Support expanding tabs

src/buffer.rs

@@ -210,6 +210,7 @@ pub struct Buffer {
     redraw: bool,
     wrap: Wrap,
     monospace_width: Option<f32>,
+    tab_width: u16,
 
     /// Scratch buffer for shaping and laying out.
     scratch: ShapeBuffer,
@@ -226,6 +227,7 @@ impl Clone for Buffer {
             redraw: self.redraw,
             wrap: self.wrap,
             monospace_width: self.monospace_width,
+            tab_width: self.tab_width,
             scratch: ShapeBuffer::default(),
         }
     }
@@ -255,6 +257,7 @@ impl Buffer {
             wrap: Wrap::WordOrGlyph,
             scratch: ShapeBuffer::default(),
             monospace_width: None,
+            tab_width: 8,
         }
     }
 
@@ -294,6 +297,7 @@ impl Buffer {
                     self.width,
                     self.wrap,
                     self.monospace_width,
+                    self.tab_width,
                 );
             }
         }
@@ -510,7 +514,7 @@ impl Buffer {
         line_i: usize,
     ) -> Option<&ShapeLine> {
         let line = self.lines.get_mut(line_i)?;
-        Some(line.shape_in_buffer(&mut self.scratch, font_system))
+        Some(line.shape_in_buffer(&mut self.scratch, font_system, self.tab_width))
     }
 
     /// Lay out the provided line index and return the result
@@ -527,6 +531,7 @@ impl Buffer {
             self.width,
             self.wrap,
             self.monospace_width,
+            self.tab_width,
         ))
     }
 
@@ -576,6 +581,30 @@ impl Buffer {
         }
     }
 
+    /// Get the current `tab_width`
+    pub fn tab_width(&self) -> u16 {
+        self.tab_width
+    }
+
+    /// Set tab width (number of spaces between tab stops)
+    pub fn set_tab_width(&mut self, font_system: &mut FontSystem, tab_width: u16) {
+        // A tab width of 0 is not allowed
+        if tab_width == 0 {
+            return;
+        }
+        if tab_width != self.tab_width {
+            self.tab_width = tab_width;
+            // Shaping must be reset when tab width is changed
+            for line in self.lines.iter_mut() {
+                if line.text().contains('\t') {
+                    line.reset_shaping();
+                }
+            }
+            self.redraw = true;
+            self.shape_until_scroll(font_system, false);
+        }
+    }
+
     /// Get the current buffer dimensions (width, height)
     pub fn size(&self) -> (f32, f32) {
         (self.width, self.height)

src/buffer_line.rs

@@ -182,8 +182,8 @@ impl BufferLine {
     }
 
     /// Shape line, will cache results
-    pub fn shape(&mut self, font_system: &mut FontSystem) -> &ShapeLine {
-        self.shape_in_buffer(&mut ShapeBuffer::default(), font_system)
+    pub fn shape(&mut self, font_system: &mut FontSystem, tab_width: u16) -> &ShapeLine {
+        self.shape_in_buffer(&mut ShapeBuffer::default(), font_system, tab_width)
     }
 
     /// Shape a line using a pre-existing shape buffer, will cache results
@@ -191,6 +191,7 @@ impl BufferLine {
         &mut self,
         scratch: &mut ShapeBuffer,
         font_system: &mut FontSystem,
+        tab_width: u16,
     ) -> &ShapeLine {
         if self.shape_opt.is_none() {
             self.shape_opt = Some(ShapeLine::new_in_buffer(
@@ -199,6 +200,7 @@ impl BufferLine {
                 &self.text,
                 &self.attrs_list,
                 self.shaping,
+                tab_width,
             ));
             self.layout_opt = None;
         }
@@ -218,6 +220,7 @@ impl BufferLine {
         width: f32,
         wrap: Wrap,
         match_mono_width: Option<f32>,
+        tab_width: u16,
     ) -> &[LayoutLine] {
         self.layout_in_buffer(
             &mut ShapeBuffer::default(),
@@ -226,6 +229,7 @@ impl BufferLine {
             width,
             wrap,
             match_mono_width,
+            tab_width,
         )
     }
 
@@ -238,10 +242,11 @@ impl BufferLine {
         width: f32,
         wrap: Wrap,
         match_mono_width: Option<f32>,
+        tab_width: u16,
     ) -> &[LayoutLine] {
         if self.layout_opt.is_none() {
             let align = self.align;
-            let shape = self.shape_in_buffer(scratch, font_system);
+            let shape = self.shape_in_buffer(scratch, font_system, tab_width);
             let mut layout = Vec::with_capacity(1);
             shape.layout_to_buffer(
                 scratch,

src/edit/editor.rs

@@ -24,7 +24,6 @@ pub struct Editor<'buffer> {
     selection: Selection,
     cursor_moved: bool,
     auto_indent: bool,
-    tab_width: u16,
     change: Option<Change>,
 }
 
@@ -38,7 +37,6 @@ impl<'buffer> Editor<'buffer> {
             selection: Selection::None,
             cursor_moved: false,
             auto_indent: false,
-            tab_width: 4,
             change: None,
         }
     }
@@ -259,18 +257,11 @@ impl<'buffer> Edit<'buffer> for Editor<'buffer> {
     }
 
     fn tab_width(&self) -> u16 {
-        self.tab_width
+        self.with_buffer(|buffer| buffer.tab_width())
     }
 
-    fn set_tab_width(&mut self, tab_width: u16) {
-        // A tab width of 0 is not allowed
-        if tab_width == 0 {
-            return;
-        }
-        if self.tab_width != tab_width {
-            self.tab_width = tab_width;
-            self.with_buffer_mut(|buffer| buffer.set_redraw(true));
-        }
+    fn set_tab_width(&mut self, font_system: &mut FontSystem, tab_width: u16) {
+        self.with_buffer_mut(|buffer| buffer.set_tab_width(font_system, tab_width));
     }
 
     fn shape_as_needed(&mut self, font_system: &mut FontSystem, prune: bool) {
@@ -682,7 +673,7 @@ impl<'buffer> Edit<'buffer> for Editor<'buffer> {
                 };
 
                 // For every line in selection
-                let tab_width: usize = self.tab_width.into();
+                let tab_width: usize = self.tab_width().into();
                 for line_i in start.line..=end.line {
                     // Determine indexes of last indent and first character after whitespace
                     let mut after_whitespace = 0;
@@ -745,7 +736,7 @@ impl<'buffer> Edit<'buffer> for Editor<'buffer> {
                 };
 
                 // For every line in selection
-                let tab_width: usize = self.tab_width.into();
+                let tab_width: usize = self.tab_width().into();
                 for line_i in start.line..=end.line {
                     // Determine indexes of last indent and first character after whitespace
                     let mut last_indent = 0;

src/edit/mod.rs

@@ -282,7 +282,7 @@ pub trait Edit<'buffer> {
     fn tab_width(&self) -> u16;
 
     /// Set the current tab width. A `tab_width` of 0 is not allowed, and will be ignored
-    fn set_tab_width(&mut self, tab_width: u16);
+    fn set_tab_width(&mut self, font_system: &mut FontSystem, tab_width: u16);
 
     /// Shape lines until scroll, after adjusting scroll if the cursor moved
     fn shape_as_needed(&mut self, font_system: &mut FontSystem, prune: bool);
@@ -336,6 +336,11 @@ impl<'font_system, 'buffer, E: Edit<'buffer>> BorrowedWithFontSystem<'font_syste
         })
     }
 
+    /// Set the current tab width. A `tab_width` of 0 is not allowed, and will be ignored
+    pub fn set_tab_width(&mut self, tab_width: u16) {
+        self.inner.set_tab_width(self.font_system, tab_width);
+    }
+
     /// Shape lines until scroll, after adjusting scroll if the cursor moved
     pub fn shape_as_needed(&mut self, prune: bool) {
         self.inner.shape_as_needed(self.font_system, prune);

src/edit/syntect.rs

@@ -250,8 +250,8 @@ impl<'syntax_system, 'buffer> Edit<'buffer> for SyntaxEditor<'syntax_system, 'bu
         self.editor.tab_width()
     }
 
-    fn set_tab_width(&mut self, tab_width: u16) {
-        self.editor.set_tab_width(tab_width);
+    fn set_tab_width(&mut self, font_system: &mut FontSystem, tab_width: u16) {
+        self.editor.set_tab_width(font_system, tab_width);
     }
 
     fn shape_as_needed(&mut self, font_system: &mut FontSystem, prune: bool) {

src/edit/vi.rs

@@ -550,8 +550,8 @@ impl<'syntax_system, 'buffer> Edit<'buffer> for ViEditor<'syntax_system, 'buffer
         self.editor.tab_width()
     }
 
-    fn set_tab_width(&mut self, tab_width: u16) {
-        self.editor.set_tab_width(tab_width);
+    fn set_tab_width(&mut self, font_system: &mut FontSystem, tab_width: u16) {
+        self.editor.set_tab_width(font_system, tab_width);
     }
 
     fn shape_as_needed(&mut self, font_system: &mut FontSystem, prune: bool) {

src/math.rs

@@ -1,5 +1,11 @@
 #[cfg(not(feature = "std"))]
-pub use libm::{roundf, truncf};
+pub use libm::{floorf, roundf, truncf};
+
+#[cfg(feature = "std")]
+#[inline]
+pub fn floorf(x: f32) -> f32 {
+    x.floor()
+}
 
 #[cfg(feature = "std")]
 #[inline]

src/shape.rs

@@ -763,6 +763,7 @@ impl ShapeLine {
         line: &str,
         attrs_list: &AttrsList,
         shaping: Shaping,
+        tab_width: u16,
     ) -> Self {
         Self::new_in_buffer(
             &mut ShapeBuffer::default(),
@@ -770,6 +771,7 @@ impl ShapeLine {
             line,
             attrs_list,
             shaping,
+            tab_width,
         )
     }
 
@@ -785,6 +787,7 @@ impl ShapeLine {
         line: &str,
         attrs_list: &AttrsList,
         shaping: Shaping,
+        tab_width: u16,
     ) -> Self {
         let mut spans = Vec::new();
 
@@ -844,6 +847,24 @@ impl ShapeLine {
             ));
         }
 
+        // Adjust for tabs
+        let mut x = 0.0;
+        for span in spans.iter_mut() {
+            for word in span.words.iter_mut() {
+                for glyph in word.glyphs.iter_mut() {
+                    if &line[glyph.start..glyph.end] == "\t" {
+                        //TODO: better fallback for width
+                        let space_x_advance =
+                            glyph.font_monospace_em_width.unwrap_or(glyph.x_advance);
+                        let tab_x_advance = (tab_width as f32) * space_x_advance;
+                        let tab_stop = (math::floorf(x / tab_x_advance) + 1.0) * tab_x_advance;
+                        glyph.x_advance = tab_stop - x;
+                    }
+                    x += glyph.x_advance;
+                }
+            }
+        }
+
         Self {
             rtl,
             spans,

tests/wrap_stability.rs

@@ -21,7 +21,7 @@ fn stable_wrap() {
     font_system.db_mut().load_font_data(font);
 
     let mut check_wrap = |text: &_, wrap, start_width| {
-        let line = ShapeLine::new(&mut font_system, text, &attrs, Shaping::Advanced);
+        let line = ShapeLine::new(&mut font_system, text, &attrs, Shaping::Advanced, 8);
 
         let layout_unbounded = line.layout(font_size, start_width, wrap, Some(Align::Left), None);
         let max_width = layout_unbounded.iter().map(|l| l.w).fold(0.0, f32::max);