc
};

glyph_brush.queue(section);
glyph_brush.queue(some_other_section);

glyph_brush.draw_queued(&mut gfx_encoder, &gfx_color, &gfx_depth).unwrap();

Limitations

The current implementation only supports OpenGL 3.0 or later. But other rendering languages (that are supported by gfx) should be easy enough to add. Send in your PRs!

Examples

Have a look at

• cargo run --example paragraph --release
• cargo run --example performance --release

Changelog

0.4

• Support depth testing with configurable gfx depth test (via GlyphBrushBuilder::depth_test).
  • Sections now have a z value to indicate the depth.
  • Actual depth testing is disabled by default, but a reference to the depth buffer is now required to draw.
• Streamline API for use with built-in Layouts, while still allowing custom layouts.
  • Built-in layouts are now a member of Section.
  • Custom layouts can still be used by using GlyphBrush::queue_custom_layout method instead of queue.
  • Section<'a, L> are now generic to allow pluggable LineBreaker logic in the layout. This is a little unfortunate for the API surface.
• Remove unnecessary OwnedSection and StaticSection to simplify the API.
• pixel_bounding_box renamed to pixel_bounds & pixel_bounds_custom_layout
  • These now return Option<_> to handle the bounds of 'nothing' properly
• GlyphBrushBuilder gpu_cache_position_tolerance default reduced to 0.1 (from 1.0)

0.3

• Use Into<SharedBytes> instead of explicit &[u8] for font byte input to improve flexibility.

Notable non-breaking changes:

• 0.3.2
  • Move fixed GPU caching logic into crate replacing rusttype::gpu_cache
  • Section & StaticSection implement Copy
• 0.3.3
  • Fix another GPU caching issue that could cause missing glyphs
  • Fix a layout issue that could miss a character immediately preceding EOF
  • Optimise GPU cache sorting performance

0.2

• Adopt default line breaking logic according to the Unicode Standard Annex #14 with StandardLineBreaker (included in Layout::default()). A LineBreaker implementation can be provided instead of using one of these.