Merge pull request #201 from kas-gui/work

Fontdue rasterizer and other font adjustments

.github/workflows/test.yml

@@ -39,7 +39,7 @@ jobs:
  run: cargo test --manifest-path kas-theme/Cargo.toml --all-features
  - name: test (kas-wgpu)
  run: |
- cargo test --manifest-path kas-wgpu/Cargo.toml --no-default-features
+ cargo test --manifest-path kas-wgpu/Cargo.toml --no-default-features --features ab_glyph
  cargo test --manifest-path kas-wgpu/Cargo.toml --all-features
 
  test:
@@ -74,4 +74,4 @@ jobs:
  - name: test (kas-theme)
  run: cargo test --manifest-path kas-theme/Cargo.toml
  - name: test (kas-wgpu)
- run: cargo test --manifest-path kas-wgpu/Cargo.toml --features clipboard
+ run: cargo test --manifest-path kas-wgpu/Cargo.toml

Cargo.toml

@@ -89,4 +89,4 @@ features = ["serde"]
 members = ["kas-macros", "kas-theme", "kas-wgpu"]
 
 [patch.crates-io]
-kas-text = { git = "https://github.com/kas-gui/kas-text.git", rev = "05b50366a0a2fe7d1e611d93acbb2d9f83c52f0a" }
+kas-text = { git = "https://github.com/kas-gui/kas-text.git", rev = "8e85e49df78f7908662d1356cacdf0b796274530" }

example-config/theme.yaml

@@ -54,3 +54,7 @@ fonts:
  families:
  - sans-serif
  weight: 600
+raster:
+ mode: 0
+ subpixel_threshold: 0
+ subpixel_steps: 1

kas-theme/src/config.rs

@@ -39,6 +39,10 @@ pub struct Config {
  /// Standard fonts
  #[cfg_attr(feature = "config", serde(default))]
  fonts: BTreeMap<TextClass, FontSelector<'static>>,
+
+ /// Text glyph rastering settings
+ #[cfg_attr(feature = "config", serde(default))]
+ raster: RasterConfig,
 }
 
 impl Default for Config {
@@ -50,6 +54,61 @@ impl Default for Config {
  color_schemes: defaults::color_schemes(),
  font_aliases: Default::default(),
  fonts: defaults::fonts(),
+ raster: Default::default(),
+ }
+ }
+}
+
+/// Font raster settings
+///
+/// These are not used by the theme, but passed through to the rendering
+/// backend.
+#[derive(Clone, Debug, PartialEq)]
+#[cfg_attr(feature = "config", derive(serde::Serialize, serde::Deserialize))]
+pub struct RasterConfig {
+ //// Raster mode/engine (backend dependent)
+ #[cfg_attr(feature = "config", serde(default))]
+ pub mode: u8,
+ /// Scale multiplier for fixed-precision
+ ///
+ /// This should be an integer `n >= 1`, e.g. `n = 4` provides four sub-pixel
+ /// steps of precision. It is also required that `n * h < (1 << 24)` where
+ /// `h` is the text height in pixels.
+ #[cfg_attr(feature = "config", serde(default = "defaults::scale_steps"))]
+ pub scale_steps: u8,
+ /// Subpixel positioning threshold
+ ///
+ /// Text with height `h` less than this threshold will use sub-pixel
+ /// positioning, which should make letter spacing more accurate for small
+ /// fonts (though exact behaviour depends on the font; it may be worse).
+ /// This may make rendering worse by breaking pixel alignment.
+ ///
+ /// Note: this feature may not be available, depending on the backend and
+ /// the mode.
+ ///
+ /// See also sub-pixel positioning steps.
+ #[cfg_attr(feature = "config", serde(default = "defaults::subpixel_threshold"))]
+ pub subpixel_threshold: u8,
+ /// Subpixel steps
+ ///
+ /// The number of sub-pixel positioning steps to use. 1 is the minimum and
+ /// equivalent to no sub-pixel positioning. 16 is the maximum.
+ ///
+ /// Note that since this applies to horizontal and vertical positioning, the
+ /// maximum number of rastered glyphs is multiplied by the square of this
+ /// value, though this maxmimum may not be reached in practice. Since this
+ /// feature is usually only used for small fonts this likely acceptable.
+ #[cfg_attr(feature = "config", serde(default = "defaults::subpixel_steps"))]
+ pub subpixel_steps: u8,
+}
+
+impl Default for RasterConfig {
+ fn default() -> Self {
+ RasterConfig {
+ mode: 0,
+ scale_steps: defaults::scale_steps(),
+ subpixel_threshold: defaults::subpixel_threshold(),
+ subpixel_steps: defaults::subpixel_steps(),
  }
  }
 }
@@ -152,6 +211,12 @@ impl ThemeConfig for Config {
  });
  }
  }
+
+ /// Get raster config
+ #[inline]
+ fn raster(&self) -> &RasterConfig {
+ &self.raster
+ }
 }
 
 #[derive(Clone, Debug, PartialEq)]
@@ -185,4 +250,14 @@ mod defaults {
  ];
  list.iter().cloned().collect()
  }
+
+ pub fn scale_steps() -> u8 {
+ 4
+ }
+ pub fn subpixel_threshold() -> u8 {
+ 0
+ }
+ pub fn subpixel_steps() -> u8 {
+ 5
+ }
 }

kas-theme/src/flat_theme.rs

@@ -114,10 +114,10 @@ where
  }
 
  fn init(&mut self, _draw: &mut D) {
- if let Err(e) = kas::text::fonts::fonts().select_default() {
+ let fonts = fonts::fonts();
+ if let Err(e) = fonts.select_default() {
  panic!("Error loading font: {}", e);
  }
- let fonts = fonts::fonts();
  self.fonts = Some(Rc::new(
  self.config
  .iter_fonts()

kas-theme/src/lib.rs

@@ -32,7 +32,7 @@ mod traits;
 pub use kas;
 
 pub use colors::{Colors, ColorsLinear, ColorsSrgb};
-pub use config::Config;
+pub use config::{Config, RasterConfig};
 pub use dim::{Dimensions, DimensionsParams, DimensionsWindow};
 pub use flat_theme::FlatTheme;
 #[cfg(feature = "stack_dst")]

kas-theme/src/traits.rs

@@ -15,6 +15,9 @@ use std::ops::{Deref, DerefMut};
 pub trait ThemeConfig: Clone + std::fmt::Debug + 'static {
  /// Apply startup effects
  fn apply_startup(&self);
+
+ /// Get raster config
+ fn raster(&self) -> &crate::RasterConfig;
 }
 
 /// Requirements on theme config (with `config` feature)
@@ -27,6 +30,9 @@ pub trait ThemeConfig:
 
  /// Apply startup effects
  fn apply_startup(&self);
+
+ /// Get raster config
+ fn raster(&self) -> &crate::RasterConfig;
 }
 
 /// A *theme* provides widget sizing and drawing implementations.

kas-wgpu/Cargo.toml

@@ -18,7 +18,7 @@ no-default-features = true
 features = ["stack_dst"]
 
 [features]
-default = ["clipboard", "stack_dst"]
+default = ["ab_glyph", "clipboard", "stack_dst"]
 nightly = ["unsize", "kas/nightly", "kas-theme/nightly"]
 
 # Use Generic Associated Types (this is too unstable to include in nightly!)
@@ -33,6 +33,9 @@ stack_dst = ["kas-theme/stack_dst"]
 # Use kas-theme's unsize feature (nightly-only)
 unsize = ["kas-theme/unsize"]
 
+# Also:
+# ab_glyph, fontdue: enable at least one of these for text rasterisation
+
 [dependencies]
 kas = { path = "..", version = "0.7.0", features = ["config", "winit"] }
 kas-theme = { path = "../kas-theme", features = ["config"], version = "0.7.0" }
@@ -41,12 +44,14 @@ futures = "0.3"
 log = "0.4"
 smallvec = "1.6.1"
 wgpu = "0.8.0"
-ab_glyph = "0.2.10"
+ab_glyph = { version = "0.2.10", optional = true }
 winit = "0.25"
 thiserror = "1.0.23"
 window_clipboard = { version = "0.2.0", optional = true }
 image = "0.23.14"
 guillotiere = "0.6.0"
+fontdue = { version = "0.5.2", optional = true }
+cfg-if = "1.0.0"
 
 [dev-dependencies]
 chrono = "0.4"

kas-wgpu/README.md

@@ -31,12 +31,15 @@ Optional features
 This crate has the following feature flags:
 
 - `clipboard` (enabled by default): clipboard integration
+- `fontdue`: use [fontdue] library for font rasterisation (otherwise, `ab_glyph` is used)
 - `stack_dst` (enabled by default): enables `kas-theme::MultiTheme`
 - `gat`: enables usage of the Generic Associated Types feature (nightly only
  and currently unstable), allowing some usages of `unsafe` to be avoided.
  (The plan is to enable this by default once the feature is mature.)
 - `unsize`: forwards this feature flag to `kas-theme`
 
+[fontdue]: https://github.com/mooman219/fontdue
+
 Copyright and Licence
 -------
 

kas-wgpu/src/draw/draw_pipe.rs

@@ -24,6 +24,7 @@ impl<C: CustomPipe> DrawPipe<C> {
  mut custom: CB,
  device: &wgpu::Device,
  shaders: &ShaderManager,
+ raster_config: &kas_theme::RasterConfig,
  ) -> Self {
  // Create staging belt and a local pool
  let staging_belt = wgpu::util::StagingBelt::new(1024);
@@ -60,7 +61,7 @@ impl<C: CustomPipe> DrawPipe<C> {
  let shaded_round = shaded_round::Pipeline::new(device, shaders, &bgl_common);
  let flat_round = flat_round::Pipeline::new(device, shaders, &bgl_common);
  let custom = custom.build(&device, &bgl_common, RENDER_TEX_FORMAT);
- let text = text_pipe::Pipeline::new(device, shaders, &bgl_common);
+ let text = text_pipe::Pipeline::new(device, shaders, &bgl_common, raster_config);
 
  DrawPipe {
  local_pool,