Fixes the overly aggressive overflow elision in truncate() and similar for os scaling other than 100% (#7867)

* Closes #7818
* [x] I have followed the instructions in the PR template

---------

Co-authored-by: Emil Ernerfeldt <emil.ernerfeldt@gmail.com>

crates/epaint/src/text/text_layout.rs

@@ -495,7 +495,9 @@ fn replace_last_glyph_with_overflow_character(
         let replacement_glyph_width = font_face
             .as_mut()
             .and_then(|f| f.glyph_info(overflow_character))
-            .map(|i| i.advance_width_unscaled.0 * font_face_metrics.px_scale_factor)
+            .map(|i| {
+                i.advance_width_unscaled.0 * font_face_metrics.px_scale_factor / pixels_per_point
+            })
             .unwrap_or_default();
 
         // Check if we're within width budget:
@@ -1166,6 +1168,42 @@ mod tests {
         assert_eq!(row.rect().max.x, row.glyphs.last().unwrap().max_x());
     }
 
+    #[test]
+    fn test_truncate_with_pixels_per_point() {
+        let mut fonts = FontsImpl::new(TextOptions::default(), FontDefinitions::default());
+
+        for pixels_per_point in [
+            0.33, 0.5, 0.67, 1.0, 1.25, 1.33, 1.5, 1.75, 2.0, 3.0, 4.0, 5.0,
+        ] {
+            for ch in ['W', 'A', 'n', 't', 'i'] {
+                let target_width = 50.0;
+                let text = (0..20).map(|_| ch).collect::<String>();
+
+                let mut job = LayoutJob::single_section(text, TextFormat::default());
+                job.wrap.max_width = target_width;
+                job.wrap.max_rows = 1;
+                let elided_galley = layout(&mut fonts, pixels_per_point, job.into());
+                assert!(elided_galley.elided);
+
+                let test_galley = layout(
+                    &mut fonts,
+                    pixels_per_point,
+                    Arc::new(LayoutJob::single_section(
+                        (0..elided_galley.rows[0].char_count_excluding_newline())
+                            .map(|_| ch)
+                            .chain(std::iter::once('…'))
+                            .collect::<String>(),
+                        TextFormat::default(),
+                    )),
+                );
+
+                assert!(elided_galley.size().x >= 0.0);
+                assert!(elided_galley.size().x <= target_width);
+                assert!(test_galley.size().x > target_width);
+            }
+        }
+    }
+
     #[test]
     fn test_empty_row() {
         let pixels_per_point = 1.0;