Merge pull request #122 from hecrj/feature/shaping-switch

`Shaping` strategy selection

examples/rich-text/src/main.rs

@@ -2,7 +2,7 @@
 
 use cosmic_text::{
     Action, Attrs, AttrsList, Buffer, BufferLine, Color, Edit, Editor, Family, FontSystem, Metrics,
-    Style, SwashCache, Weight,
+    Shaping, Style, SwashCache, Weight,
 };
 use orbclient::{EventOption, Renderer, Window, WindowFlag};
 use std::{
@@ -143,7 +143,7 @@ fn main() {
         editor
             .buffer_mut()
             .lines
-            .push(BufferLine::new(line_text, attrs_list));
+            .push(BufferLine::new(line_text, attrs_list, Shaping::Advanced));
     }
 
     let mut swash_cache = SwashCache::new();

examples/terminal/src/main.rs

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: MIT OR Apache-2.0
 
-use cosmic_text::{Attrs, Buffer, Color, FontSystem, Metrics, SwashCache};
+use cosmic_text::{Attrs, Buffer, Color, FontSystem, Metrics, Shaping, SwashCache};
 use std::cmp::{self, Ordering};
 use termion::{color, cursor};
 
@@ -28,7 +28,7 @@ fn main() {
     let attrs = Attrs::new();
 
     // Add some text!
-    buffer.set_text(" Hi, Rust! 🦀", attrs);
+    buffer.set_text(" Hi, Rust! 🦀", attrs, Shaping::Advanced);
 
     // Perform shaping as desired
     buffer.shape_until_scroll();

src/buffer.rs

@@ -12,7 +12,7 @@ use unicode_segmentation::UnicodeSegmentation;
 use crate::Color;
 use crate::{
     Attrs, AttrsList, BorrowedWithFontSystem, BufferLine, FontSystem, LayoutGlyph, LayoutLine,
-    ShapeLine, Wrap,
+    ShapeLine, Shaping, Wrap,
 };
 
 /// Current cursor location
@@ -331,7 +331,7 @@ impl Buffer {
             redraw: false,
             wrap: Wrap::Word,
         };
-        buffer.set_text(font_system, "", Attrs::new());
+        buffer.set_text(font_system, "", Attrs::new(), Shaping::Advanced);
         buffer
     }
 
@@ -562,16 +562,28 @@ impl Buffer {
     }
 
     /// Set text of buffer, using provided attributes for each line by default
-    pub fn set_text(&mut self, font_system: &mut FontSystem, text: &str, attrs: Attrs) {
+    pub fn set_text(
+        &mut self,
+        font_system: &mut FontSystem,
+        text: &str,
+        attrs: Attrs,
+        shaping: Shaping,
+    ) {
         self.lines.clear();
         for line in text.lines() {
-            self.lines
-                .push(BufferLine::new(line.to_string(), AttrsList::new(attrs)));
+            self.lines.push(BufferLine::new(
+                line.to_string(),
+                AttrsList::new(attrs),
+                shaping,
+            ));
         }
         // Make sure there is always one line
         if self.lines.is_empty() {
-            self.lines
-                .push(BufferLine::new(String::new(), AttrsList::new(attrs)));
+            self.lines.push(BufferLine::new(
+                String::new(),
+                AttrsList::new(attrs),
+                shaping,
+            ));
         }
 
         self.scroll = 0;
@@ -769,8 +781,8 @@ impl<'a> BorrowedWithFontSystem<'a, Buffer> {
     }
 
     /// Set text of buffer, using provided attributes for each line by default
-    pub fn set_text(&mut self, text: &str, attrs: Attrs) {
-        self.inner.set_text(self.font_system, text, attrs);
+    pub fn set_text(&mut self, text: &str, attrs: Attrs, shaping: Shaping) {
+        self.inner.set_text(self.font_system, text, attrs, shaping);
     }
 
     /// Draw the buffer

src/buffer_line.rs

@@ -1,7 +1,7 @@
 #[cfg(not(feature = "std"))]
 use alloc::{string::String, vec::Vec};
 
-use crate::{Align, AttrsList, FontSystem, LayoutLine, ShapeLine, Wrap};
+use crate::{Align, AttrsList, FontSystem, LayoutLine, ShapeLine, Shaping, Wrap};
 
 /// A line (or paragraph) of text that is shaped and laid out
 pub struct BufferLine {
@@ -12,13 +12,14 @@ pub struct BufferLine {
     align: Option<Align>,
     shape_opt: Option<ShapeLine>,
     layout_opt: Option<Vec<LayoutLine>>,
+    shaping: Shaping,
 }
 
 impl BufferLine {
     /// Create a new line with the given text and attributes list
     /// Cached shaping and layout can be done using the [`Self::shape`] and
     /// [`Self::layout`] functions
-    pub fn new<T: Into<String>>(text: T, attrs_list: AttrsList) -> Self {
+    pub fn new<T: Into<String>>(text: T, attrs_list: AttrsList, shaping: Shaping) -> Self {
         Self {
             text: text.into(),
             attrs_list,
@@ -26,6 +27,7 @@ impl BufferLine {
             align: None,
             shape_opt: None,
             layout_opt: None,
+            shaping,
         }
     }
 
@@ -142,7 +144,7 @@ impl BufferLine {
         let attrs_list = self.attrs_list.split_off(index);
         self.reset();
 
-        let mut new = Self::new(text, attrs_list);
+        let mut new = Self::new(text, attrs_list, self.shaping);
         new.wrap = self.wrap;
         new
     }
@@ -167,7 +169,12 @@ impl BufferLine {
     /// Shape line, will cache results
     pub fn shape(&mut self, font_system: &mut FontSystem) -> &ShapeLine {
         if self.shape_opt.is_none() {
-            self.shape_opt = Some(ShapeLine::new(font_system, &self.text, &self.attrs_list));
+            self.shape_opt = Some(ShapeLine::new(
+                font_system,
+                &self.text,
+                &self.attrs_list,
+                self.shaping,
+            ));
             self.layout_opt = None;
         }
         self.shape_opt.as_ref().expect("shape not found")

src/edit/editor.rs

@@ -12,6 +12,7 @@ use unicode_segmentation::UnicodeSegmentation;
 use crate::Color;
 use crate::{
     Action, Affinity, AttrsList, Buffer, BufferLine, Cursor, Edit, FontSystem, LayoutCursor,
+    Shaping,
 };
 
 /// A wrapper of [`Buffer`] for easy editing
@@ -245,6 +246,7 @@ impl Edit for Editor {
                     .strip_suffix(char::is_control)
                     .unwrap_or(data_line),
                 these_attrs,
+                Shaping::Advanced,
             ));
         } else {
             panic!("str::lines() did not yield any elements");
@@ -256,6 +258,7 @@ impl Edit for Editor {
                     .strip_suffix(char::is_control)
                     .unwrap_or(data_line),
                 final_attrs.split_off(remaining_split_len),
+                Shaping::Advanced,
             );
             tmp.append(after);
             self.buffer.lines.insert(insert_line, tmp);
@@ -270,6 +273,7 @@ impl Edit for Editor {
                     .strip_suffix(char::is_control)
                     .unwrap_or(data_line),
                 final_attrs.split_off(remaining_split_len),
+                Shaping::Advanced,
             );
             self.buffer.lines.insert(insert_line, tmp);
             self.cursor.line += 1;

src/edit/syntect.rs

@@ -9,7 +9,7 @@ use syntect::parsing::{ParseState, ScopeStack, SyntaxReference, SyntaxSet};
 
 use crate::{
     Action, AttrsList, BorrowedWithFontSystem, Buffer, Color, Cursor, Edit, Editor, FontSystem,
-    Style, Weight, Wrap,
+    Shaping, Style, Weight, Wrap,
 };
 
 pub struct SyntaxSystem {
@@ -75,7 +75,9 @@ impl<'a> SyntaxEditor<'a> {
         let path = path.as_ref();
 
         let text = fs::read_to_string(path)?;
-        self.editor.buffer_mut().set_text(font_system, &text, attrs);
+        self.editor
+            .buffer_mut()
+            .set_text(font_system, &text, attrs, Shaping::Advanced);
 
         //TODO: re-use text
         self.syntax = match self.syntax_system.syntax_set.find_syntax_for_file(path) {

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};
+//! use cosmic_text::{Attrs, Color, FontSystem, SwashCache, Buffer, Metrics, Shaping};
 //!
 //! // A FontSystem provides access to detected system fonts, create one per application
 //! let mut font_system = FontSystem::new();
@@ -36,7 +36,7 @@
 //! let attrs = Attrs::new();
 //!
 //! // Add some text!
-//! buffer.set_text("Hello, Rust! 🦀\n", attrs);
+//! buffer.set_text("Hello, Rust! 🦀\n", attrs, Shaping::Advanced);
 //!
 //! // Perform shaping as desired
 //! buffer.shape_until_scroll();

src/shape.rs

@@ -11,6 +11,46 @@ use unicode_segmentation::UnicodeSegmentation;
 use crate::fallback::FontFallbackIter;
 use crate::{Align, AttrsList, CacheKey, Color, Font, FontSystem, LayoutGlyph, LayoutLine, Wrap};
 
+/// The shaping strategy of some text.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
+pub enum Shaping {
+    /// Basic shaping with no font fallback.
+    ///
+    /// This shaping strategy is very cheap, but it will not display complex
+    /// scripts properly nor try to find missing glyphs in your system fonts.
+    ///
+    /// You should use this strategy when you have complete control of the text
+    /// and the font you are displaying in your application.
+    #[cfg(feature = "swash")]
+    Basic,
+    /// Advanced text shaping and font fallback.
+    ///
+    /// You will need to enable this strategy if the text contains a complex
+    /// script, the font used needs it, and/or multiple fonts in your system
+    /// may be needed to display all of the glyphs.
+    Advanced,
+}
+
+impl Shaping {
+    fn run(
+        self,
+        font_system: &mut FontSystem,
+        line: &str,
+        attrs_list: &AttrsList,
+        start_run: usize,
+        end_run: usize,
+        span_rtl: bool,
+    ) -> Vec<ShapeGlyph> {
+        match self {
+            #[cfg(feature = "swash")]
+            Self::Basic => shape_skip(font_system, line, attrs_list, start_run, end_run),
+            Self::Advanced => {
+                shape_run(font_system, line, attrs_list, start_run, end_run, span_rtl)
+            }
+        }
+    }
+}
+
 fn shape_fallback(
     font: &Font,
     line: &str,
@@ -213,6 +253,50 @@ fn shape_run(
     glyphs
 }
 
+#[cfg(feature = "swash")]
+fn shape_skip(
+    font_system: &mut FontSystem,
+    line: &str,
+    attrs_list: &AttrsList,
+    start_run: usize,
+    end_run: usize,
+) -> Vec<ShapeGlyph> {
+    let attrs = attrs_list.get_span(start_run);
+    let fonts = font_system.get_font_matches(attrs);
+
+    let default_families = [&attrs.family];
+    let mut font_iter = FontFallbackIter::new(font_system, &fonts, &default_families, Vec::new());
+
+    let font = font_iter.next().expect("no default font found");
+    let font_id = font.id();
+    let font = font.as_swash();
+
+    let charmap = font.charmap();
+    let glyph_metrics = font.glyph_metrics(&[]).scale(1.0);
+
+    line[start_run..end_run]
+        .chars()
+        .enumerate()
+        .map(|(i, codepoint)| {
+            let glyph_id = charmap.map(codepoint);
+            let x_advance = glyph_metrics.advance_width(glyph_id);
+
+            ShapeGlyph {
+                start: i,
+                end: i + 1,
+                x_advance,
+                y_advance: 0.0,
+                x_offset: 0.0,
+                y_offset: 0.0,
+                font_id,
+                glyph_id,
+                color_opt: attrs.color_opt,
+                metadata: attrs.metadata,
+            }
+        })
+        .collect()
+}
+
 /// A shaped glyph
 pub struct ShapeGlyph {
     pub start: usize,
@@ -278,6 +362,7 @@ impl ShapeWord {
         word_range: Range<usize>,
         level: unicode_bidi::Level,
         blank: bool,
+        shaping: Shaping,
     ) -> Self {
         let word = &line[word_range.clone()];
 
@@ -297,7 +382,7 @@ impl ShapeWord {
             let attrs_egc = attrs_list.get_span(start_egc);
             if !attrs.compatible(&attrs_egc) {
                 //TODO: more efficient
-                glyphs.append(&mut shape_run(
+                glyphs.append(&mut shaping.run(
                     font_system,
                     line,
                     attrs_list,
@@ -312,7 +397,7 @@ impl ShapeWord {
         }
         if start_run < word_range.end {
             //TODO: more efficient
-            glyphs.append(&mut shape_run(
+            glyphs.append(&mut shaping.run(
                 font_system,
                 line,
                 attrs_list,
@@ -352,6 +437,7 @@ impl ShapeSpan {
         span_range: Range<usize>,
         line_rtl: bool,
         level: unicode_bidi::Level,
+        shaping: Shaping,
     ) -> Self {
         let span = &line[span_range.start..span_range.end];
 
@@ -382,6 +468,7 @@ impl ShapeSpan {
                     (span_range.start + start_word)..(span_range.start + start_lb),
                     level,
                     false,
+                    shaping,
                 ));
             }
             if start_lb < end_lb {
@@ -395,6 +482,7 @@ impl ShapeSpan {
                             ..(span_range.start + start_lb + i + c.len_utf8()),
                         level,
                         true,
+                        shaping,
                     ));
                 }
             }
@@ -437,7 +525,12 @@ impl ShapeLine {
     /// # Panics
     ///
     /// Will panic if `line` contains more than one paragraph.
-    pub fn new(font_system: &mut FontSystem, line: &str, attrs_list: &AttrsList) -> Self {
+    pub fn new(
+        font_system: &mut FontSystem,
+        line: &str,
+        attrs_list: &AttrsList,
+        shaping: Shaping,
+    ) -> Self {
         let mut spans = Vec::new();
 
         let bidi = unicode_bidi::BidiInfo::new(line, None);
@@ -473,6 +566,7 @@ impl ShapeLine {
                         start..i,
                         line_rtl,
                         run_level,
+                        shaping,
                     ));
                     start = i;
                     run_level = new_level;
@@ -485,6 +579,7 @@ impl ShapeLine {
                 start..line_range.end,
                 line_rtl,
                 run_level,
+                shaping,
             ));
             line_rtl
         };