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.

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