WIP: text_system

crates/gpui/src/platform/mac/text_system.rs

@@ -143,7 +143,7 @@ impl PlatformTextSystem for MacTextSystem {
 
     fn typographic_bounds(&self, font_id: FontId, glyph_id: GlyphId) -> Result<Bounds<f32>> {
         Ok(self.0.read().fonts[font_id.0]
-            .typographic_bounds(glyph_id.into())?
+            .typographic_bounds(glyph_id.0)?
             .into())
     }
 
@@ -221,11 +221,13 @@ impl MacTextSystemState {
     }
 
     fn advance(&self, font_id: FontId, glyph_id: GlyphId) -> Result<Size<f32>> {
-        Ok(self.fonts[font_id.0].advance(glyph_id.into())?.into())
+        Ok(self.fonts[font_id.0].advance(glyph_id.0)?.into())
     }
 
     fn glyph_for_char(&self, font_id: FontId, ch: char) -> Option<GlyphId> {
-        self.fonts[font_id.0].glyph_for_char(ch).map(Into::into)
+        self.fonts[font_id.0]
+            .glyph_for_char(ch)
+            .map(|glyph_id| GlyphId(glyph_id))
     }
 
     fn id_for_native_font(&mut self, requested_font: CTFont) -> FontId {
@@ -259,7 +261,7 @@ impl MacTextSystemState {
         let scale = Transform2F::from_scale(params.scale_factor);
         Ok(font
             .raster_bounds(
-                params.glyph_id.into(),
+                params.glyph_id.0,
                 params.font_size.into(),
                 scale,
                 HintingOptions::None,
@@ -334,7 +336,7 @@ impl MacTextSystemState {
                 .native_font()
                 .clone_with_font_size(f32::from(params.font_size) as CGFloat)
                 .draw_glyphs(
-                    &[u32::from(params.glyph_id) as CGGlyph],
+                    &[params.glyph_id.0 as CGGlyph],
                     &[CGPoint::new(
                         (subpixel_shift.x / params.scale_factor) as CGFloat,
                         (subpixel_shift.y / params.scale_factor) as CGFloat,
@@ -419,7 +421,7 @@ impl MacTextSystemState {
                 let glyph_utf16_ix = usize::try_from(*glyph_utf16_ix).unwrap();
                 ix_converter.advance_to_utf16_ix(glyph_utf16_ix);
                 glyphs.push(ShapedGlyph {
-                    id: (*glyph_id).into(),
+                    id: GlyphId(*glyph_id as u32),
                     position: point(position.x as f32, position.y as f32).map(px),
                     index: ix_converter.utf8_ix,
                     is_emoji: self.is_emoji(font_id),

crates/gpui/src/text_system.rs

@@ -26,15 +26,18 @@ use std::{
     sync::Arc,
 };
 
+/// An opaque identifier for a specific font.
 #[derive(Hash, PartialEq, Eq, Clone, Copy, Debug)]
 #[repr(C)]
 pub struct FontId(pub usize);
 
+/// An opaque identifier for a specific font family.
 #[derive(Hash, PartialEq, Eq, Clone, Copy, Debug)]
 pub struct FontFamilyId(pub usize);
 
 pub(crate) const SUBPIXEL_VARIANTS: u8 = 4;
 
+/// The GPUI text layout and rendering sub system.
 pub struct TextSystem {
     line_layout_cache: Arc<LineLayoutCache>,
     platform_text_system: Arc<dyn PlatformTextSystem>,
@@ -65,6 +68,7 @@ impl TextSystem {
         }
     }
 
+    /// Get a list of all available font names from the operating system.
     pub fn all_font_names(&self) -> Vec<String> {
         let mut names: BTreeSet<_> = self
             .platform_text_system
@@ -79,10 +83,13 @@ impl TextSystem {
         );
         names.into_iter().collect()
     }
+
+    /// Add a font's data to the text system.
     pub fn add_fonts(&self, fonts: &[Arc<Vec<u8>>]) -> Result<()> {
         self.platform_text_system.add_fonts(fonts)
     }
 
+    /// Get the FontId for the configure font family and style.
     pub fn font_id(&self, font: &Font) -> Result<FontId> {
         let font_id = self.font_ids_by_font.read().get(font).copied();
         if let Some(font_id) = font_id {
@@ -120,10 +127,14 @@ impl TextSystem {
         );
     }
 
+    /// Get the bounding box for the given font and font size.
+    /// A font's bounding box is the smallest rectangle that could enclose all glyphs
+    /// in the font. superimposed over one another.
     pub fn bounding_box(&self, font_id: FontId, font_size: Pixels) -> Bounds<Pixels> {
         self.read_metrics(font_id, |metrics| metrics.bounding_box(font_size))
     }
 
+    /// Get the typographic bounds for the given character, in the given font and size.
     pub fn typographic_bounds(
         &self,
         font_id: FontId,
@@ -142,6 +153,7 @@ impl TextSystem {
         }))
     }
 
+    /// Get the advance width for the given character, in the given font and size.
     pub fn advance(&self, font_id: FontId, font_size: Pixels, ch: char) -> Result<Size<Pixels>> {
         let glyph_id = self
             .platform_text_system
@@ -153,26 +165,35 @@ impl TextSystem {
         Ok(result * font_size)
     }
 
+    /// Get the number of font size units per 'em square',
+    /// Per MDN: "an abstract square whose height is the intended distance between
+    /// lines of type in the same type size"
     pub fn units_per_em(&self, font_id: FontId) -> u32 {
         self.read_metrics(font_id, |metrics| metrics.units_per_em)
     }
 
+    /// Get the height of a captial letter in the given font and size.
     pub fn cap_height(&self, font_id: FontId, font_size: Pixels) -> Pixels {
         self.read_metrics(font_id, |metrics| metrics.cap_height(font_size))
     }
 
+    /// Get the height of the x character in the given font and size.
     pub fn x_height(&self, font_id: FontId, font_size: Pixels) -> Pixels {
         self.read_metrics(font_id, |metrics| metrics.x_height(font_size))
     }
 
+    /// Get the recommended distance from the baseline for the given font
     pub fn ascent(&self, font_id: FontId, font_size: Pixels) -> Pixels {
         self.read_metrics(font_id, |metrics| metrics.ascent(font_size))
     }
 
+    /// Get the recommended distance below the baseline for the given font,
+    /// in single spaced text.
     pub fn descent(&self, font_id: FontId, font_size: Pixels) -> Pixels {
         self.read_metrics(font_id, |metrics| metrics.descent(font_size))
     }
 
+    /// Get the recommended baseline offset for the given font and line height.
     pub fn baseline_offset(
         &self,
         font_id: FontId,
@@ -199,10 +220,14 @@ impl TextSystem {
         }
     }
 
-    pub fn with_view<R>(&self, view_id: EntityId, f: impl FnOnce() -> R) -> R {
+    pub(crate) fn with_view<R>(&self, view_id: EntityId, f: impl FnOnce() -> R) -> R {
         self.line_layout_cache.with_view(view_id, f)
     }
 
+    /// Layout the given line of text, at the given font_size.
+    /// Subsets of the line can be styled independently with the `runs` parameter.
+    /// Generally, you should prefer to use `TextLayout::shape_line` instead, which
+    /// can be painted directly.
     pub fn layout_line(
         &self,
         text: &str,
@@ -234,6 +259,12 @@ impl TextSystem {
         Ok(layout)
     }
 
+    /// Shape the given line, at the given font_size, for painting to the screen.
+    /// Subsets of the line can be styled independently with the `runs` parameter.
+    ///
+    /// Note that this method can only shape a single line of text. It will panic
+    /// if the text contains newlines. If you need to shape multiple lines of text,
+    /// use `TextLayout::shape_text` instead.
     pub fn shape_line(
         &self,
         text: SharedString,
@@ -273,6 +304,9 @@ impl TextSystem {
         })
     }
 
+    /// Shape a multi line string of text, at the given font_size, for painting to the screen.
+    /// Subsets of the text can be styled independently with the `runs` parameter.
+    /// If `wrap_width` is provided, the line breaks will be adjusted to fit within the given width.
     pub fn shape_text(
         &self,
         text: SharedString,
@@ -381,6 +415,7 @@ impl TextSystem {
         self.line_layout_cache.finish_frame(reused_views)
     }
 
+    /// Returns a handle to a line wrapper, for the given font and font size.
     pub fn line_wrapper(self: &Arc<Self>, font: Font, font_size: Pixels) -> LineWrapperHandle {
         let lock = &mut self.wrapper_pool.lock();
         let font_id = self.resolve_font(&font);
@@ -397,7 +432,8 @@ impl TextSystem {
         }
     }
 
-    pub fn raster_bounds(&self, params: &RenderGlyphParams) -> Result<Bounds<DevicePixels>> {
+    /// Get the rasterized size and location of a specific, rendered glyph.
+    pub(crate) fn raster_bounds(&self, params: &RenderGlyphParams) -> Result<Bounds<DevicePixels>> {
         let raster_bounds = self.raster_bounds.upgradable_read();
         if let Some(bounds) = raster_bounds.get(params) {
             Ok(*bounds)
@@ -409,7 +445,7 @@ impl TextSystem {
         }
     }
 
-    pub fn rasterize_glyph(
+    pub(crate) fn rasterize_glyph(
         &self,
         params: &RenderGlyphParams,
     ) -> Result<(Size<DevicePixels>, Vec<u8>)> {
@@ -425,6 +461,7 @@ struct FontIdWithSize {
     font_size: Pixels,
 }
 
+/// A handle into the text system, which can be used to compute the wrapped layout of text
 pub struct LineWrapperHandle {
     wrapper: Option<LineWrapper>,
     text_system: Arc<TextSystem>,
@@ -517,40 +554,28 @@ impl Display for FontStyle {
     }
 }
 
+/// A styled run of text, for use in [`TextLayout`].
 #[derive(Clone, Debug, PartialEq, Eq)]
 pub struct TextRun {
-    // number of utf8 bytes
+    /// A number of utf8 bytes
     pub len: usize,
+    /// The font to use for this run.
     pub font: Font,
+    /// The color
     pub color: Hsla,
+    /// The background color (if any)
     pub background_color: Option<Hsla>,
+    /// The underline style (if any)
     pub underline: Option<UnderlineStyle>,
 }
 
+/// An identifier for a specific glyph, as returned by [`TextSystem::layout_line`].
 #[derive(Copy, Clone, Debug, Eq, PartialEq, Hash)]
 #[repr(C)]
-pub struct GlyphId(u32);
+pub struct GlyphId(pub(crate) u32);
-
-impl From<GlyphId> for u32 {
-    fn from(value: GlyphId) -> Self {
-        value.0
-    }
-}
-
-impl From<u16> for GlyphId {
-    fn from(num: u16) -> Self {
-        GlyphId(num as u32)
-    }
-}
-
-impl From<u32> for GlyphId {
-    fn from(num: u32) -> Self {
-        GlyphId(num)
-    }
-}
 
 #[derive(Clone, Debug, PartialEq)]
-pub struct RenderGlyphParams {
+pub(crate) struct RenderGlyphParams {
     pub(crate) font_id: FontId,
     pub(crate) glyph_id: GlyphId,
     pub(crate) font_size: Pixels,
@@ -571,6 +596,7 @@ impl Hash for RenderGlyphParams {
     }
 }
 
+/// The parameters for rendering an emoji glyph.
 #[derive(Clone, Debug, PartialEq)]
 pub struct RenderEmojiParams {
     pub(crate) font_id: FontId,
@@ -590,14 +616,23 @@ impl Hash for RenderEmojiParams {
     }
 }
 
+/// The configuration details for identifying a specific font.
 #[derive(Clone, Debug, Eq, PartialEq, Hash)]
 pub struct Font {
+    /// The font family name.
     pub family: SharedString,
+
+    /// The font features to use.
     pub features: FontFeatures,
+
+    /// The font weight.
     pub weight: FontWeight,
+
+    /// The font style.
     pub style: FontStyle,
 }
 
+/// Get a [`Font`] for a given name.
 pub fn font(family: impl Into<SharedString>) -> Font {
     Font {
         family: family.into(),
@@ -608,10 +643,17 @@ pub fn font(family: impl Into<SharedString>) -> Font {
 }
 
 impl Font {
+    /// Set this Font to be bold
     pub fn bold(mut self) -> Self {
         self.weight = FontWeight::BOLD;
         self
     }
+
+    /// Set this Font to be italic
+    pub fn italic(mut self) -> Self {
+        self.style = FontStyle::Italic;
+        self
+    }
 }
 
 /// A struct for storing font metrics.

crates/gpui/src/text_system/font_features.rs

@@ -4,7 +4,9 @@ use schemars::{
 };
 
 macro_rules! create_definitions {
-    ($($(#[$meta:meta])* ($name:ident, $idx:expr)),* $(,)?) => {
+    ($($(#[$meta:meta])* ($name:ident, $idx:expr), ($comment:tt)),* $(,)?) => {
+
+        /// The font features that can be configured for a given font.
         #[derive(Default, Copy, Clone, Eq, PartialEq, Hash)]
         pub struct FontFeatures {
             enabled: u64,
@@ -13,6 +15,7 @@ macro_rules! create_definitions {
 
         impl FontFeatures {
             $(
+                /// $comment
                 pub fn $name(&self) -> Option<bool> {
                     if (self.enabled & (1 << $idx)) != 0 {
                         Some(true)
@@ -125,7 +128,7 @@ macro_rules! create_definitions {
 }
 
 create_definitions!(
-    (calt, 0),
+    (calt, 0, CALT),
     (case, 1),
     (cpsp, 2),
     (frac, 3),

crates/gpui/src/window/element_cx.rs

@@ -1,3 +1,17 @@
+//! The element context is the main interface for interacting with the frame during a paint.
+//!
+//! Elements are hierarchical and with a few exceptions the context accumulates state in a stack
+//! as it processes all of the elements in the frame. The methods that interact with this stack
+//! are generally marked with `with_*`, and take a callback to denote the region of code that
+//! should be executed with that state.
+//!
+//! The other main interface is the `paint_*` family of methods, which push basic drawing commands
+//! to the GPU. Everything in a GPUI app is drawn with these methods.
+//!
+//! There are also several internal methds that GPUI uses, such as [`ElementContext::with_element_state`]
+//! to call the paint and layout methods on elements. These have been included as they're often useful
+//! for taking manual control of the layouting or painting of specialized elements.
+
 use std::{
     any::{Any, TypeId},
     borrow::{Borrow, BorrowMut, Cow},
@@ -153,6 +167,9 @@ pub struct ElementContext<'a> {
 }
 
 impl<'a> WindowContext<'a> {
+    /// Convert this window context into an ElementContext in this callback.
+    /// If you need to use this method, you're probably intermixing the imperative
+    /// and declarative APIs, which is not recommended.
     pub fn with_element_context<R>(&mut self, f: impl FnOnce(&mut ElementContext) -> R) -> R {
         f(&mut ElementContext {
             cx: WindowContext::new(self.app, self.window),
@@ -338,6 +355,8 @@ impl<'a> ElementContext<'a> {
         self.window.next_frame.next_stacking_order_id = next_stacking_order_id;
     }
 
+    /// Push a text style onto the stack, and call a function with that style active.
+    /// Use [`AppContext::text_style`] to get the current, combined text style.
     pub fn with_text_style<F, R>(&mut self, style: Option<TextStyleRefinement>, f: F) -> R
     where
         F: FnOnce(&mut Self) -> R,
@@ -979,9 +998,8 @@ impl<'a> ElementContext<'a> {
         self.window.layout_engine = Some(layout_engine);
     }
 
-    /// Obtain the bounds computed for the given LayoutId relative to the window. This method should not
+    /// Obtain the bounds computed for the given LayoutId relative to the window. This method will usually be invoked by
-    /// be invoked until the paint phase begins, and will usually be invoked by GPUI itself automatically
+    /// GPUI itself automatically in order to pass your element its `Bounds` automatically.
-    /// in order to pass your element its `Bounds` automatically.
     pub fn layout_bounds(&mut self, layout_id: LayoutId) -> Bounds<Pixels> {
         let mut bounds = self
             .window

crates/refineable/derive_refineable/src/derive_refineable.rs

@@ -245,10 +245,14 @@ pub fn derive_refineable(input: TokenStream) -> TokenStream {
     }
 
     let gen = quote! {
+        /// A refinable version of [`#ident`], see that documentation for details.
         #[derive(Clone)]
         #derive_stream
         pub struct #refinement_ident #impl_generics {
-            #( #field_visibilities #field_names: #wrapped_types ),*
+            #(
+                #[allow(missing_docs)]
+                #field_visibilities #field_names: #wrapped_types
+            ),*
         }
 
         impl #impl_generics Refineable for #ident #ty_generics
@@ -304,6 +308,7 @@ pub fn derive_refineable(input: TokenStream) -> TokenStream {
         impl #impl_generics #refinement_ident #ty_generics
             #where_clause
         {
+            /// Returns `true` if all fields are `Some`
             pub fn is_some(&self) -> bool {
                 #(
                     if self.#field_names.is_some() {