Allow changing ProgressBar fill color (#2618)

CHANGELOG.md

@@ -13,6 +13,7 @@ NOTE: [`epaint`](crates/epaint/CHANGELOG.md), [`eframe`](crates/eframe/CHANGELOG
 * Add `ScrollArea::drag_to_scroll` if you want to turn off that feature.
 * Add `Response::on_hover_and_drag_cursor`.
 * Add `Window::default_open` ([#2539](https://github.com/emilk/egui/pull/2539))
+* Add `ProgressBar::fill` if you want to set the fill color manually. ([#2618](https://github.com/emilk/egui/pull/2618))
 * Add `Button::rounding` to enable round buttons ([#2539](https://github.com/emilk/egui/pull/2539))
 
 ### Changed 🔧

crates/egui/src/widgets/progress_bar.rs

@@ -13,6 +13,7 @@ pub struct ProgressBar {
     progress: f32,
     desired_width: Option<f32>,
     text: Option<ProgressBarText>,
+    fill: Option<Color32>,
     animate: bool,
 }
 
@@ -23,6 +24,7 @@ impl ProgressBar {
             progress: progress.clamp(0.0, 1.0),
             desired_width: None,
             text: None,
+            fill: None,
             animate: false,
         }
     }
@@ -33,6 +35,12 @@ impl ProgressBar {
         self
     }
 
+    /// The fill color of the bar.
+    pub fn fill(mut self, color: Color32) -> Self {
+        self.fill = Some(color);
+        self
+    }
+
     /// A custom text to display on the progress bar.
     pub fn text(mut self, text: impl Into<WidgetText>) -> Self {
         self.text = Some(ProgressBarText::Custom(text.into()));
@@ -60,6 +68,7 @@ impl Widget for ProgressBar {
             progress,
             desired_width,
             text,
+            fill,
             animate,
         } = self;
 
@@ -98,7 +107,9 @@ impl Widget for ProgressBar {
             ui.painter().rect(
                 inner_rect,
                 rounding,
-                Color32::from(Rgba::from(visuals.selection.bg_fill) * color_factor as f32),
+                Color32::from(
+                    Rgba::from(fill.unwrap_or(visuals.selection.bg_fill)) * color_factor as f32,
+                ),
                 Stroke::NONE,
             );