Ellipsize (#467)

* feat: add Ellipsize enum

* chore: API changes needed for ellipsize

Decided not to change "layout()" function for now to avoid breaking the
interface. For now.

* chore: shape ellipsis

* feat: Ellipsize::Start

Since it can only have 1 line, it's easier to implement.

* DROPME: temporarily change rich-text for testing

* test(ellipsize): Testing Ellipsize::Start

Long text in small buffer should produce ellipsis glyphs

* fix: do not need font_system anymore

We moved ellipsis shaping elsewhere so no need to pass font_system to
layout function (which also was recreating a new one in the tests every
time making them take forever).

* feat: Ellipsize::End

* improv(ellipsize): use a single ellipsis shape

* improv: Ellipsie::End && Wrap::None

There is no need to layout the whole line if it's not going to fit.

* fix: mixed bidi text when Ellipsize::End && Wrap::None

* chore: clean up and simplify when line.RTL==span.RTL

* fix(ellipsize): last word is not (word_count -1) if iter().rev()

* refactor(layout): extract the layout algorithm to make it more readable

* improv(ellipsize): Ellipsize::Start && Wrap::None

we iterate in reverse and only layout what's going to be visible

* Revert: delete the previous approach of post processing ellipsis

* doc: explain the interaction between Ellipsize and Wrap

* chore: lower the scope

* feat: Ellipsize the last line of a paragraph

For now only the number of lines is supported

* fix: clear ellipsized field on visual lines

This was causing ellipsis to show on random lines

* chore: remove old tests

will add better tests soon

* chore: clean up changes from previous attempt

* fix: consider the ellipsis width when doing alignment

* feat(ellipsize): add `Height` limit to `Ellipsize`

* fix: ellipsize the start of the last line correctly

* fix: ellipsize at the start of mixed bidi lines

* feat: Ellipsize::Middle

* fix: consider ellipsize::middle when calculating alignment correction

* refactor: improve readability

* refactor: deduplicate "fit_glyphs"

* refactor: combine backward and forward layout into one (wip)

* fix: Backward works in the unified layout_spans

* chore: clean up

* fix: Ellipsize::Middle

* fix: handle large words in bidi boundaries

* chore: clean up and some refactoring

* fix: ellipsis is now the same level as the surrounding text

* fix: try to fit more when ellipsizing::middle

* improv: ellipsis now have the same level as the neighbors

This makes ellipsized RTL text inside a LTR line more readable.

before:

Hello سلام...خوبی؟
Hello خولی؟...سلام

* fix: some extra words were being rendered in Ellipsize::Middle

This was causing the last word (if it's not the same level as the rest)
to be rendered outside the buffer.

* test: a few test cases for ellipsize

* fix: assign the correct byte range to ellipsis

this should fix the panic when selecting or clicking on or near the
ellipsis in the editor.

src/buffer.rs

@@ -11,8 +11,8 @@ use unicode_segmentation::UnicodeSegmentation;
 
 use crate::{
     Affinity, Align, Attrs, AttrsList, BidiParagraphs, BorrowedWithFontSystem, BufferLine, Color,
-    Cursor, FontSystem, Hinting, LayoutCursor, LayoutGlyph, LayoutLine, LineEnding, LineIter,
-    Motion, Renderer, Scroll, ShapeLine, Shaping, Wrap,
+    Cursor, Ellipsize, FontSystem, Hinting, LayoutCursor, LayoutGlyph, LayoutLine, LineEnding,
+    LineIter, Motion, Renderer, Scroll, ShapeLine, Shaping, Wrap,
 };
 
 /// A line of visible text for rendering
@@ -214,6 +214,7 @@ pub struct Buffer {
     /// True if a redraw is requires. Set to false after processing
     redraw: bool,
     wrap: Wrap,
+    ellipsize: Ellipsize,
     monospace_width: Option<f32>,
     tab_width: u16,
     hinting: Hinting,
@@ -229,6 +230,7 @@ impl Clone for Buffer {
             scroll: self.scroll,
             redraw: self.redraw,
             wrap: self.wrap,
+            ellipsize: self.ellipsize,
             monospace_width: self.monospace_width,
             tab_width: self.tab_width,
             hinting: self.hinting,
@@ -258,6 +260,7 @@ impl Buffer {
             scroll: Scroll::default(),
             redraw: false,
             wrap: Wrap::WordOrGlyph,
+            ellipsize: Ellipsize::None,
             monospace_width: None,
             tab_width: 8,
             hinting: Hinting::default(),
@@ -298,6 +301,7 @@ impl Buffer {
                     self.metrics.font_size,
                     self.width_opt,
                     self.wrap,
+                    self.ellipsize,
                     self.monospace_width,
                     self.tab_width,
                     self.hinting,
@@ -542,6 +546,7 @@ impl Buffer {
             self.metrics.font_size,
             self.width_opt,
             self.wrap,
+            self.ellipsize,
             self.monospace_width,
             self.tab_width,
             self.hinting,
@@ -590,6 +595,20 @@ impl Buffer {
         }
     }
 
+    /// Get the current [`Ellipsize`]
+    pub const fn ellipsize(&self) -> Ellipsize {
+        self.ellipsize
+    }
+
+    /// Set the current [`Ellipsize`]
+    pub fn set_ellipsize(&mut self, font_system: &mut FontSystem, ellipsize: Ellipsize) {
+        if ellipsize != self.ellipsize {
+            self.ellipsize = ellipsize;
+            self.relayout(font_system);
+            self.shape_until_scroll(font_system, false);
+        }
+    }
+
     /// Get the current `monospace_width`
     pub const fn monospace_width(&self) -> Option<f32> {
         self.monospace_width
@@ -1406,6 +1425,11 @@ impl BorrowedWithFontSystem<'_, Buffer> {
         self.inner.set_wrap(self.font_system, wrap);
     }
 
+    /// Set the current [`Ellipsize`]
+    pub fn set_ellipsize(&mut self, ellipsize: Ellipsize) {
+        self.inner.set_ellipsize(self.font_system, ellipsize);
+    }
+
     /// Set the current buffer dimensions
     pub fn set_size(&mut self, width_opt: Option<f32>, height_opt: Option<f32>) {
         self.inner.set_size(self.font_system, width_opt, height_opt);

src/buffer_line.rs

@@ -1,10 +1,12 @@
+#![allow(clippy::too_many_arguments)]
+
 #[cfg(not(feature = "std"))]
 use alloc::{string::String, vec::Vec};
 use core::mem;
 
 use crate::{
-    Align, Attrs, AttrsList, Cached, FontSystem, Hinting, LayoutLine, LineEnding, ShapeLine,
-    Shaping, Wrap,
+    Align, Attrs, AttrsList, Cached, Ellipsize, FontSystem, Hinting, LayoutLine, LineEnding,
+    ShapeLine, Shaping, Wrap,
 };
 
 /// A line (or paragraph) of text that is shaped and laid out
@@ -242,6 +244,7 @@ impl BufferLine {
         font_size: f32,
         width_opt: Option<f32>,
         wrap: Wrap,
+        ellipsize: Ellipsize,
         match_mono_width: Option<f32>,
         tab_width: u16,
         hinting: Hinting,
@@ -258,6 +261,7 @@ impl BufferLine {
                 font_size,
                 width_opt,
                 wrap,
+                ellipsize,
                 align,
                 &mut layout,
                 match_mono_width,

src/layout.rs

@@ -152,6 +152,29 @@ impl Display for Align {
     }
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Default)]
+pub enum Ellipsize {
+    /// No Ellipsizing
+    #[default]
+    None,
+    /// Ellipsizes the start of the last visual line that fits within the `EllipsizeHeightLimit`
+    Start(EllipsizeHeightLimit),
+    /// Ellipsizes the middle of the last visual line that fits within the `EllipsizeHeightLimit`.
+    Middle(EllipsizeHeightLimit),
+    /// Ellipsizes the end of the last visual line that fits within the `EllipsizeHeightLimit`.
+    End(EllipsizeHeightLimit),
+}
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+pub enum EllipsizeHeightLimit {
+    /// Number of lines to show before ellipsizing the rest. Only works if `Wrap` is NOT set to
+    /// `Wrap::None`. Otherwise, it will be ignored and the behavior will be the same as `Lines(1)`
+    Lines(usize),
+    /// Ellipsizes the last line that fits within the given height limit. If `Wrap` is set to
+    /// `Wrap::None`, the behavior will be the same as `Lines(1)`
+    Height(f32),
+}
+
 /// Metrics hinting strategy
 #[derive(Debug, Eq, PartialEq, Clone, Copy, Default)]
 pub enum Hinting {

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,
-    SwashCache,
+    fontdb::Database, Align, Attrs, AttrsOwned, Buffer, Color, Ellipsize, Family, FontSystem,
+    Metrics, Shaping, SwashCache, Wrap,
 };
 use tiny_skia::{Paint, Pixmap, Rect, Transform};
 
@@ -29,6 +29,9 @@ pub struct DrawTestCfg {
     line_height: f32,
     canvas_width: u32,
     canvas_height: u32,
+    wrap: Wrap,
+    ellipsize: Ellipsize,
+    alignment: Option<Align>,
 }
 
 impl Default for DrawTestCfg {
@@ -42,6 +45,9 @@ impl Default for DrawTestCfg {
             line_height: 20.0,
             canvas_width: 300,
             canvas_height: 300,
+            wrap: Wrap::WordOrGlyph,
+            ellipsize: Ellipsize::None,
+            alignment: None,
         }
     }
 }
@@ -76,6 +82,21 @@ impl DrawTestCfg {
         self
     }
 
+    pub fn wrap(mut self, wrap: Wrap) -> Self {
+        self.wrap = wrap;
+        self
+    }
+
+    pub fn ellipsize(mut self, ellipsize: Ellipsize) -> Self {
+        self.ellipsize = ellipsize;
+        self
+    }
+
+    pub fn alignment(mut self, alignment: Option<Align>) -> Self {
+        self.alignment = alignment;
+        self
+    }
+
     pub fn validate_text_rendering(self) {
         let repo_dir = std::env::var("CARGO_MANIFEST_DIR").unwrap();
         // Create a db with just the fonts in our fonts dir to make sure we only test those
@@ -88,11 +109,18 @@ impl DrawTestCfg {
         let mut buffer = Buffer::new(&mut font_system, metrics);
         let mut buffer = buffer.borrow_with(&mut font_system);
         let margins = 5;
+        buffer.set_wrap(self.wrap);
+        buffer.set_ellipsize(self.ellipsize);
         buffer.set_size(
             Some((self.canvas_width - margins * 2) as f32),
             Some((self.canvas_height - margins * 2) as f32),
         );
-        buffer.set_text(&self.text, &self.font.as_attrs(), Shaping::Advanced, None);
+        buffer.set_text(
+            &self.text,
+            &self.font.as_attrs(),
+            Shaping::Advanced,
+            self.alignment,
+        );
         buffer.shape_until_scroll(true);
 
         // Black

tests/ellipsize_rendering.rs

@@ -0,0 +1,161 @@
+use common::DrawTestCfg;
+use cosmic_text::{Align, Attrs, Ellipsize, EllipsizeHeightLimit, Family, Wrap};
+
+mod common;
+
+#[test]
+fn test_ellipsize_ltr_end_single_line() {
+    let attrs = Attrs::new().family(Family::Name("Inter"));
+    DrawTestCfg::new("ellipsize_ltr_end_single_line")
+        .font_size(20., 26.)
+        .font_attrs(attrs)
+        .text("The quick brown fox jumps over the lazy dog.")
+        .wrap(Wrap::None)
+        .ellipsize(Ellipsize::End(EllipsizeHeightLimit::Lines(1)))
+        .canvas(180, 50)
+        .validate_text_rendering();
+}
+
+#[test]
+fn test_ellipsize_ltr_end_single_line_aligned_right() {
+    let attrs = Attrs::new().family(Family::Name("Inter"));
+    DrawTestCfg::new("ellipsize_ltr_end_single_line_aligned_right")
+        .font_size(20., 26.)
+        .font_attrs(attrs)
+        .text("The quick brown fox jumps over the lazy dog.")
+        .wrap(Wrap::None)
+        .ellipsize(Ellipsize::End(EllipsizeHeightLimit::Lines(1)))
+        .alignment(Some(Align::Right))
+        .canvas(180, 50)
+        .validate_text_rendering();
+}
+
+#[test]
+fn test_ellipsize_rtl_end_single_line() {
+    let attrs = Attrs::new().family(Family::Name("Noto Sans"));
+    DrawTestCfg::new("ellipsize_rtl_end_single_line")
+        .font_size(22., 28.)
+        .font_attrs(attrs)
+        .text("توانا بود هرکه دانا بود.")
+        .wrap(Wrap::None)
+        .ellipsize(Ellipsize::End(EllipsizeHeightLimit::Lines(1)))
+        .canvas(180, 55)
+        .validate_text_rendering();
+}
+
+#[test]
+fn test_ellipsize_mixed_end_single_line() {
+    let attrs = Attrs::new().family(Family::Name("Noto Sans"));
+    DrawTestCfg::new("ellipsize_mixed_end_single_line")
+        .font_size(20., 26.)
+        .font_attrs(attrs)
+        .text("Hello سلام mixed RTL/LTR world with extra words")
+        .wrap(Wrap::None)
+        .ellipsize(Ellipsize::End(EllipsizeHeightLimit::Lines(1)))
+        .canvas(190, 50)
+        .validate_text_rendering();
+}
+
+#[test]
+fn test_ellipsize_ltr_start_single_line() {
+    let attrs = Attrs::new().family(Family::Name("Inter"));
+    DrawTestCfg::new("ellipsize_ltr_start_single_line")
+        .font_size(20., 26.)
+        .font_attrs(attrs)
+        .text("The quick brown fox jumps over the lazy dog.")
+        .wrap(Wrap::None)
+        .ellipsize(Ellipsize::Start(EllipsizeHeightLimit::Lines(1)))
+        .canvas(180, 50)
+        .validate_text_rendering();
+}
+
+#[test]
+fn test_ellipsize_ltr_middle_single_line() {
+    let attrs = Attrs::new().family(Family::Name("Inter"));
+    DrawTestCfg::new("ellipsize_ltr_middle_single_line")
+        .font_size(20., 26.)
+        .font_attrs(attrs)
+        .text("The quick brown fox jumps over the lazy dog.")
+        .wrap(Wrap::None)
+        .ellipsize(Ellipsize::Middle(EllipsizeHeightLimit::Lines(1)))
+        .canvas(180, 50)
+        .validate_text_rendering();
+}
+
+#[test]
+fn test_ellipsize_ltr_end_two_lines() {
+    let attrs = Attrs::new().family(Family::Name("Inter"));
+    DrawTestCfg::new("ellipsize_ltr_end_two_lines")
+        .font_size(18., 24.)
+        .font_attrs(attrs)
+        .text("Pack my box with five dozen liquor jugs. Sphinx of black quartz, judge my vow.")
+        .wrap(Wrap::Word)
+        .ellipsize(Ellipsize::End(EllipsizeHeightLimit::Lines(2)))
+        .canvas(200, 80)
+        .validate_text_rendering();
+}
+
+#[test]
+fn test_ellipsize_mixed_middle_single_line() {
+    let attrs = Attrs::new().family(Family::Name("Inter"));
+    DrawTestCfg::new("ellipsize_mixed_middle_single_line")
+        .font_size(20., 26.)
+        .font_attrs(attrs)
+        .text("Hello سلام mixed RTL/LTR world with extra words")
+        .wrap(Wrap::None)
+        .ellipsize(Ellipsize::Middle(EllipsizeHeightLimit::Lines(1)))
+        .canvas(180, 50)
+        .validate_text_rendering();
+}
+
+#[test]
+fn test_ellipsize_mixed_ltr_rtl_middle_two_lines() {
+    let attrs = Attrs::new().family(Family::Name("Inter"));
+    DrawTestCfg::new("ellipsize_mixed_ltr_rtl_middle_two_lines")
+        .font_size(20., 26.)
+        .font_attrs(attrs)
+        .text("First line is LTR خط دوم از راست به چپ")
+        .wrap(Wrap::WordOrGlyph)
+        .ellipsize(Ellipsize::Middle(EllipsizeHeightLimit::Lines(2)))
+        .canvas(180, 80)
+        .validate_text_rendering();
+}
+
+#[test]
+fn test_ellipsize_mixed_rtl_ltr_middle_two_lines() {
+    let attrs = Attrs::new().family(Family::Name("Inter"));
+    DrawTestCfg::new("ellipsize_mixed_rtl_ltr_middle_two_lines")
+        .font_size(20., 26.)
+        .font_attrs(attrs)
+        .text("خط اول از راست به چپ Second line is LTR and has more words")
+        .wrap(Wrap::WordOrGlyph)
+        .ellipsize(Ellipsize::Middle(EllipsizeHeightLimit::Lines(2)))
+        .canvas(210, 80)
+        .validate_text_rendering();
+}
+
+#[test]
+fn test_ellipsize_ltr_single_word_middle_two_lines() {
+    let attrs = Attrs::new().family(Family::Name("Inter"));
+    DrawTestCfg::new("ellipsize_ltr_single_word_middle_two_lines")
+        .font_size(20., 26.)
+        .font_attrs(attrs)
+        .text("AVeryLongWordThatExceedsTheWidth")
+        .wrap(Wrap::WordOrGlyph)
+        .ellipsize(Ellipsize::Middle(EllipsizeHeightLimit::Lines(2)))
+        .canvas(180, 80)
+        .validate_text_rendering();
+}
+
+#[test]
+fn test_ellipsize_mixed_ltr_rtl_ltr_middle_three_lines() {
+    let attrs = Attrs::new().family(Family::Name("Inter"));
+    DrawTestCfg::new("ellipsize_mixed_ltr_rtl_ltr_middle_three_lines")
+        .font_size(20., 26.)
+        .font_attrs(attrs)
+        .text("This is some LTR text that keeps و یه مشت متن فارسیی.zippy")
+        .wrap(Wrap::WordOrGlyph)
+        .ellipsize(Ellipsize::Middle(EllipsizeHeightLimit::Lines(3)))
+        .canvas(200, 100)
+        .validate_text_rendering();
+}

tests/images/ellipsize_ltr_end_single_line.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:0de01fa40e15779c52c39652369f6c636ce0c018c3ef488d99cc7cfcd0d53eb4
+size 4957

tests/images/ellipsize_ltr_end_single_line_aligned_right.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:cb2f9fccbe5dd17854cc9975cba81a8357ca299d1970585dac025d81beaa6a29
+size 5099

tests/images/ellipsize_ltr_end_two_lines.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:ab08b3a7061db4e32ece8aec5bc6c4a32939fa91186c31f76eb901adcdbdd0fc
+size 12218

tests/images/ellipsize_ltr_middle_single_line.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:181b48bf70119b2df56521c287b2cd1b60ab1677ebaa03ea5f01dee522693370
+size 5412

tests/images/ellipsize_ltr_single_word_middle_two_lines.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:0fb2a94c8892736ae1e05ef5d42e541eff7eae8826cae6e19fb34727b1ff6ee6
+size 12179

tests/images/ellipsize_ltr_start_single_line.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:e2a705f931aae72c693a2a1ae56ad2455ee3a8f7f2309ca99864eedbf7c59d40
+size 5518

tests/images/ellipsize_mixed_end_single_line.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:6438bf5df040bfe61566af722823f2f78d519e4719547c766fbe19e2dc4a07f6
+size 5985

tests/images/ellipsize_mixed_ltr_rtl_ltr_middle_three_lines.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:4cf481f25cf06518eddfc8794322bb13998f39709076a2d07ece2e2528d7364e
+size 16096

tests/images/ellipsize_mixed_ltr_rtl_middle_two_lines.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:36156e31793901ede07b4db53ddf671b5c134afe82a8328fd7eacad1cebcd339
+size 8960

tests/images/ellipsize_mixed_middle_single_line.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:88bf081f80aac508baa685718fce15e3acf888b43c199aa902494a2c47ed22e3
+size 5501

tests/images/ellipsize_mixed_rtl_ltr_middle_two_lines.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:56fcff35d50673ec790dfacc82b55513f643628d6745a7eec2a7082b4ced04f7
+size 12004

tests/images/ellipsize_rtl_end_single_line.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:0e9d984a59003766fda15d1bb35069d6f5a9638b00c0560f2fad3431c0283aa9
+size 5585