ui: add feathering-resistant hline separator fn

"pixel-aligned" Separators get feathered into a blurry mess. This seems
to help.

Signed-off-by: William Casarin <[email protected]>

Author: jb55

src/timeline.rs

@@ -99,7 +99,8 @@ pub fn timeline_view(ui: &mut egui::Ui, app: &mut Damus, timeline: usize) {
                     let textmode = app.textmode;
                     let note_ui = ui::Note::new(app, &note).note_previews(!textmode);
                     ui.add(note_ui);
-                    ui.add(egui::Separator::default().spacing(0.0));
+                    ui::hline(ui);
+                    //ui.add(egui::Separator::default().spacing(0.0));
 
                     1
                 });

src/ui/mod.rs

@@ -39,6 +39,14 @@ pub fn padding<R>(
         .show(ui, add_contents)
 }
 
+pub fn hline(ui: &egui::Ui) {
+    // pixel perfect horizontal line
+    let rect = ui.available_rect_before_wrap();
+    let resize_y = ui.painter().round_to_pixel(rect.top()) - 0.5;
+    let stroke = ui.style().visuals.widgets.noninteractive.bg_stroke;
+    ui.painter().hline(rect.x_range(), resize_y, stroke);
+}
+
 #[inline]
 #[allow(unreachable_code)]
 pub fn is_mobile(_ctx: &egui::Context) -> bool {