Replace magic boolean with new Hinting enum

benches/layout.rs

@@ -9,7 +9,7 @@ fn load_font_system(c: &mut Criterion) {
 
 fn layout(c: &mut Criterion) {
     let mut fs = ct::FontSystem::new();
-    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(10.0, 10.0), false);
+    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(10.0, 10.0), ct::Hinting::Disabled);
     buffer.set_size(&mut fs, Some(80.0), None);
 
     for (wrap_name, wrap) in &[

benches/text_shaping_benchmarks.rs

@@ -4,7 +4,7 @@ use criterion::{black_box, criterion_group, criterion_main, Criterion};
 
 fn bench_ascii_fast_path(c: &mut Criterion) {
     let mut fs = ct::FontSystem::new();
-    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(14.0, 20.0), false);
+    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(14.0, 20.0), ct::Hinting::Disabled);
     buffer.set_size(&mut fs, Some(500.0), None);
 
     let ascii_text = "Pure ASCII text for BidiParagraphs optimization testing.\n".repeat(50);
@@ -25,7 +25,7 @@ fn bench_ascii_fast_path(c: &mut Criterion) {
 
 fn bench_bidi_processing(c: &mut Criterion) {
     let mut fs = ct::FontSystem::new();
-    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(14.0, 20.0), false);
+    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(14.0, 20.0), ct::Hinting::Disabled);
     buffer.set_size(&mut fs, Some(500.0), None);
 
     let bidi_text = "Mixed English and العربية النص العربي text for BiDi testing.\nThis tests adjust_levels and combined BiDi optimizations.\n".repeat(30);
@@ -46,7 +46,7 @@ fn bench_bidi_processing(c: &mut Criterion) {
 
 fn bench_lang_mixed(c: &mut Criterion) {
     let mut fs = ct::FontSystem::new();
-    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(14.0, 20.0), false);
+    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(14.0, 20.0), ct::Hinting::Disabled);
     buffer.set_size(&mut fs, Some(500.0), None);
 
     let bidi_text = include_str!("../sample/hello.txt");
@@ -69,7 +69,7 @@ fn bench_lang_mixed(c: &mut Criterion) {
 
 fn bench_layout_heavy(c: &mut Criterion) {
     let mut fs = ct::FontSystem::new();
-    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(14.0, 20.0), false);
+    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(14.0, 20.0), ct::Hinting::Disabled);
     buffer.set_size(&mut fs, Some(500.0), None);
 
     let layout_text = "This is a very long line that will wrap multiple times and stress the reorder optimization through intensive layout processing with comprehensive buffer reuse testing. ".repeat(30);
@@ -90,7 +90,7 @@ fn bench_layout_heavy(c: &mut Criterion) {
 
 fn bench_combined_stress(c: &mut Criterion) {
     let mut fs = ct::FontSystem::new();
-    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(14.0, 20.0), false);
+    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(14.0, 20.0), ct::Hinting::Disabled);
     buffer.set_size(&mut fs, Some(500.0), None);
 
     let stress_text = format!("{}\n{}\n{}\n{}\n",

examples/editor-test/src/main.rs

@@ -2,7 +2,7 @@
 
 use cosmic_text::{
     Action, BidiParagraphs, BorrowedWithFontSystem, Buffer, Color, Edit, Editor, FontSystem,
-    Metrics, Motion, SwashCache,
+    Hinting, Metrics, Motion, SwashCache,
 };
 use orbclient::{EventOption, Renderer, Window, WindowFlag};
 use std::{env, fs, process, time::Instant};
@@ -71,7 +71,11 @@ fn main() {
     ];
     let font_size_default = 1; // Body
 
-    let mut buffer = Buffer::new(&mut font_system, font_sizes[font_size_default], false);
+    let mut buffer = Buffer::new(
+        &mut font_system,
+        font_sizes[font_size_default],
+        Hinting::Disabled,
+    );
     buffer
         .borrow_with(&mut font_system)
         .set_size(Some(window.width() as f32), Some(window.height() as f32));

examples/editor/src/main.rs

@@ -1,8 +1,8 @@
 // SPDX-License-Identifier: MIT OR Apache-2.0
 
 use cosmic_text::{
-    Action, Attrs, Buffer, Edit, Family, FontSystem, Metrics, Motion, SwashCache, SyntaxEditor,
+    Action, Attrs, Buffer, Edit, Family, FontSystem, Hinting, Metrics, Motion, SwashCache,
-    SyntaxSystem,
+    SyntaxEditor, SyntaxSystem,
 };
 use std::{env, fs, num::NonZeroU32, rc::Rc, slice};
 use tiny_skia::{Paint, PixmapMut, Rect, Transform};
@@ -45,7 +45,7 @@ fn main() {
         Buffer::new(
             &mut font_system,
             font_sizes[font_size_i].scale(display_scale),
-            false,
+            Hinting::Disabled,
         ),
         &syntax_system,
         "base16-eighties.dark",

examples/multiview/src/main.rs

@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT OR Apache-2.0
 
 use cosmic_text::{
-    Action, Attrs, Buffer, Edit, Family, FontSystem, Metrics, Scroll, Shaping, SwashCache,
+    Action, Attrs, Buffer, Edit, Family, FontSystem, Hinting, Metrics, Scroll, Shaping, SwashCache,
 };
 use std::{collections::HashMap, env, fs, num::NonZeroU32, rc::Rc, slice};
 use tiny_skia::{Color, Paint, PixmapMut, Rect, Transform};
@@ -25,7 +25,7 @@ fn main() {
 
     let mut swash_cache = SwashCache::new();
 
-    let mut buffer = Buffer::new_empty(Metrics::new(14.0, 20.0), false);
+    let mut buffer = Buffer::new_empty(Metrics::new(14.0, 20.0), Hinting::Disabled);
 
     let mut buffer = buffer.borrow_with(&mut font_system);
 

examples/rich-text/src/main.rs

@@ -7,7 +7,7 @@ use cosmic_text::Editor;
 use cosmic_text::Shaping;
 use cosmic_text::Style;
 use cosmic_text::{
-    Action, Attrs, Buffer, Edit, Family, FontSystem, Metrics, Motion, SwashCache, Weight,
+    Action, Attrs, Buffer, Edit, Family, FontSystem, Hinting, Metrics, Motion, SwashCache, Weight,
 };
 use std::{num::NonZeroU32, rc::Rc, slice};
 use tiny_skia::{Paint, PixmapMut, Rect, Transform};
@@ -172,7 +172,10 @@ fn main() {
 
     let mut display_scale = window.scale_factor() as f32;
     let metrics = Metrics::new(32.0, 44.0);
-    let mut editor = Editor::new(Buffer::new_empty(metrics.scale(display_scale), false));
+    let mut editor = Editor::new(Buffer::new_empty(
+        metrics.scale(display_scale),
+        Hinting::Disabled,
+    ));
     let mut editor = editor.borrow_with(&mut font_system);
     editor.with_buffer_mut(|buffer| {
         buffer.set_size(

examples/terminal/src/main.rs

@@ -4,7 +4,7 @@
 //! or `cargo run --package terminal -- "my own text"`
 
 use colored::Colorize;
-use cosmic_text::{Attrs, Buffer, Color, FontSystem, Metrics, Shaping, SwashCache};
+use cosmic_text::{Attrs, Buffer, Color, FontSystem, Hinting, Metrics, Shaping, SwashCache};
 use std::fmt::Write;
 
 fn main() {
@@ -20,7 +20,7 @@ fn main() {
     let metrics = Metrics::new(FONT_SIZE, LINE_HEIGHT);
 
     // A Buffer provides shaping and layout for a UTF-8 string, create one per text widget
-    let mut buffer = Buffer::new(&mut font_system, metrics, false);
+    let mut buffer = Buffer::new(&mut font_system, metrics, Hinting::Disabled);
 
     let mut buffer = buffer.borrow_with(&mut font_system);
 

src/buffer.rs

@@ -11,8 +11,8 @@ use unicode_segmentation::UnicodeSegmentation;
 
 use crate::{
     Affinity, Align, Attrs, AttrsList, BidiParagraphs, BorrowedWithFontSystem, BufferLine, Color,
-    Cursor, FontSystem, LayoutCursor, LayoutGlyph, LayoutLine, LineEnding, LineIter, Motion,
+    Cursor, FontSystem, Hinting, LayoutCursor, LayoutGlyph, LayoutLine, LineEnding, LineIter,
-    Renderer, Scroll, ShapeLine, Shaping, Wrap,
+    Motion, Renderer, Scroll, ShapeLine, Shaping, Wrap,
 };
 
 /// A line of visible text for rendering
@@ -216,7 +216,7 @@ pub struct Buffer {
     wrap: Wrap,
     monospace_width: Option<f32>,
     tab_width: u16,
-    hint: bool,
+    hint: Hinting,
 }
 
 impl Clone for Buffer {
@@ -248,7 +248,7 @@ impl Buffer {
     /// # Panics
     ///
     /// Will panic if `metrics.line_height` is zero.
-    pub fn new_empty(metrics: Metrics, hint: bool) -> Self {
+    pub fn new_empty(metrics: Metrics, hint: Hinting) -> Self {
         assert_ne!(metrics.line_height, 0.0, "line height cannot be 0");
         Self {
             lines: Vec::new(),
@@ -269,7 +269,7 @@ impl Buffer {
     /// # Panics
     ///
     /// Will panic if `metrics.line_height` is zero.
-    pub fn new(font_system: &mut FontSystem, metrics: Metrics, hint: bool) -> Self {
+    pub fn new(font_system: &mut FontSystem, metrics: Metrics, hint: Hinting) -> Self {
         let mut buffer = Self::new_empty(metrics, hint);
         buffer.set_text(font_system, "", &Attrs::new(), Shaping::Advanced, None);
         buffer
@@ -722,9 +722,9 @@ impl Buffer {
     /// Set text of buffer, using an iterator of styled spans (pairs of text and attributes)
     ///
     /// ```
-    /// # use cosmic_text::{Attrs, Buffer, Family, FontSystem, Metrics, Shaping};
+    /// # use cosmic_text::{Attrs, Buffer, Family, FontSystem, Metrics, Hinting, Shaping};
     /// # let mut font_system = FontSystem::new();
-    /// let mut buffer = Buffer::new_empty(Metrics::new(32.0, 44.0), false);
+    /// let mut buffer = Buffer::new_empty(Metrics::new(32.0, 44.0), Hinting::Disabled);
     /// let attrs = Attrs::new().family(Family::Serif);
     /// buffer.set_rich_text(
     ///     &mut font_system,
@@ -1451,9 +1451,9 @@ impl BorrowedWithFontSystem<'_, Buffer> {
     /// Set text of buffer, using an iterator of styled spans (pairs of text and attributes)
     ///
     /// ```
-    /// # use cosmic_text::{Attrs, Buffer, Family, FontSystem, Metrics, Shaping};
+    /// # use cosmic_text::{Attrs, Buffer, Family, FontSystem, Metrics, Hinting, Shaping};
     /// # let mut font_system = FontSystem::new();
-    /// let mut buffer = Buffer::new_empty(Metrics::new(32.0, 44.0), false);
+    /// let mut buffer = Buffer::new_empty(Metrics::new(32.0, 44.0), Hinting::Disabled);
     /// let attrs = Attrs::new().family(Family::Serif);
     /// buffer.set_rich_text(
     ///     &mut font_system,

src/buffer_line.rs

@@ -3,7 +3,8 @@ use alloc::{string::String, vec::Vec};
 use core::mem;
 
 use crate::{
-    Align, Attrs, AttrsList, Cached, FontSystem, LayoutLine, LineEnding, ShapeLine, Shaping, Wrap,
+    Align, Attrs, AttrsList, Cached, FontSystem, Hinting, LayoutLine, LineEnding, ShapeLine,
+    Shaping, Wrap,
 };
 
 /// A line (or paragraph) of text that is shaped and laid out
@@ -243,7 +244,7 @@ impl BufferLine {
         wrap: Wrap,
         match_mono_width: Option<f32>,
         tab_width: u16,
-        hint: bool,
+        hint: Hinting,
     ) -> &[LayoutLine] {
         if self.layout_opt.is_unused() {
             let align = self.align;

src/layout.rs

@@ -151,3 +151,28 @@ impl Display for Align {
         }
     }
 }
+
+/// Metrics hinting strategy
+#[derive(Debug, Eq, PartialEq, Clone, Copy, Default)]
+pub enum Hinting {
+    /// No metrics hinting.
+    ///
+    /// Glyphs will have subpixel coordinates.
+    ///
+    /// This is the default.
+    #[default]
+    Disabled,
+
+    /// Metrics hinting.
+    ///
+    /// Glyphs will be snapped to integral coordinates in the X-axis during layout.
+    /// This can improve readability for smaller text and/or low-DPI screens.
+    ///
+    /// However, in order to get the right effect, you must use physical coordinates
+    /// during layout and avoid further scaling when rendering. Otherwise, the rounding
+    /// errors can accumulate and glyph distances may look erratic.
+    ///
+    /// In other words, metrics hinting makes layouting dependent of the target
+    /// resolution.
+    Enabled,
+}

src/lib.rs

@@ -12,7 +12,7 @@
 //! point, you can use the `SwashCache` to rasterize glyphs into either images or pixels.
 //!
 //! ```
-//! use cosmic_text::{Attrs, Color, FontSystem, SwashCache, Buffer, Metrics, Shaping};
+//! use cosmic_text::{Attrs, Color, FontSystem, SwashCache, Buffer, Metrics, Hinting, Shaping};
 //!
 //! // A FontSystem provides access to detected system fonts, create one per application
 //! let mut font_system = FontSystem::new();
@@ -24,7 +24,7 @@
 //! let metrics = Metrics::new(14.0, 20.0);
 //!
 //! // A Buffer provides shaping and layout for a UTF-8 string, create one per text widget
-//! let mut buffer = Buffer::new(&mut font_system, metrics, false);
+//! let mut buffer = Buffer::new(&mut font_system, metrics, Hinting::Disabled);
 //!
 //! // Borrow buffer together with the font system for more convenient method calls
 //! let mut buffer = buffer.borrow_with(&mut font_system);

src/shape.rs

@@ -4,8 +4,8 @@
 
 use crate::fallback::FontFallbackIter;
 use crate::{
-    math, Align, AttrsList, CacheKeyFlags, Color, Font, FontSystem, LayoutGlyph, LayoutLine,
+    math, Align, AttrsList, CacheKeyFlags, Color, Font, FontSystem, Hinting, LayoutGlyph,
-    Metrics, Wrap,
+    LayoutLine, Metrics, Wrap,
 };
 #[cfg(not(feature = "std"))]
 use alloc::vec::Vec;
@@ -1152,7 +1152,7 @@ impl ShapeLine {
         wrap: Wrap,
         align: Option<Align>,
         match_mono_width: Option<f32>,
-        hint: bool,
+        hinting: Hinting,
     ) -> Vec<LayoutLine> {
         let mut lines = Vec::with_capacity(1);
         self.layout_to_buffer(
@@ -1163,7 +1163,7 @@ impl ShapeLine {
             align,
             &mut lines,
             match_mono_width,
-            hint,
+            hinting,
         );
         lines
     }
@@ -1177,7 +1177,7 @@ impl ShapeLine {
         align: Option<Align>,
         layout_lines: &mut Vec<LayoutLine>,
         match_mono_width: Option<f32>,
-        hint: bool,
+        hinting: Hinting,
     ) {
         fn add_to_visual_line(
             vl: &mut VisualLine,
@@ -1553,7 +1553,7 @@ impl ShapeLine {
                 x += alignment_correction;
             }
 
-            if hint {
+            if hinting == Hinting::Enabled {
                 x = x.round();
             }
 
@@ -1635,7 +1635,7 @@ impl ShapeLine {
                                 // Round to nearest monospace width
                                 x_advance = ((x_advance / match_em_width).round()) * match_em_width;
                             }
-                            if hint {
+                            if hinting == Hinting::Enabled {
                                 x_advance = x_advance.round();
                             }
                             if self.rtl {

tests/common/mod.rs

@@ -1,8 +1,8 @@
 use std::path::PathBuf;
 
 use cosmic_text::{
-    fontdb::Database, Attrs, AttrsOwned, Buffer, Color, Family, FontSystem, Metrics, Shaping,
+    fontdb::Database, Attrs, AttrsOwned, Buffer, Color, Family, FontSystem, Hinting, Metrics,
-    SwashCache,
+    Shaping, SwashCache,
 };
 use tiny_skia::{Paint, Pixmap, Rect, Transform};
 
@@ -85,7 +85,7 @@ impl DrawTestCfg {
         let mut font_system = FontSystem::new_with_locale_and_db("En-US".into(), font_db);
         let mut swash_cache = SwashCache::new();
         let metrics = Metrics::new(self.font_size, self.line_height);
-        let mut buffer = Buffer::new(&mut font_system, metrics, false);
+        let mut buffer = Buffer::new(&mut font_system, metrics, Hinting::Disabled);
         let mut buffer = buffer.borrow_with(&mut font_system);
         let margins = 5;
         buffer.set_size(

tests/editor_modified_state.rs

@@ -2,7 +2,7 @@
 
 use std::sync::OnceLock;
 
-use cosmic_text::{Buffer, Cursor, Edit, Metrics, SyntaxEditor, SyntaxSystem, ViEditor};
+use cosmic_text::{Buffer, Cursor, Edit, Hinting, Metrics, SyntaxEditor, SyntaxSystem, ViEditor};
 
 static SYNTAX_SYSTEM: OnceLock<SyntaxSystem> = OnceLock::new();
 
@@ -13,7 +13,7 @@ fn editor() -> ViEditor<'static, 'static> {
     let line_height = (font_size * 1.4).ceil();
 
     let metrics = Metrics::new(font_size, line_height);
-    let buffer = Buffer::new_empty(metrics, false);
+    let buffer = Buffer::new_empty(metrics, Hinting::Disabled);
     let editor = SyntaxEditor::new(
         buffer,
         SYNTAX_SYSTEM.get_or_init(SyntaxSystem::new),

tests/wrap_stability.rs

@@ -1,6 +1,6 @@
 use cosmic_text::{
-    fontdb, Align, Attrs, AttrsList, BidiParagraphs, Buffer, Family, FontSystem, LayoutLine,
+    fontdb, Align, Attrs, AttrsList, BidiParagraphs, Buffer, Family, FontSystem, Hinting,
-    Metrics, ShapeLine, Shaping, Weight, Wrap,
+    LayoutLine, Metrics, ShapeLine, Shaping, Weight, Wrap,
 };
 
 // Test for https://github.com/pop-os/cosmic-text/issues/134
@@ -23,15 +23,28 @@ fn stable_wrap() {
     let mut check_wrap = |text: &_, wrap, align_opt, start_width_opt| {
         let line = ShapeLine::new(&mut font_system, text, &attrs, Shaping::Advanced, 8);
 
-        let layout_unbounded =
+        let layout_unbounded = line.layout(
-            line.layout(font_size, start_width_opt, wrap, align_opt, None, false);
+            font_size,
+            start_width_opt,
+            wrap,
+            align_opt,
+            None,
+            Hinting::Disabled,
+        );
         let max_width = layout_unbounded.iter().map(|l| l.w).fold(0.0, f32::max);
         let new_limit = match start_width_opt {
             Some(start_width) => f32::min(start_width, max_width),
             None => max_width,
         };
 
-        let layout_bounded = line.layout(font_size, Some(new_limit), wrap, align_opt, None, false);
+        let layout_bounded = line.layout(
+            font_size,
+            Some(new_limit),
+            wrap,
+            align_opt,
+            None,
+            Hinting::Disabled,
+        );
         let bounded_max_width = layout_bounded.iter().map(|l| l.w).fold(0.0, f32::max);
 
         // For debugging:
@@ -100,7 +113,7 @@ fn wrap_extra_line() {
     let mut font_system = FontSystem::new();
     let metrics = Metrics::new(14.0, 20.0);
 
-    let mut buffer = Buffer::new(&mut font_system, metrics, false);
+    let mut buffer = Buffer::new(&mut font_system, metrics, Hinting::Disabled);
 
     let mut buffer = buffer.borrow_with(&mut font_system);
 

tests/wrap_word_fallback.rs

@@ -1,4 +1,4 @@
-use cosmic_text::{Attrs, Buffer, FontSystem, Metrics, Shaping, Wrap};
+use cosmic_text::{Attrs, Buffer, FontSystem, Hinting, Metrics, Shaping, Wrap};
 
 // Tests the ability to fallback to glyph wrapping when a word can't fit on a line by itself.
 // No line should ever overflow the buffer size.
@@ -10,7 +10,7 @@ fn wrap_word_fallback() {
     font_system.db_mut().load_font_data(font);
     let metrics = Metrics::new(14.0, 20.0);
 
-    let mut buffer = Buffer::new(&mut font_system, metrics, false);
+    let mut buffer = Buffer::new(&mut font_system, metrics, Hinting::Disabled);
 
     let mut buffer = buffer.borrow_with(&mut font_system);