Draft metrics hinting support

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));
+    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(10.0, 10.0), false);
     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));
+    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(14.0, 20.0), false);
     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));
+    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(14.0, 20.0), false);
     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));
+    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(14.0, 20.0), false);
     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));
+    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(14.0, 20.0), false);
     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));
+    let mut buffer = ct::Buffer::new(&mut fs, ct::Metrics::new(14.0, 20.0), false);
     buffer.set_size(&mut fs, Some(500.0), None);
 
     let stress_text = format!("{}\n{}\n{}\n{}\n",

examples/editor-test/src/main.rs

@@ -71,7 +71,7 @@ fn main() {
     ];
     let font_size_default = 1; // Body
 
-    let mut buffer = Buffer::new(&mut font_system, font_sizes[font_size_default]);
+    let mut buffer = Buffer::new(&mut font_system, font_sizes[font_size_default], false);
     buffer
         .borrow_with(&mut font_system)
         .set_size(Some(window.width() as f32), Some(window.height() as f32));

examples/editor/src/main.rs

@@ -45,6 +45,7 @@ fn main() {
         Buffer::new(
             &mut font_system,
             font_sizes[font_size_i].scale(display_scale),
+            false,
         ),
         &syntax_system,
         "base16-eighties.dark",

examples/multiview/src/main.rs

@@ -25,7 +25,7 @@ fn main() {
 
     let mut swash_cache = SwashCache::new();
 
-    let mut buffer = Buffer::new_empty(Metrics::new(14.0, 20.0));
+    let mut buffer = Buffer::new_empty(Metrics::new(14.0, 20.0), false);
 
     let mut buffer = buffer.borrow_with(&mut font_system);
 

examples/rich-text/src/main.rs

@@ -172,7 +172,7 @@ 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)));
+    let mut editor = Editor::new(Buffer::new_empty(metrics.scale(display_scale), false));
     let mut editor = editor.borrow_with(&mut font_system);
     editor.with_buffer_mut(|buffer| {
         buffer.set_size(

examples/terminal/src/main.rs

@@ -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);
+    let mut buffer = Buffer::new(&mut font_system, metrics, false);
 
     let mut buffer = buffer.borrow_with(&mut font_system);
 

src/buffer.rs

@@ -216,6 +216,7 @@ pub struct Buffer {
     wrap: Wrap,
     monospace_width: Option<f32>,
     tab_width: u16,
+    hint: bool,
 }
 
 impl Clone for Buffer {
@@ -230,6 +231,7 @@ impl Clone for Buffer {
             wrap: self.wrap,
             monospace_width: self.monospace_width,
             tab_width: self.tab_width,
+            hint: self.hint,
         }
     }
 }
@@ -246,7 +248,7 @@ impl Buffer {
     /// # Panics
     ///
     /// Will panic if `metrics.line_height` is zero.
-    pub fn new_empty(metrics: Metrics) -> Self {
+    pub fn new_empty(metrics: Metrics, hint: bool) -> Self {
         assert_ne!(metrics.line_height, 0.0, "line height cannot be 0");
         Self {
             lines: Vec::new(),
@@ -258,6 +260,7 @@ impl Buffer {
             wrap: Wrap::WordOrGlyph,
             monospace_width: None,
             tab_width: 8,
+            hint,
         }
     }
 
@@ -266,8 +269,8 @@ impl Buffer {
     /// # Panics
     ///
     /// Will panic if `metrics.line_height` is zero.
-    pub fn new(font_system: &mut FontSystem, metrics: Metrics) -> Self {
+    pub fn new(font_system: &mut FontSystem, metrics: Metrics, hint: bool) -> Self {
-        let mut buffer = Self::new_empty(metrics);
+        let mut buffer = Self::new_empty(metrics, hint);
         buffer.set_text(font_system, "", &Attrs::new(), Shaping::Advanced, None);
         buffer
     }
@@ -297,6 +300,7 @@ impl Buffer {
                     self.wrap,
                     self.monospace_width,
                     self.tab_width,
+                    self.hint,
                 );
             }
         }
@@ -540,6 +544,7 @@ impl Buffer {
             self.wrap,
             self.monospace_width,
             self.tab_width,
+            self.hint,
         ))
     }
 
@@ -719,7 +724,7 @@ impl Buffer {
     /// ```
     /// # use cosmic_text::{Attrs, Buffer, Family, FontSystem, Metrics, Shaping};
     /// # let mut font_system = FontSystem::new();
-    /// let mut buffer = Buffer::new_empty(Metrics::new(32.0, 44.0));
+    /// let mut buffer = Buffer::new_empty(Metrics::new(32.0, 44.0), false);
     /// let attrs = Attrs::new().family(Family::Serif);
     /// buffer.set_rich_text(
     ///     &mut font_system,
@@ -1448,7 +1453,7 @@ impl BorrowedWithFontSystem<'_, Buffer> {
     /// ```
     /// # use cosmic_text::{Attrs, Buffer, Family, FontSystem, Metrics, Shaping};
     /// # let mut font_system = FontSystem::new();
-    /// let mut buffer = Buffer::new_empty(Metrics::new(32.0, 44.0));
+    /// let mut buffer = Buffer::new_empty(Metrics::new(32.0, 44.0), false);
     /// let attrs = Attrs::new().family(Family::Serif);
     /// buffer.set_rich_text(
     ///     &mut font_system,

src/buffer_line.rs

@@ -243,6 +243,7 @@ impl BufferLine {
         wrap: Wrap,
         match_mono_width: Option<f32>,
         tab_width: u16,
+        hint: bool,
     ) -> &[LayoutLine] {
         if self.layout_opt.is_unused() {
             let align = self.align;
@@ -259,6 +260,7 @@ impl BufferLine {
                 align,
                 &mut layout,
                 match_mono_width,
+                hint,
             );
             self.layout_opt.set_used(layout);
         }

src/lib.rs

@@ -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);
+//! let mut buffer = Buffer::new(&mut font_system, metrics, false);
 //!
 //! // Borrow buffer together with the font system for more convenient method calls
 //! let mut buffer = buffer.borrow_with(&mut font_system);

src/shape.rs

@@ -1152,6 +1152,7 @@ impl ShapeLine {
         wrap: Wrap,
         align: Option<Align>,
         match_mono_width: Option<f32>,
+        hint: bool,
     ) -> Vec<LayoutLine> {
         let mut lines = Vec::with_capacity(1);
         self.layout_to_buffer(
@@ -1162,6 +1163,7 @@ impl ShapeLine {
             align,
             &mut lines,
             match_mono_width,
+            hint,
         );
         lines
     }
@@ -1175,6 +1177,7 @@ impl ShapeLine {
         align: Option<Align>,
         layout_lines: &mut Vec<LayoutLine>,
         match_mono_width: Option<f32>,
+        hint: bool,
     ) {
         fn add_to_visual_line(
             vl: &mut VisualLine,
@@ -1550,6 +1553,10 @@ impl ShapeLine {
                 x += alignment_correction;
             }
 
+            if hint {
+                x = x.round();
+            }
+
             // TODO: Only certain `is_whitespace` chars are typically expanded but this is what is
             // currently used to compute `visual_line.spaces`.
             //
@@ -1628,6 +1635,9 @@ impl ShapeLine {
                                 // Round to nearest monospace width
                                 x_advance = ((x_advance / match_em_width).round()) * match_em_width;
                             }
+                            if hint {
+                                x_advance = x_advance.round();
+                            }
                             if self.rtl {
                                 x -= x_advance;
                             }

tests/common/mod.rs

@@ -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);
+        let mut buffer = Buffer::new(&mut font_system, metrics, false);
         let mut buffer = buffer.borrow_with(&mut font_system);
         let margins = 5;
         buffer.set_size(

tests/editor_modified_state.rs

@@ -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);
+    let buffer = Buffer::new_empty(metrics, false);
     let editor = SyntaxEditor::new(
         buffer,
         SYNTAX_SYSTEM.get_or_init(SyntaxSystem::new),

tests/wrap_stability.rs

@@ -23,14 +23,15 @@ 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 = line.layout(font_size, start_width_opt, wrap, align_opt, None);
+        let layout_unbounded =
+            line.layout(font_size, start_width_opt, wrap, align_opt, None, false);
         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);
+        let layout_bounded = line.layout(font_size, Some(new_limit), wrap, align_opt, None, false);
         let bounded_max_width = layout_bounded.iter().map(|l| l.w).fold(0.0, f32::max);
 
         // For debugging:
@@ -99,7 +100,7 @@ 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);
+    let mut buffer = Buffer::new(&mut font_system, metrics, false);
 
     let mut buffer = buffer.borrow_with(&mut font_system);
 

tests/wrap_word_fallback.rs

@@ -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);
+    let mut buffer = Buffer::new(&mut font_system, metrics, false);
 
     let mut buffer = buffer.borrow_with(&mut font_system);