Use Rgba (4xf32) instead of Color32 in all interfaces

This simplifies a few things, but some benchmarks gets worse,
probably due to the increased memory use (and thus more cache misses).

I don't plan to merge this, but leave it here as an experiment

egui/src/containers/frame.rs

@@ -11,7 +11,7 @@ pub struct Frame {
     pub margin: Vec2,
     pub corner_radius: f32,
     pub shadow: Shadow,
-    pub fill: Color32,
+    pub fill: Rgba,
     pub stroke: Stroke,
 }
 
@@ -85,7 +85,7 @@ impl Frame {
         Self {
             margin: Vec2::new(10.0, 10.0),
             corner_radius: style.visuals.widgets.noninteractive.corner_radius,
-            fill: Color32::from_black_alpha(250),
+            fill: Color32::from_black_alpha(250).into(),
             stroke: style.visuals.window_stroke(),
             ..Default::default()
         }
@@ -93,7 +93,7 @@ impl Frame {
 }
 
 impl Frame {
-    pub fn fill(mut self, fill: Color32) -> Self {
+    pub fn fill(mut self, fill: Rgba) -> Self {
         self.fill = fill;
         self
     }
@@ -120,9 +120,9 @@ impl Frame {
     }
 
     pub fn multiply_with_opacity(mut self, opacity: f32) -> Self {
-        self.fill = self.fill.linear_multiply(opacity);
+        self.fill = self.fill * opacity;
-        self.stroke.color = self.stroke.color.linear_multiply(opacity);
+        self.stroke.color = self.stroke.color * opacity;
-        self.shadow.color = self.shadow.color.linear_multiply(opacity);
+        self.shadow.color = self.shadow.color * opacity;
         self
     }
 }

egui/src/containers/resize.rs

@@ -303,12 +303,12 @@ impl Resize {
         if ui.ctx().style().debug.show_resize {
             ui.ctx().debug_painter().debug_rect(
                 Rect::from_min_size(content_ui.min_rect().left_top(), state.desired_size),
-                Color32::GREEN,
+                Rgba::GREEN,
                 "desired_size",
             );
             ui.ctx().debug_painter().debug_rect(
                 Rect::from_min_size(content_ui.min_rect().left_top(), state.last_content_size),
-                Color32::LIGHT_BLUE,
+                Rgba::LIGHT_BLUE,
                 "last_content_size",
             );
         }

egui/src/context.rs

@@ -888,7 +888,7 @@ impl Context {
                     {
                         ui.ctx()
                             .debug_painter()
-                            .debug_rect(area.rect(), Color32::RED, "");
+                            .debug_rect(area.rect(), Rgba::RED, "");
                     }
                 }
             }

egui/src/introspection.rs

@@ -20,11 +20,7 @@ impl Widget for &epaint::Texture {
             }
             let (rect, response) = ui.allocate_at_least(size, Sense::hover());
             let mut mesh = Mesh::default();
-            mesh.add_rect_with_uv(
+            mesh.add_rect_with_uv(rect, [pos2(0.0, 0.0), pos2(1.0, 1.0)].into(), Rgba::WHITE);
-                rect,
-                [pos2(0.0, 0.0), pos2(1.0, 1.0)].into(),
-                Color32::WHITE,
-            );
             ui.painter().add(Shape::mesh(mesh));
 
             let (tex_w, tex_h) = (self.width as f32, self.height as f32);
@@ -46,7 +42,7 @@ impl Widget for &epaint::Texture {
                             pos2((u + texel_radius) / tex_w, (v + texel_radius) / tex_h),
                         );
                         let mut mesh = Mesh::default();
-                        mesh.add_rect_with_uv(zoom_rect, uv_rect, Color32::WHITE);
+                        mesh.add_rect_with_uv(zoom_rect, uv_rect, Rgba::WHITE);
                         ui.painter().add(Shape::mesh(mesh));
                     }
                 });

egui/src/menu.rs

@@ -43,11 +43,11 @@ pub fn bar<R>(ui: &mut Ui, add_contents: impl FnOnce(&mut Ui) -> R) -> InnerResp
     ui.horizontal(|ui| {
         let mut style = (**ui.style()).clone();
         style.spacing.button_padding = vec2(2.0, 0.0);
-        // style.visuals.widgets.active.bg_fill = Color32::TRANSPARENT;
+        // style.visuals.widgets.active.bg_fill = Rgba::TRANSPARENT;
         style.visuals.widgets.active.bg_stroke = Stroke::none();
-        // style.visuals.widgets.hovered.bg_fill = Color32::TRANSPARENT;
+        // style.visuals.widgets.hovered.bg_fill = Rgba::TRANSPARENT;
         style.visuals.widgets.hovered.bg_stroke = Stroke::none();
-        style.visuals.widgets.inactive.bg_fill = Color32::TRANSPARENT;
+        style.visuals.widgets.inactive.bg_fill = Rgba::TRANSPARENT;
         style.visuals.widgets.inactive.bg_stroke = Stroke::none();
         ui.set_style(style);
 
@@ -114,11 +114,11 @@ fn menu_impl<'c, R>(
                     .show(ui, |ui| {
                         let mut style = (**ui.style()).clone();
                         style.spacing.button_padding = vec2(2.0, 0.0);
-                        // style.visuals.widgets.active.bg_fill = Color32::TRANSPARENT;
+                        // style.visuals.widgets.active.bg_fill = Rgba::TRANSPARENT;
                         style.visuals.widgets.active.bg_stroke = Stroke::none();
-                        // style.visuals.widgets.hovered.bg_fill = Color32::TRANSPARENT;
+                        // style.visuals.widgets.hovered.bg_fill = Rgba::TRANSPARENT;
                         style.visuals.widgets.hovered.bg_stroke = Stroke::none();
-                        style.visuals.widgets.inactive.bg_fill = Color32::TRANSPARENT;
+                        style.visuals.widgets.inactive.bg_fill = Rgba::TRANSPARENT;
                         style.visuals.widgets.inactive.bg_stroke = Stroke::none();
                         ui.set_style(style);
                         ui.with_layout(Layout::top_down_justified(Align::LEFT), add_contents)

egui/src/painter.rs

@@ -1,7 +1,7 @@
 use crate::{
     emath::{Align2, Pos2, Rect, Vec2},
     layers::{LayerId, PaintList, ShapeIdx},
-    Color32, CtxRef,
+    Color32, CtxRef, Rgba,
 };
 use epaint::{
     mutex::Mutex,
@@ -28,7 +28,7 @@ pub struct Painter {
 
     /// If set, all shapes will have their colors modified to be closer to this.
     /// This is used to implement grayed out interfaces.
-    fade_to_color: Option<Color32>,
+    fade_to_color: Option<Rgba>,
 }
 
 impl Painter {
@@ -62,17 +62,17 @@ impl Painter {
     }
 
     /// If set, colors will be modified to look like this
-    pub(crate) fn set_fade_to_color(&mut self, fade_to_color: Option<Color32>) {
+    pub(crate) fn set_fade_to_color(&mut self, fade_to_color: Option<Rgba>) {
         self.fade_to_color = fade_to_color;
     }
 
     pub(crate) fn visible(&self) -> bool {
-        self.fade_to_color != Some(Color32::TRANSPARENT)
+        self.fade_to_color != Some(Rgba::TRANSPARENT)
     }
 
     /// If `false`, nothing added to the painter will be visible
     pub(crate) fn set_invisible(&mut self) {
-        self.fade_to_color = Some(Color32::TRANSPARENT)
+        self.fade_to_color = Some(Rgba::TRANSPARENT)
     }
 
     /// Create a painter for a sub-region of this `Painter`.
@@ -155,7 +155,7 @@ impl Painter {
     /// Can be used for free painting.
     /// NOTE: all coordinates are screen coordinates!
     pub fn add(&self, mut shape: Shape) -> ShapeIdx {
-        if self.fade_to_color == Some(Color32::TRANSPARENT) {
+        if self.fade_to_color == Some(Rgba::TRANSPARENT) {
             self.paint_list.lock().add(self.clip_rect, Shape::Noop)
         } else {
             self.transform_shape(&mut shape);
@@ -167,7 +167,7 @@ impl Painter {
     ///
     /// Calling this once is generally faster than calling [`Self::add`] multiple times.
     pub fn extend(&self, mut shapes: Vec<Shape>) {
-        if self.fade_to_color == Some(Color32::TRANSPARENT) {
+        if self.fade_to_color == Some(Rgba::TRANSPARENT) {
             return;
         }
         if !shapes.is_empty() {
@@ -183,7 +183,7 @@ impl Painter {
 
     /// Modify an existing [`Shape`].
     pub fn set(&self, idx: ShapeIdx, mut shape: Shape) {
-        if self.fade_to_color == Some(Color32::TRANSPARENT) {
+        if self.fade_to_color == Some(Rgba::TRANSPARENT) {
             return;
         }
         self.transform_shape(&mut shape);
@@ -194,7 +194,7 @@ impl Painter {
 /// ## Debug painting
 impl Painter {
     #[allow(clippy::needless_pass_by_value)]
-    pub fn debug_rect(&mut self, rect: Rect, color: Color32, text: impl ToString) {
+    pub fn debug_rect(&mut self, rect: Rect, color: Rgba, text: impl ToString) {
         self.rect_stroke(rect, 0.0, (1.0, color));
         let text_style = TextStyle::Monospace;
         self.text(
@@ -207,18 +207,12 @@ impl Painter {
     }
 
     pub fn error(&self, pos: Pos2, text: impl std::fmt::Display) -> Rect {
-        self.debug_text(pos, Align2::LEFT_TOP, Color32::RED, format!("🔥 {}", text))
+        self.debug_text(pos, Align2::LEFT_TOP, Rgba::RED, format!("🔥 {}", text))
     }
 
     /// text with a background
     #[allow(clippy::needless_pass_by_value)]
-    pub fn debug_text(
+    pub fn debug_text(&self, pos: Pos2, anchor: Align2, color: Rgba, text: impl ToString) -> Rect {
-        &self,
-        pos: Pos2,
-        anchor: Align2,
-        color: Color32,
-        text: impl ToString,
-    ) -> Rect {
         let galley = self
             .fonts()
             .layout_no_wrap(TextStyle::Monospace, text.to_string());
@@ -227,7 +221,7 @@ impl Painter {
         self.add(Shape::Rect {
             rect: frame_rect,
             corner_radius: 0.0,
-            fill: Color32::from_black_alpha(240),
+            fill: Color32::from_black_alpha(240).into(),
             // stroke: Stroke::new(1.0, color),
             stroke: Default::default(),
         });
@@ -249,7 +243,7 @@ impl Painter {
         &self,
         center: Pos2,
         radius: f32,
-        fill_color: impl Into<Color32>,
+        fill_color: impl Into<Rgba>,
         stroke: impl Into<Stroke>,
     ) {
         self.add(Shape::Circle {
@@ -260,7 +254,7 @@ impl Painter {
         });
     }
 
-    pub fn circle_filled(&self, center: Pos2, radius: f32, fill_color: impl Into<Color32>) {
+    pub fn circle_filled(&self, center: Pos2, radius: f32, fill_color: impl Into<Rgba>) {
         self.add(Shape::Circle {
             center,
             radius,
@@ -282,7 +276,7 @@ impl Painter {
         &self,
         rect: Rect,
         corner_radius: f32,
-        fill_color: impl Into<Color32>,
+        fill_color: impl Into<Rgba>,
         stroke: impl Into<Stroke>,
     ) {
         self.add(Shape::Rect {
@@ -293,7 +287,7 @@ impl Painter {
         });
     }
 
-    pub fn rect_filled(&self, rect: Rect, corner_radius: f32, fill_color: impl Into<Color32>) {
+    pub fn rect_filled(&self, rect: Rect, corner_radius: f32, fill_color: impl Into<Rgba>) {
         self.add(Shape::Rect {
             rect,
             corner_radius,
@@ -341,7 +335,7 @@ impl Painter {
         anchor: Align2,
         text: impl ToString,
         text_style: TextStyle,
-        text_color: Color32,
+        text_color: Rgba,
     ) -> Rect {
         let galley = self.layout_no_wrap(text_style, text.to_string());
         let rect = anchor.anchor_rect(Rect::from_min_size(pos, galley.size));
@@ -377,7 +371,7 @@ impl Painter {
     ///
     /// You can create the `Galley` with [`Self::layout_no_wrap`] or [`Self::layout_multiline`].
     #[inline(always)]
-    pub fn galley(&self, pos: Pos2, galley: std::sync::Arc<Galley>, color: Color32) {
+    pub fn galley(&self, pos: Pos2, galley: std::sync::Arc<Galley>, color: Rgba) {
         self.galley_with_italics(pos, galley, color, false)
     }
 
@@ -385,7 +379,7 @@ impl Painter {
         &self,
         pos: Pos2,
         galley: std::sync::Arc<Galley>,
-        color: Color32,
+        color: Rgba,
         fake_italics: bool,
     ) {
         if !galley.is_empty() {
@@ -399,8 +393,8 @@ impl Painter {
     }
 }
 
-fn tint_shape_towards(shape: &mut Shape, target: Color32) {
+fn tint_shape_towards(shape: &mut Shape, target: Rgba) {
     epaint::shape_transform::adjust_colors(shape, &|color| {
-        *color = crate::color::tint_color_towards(*color, target);
+        *color = crate::color::tint_rgba_towards(*color, target);
     });
 }

egui/src/style.rs

@@ -189,7 +189,7 @@ pub struct Visuals {
     /// so that `visuals.text_color` is always used,
     /// but its alpha may be different based on whether or not
     /// it is disabled, non-interactive, hovered etc.
-    pub override_text_color: Option<Color32>,
+    pub override_text_color: Option<Rgba>,
 
     /// Visual styles of widgets
     pub widgets: Widgets,
@@ -197,19 +197,19 @@ pub struct Visuals {
     pub selection: Selection,
 
     /// The color used for `Hyperlink`,
-    pub hyperlink_color: Color32,
+    pub hyperlink_color: Rgba,
 
     /// Something just barely different from the background color.
     /// Used for [`crate::Grid::striped`].
-    pub faint_bg_color: Color32,
+    pub faint_bg_color: Rgba,
 
     /// Very dark or light color (for corresponding theme).
     /// Used as the background of text edits, scroll bars and others things
     /// that needs to look different from other interactive stuff.
-    pub extreme_bg_color: Color32,
+    pub extreme_bg_color: Rgba,
 
     /// Background color behind code-styled monospaced labels.
-    pub code_bg_color: Color32,
+    pub code_bg_color: Rgba,
 
     pub window_corner_radius: f32,
     pub window_shadow: Shadow,
@@ -237,20 +237,20 @@ impl Visuals {
         &self.widgets.noninteractive
     }
 
-    pub fn text_color(&self) -> Color32 {
+    pub fn text_color(&self) -> Rgba {
         self.override_text_color
             .unwrap_or_else(|| self.widgets.noninteractive.text_color())
     }
 
-    pub fn weak_text_color(&self) -> Color32 {
+    pub fn weak_text_color(&self) -> Rgba {
-        crate::color::tint_color_towards(self.text_color(), self.window_fill())
+        crate::color::tint_rgba_towards(self.text_color(), self.window_fill())
     }
 
-    pub fn strong_text_color(&self) -> Color32 {
+    pub fn strong_text_color(&self) -> Rgba {
         self.widgets.active.text_color()
     }
 
-    pub fn window_fill(&self) -> Color32 {
+    pub fn window_fill(&self) -> Rgba {
         self.widgets.noninteractive.bg_fill
     }
 
@@ -264,7 +264,7 @@ impl Visuals {
 #[cfg_attr(feature = "persistence", derive(serde::Deserialize, serde::Serialize))]
 #[cfg_attr(feature = "persistence", serde(default))]
 pub struct Selection {
-    pub bg_fill: Color32,
+    pub bg_fill: Rgba,
     pub stroke: Stroke,
 }
 
@@ -307,7 +307,7 @@ impl Widgets {
 #[cfg_attr(feature = "persistence", derive(serde::Deserialize, serde::Serialize))]
 pub struct WidgetVisuals {
     /// Background color of widget.
-    pub bg_fill: Color32,
+    pub bg_fill: Rgba,
 
     /// For surrounding rectangle of things that need it,
     /// like buttons, the box of the checkbox, etc.
@@ -325,7 +325,7 @@ pub struct WidgetVisuals {
 }
 
 impl WidgetVisuals {
-    pub fn text_color(&self) -> Color32 {
+    pub fn text_color(&self) -> Rgba {
         self.fg_stroke.color
     }
 }
@@ -398,10 +398,10 @@ impl Visuals {
             override_text_color: None,
             widgets: Widgets::default(),
             selection: Selection::default(),
-            hyperlink_color: Color32::from_rgb(90, 170, 255),
+            hyperlink_color: Color32::from_rgb(90, 170, 255).into(),
-            faint_bg_color: Color32::from_gray(24),
+            faint_bg_color: Color32::from_gray(24).into(),
-            extreme_bg_color: Color32::from_gray(10),
+            extreme_bg_color: Color32::from_gray(10).into(),
-            code_bg_color: Color32::from_gray(64),
+            code_bg_color: Color32::from_gray(64).into(),
             window_corner_radius: 6.0,
             window_shadow: Shadow::big_dark(),
             popup_shadow: Shadow::small_dark(),
@@ -420,10 +420,10 @@ impl Visuals {
             dark_mode: false,
             widgets: Widgets::light(),
             selection: Selection::light(),
-            hyperlink_color: Color32::from_rgb(0, 155, 255),
+            hyperlink_color: Color32::from_rgb(0, 155, 255).into(),
-            faint_bg_color: Color32::from_gray(240),
+            faint_bg_color: Color32::from_gray(240).into(),
-            extreme_bg_color: Color32::from_gray(250),
+            extreme_bg_color: Color32::from_gray(250).into(),
-            code_bg_color: Color32::from_gray(200),
+            code_bg_color: Color32::from_gray(200).into(),
             window_shadow: Shadow::big_light(),
             popup_shadow: Shadow::small_light(),
             ..Self::dark()
@@ -440,13 +440,13 @@ impl Default for Visuals {
 impl Selection {
     fn dark() -> Self {
         Self {
-            bg_fill: Color32::from_rgb(0, 92, 128),
+            bg_fill: Color32::from_rgb(0, 92, 128).into(),
             stroke: Stroke::new(1.0, Color32::from_rgb(192, 222, 255)),
         }
     }
     fn light() -> Self {
         Self {
-            bg_fill: Color32::from_rgb(144, 209, 255),
+            bg_fill: Color32::from_rgb(144, 209, 255).into(),
             stroke: Stroke::new(1.0, Color32::from_rgb(0, 83, 125)),
         }
     }
@@ -462,35 +462,35 @@ impl Widgets {
     pub fn dark() -> Self {
         Self {
             noninteractive: WidgetVisuals {
-                bg_fill: Color32::from_gray(27), // window background
+                bg_fill: Color32::from_gray(27).into(), // window background
                 bg_stroke: Stroke::new(1.0, Color32::from_gray(60)), // separators, indentation lines, windows outlines
                 fg_stroke: Stroke::new(1.0, Color32::from_gray(140)), // normal text color
                 corner_radius: 2.0,
                 expansion: 0.0,
             },
             inactive: WidgetVisuals {
-                bg_fill: Color32::from_gray(60), // button background
+                bg_fill: Color32::from_gray(60).into(), // button background
                 bg_stroke: Default::default(),
                 fg_stroke: Stroke::new(1.0, Color32::from_gray(180)), // button text
                 corner_radius: 2.0,
                 expansion: 0.0,
             },
             hovered: WidgetVisuals {
-                bg_fill: Color32::from_gray(70),
+                bg_fill: Color32::from_gray(70).into(),
                 bg_stroke: Stroke::new(1.0, Color32::from_gray(150)), // e.g. hover over window edge or button
                 fg_stroke: Stroke::new(1.5, Color32::from_gray(240)),
                 corner_radius: 3.0,
                 expansion: 1.0,
             },
             active: WidgetVisuals {
-                bg_fill: Color32::from_gray(55),
+                bg_fill: Color32::from_gray(55).into(),
-                bg_stroke: Stroke::new(1.0, Color32::WHITE),
+                bg_stroke: Stroke::new(1.0, Rgba::WHITE),
-                fg_stroke: Stroke::new(2.0, Color32::WHITE),
+                fg_stroke: Stroke::new(2.0, Rgba::WHITE),
                 corner_radius: 2.0,
                 expansion: 1.0,
             },
             open: WidgetVisuals {
-                bg_fill: Color32::from_gray(27),
+                bg_fill: Color32::from_gray(27).into(),
                 bg_stroke: Stroke::new(1.0, Color32::from_gray(60)),
                 fg_stroke: Stroke::new(1.0, Color32::from_gray(210)),
                 corner_radius: 2.0,
@@ -502,37 +502,37 @@ impl Widgets {
     pub fn light() -> Self {
         Self {
             noninteractive: WidgetVisuals {
-                bg_fill: Color32::from_gray(235), // window background
+                bg_fill: Color32::from_gray(235).into(), // window background
                 bg_stroke: Stroke::new(1.0, Color32::from_gray(190)), // separators, indentation lines, windows outlines
                 fg_stroke: Stroke::new(1.0, Color32::from_gray(100)), // normal text color
                 corner_radius: 2.0,
                 expansion: 0.0,
             },
             inactive: WidgetVisuals {
-                bg_fill: Color32::from_gray(215), // button background
+                bg_fill: Color32::from_gray(215).into(), // button background
                 bg_stroke: Default::default(),
                 fg_stroke: Stroke::new(1.0, Color32::from_gray(80)), // button text
                 corner_radius: 2.0,
                 expansion: 0.0,
             },
             hovered: WidgetVisuals {
-                bg_fill: Color32::from_gray(210),
+                bg_fill: Color32::from_gray(210).into(),
                 bg_stroke: Stroke::new(1.0, Color32::from_gray(105)), // e.g. hover over window edge or button
-                fg_stroke: Stroke::new(1.5, Color32::BLACK),
+                fg_stroke: Stroke::new(1.5, Rgba::BLACK),
                 corner_radius: 3.0,
                 expansion: 1.0,
             },
             active: WidgetVisuals {
-                bg_fill: Color32::from_gray(165),
+                bg_fill: Color32::from_gray(165).into(),
-                bg_stroke: Stroke::new(1.0, Color32::BLACK),
+                bg_stroke: Stroke::new(1.0, Rgba::BLACK),
-                fg_stroke: Stroke::new(2.0, Color32::BLACK),
+                fg_stroke: Stroke::new(2.0, Rgba::BLACK),
                 corner_radius: 2.0,
                 expansion: 1.0,
             },
             open: WidgetVisuals {
-                bg_fill: Color32::from_gray(220),
+                bg_fill: Color32::from_gray(220).into(),
                 bg_stroke: Stroke::new(1.0, Color32::from_gray(160)),
-                fg_stroke: Stroke::new(1.0, Color32::BLACK),
+                fg_stroke: Stroke::new(1.0, Rgba::BLACK),
                 corner_radius: 2.0,
                 expansion: 0.0,
             },
@@ -934,9 +934,9 @@ fn slider_vec2<'a>(
     }
 }
 
-fn ui_color(ui: &mut Ui, srgba: &mut Color32, text: impl Into<Label>) -> Response {
+fn ui_color(ui: &mut Ui, rgba: &mut Rgba, text: impl Into<Label>) -> Response {
     ui.horizontal(|ui| {
-        ui.color_edit_button_srgba(srgba);
+        ui.color_edit_button_rgba(rgba);
         ui.label(text);
     })
     .response

egui/src/ui.rs

@@ -945,11 +945,7 @@ impl Ui {
     }
 
     /// Shortcut for `add(Label::new(text).text_color(color))`
-    pub fn colored_label(
+    pub fn colored_label(&mut self, color: impl Into<Rgba>, label: impl Into<Label>) -> Response {
-        &mut self,
-        color: impl Into<Color32>,
-        label: impl Into<Label>,
-    ) -> Response {
         label.into().text_color(color).ui(self)
     }
 
@@ -1172,6 +1168,12 @@ impl Ui {
 
 /// # Colors
 impl Ui {
+    /// Shows a button with the given color.
+    /// If the user clicks the button, a full color picker is shown.
+    pub fn color_edit_button_rgba(&mut self, rgba: &mut Rgba) -> Response {
+        color_picker::color_edit_button_rgba(self, rgba, color_picker::Alpha::BlendOrAdditive)
+    }
+
     /// Shows a button with the given color.
     /// If the user clicks the button, a full color picker is shown.
     pub fn color_edit_button_srgba(&mut self, srgba: &mut Color32) -> Response {

egui/src/widgets/button.rs

@@ -14,10 +14,10 @@ use crate::*;
 #[must_use = "You should put this widget in an ui with `ui.add(widget);`"]
 pub struct Button {
     text: String,
-    text_color: Option<Color32>,
+    text_color: Option<Rgba>,
     text_style: Option<TextStyle>,
     /// None means default for interact
-    fill: Option<Color32>,
+    fill: Option<Rgba>,
     stroke: Option<Stroke>,
     sense: Sense,
     small: bool,
@@ -43,12 +43,12 @@ impl Button {
         }
     }
 
-    pub fn text_color(mut self, text_color: Color32) -> Self {
+    pub fn text_color(mut self, text_color: impl Into<Rgba>) -> Self {
-        self.text_color = Some(text_color);
+        self.text_color = Some(text_color.into());
         self
     }
 
-    pub fn text_color_opt(mut self, text_color: Option<Color32>) -> Self {
+    pub fn text_color_opt(mut self, text_color: Option<Rgba>) -> Self {
         self.text_color = text_color;
         self
     }
@@ -60,7 +60,7 @@ impl Button {
 
     /// Override background fill color. Note that this will override any on-hover effects.
     /// Calling this will also turn on the frame.
-    pub fn fill(mut self, fill: impl Into<Color32>) -> Self {
+    pub fn fill(mut self, fill: impl Into<Rgba>) -> Self {
         self.fill = Some(fill.into());
         self.frame = Some(true);
         self
@@ -229,7 +229,7 @@ impl Widget for Button {
 pub struct Checkbox<'a> {
     checked: &'a mut bool,
     text: String,
-    text_color: Option<Color32>,
+    text_color: Option<Rgba>,
     text_style: Option<TextStyle>,
 }
 
@@ -244,7 +244,7 @@ impl<'a> Checkbox<'a> {
         }
     }
 
-    pub fn text_color(mut self, text_color: Color32) -> Self {
+    pub fn text_color(mut self, text_color: Rgba) -> Self {
         self.text_color = Some(text_color);
         self
     }
@@ -351,7 +351,7 @@ impl<'a> Widget for Checkbox<'a> {
 pub struct RadioButton {
     checked: bool,
     text: String,
-    text_color: Option<Color32>,
+    text_color: Option<Rgba>,
     text_style: Option<TextStyle>,
 }
 
@@ -366,7 +366,7 @@ impl RadioButton {
         }
     }
 
-    pub fn text_color(mut self, text_color: Color32) -> Self {
+    pub fn text_color(mut self, text_color: Rgba) -> Self {
         self.text_color = Some(text_color);
         self
     }
@@ -475,7 +475,7 @@ impl ImageButton {
     }
 
     /// Multiply image color with this. Default is WHITE (no tint).
-    pub fn tint(mut self, tint: impl Into<Color32>) -> Self {
+    pub fn tint(mut self, tint: impl Into<Rgba>) -> Self {
         self.image = self.image.tint(tint);
         self
     }

egui/src/widgets/color_picker.rs

@@ -23,8 +23,8 @@ fn background_checkers(painter: &Painter, rect: Rect) {
         return;
     }
 
-    let mut top_color = Color32::from_gray(128);
+    let mut top_color = Color32::from_gray(128).into();
-    let mut bottom_color = Color32::from_gray(32);
+    let mut bottom_color = Color32::from_gray(32).into();
     let checker_size = Vec2::splat(rect.height() / 2.0);
     let n = (rect.width() / checker_size.x).round() as u32;
 
@@ -92,7 +92,7 @@ fn color_button(ui: &mut Ui, color: Color32, open: bool) -> Response {
     response
 }
 
-fn color_slider_1d(ui: &mut Ui, value: &mut f32, color_at: impl Fn(f32) -> Color32) -> Response {
+fn color_slider_1d(ui: &mut Ui, value: &mut f32, color_at: impl Fn(f32) -> Rgba) -> Response {
     #![allow(clippy::identity_op)]
 
     let desired_size = vec2(
@@ -151,7 +151,7 @@ fn color_slider_2d(
     ui: &mut Ui,
     x_value: &mut f32,
     y_value: &mut f32,
-    color_at: impl Fn(f32, f32) -> Color32,
+    color_at: impl Fn(f32, f32) -> Rgba,
 ) -> Response {
     let desired_size = Vec2::splat(ui.spacing().slider_width);
     let (rect, response) = ui.allocate_at_least(desired_size, Sense::click_and_drag());
@@ -211,7 +211,7 @@ pub enum Alpha {
     BlendOrAdditive,
 }
 
-fn color_text_ui(ui: &mut Ui, color: impl Into<Color32>) {
+fn color_text_ui(ui: &mut Ui, color: impl Into<Rgba>) {
     let color = color.into();
     ui.horizontal(|ui| {
         let [r, g, b, a] = color.to_array();
@@ -368,6 +368,17 @@ pub fn color_edit_button_hsva(ui: &mut Ui, hsva: &mut Hsva, alpha: Alpha) -> Res
     button_response
 }
 
+/// Shows a button with the given color.
+/// If the user clicks the button, a full color picker is shown.
+pub fn color_edit_button_rgba(ui: &mut Ui, rgba: &mut Rgba, alpha: Alpha) -> Response {
+    let mut srgba = (*rgba).into();
+    let response = color_edit_button_srgba(ui, &mut srgba, alpha);
+    if response.changed() {
+        *rgba = srgba.into();
+    }
+    response
+}
+
 /// Shows a button with the given color.
 /// If the user clicks the button, a full color picker is shown.
 pub fn color_edit_button_srgba(ui: &mut Ui, srgba: &mut Color32, alpha: Alpha) -> Response {

egui/src/widgets/image.rs

@@ -18,8 +18,8 @@ pub struct Image {
     texture_id: TextureId,
     uv: Rect,
     size: Vec2,
-    bg_fill: Color32,
+    bg_fill: Rgba,
-    tint: Color32,
+    tint: Rgba,
     sense: Sense,
 }
 
@@ -30,7 +30,7 @@ impl Image {
             uv: Rect::from_min_max(pos2(0.0, 0.0), pos2(1.0, 1.0)),
             size: size.into(),
             bg_fill: Default::default(),
-            tint: Color32::WHITE,
+            tint: Rgba::WHITE,
             sense: Sense::hover(),
         }
     }
@@ -42,13 +42,13 @@ impl Image {
     }
 
     /// A solid color to put behind the image. Useful for transparent images.
-    pub fn bg_fill(mut self, bg_fill: impl Into<Color32>) -> Self {
+    pub fn bg_fill(mut self, bg_fill: impl Into<Rgba>) -> Self {
         self.bg_fill = bg_fill.into();
         self
     }
 
     /// Multiply image color with this. Default is WHITE (no tint).
-    pub fn tint(mut self, tint: impl Into<Color32>) -> Self {
+    pub fn tint(mut self, tint: impl Into<Rgba>) -> Self {
         self.tint = tint.into();
         self
     }

egui/src/widgets/label.rs

@@ -8,7 +8,7 @@ use std::sync::Arc;
 /// # let ui = &mut egui::Ui::__test();
 /// ui.label("Equivalent");
 /// ui.add(egui::Label::new("Equivalent"));
-/// ui.add(egui::Label::new("With Options").text_color(egui::Color32::RED));
+/// ui.add(egui::Label::new("With Options").text_color(egui::Rgba::RED));
 /// ```
 #[must_use = "You should put this widget in an ui with `ui.add(widget);`"]
 pub struct Label {
@@ -16,8 +16,8 @@ pub struct Label {
     pub(crate) text: String,
     pub(crate) wrap: Option<bool>,
     pub(crate) text_style: Option<TextStyle>,
-    pub(crate) background_color: Color32,
+    pub(crate) background_color: Rgba,
-    pub(crate) text_color: Option<Color32>,
+    pub(crate) text_color: Option<Rgba>,
     code: bool,
     strong: bool,
     weak: bool,
@@ -35,7 +35,7 @@ impl Label {
             text: text.to_string(),
             wrap: None,
             text_style: None,
-            background_color: Color32::TRANSPARENT,
+            background_color: Rgba::TRANSPARENT,
             text_color: None,
             code: false,
             strong: false,
@@ -135,12 +135,12 @@ impl Label {
     }
 
     /// Fill-color behind the text
-    pub fn background_color(mut self, background_color: impl Into<Color32>) -> Self {
+    pub fn background_color(mut self, background_color: impl Into<Rgba>) -> Self {
         self.background_color = background_color.into();
         self
     }
 
-    pub fn text_color(mut self, text_color: impl Into<Color32>) -> Self {
+    pub fn text_color(mut self, text_color: impl Into<Rgba>) -> Self {
         self.text_color = Some(text_color.into());
         self
     }
@@ -206,7 +206,7 @@ impl Label {
         pos: Pos2,
         galley: Arc<Galley>,
         has_focus: bool,
-        response_color: Color32,
+        response_color: Rgba,
     ) {
         let Self {
             mut background_color,
@@ -238,11 +238,11 @@ impl Label {
 
         let mut lines = vec![];
 
-        if strikethrough || underline || background_color != Color32::TRANSPARENT {
+        if strikethrough || underline || background_color != Rgba::TRANSPARENT {
             for row in &galley.rows {
                 let rect = row.rect().translate(pos.to_vec2());
 
-                if background_color != Color32::TRANSPARENT {
+                if background_color != Rgba::TRANSPARENT {
                     let rect = rect.expand(1.0); // looks better
                     ui.painter().rect_filled(rect, 0.0, background_color);
                 }

egui/src/widgets/mod.rs

@@ -97,7 +97,7 @@ pub fn stroke_ui(ui: &mut crate::Ui, stroke: &mut epaint::Stroke, text: &str) {
     ui.horizontal(|ui| {
         ui.add(DragValue::new(width).speed(0.1).clamp_range(0.0..=5.0))
             .on_hover_text("Width");
-        ui.color_edit_button_srgba(color);
+        ui.color_edit_button_rgba(color);
         ui.label(text);
 
         // stroke preview:
@@ -118,6 +118,6 @@ pub(crate) fn shadow_ui(ui: &mut Ui, shadow: &mut epaint::Shadow, text: &str) {
                 .clamp_range(0.0..=100.0),
         )
         .on_hover_text("Extrusion");
-        ui.color_edit_button_srgba(color);
+        ui.color_edit_button_rgba(color);
     });
 }

egui/src/widgets/plot/items.rs

@@ -135,7 +135,7 @@ impl HLine {
     pub fn new(y: impl Into<f64>) -> Self {
         Self {
             y: y.into(),
-            stroke: Stroke::new(1.0, Color32::TRANSPARENT),
+            stroke: Stroke::new(1.0, Rgba::TRANSPARENT),
             name: String::default(),
             highlight: false,
             style: LineStyle::Solid,
@@ -160,8 +160,8 @@ impl HLine {
         self
     }
 
-    /// Stroke color. Default is `Color32::TRANSPARENT` which means a color will be auto-assigned.
+    /// Stroke color. Default is `Rgba::TRANSPARENT` which means a color will be auto-assigned.
-    pub fn color(mut self, color: impl Into<Color32>) -> Self {
+    pub fn color(mut self, color: impl Into<Rgba>) -> Self {
         self.stroke.color = color.into();
         self
     }
@@ -207,7 +207,7 @@ impl PlotItem for HLine {
         &self.name
     }
 
-    fn color(&self) -> Color32 {
+    fn color(&self) -> Rgba {
         self.stroke.color
     }
 
@@ -245,7 +245,7 @@ impl VLine {
     pub fn new(x: impl Into<f64>) -> Self {
         Self {
             x: x.into(),
-            stroke: Stroke::new(1.0, Color32::TRANSPARENT),
+            stroke: Stroke::new(1.0, Rgba::TRANSPARENT),
             name: String::default(),
             highlight: false,
             style: LineStyle::Solid,
@@ -270,8 +270,8 @@ impl VLine {
         self
     }
 
-    /// Stroke color. Default is `Color32::TRANSPARENT` which means a color will be auto-assigned.
+    /// Stroke color. Default is `Rgba::TRANSPARENT` which means a color will be auto-assigned.
-    pub fn color(mut self, color: impl Into<Color32>) -> Self {
+    pub fn color(mut self, color: impl Into<Rgba>) -> Self {
         self.stroke.color = color.into();
         self
     }
@@ -317,7 +317,7 @@ impl PlotItem for VLine {
         &self.name
     }
 
-    fn color(&self) -> Color32 {
+    fn color(&self) -> Rgba {
         self.stroke.color
     }
 
@@ -346,7 +346,7 @@ pub(super) trait PlotItem {
     fn get_shapes(&self, ui: &mut Ui, transform: &ScreenTransform, shapes: &mut Vec<Shape>);
     fn initialize(&mut self, x_range: RangeInclusive<f64>);
     fn name(&self) -> &str;
-    fn color(&self) -> Color32;
+    fn color(&self) -> Rgba;
     fn highlight(&mut self);
     fn highlighted(&self) -> bool;
     fn values(&self) -> Option<&Values>;
@@ -552,7 +552,7 @@ impl Line {
     pub fn new(series: Values) -> Self {
         Self {
             series,
-            stroke: Stroke::new(1.0, Color32::TRANSPARENT),
+            stroke: Stroke::new(1.0, Rgba::TRANSPARENT),
             name: Default::default(),
             highlight: false,
             fill: None,
@@ -578,8 +578,8 @@ impl Line {
         self
     }
 
-    /// Stroke color. Default is `Color32::TRANSPARENT` which means a color will be auto-assigned.
+    /// Stroke color. Default is `Rgba::TRANSPARENT` which means a color will be auto-assigned.
-    pub fn color(mut self, color: impl Into<Color32>) -> Self {
+    pub fn color(mut self, color: impl Into<Rgba>) -> Self {
         self.stroke.color = color.into();
         self
     }
@@ -684,7 +684,7 @@ impl PlotItem for Line {
         self.name.as_str()
     }
 
-    fn color(&self) -> Color32 {
+    fn color(&self) -> Rgba {
         self.stroke.color
     }
 
@@ -719,7 +719,7 @@ impl Polygon {
     pub fn new(series: Values) -> Self {
         Self {
             series,
-            stroke: Stroke::new(1.0, Color32::TRANSPARENT),
+            stroke: Stroke::new(1.0, Rgba::TRANSPARENT),
             name: Default::default(),
             highlight: false,
             fill_alpha: DEFAULT_FILL_ALPHA,
@@ -746,8 +746,8 @@ impl Polygon {
         self
     }
 
-    /// Stroke color. Default is `Color32::TRANSPARENT` which means a color will be auto-assigned.
+    /// Stroke color. Default is `Rgba::TRANSPARENT` which means a color will be auto-assigned.
-    pub fn color(mut self, color: impl Into<Color32>) -> Self {
+    pub fn color(mut self, color: impl Into<Rgba>) -> Self {
         self.stroke.color = color.into();
         self
     }
@@ -819,7 +819,7 @@ impl PlotItem for Polygon {
         self.name.as_str()
     }
 
-    fn color(&self) -> Color32 {
+    fn color(&self) -> Rgba {
         self.stroke.color
     }
 
@@ -847,7 +847,7 @@ pub struct Text {
     pub(super) position: Value,
     pub(super) name: String,
     pub(super) highlight: bool,
-    pub(super) color: Color32,
+    pub(super) color: Rgba,
     pub(super) anchor: Align2,
 }
 
@@ -860,7 +860,7 @@ impl Text {
             position,
             name: Default::default(),
             highlight: false,
-            color: Color32::TRANSPARENT,
+            color: Rgba::TRANSPARENT,
             anchor: Align2::CENTER_CENTER,
         }
     }
@@ -877,8 +877,8 @@ impl Text {
         self
     }
 
-    /// Text color. Default is `Color32::TRANSPARENT` which means a color will be auto-assigned.
+    /// Text color. Default is `Rgba::TRANSPARENT` which means a color will be auto-assigned.
-    pub fn color(mut self, color: impl Into<Color32>) -> Self {
+    pub fn color(mut self, color: impl Into<Rgba>) -> Self {
         self.color = color.into();
         self
     }
@@ -904,7 +904,7 @@ impl Text {
 
 impl PlotItem for Text {
     fn get_shapes(&self, ui: &mut Ui, transform: &ScreenTransform, shapes: &mut Vec<Shape>) {
-        let color = if self.color == Color32::TRANSPARENT {
+        let color = if self.color == Rgba::TRANSPARENT {
             ui.style().visuals.text_color()
         } else {
             self.color
@@ -937,7 +937,7 @@ impl PlotItem for Text {
         self.name.as_str()
     }
 
-    fn color(&self) -> Color32 {
+    fn color(&self) -> Rgba {
         self.color
     }
 
@@ -964,8 +964,8 @@ impl PlotItem for Text {
 pub struct Points {
     pub(super) series: Values,
     pub(super) shape: MarkerShape,
-    /// Color of the marker. `Color32::TRANSPARENT` means that it will be picked automatically.
+    /// Color of the marker. `Rgba::TRANSPARENT` means that it will be picked automatically.
-    pub(super) color: Color32,
+    pub(super) color: Rgba,
     /// Whether to fill the marker. Does not apply to all types.
     pub(super) filled: bool,
     /// The maximum extent of the marker from its center.
@@ -980,7 +980,7 @@ impl Points {
         Self {
             series,
             shape: MarkerShape::Circle,
-            color: Color32::TRANSPARENT,
+            color: Rgba::TRANSPARENT,
             filled: true,
             radius: 1.0,
             name: Default::default(),
@@ -1002,7 +1002,7 @@ impl Points {
     }
 
     /// Set the marker's color.
-    pub fn color(mut self, color: impl Into<Color32>) -> Self {
+    pub fn color(mut self, color: impl Into<Rgba>) -> Self {
         self.color = color.into();
         self
     }
@@ -1200,7 +1200,7 @@ impl PlotItem for Points {
         self.name.as_str()
     }
 
-    fn color(&self) -> Color32 {
+    fn color(&self) -> Rgba {
         self.color
     }
 
@@ -1225,7 +1225,7 @@ impl PlotItem for Points {
 pub struct Arrows {
     pub(super) origins: Values,
     pub(super) tips: Values,
-    pub(super) color: Color32,
+    pub(super) color: Rgba,
     pub(super) name: String,
     pub(super) highlight: bool,
 }
@@ -1235,7 +1235,7 @@ impl Arrows {
         Self {
             origins,
             tips,
-            color: Color32::TRANSPARENT,
+            color: Rgba::TRANSPARENT,
             name: Default::default(),
             highlight: false,
         }
@@ -1248,7 +1248,7 @@ impl Arrows {
     }
 
     /// Set the arrows' color.
-    pub fn color(mut self, color: impl Into<Color32>) -> Self {
+    pub fn color(mut self, color: impl Into<Rgba>) -> Self {
         self.color = color.into();
         self
     }
@@ -1315,7 +1315,7 @@ impl PlotItem for Arrows {
         self.name.as_str()
     }
 
-    fn color(&self) -> Color32 {
+    fn color(&self) -> Rgba {
         self.color
     }
 
@@ -1342,8 +1342,8 @@ pub struct PlotImage {
     pub(super) texture_id: TextureId,
     pub(super) uv: Rect,
     pub(super) size: Vec2,
-    pub(super) bg_fill: Color32,
+    pub(super) bg_fill: Rgba,
-    pub(super) tint: Color32,
+    pub(super) tint: Rgba,
     pub(super) highlight: bool,
     pub(super) name: String,
 }
@@ -1359,7 +1359,7 @@ impl PlotImage {
             uv: Rect::from_min_max(pos2(0.0, 0.0), pos2(1.0, 1.0)),
             size: size.into(),
             bg_fill: Default::default(),
-            tint: Color32::WHITE,
+            tint: Rgba::WHITE,
         }
     }
 
@@ -1376,13 +1376,13 @@ impl PlotImage {
     }
 
     /// A solid color to put behind the image. Useful for transparent images.
-    pub fn bg_fill(mut self, bg_fill: impl Into<Color32>) -> Self {
+    pub fn bg_fill(mut self, bg_fill: impl Into<Rgba>) -> Self {
         self.bg_fill = bg_fill.into();
         self
     }
 
     /// Multiply image color with this. Default is WHITE (no tint).
-    pub fn tint(mut self, tint: impl Into<Color32>) -> Self {
+    pub fn tint(mut self, tint: impl Into<Rgba>) -> Self {
         self.tint = tint.into();
         self
     }
@@ -1445,8 +1445,8 @@ impl PlotItem for PlotImage {
         self.name.as_str()
     }
 
-    fn color(&self) -> Color32 {
+    fn color(&self) -> Rgba {
-        Color32::TRANSPARENT
+        Rgba::TRANSPARENT
     }
 
     fn highlight(&mut self) {

egui/src/widgets/plot/legend.rs

@@ -69,13 +69,13 @@ impl Legend {
 
 #[derive(Clone)]
 struct LegendEntry {
-    color: Color32,
+    color: Rgba,
     checked: bool,
     hovered: bool,
 }
 
 impl LegendEntry {
-    fn new(color: Color32, checked: bool) -> Self {
+    fn new(color: Rgba, checked: bool) -> Self {
         Self {
             color,
             checked,
@@ -122,7 +122,7 @@ impl LegendEntry {
         });
 
         if *checked {
-            let fill = if *color == Color32::TRANSPARENT {
+            let fill = if *color == Rgba::TRANSPARENT {
                 ui.visuals().noninteractive().fg_stroke.color
             } else {
                 *color
@@ -179,7 +179,7 @@ impl LegendWidget {
                     .and_modify(|entry| {
                         if entry.color != item.color() {
                             // Multiple items with different colors
-                            entry.color = Color32::TRANSPARENT;
+                            entry.color = Rgba::TRANSPARENT;
                         }
                     })
                     .or_insert_with(|| {

egui/src/widgets/plot/mod.rs

@@ -101,7 +101,7 @@ impl Plot {
         }
     }
 
-    fn auto_color(&mut self) -> Color32 {
+    fn auto_color(&mut self) -> Rgba {
         let i = self.next_auto_color_idx;
         self.next_auto_color_idx += 1;
         let golden_ratio = (5.0_f32.sqrt() - 1.0) / 2.0; // 0.61803398875
@@ -116,7 +116,7 @@ impl Plot {
         };
 
         // Give the stroke an automatic color if no color has been assigned.
-        if line.stroke.color == Color32::TRANSPARENT {
+        if line.stroke.color == Rgba::TRANSPARENT {
             line.stroke.color = self.auto_color();
         }
         self.items.push(Box::new(line));
@@ -130,7 +130,7 @@ impl Plot {
         };
 
         // Give the stroke an automatic color if no color has been assigned.
-        if polygon.stroke.color == Color32::TRANSPARENT {
+        if polygon.stroke.color == Rgba::TRANSPARENT {
             polygon.stroke.color = self.auto_color();
         }
         self.items.push(Box::new(polygon));
@@ -154,7 +154,7 @@ impl Plot {
         };
 
         // Give the points an automatic color if no color has been assigned.
-        if points.color == Color32::TRANSPARENT {
+        if points.color == Rgba::TRANSPARENT {
             points.color = self.auto_color();
         }
         self.items.push(Box::new(points));
@@ -168,7 +168,7 @@ impl Plot {
         };
 
         // Give the arrows an automatic color if no color has been assigned.
-        if arrows.color == Color32::TRANSPARENT {
+        if arrows.color == Rgba::TRANSPARENT {
             arrows.color = self.auto_color();
         }
         self.items.push(Box::new(arrows));
@@ -185,7 +185,7 @@ impl Plot {
     /// Can be useful e.g. to show min/max bounds or similar.
     /// Always fills the full width of the plot.
     pub fn hline(mut self, mut hline: HLine) -> Self {
-        if hline.stroke.color == Color32::TRANSPARENT {
+        if hline.stroke.color == Rgba::TRANSPARENT {
             hline.stroke.color = self.auto_color();
         }
         self.items.push(Box::new(hline));
@@ -196,7 +196,7 @@ impl Plot {
     /// Can be useful e.g. to show min/max bounds or similar.
     /// Always fills the full height of the plot.
     pub fn vline(mut self, mut vline: VLine) -> Self {
-        if vline.stroke.color == Color32::TRANSPARENT {
+        if vline.stroke.color == Rgba::TRANSPARENT {
             vline.stroke.color = self.auto_color();
         }
         self.items.push(Box::new(vline));
@@ -634,7 +634,7 @@ impl Prepared {
             }
         }
 
-        fn color_from_alpha(ui: &Ui, alpha: f32) -> Color32 {
+        fn color_from_alpha(ui: &Ui, alpha: f32) -> Rgba {
             if ui.visuals().dark_mode {
                 Rgba::from_white_alpha(alpha).into()
             } else {

egui/src/widgets/progress_bar.rs

@@ -94,7 +94,7 @@ impl Widget for ProgressBar {
         ui.painter().rect(
             inner_rect,
             corner_radius,
-            Color32::from(Rgba::from(visuals.selection.bg_fill) * color_factor as f32),
+            Rgba::from(visuals.selection.bg_fill) * color_factor as f32,
             Stroke::none(),
         );
 
@@ -115,7 +115,7 @@ impl Widget for ProgressBar {
             ui.painter().add(Shape::Path {
                 points,
                 closed: false,
-                fill: Color32::TRANSPARENT,
+                fill: Rgba::TRANSPARENT,
                 stroke: Stroke::new(2.0, visuals.faint_bg_color),
             });
         }

egui/src/widgets/slider.rs

@@ -61,7 +61,7 @@ pub struct Slider<'a> {
     prefix: String,
     suffix: String,
     text: String,
-    text_color: Option<Color32>,
+    text_color: Option<Rgba>,
     min_decimals: usize,
     max_decimals: Option<usize>,
 }
@@ -180,7 +180,7 @@ impl<'a> Slider<'a> {
         self
     }
 
-    pub fn text_color(mut self, text_color: Color32) -> Self {
+    pub fn text_color(mut self, text_color: Rgba) -> Self {
         self.text_color = Some(text_color);
         self
     }

egui/src/widgets/text_edit.rs

@@ -229,7 +229,7 @@ pub struct TextEdit<'t, S: TextBuffer = String> {
     id: Option<Id>,
     id_source: Option<Id>,
     text_style: Option<TextStyle>,
-    text_color: Option<Color32>,
+    text_color: Option<Rgba>,
     password: bool,
     frame: bool,
     multiline: bool,
@@ -329,12 +329,12 @@ impl<'t, S: TextBuffer> TextEdit<'t, S> {
         self
     }
 
-    pub fn text_color(mut self, text_color: Color32) -> Self {
+    pub fn text_color(mut self, text_color: Rgba) -> Self {
         self.text_color = Some(text_color);
         self
     }
 
-    pub fn text_color_opt(mut self, text_color: Option<Color32>) -> Self {
+    pub fn text_color_opt(mut self, text_color: Option<Rgba>) -> Self {
         self.text_color = text_color;
         self
     }

egui_demo_lib/benches/benchmark.rs

@@ -90,7 +90,7 @@ pub fn criterion_benchmark(c: &mut Criterion) {
                     fonts.texture().size(),
                     egui::Pos2::ZERO,
                     &galley,
-                    egui::Color32::WHITE,
+                    egui::Rgba::WHITE,
                     fake_italics,
                     &mut mesh,
                 );

egui_demo_lib/src/apps/color_test.rs

@@ -303,7 +303,7 @@ fn vertex_gradient(ui: &mut Ui, bg_fill: Color32, gradient: &Gradient) -> Respon
     let (rect, response) = ui.allocate_at_least(GRADIENT_SIZE, Sense::hover());
     if bg_fill != Default::default() {
         let mut mesh = Mesh::default();
-        mesh.add_colored_rect(rect, bg_fill);
+        mesh.add_colored_rect(rect, bg_fill.into());
         ui.painter().add(Shape::mesh(mesh));
     }
     {
@@ -313,8 +313,8 @@ fn vertex_gradient(ui: &mut Ui, bg_fill: Color32, gradient: &Gradient) -> Respon
         for (i, &color) in gradient.0.iter().enumerate() {
             let t = i as f32 / (n as f32 - 1.0);
             let x = lerp(rect.x_range(), t);
-            mesh.colored_vertex(pos2(x, rect.top()), color);
+            mesh.colored_vertex(pos2(x, rect.top()), color.into());
-            mesh.colored_vertex(pos2(x, rect.bottom()), color);
+            mesh.colored_vertex(pos2(x, rect.bottom()), color.into());
             if i < n - 1 {
                 let i = i as u32;
                 mesh.add_triangle(2 * i, 2 * i + 1, 2 * i + 2);
@@ -333,9 +333,11 @@ impl Gradient {
     pub fn one_color(srgba: Color32) -> Self {
         Self(vec![srgba, srgba])
     }
+
     pub fn texture_gradient(left: Color32, right: Color32) -> Self {
         Self(vec![left, right])
     }
+
     pub fn ground_truth_linear_gradient(left: Color32, right: Color32) -> Self {
         let left = Rgba::from(left);
         let right = Rgba::from(right);
@@ -350,6 +352,7 @@ impl Gradient {
                 .collect(),
         )
     }
+
     /// This is how a bad person blends `sRGBA`
     pub fn ground_truth_bad_srgba_gradient(left: Color32, right: Color32) -> Self {
         let n = 255;

egui_demo_lib/src/apps/demo/demo_app_windows.rs

@@ -199,7 +199,7 @@ impl DemoWindows {
                 // Native: WrapApp uses a transparent window, so let's show that off:
                 // NOTE: the OS compositor assumes "normal" blending, so we need to hack it:
                 let [r, g, b, _] = fill.to_array();
-                fill = egui::Color32::from_rgba_premultiplied(r, g, b, 180);
+                fill = egui::Rgba::from_rgba_premultiplied(r, g, b, 0.70);
             }
             let frame = egui::Frame::none().fill(fill);
             egui::CentralPanel::default().frame(frame).show(ctx, |_| {});

egui_demo_lib/src/apps/demo/drag_and_drop.rs

@@ -59,8 +59,8 @@ pub fn drop_target<R>(
     let mut stroke = style.bg_stroke;
     if is_being_dragged && !can_accept_what_is_being_dragged {
         // gray out:
-        fill = color::tint_color_towards(fill, ui.visuals().window_fill());
+        fill = color::tint_rgba_towards(fill, ui.visuals().window_fill());
-        stroke.color = color::tint_color_towards(stroke.color, ui.visuals().window_fill());
+        stroke.color = color::tint_rgba_towards(stroke.color, ui.visuals().window_fill());
     }
 
     ui.painter().set(

egui_demo_lib/src/apps/demo/misc_demo_window.rs

@@ -363,7 +363,7 @@ impl Tree {
     fn children_ui(&mut self, ui: &mut Ui, depth: usize) -> Action {
         if depth > 0
             && ui
-                .add(Button::new("delete").text_color(Color32::RED))
+                .add(Button::new("delete").text_color(Rgba::RED))
                 .clicked()
         {
             return Action::Delete;

egui_glium/src/lib.rs

@@ -504,7 +504,7 @@ impl EguiGlium {
     pub fn on_event(&mut self, event: &glium::glutin::event::WindowEvent<'_>) {
         crate::input_to_egui(
             self.egui_ctx.pixels_per_point(),
-            &event,
+            event,
             self.clipboard.as_mut(),
             &mut self.input_state,
         );

egui_glium/src/painter.rs

@@ -127,9 +127,9 @@ impl Painter {
             struct Vertex {
                 a_pos: [f32; 2],
                 a_tc: [f32; 2],
-                a_srgba: [u8; 4],
+                a_rgba: [f32; 4],
             }
-            implement_vertex!(Vertex, a_pos, a_tc, a_srgba);
+            implement_vertex!(Vertex, a_pos, a_tc, a_rgba);
 
             let vertices: Vec<Vertex> = mesh
                 .vertices
@@ -137,7 +137,7 @@ impl Painter {
                 .map(|v| Vertex {
                     a_pos: [v.pos.x, v.pos.y],
                     a_tc: [v.uv.x, v.uv.y],
-                    a_srgba: v.color.to_array(),
+                    a_rgba: v.color.to_array(),
                 })
                 .collect();
 

egui_glium/src/shader/vertex_100es.glsl

@@ -4,21 +4,10 @@ precision mediump float;
 uniform vec2 u_screen_size;
 attribute vec2 a_pos;
 attribute vec2 a_tc;
-attribute vec4 a_srgba;
+attribute vec4 a_rgba; // 0-1
-varying vec4 v_rgba;
+varying vec4 v_rgba; // 0-1
 varying vec2 v_tc;
 
-// 0-1 linear  from  0-255 sRGB
-vec3 linear_from_srgb(vec3 srgb) {
-  bvec3 cutoff = lessThan(srgb, vec3(10.31475));
-  vec3 lower = srgb / vec3(3294.6);
-  vec3 higher = pow((srgb + vec3(14.025)) / vec3(269.025), vec3(2.4));
-  return mix(higher, lower, vec3(cutoff));
-}
-
-vec4 linear_from_srgba(vec4 srgba) {
-  return vec4(linear_from_srgb(srgba.rgb), srgba.a / 255.0);
-}
 
 void main() {
   gl_Position = vec4(
@@ -26,7 +15,6 @@ void main() {
                      1.0 - 2.0 * a_pos.y / u_screen_size.y,
                      0.0,
                      1.0);
-  // egui encodes vertex colors in gamma spaces, so we must decode the colors here:
+  v_rgba = a_srgba;
-  v_rgba = linear_from_srgba(a_srgba);
   v_tc = a_tc;
 }

egui_glium/src/shader/vertex_120.glsl

@@ -2,30 +2,17 @@
 
 uniform vec2 u_screen_size;
 attribute vec2 a_pos;
-attribute vec4 a_srgba; // 0-255 sRGB
 attribute vec2 a_tc;
-varying vec4 v_rgba;
+attribute vec4 a_rgba; // 0-1
+varying vec4 v_rgba; // 0-1
 varying vec2 v_tc;
 
-// 0-1 linear  from  0-255 sRGB
-vec3 linear_from_srgb(vec3 srgb) {
-  bvec3 cutoff = lessThan(srgb, vec3(10.31475));
-  vec3 lower = srgb / vec3(3294.6);
-  vec3 higher = pow((srgb + vec3(14.025)) / vec3(269.025), vec3(2.4));
-  return mix(higher, lower, vec3(cutoff));
-}
-
-vec4 linear_from_srgba(vec4 srgba) {
-  return vec4(linear_from_srgb(srgba.rgb), srgba.a / 255.0);
-}
-
 void main() {
   gl_Position = vec4(
                      2.0 * a_pos.x / u_screen_size.x - 1.0,
                      1.0 - 2.0 * a_pos.y / u_screen_size.y,
                      0.0,
                      1.0);
-  // egui encodes vertex colors in gamma spaces, so we must decode the colors here:
+  v_rgba = a_rgba;
-  v_rgba = linear_from_srgba(a_srgba);
   v_tc = a_tc;
 }

egui_glium/src/shader/vertex_140.glsl

@@ -2,30 +2,17 @@
 
 uniform vec2 u_screen_size;
 in vec2 a_pos;
-in vec4 a_srgba; // 0-255 sRGB
 in vec2 a_tc;
-out vec4 v_rgba;
+in vec4 a_rgba; // 0-1
+out vec4 v_rgba; // 0-1
 out vec2 v_tc;
 
-// 0-1 linear  from  0-255 sRGB
-vec3 linear_from_srgb(vec3 srgb) {
-  bvec3 cutoff = lessThan(srgb, vec3(10.31475));
-  vec3 lower = srgb / vec3(3294.6);
-  vec3 higher = pow((srgb + vec3(14.025)) / vec3(269.025), vec3(2.4));
-  return mix(higher, lower, cutoff);
-}
-
-vec4 linear_from_srgba(vec4 srgba) {
-  return vec4(linear_from_srgb(srgba.rgb), srgba.a / 255.0);
-}
-
 void main() {
   gl_Position = vec4(
                      2.0 * a_pos.x / u_screen_size.x - 1.0,
                      1.0 - 2.0 * a_pos.y / u_screen_size.y,
                      0.0,
                      1.0);
-  // egui encodes vertex colors in gamma spaces, so we must decode the colors here:
+  v_rgba = a_rgba;
-  v_rgba = linear_from_srgba(a_srgba);
   v_tc = a_tc;
 }

egui_glium/src/shader/vertex_300es.glsl

@@ -4,29 +4,16 @@ precision mediump float;
 uniform vec2 u_screen_size;
 attribute vec2 a_pos;
 attribute vec2 a_tc;
-attribute vec4 a_srgba;
+attribute vec4 a_rgba; // 0-1
-varying vec4 v_rgba;
+varying vec4 v_rgba; // 0-1
 varying vec2 v_tc;
 
-// 0-1 linear  from  0-255 sRGB
-vec3 linear_from_srgb(vec3 srgb) {
-  bvec3 cutoff = lessThan(srgb, vec3(10.31475));
-  vec3 lower = srgb / vec3(3294.6);
-  vec3 higher = pow((srgb + vec3(14.025)) / vec3(269.025), vec3(2.4));
-  return mix(higher, lower, vec3(cutoff));
-}
-
-vec4 linear_from_srgba(vec4 srgba) {
-  return vec4(linear_from_srgb(srgba.rgb), srgba.a / 255.0);
-}
-
 void main() {
   gl_Position = vec4(
                      2.0 * a_pos.x / u_screen_size.x - 1.0,
                      1.0 - 2.0 * a_pos.y / u_screen_size.y,
                      0.0,
                      1.0);
-  // egui encodes vertex colors in gamma spaces, so we must decode the colors here:
+  v_rgba = a_rgba;
-  v_rgba = linear_from_srgba(a_srgba);
   v_tc = a_tc;
 }

egui_web/src/shader/vertex_100es.glsl

@@ -2,30 +2,16 @@ precision mediump float;
 uniform vec2 u_screen_size;
 attribute vec2 a_pos;
 attribute vec2 a_tc;
-attribute vec4 a_srgba;
+attribute vec4 a_rgba; // 0-1
-varying vec4 v_rgba;
+varying vec4 v_rgba; // 0-1
 varying vec2 v_tc;
 
-// 0-1 linear  from  0-255 sRGB
-vec3 linear_from_srgb(vec3 srgb) {
-  bvec3 cutoff = lessThan(srgb, vec3(10.31475));
-  vec3 lower = srgb / vec3(3294.6);
-  vec3 higher = pow((srgb + vec3(14.025)) / vec3(269.025), vec3(2.4));
-  return mix(higher, lower, vec3(cutoff));
-}
-
-// 0-1 linear  from  0-255 sRGBA
-vec4 linear_from_srgba(vec4 srgba) {
-  return vec4(linear_from_srgb(srgba.rgb), srgba.a / 255.0);
-}
-
 void main() {
   gl_Position = vec4(
                      2.0 * a_pos.x / u_screen_size.x - 1.0,
                      1.0 - 2.0 * a_pos.y / u_screen_size.y,
                      0.0,
                      1.0);
-  // egui encodes vertex colors in gamma spaces, so we must decode the colors here:
+  v_rgba = a_rgba;
-  v_rgba = linear_from_srgba(a_srgba);
   v_tc = a_tc;
 }

egui_web/src/shader/vertex_300es.glsl

@@ -2,30 +2,16 @@ precision mediump float;
 uniform vec2 u_screen_size;
 attribute vec2 a_pos;
 attribute vec2 a_tc;
-attribute vec4 a_srgba;
+attribute vec4 a_rgba; // 0-1
-varying vec4 v_rgba;
+varying vec4 v_rgba; // 0-1
 varying vec2 v_tc;
 
-// 0-1 linear  from  0-255 sRGB
-vec3 linear_from_srgb(vec3 srgb) {
-  bvec3 cutoff = lessThan(srgb, vec3(10.31475));
-  vec3 lower = srgb / vec3(3294.6);
-  vec3 higher = pow((srgb + vec3(14.025)) / vec3(269.025), vec3(2.4));
-  return mix(higher, lower, vec3(cutoff));
-}
-
-// 0-1 linear  from  0-255 sRGBA
-vec4 linear_from_srgba(vec4 srgba) {
-  return vec4(linear_from_srgb(srgba.rgb), srgba.a / 255.0);
-}
-
 void main() {
   gl_Position = vec4(
                      2.0 * a_pos.x / u_screen_size.x - 1.0,
                      1.0 - 2.0 * a_pos.y / u_screen_size.y,
                      0.0,
                      1.0);
-  // egui encodes vertex colors in gamma spaces, so we must decode the colors here:
+  v_rgba = a_rgba;
-  v_rgba = linear_from_srgba(a_srgba);
   v_tc = a_tc;
 }

egui_web/src/webgl1.rs

@@ -210,7 +210,7 @@ impl WebGlPainter {
 
         let mut positions: Vec<f32> = Vec::with_capacity(2 * mesh.vertices.len());
         let mut tex_coords: Vec<f32> = Vec::with_capacity(2 * mesh.vertices.len());
-        let mut colors: Vec<u8> = Vec::with_capacity(4 * mesh.vertices.len());
+        let mut colors: Vec<f32> = Vec::with_capacity(4 * mesh.vertices.len());
         for v in &mesh.vertices {
             positions.push(v.pos.x);
             positions.push(v.pos.y);
@@ -289,29 +289,22 @@ impl WebGlPainter {
         let colors_memory_buffer = wasm_bindgen::memory()
             .dyn_into::<WebAssembly::Memory>()?
             .buffer();
-        let colors_ptr = colors.as_ptr() as u32;
+        let colors_ptr = colors.as_ptr() as u32 / 4;
         let colors_array = js_sys::Uint8Array::new(&colors_memory_buffer)
             .subarray(colors_ptr, colors_ptr + colors.len() as u32);
 
         gl.bind_buffer(Gl::ARRAY_BUFFER, Some(&self.color_buffer));
         gl.buffer_data_with_array_buffer_view(Gl::ARRAY_BUFFER, &colors_array, Gl::STREAM_DRAW);
 
-        let a_srgba_loc = gl.get_attrib_location(&self.program, "a_srgba");
+        let a_rgba_loc = gl.get_attrib_location(&self.program, "a_rgba");
-        assert!(a_srgba_loc >= 0);
+        assert!(a_rgba_loc >= 0);
-        let a_srgba_loc = a_srgba_loc as u32;
+        let a_rgba_loc = a_rgba_loc as u32;
 
         let normalize = false;
         let stride = 0;
         let offset = 0;
-        gl.vertex_attrib_pointer_with_i32(
+        gl.vertex_attrib_pointer_with_i32(a_rgba_loc, 4, Gl::FLOAT, normalize, stride, offset);
-            a_srgba_loc,
+        gl.enable_vertex_attrib_array(a_rgba_loc);
-            4,
-            Gl::UNSIGNED_BYTE,
-            normalize,
-            stride,
-            offset,
-        );
-        gl.enable_vertex_attrib_array(a_srgba_loc);
 
         // --------------------------------------------------------------------
 

egui_web/src/webgl2.rs

@@ -211,7 +211,7 @@ impl WebGl2Painter {
 
         let mut positions: Vec<f32> = Vec::with_capacity(2 * mesh.vertices.len());
         let mut tex_coords: Vec<f32> = Vec::with_capacity(2 * mesh.vertices.len());
-        let mut colors: Vec<u8> = Vec::with_capacity(4 * mesh.vertices.len());
+        let mut colors: Vec<f32> = Vec::with_capacity(4 * mesh.vertices.len());
         for v in &mesh.vertices {
             positions.push(v.pos.x);
             positions.push(v.pos.y);
@@ -290,29 +290,22 @@ impl WebGl2Painter {
         let colors_memory_buffer = wasm_bindgen::memory()
             .dyn_into::<WebAssembly::Memory>()?
             .buffer();
-        let colors_ptr = colors.as_ptr() as u32;
+        let colors_ptr = colors.as_ptr() as u32 / 4;
         let colors_array = js_sys::Uint8Array::new(&colors_memory_buffer)
             .subarray(colors_ptr, colors_ptr + colors.len() as u32);
 
         gl.bind_buffer(Gl::ARRAY_BUFFER, Some(&self.color_buffer));
         gl.buffer_data_with_array_buffer_view(Gl::ARRAY_BUFFER, &colors_array, Gl::STREAM_DRAW);
 
-        let a_srgba_loc = gl.get_attrib_location(&self.program, "a_srgba");
+        let a_rgba_loc = gl.get_attrib_location(&self.program, "a_rgba");
-        assert!(a_srgba_loc >= 0);
+        assert!(a_rgba_loc >= 0);
-        let a_srgba_loc = a_srgba_loc as u32;
+        let a_rgba_loc = a_rgba_loc as u32;
 
         let normalize = false;
         let stride = 0;
         let offset = 0;
-        gl.vertex_attrib_pointer_with_i32(
+        gl.vertex_attrib_pointer_with_i32(a_rgba_loc, 4, Gl::FLOAT, normalize, stride, offset);
-            a_srgba_loc,
+        gl.enable_vertex_attrib_array(a_rgba_loc);
-            4,
-            Gl::UNSIGNED_BYTE,
-            normalize,
-            stride,
-            offset,
-        );
-        gl.enable_vertex_attrib_array(a_srgba_loc);
 
         // --------------------------------------------------------------------
 

epaint/src/color.rs

@@ -201,6 +201,7 @@ impl Rgba {
     pub const RED: Rgba = Rgba::from_rgb(1.0, 0.0, 0.0);
     pub const GREEN: Rgba = Rgba::from_rgb(0.0, 1.0, 0.0);
     pub const BLUE: Rgba = Rgba::from_rgb(0.0, 0.0, 1.0);
+    pub const LIGHT_BLUE: Rgba = Rgba::from_rgb(0.26, 0.35, 1.0);
 
     #[inline(always)]
     pub const fn from_rgba_premultiplied(r: f32, g: f32, b: f32, a: f32) -> Self {
@@ -753,10 +754,11 @@ impl From<Hsva> for HsvaGamma {
 
 /// Cheap and ugly.
 /// Made for graying out disabled `Ui`:s.
-pub fn tint_color_towards(color: Color32, target: Color32) -> Color32 {
+pub fn tint_color32_towards(color: Color32, target: Color32) -> Color32 {
     let [mut r, mut g, mut b, mut a] = color.to_array();
 
     if a == 0 {
+        // Additive color.
         r /= 2;
         g /= 2;
         b /= 2;
@@ -776,6 +778,11 @@ pub fn tint_color_towards(color: Color32, target: Color32) -> Color32 {
     Color32::from_rgba_premultiplied(r, g, b, a)
 }
 
+pub fn tint_rgba_towards(color: Rgba, target: Rgba) -> Rgba {
+    // sRGBA (gamma) is more of a perceptual color space, so we use that
+    tint_color32_towards(color.into(), target.into()).into()
+}
+
 #[cfg(feature = "cint")]
 mod impl_cint {
     use super::*;

epaint/src/lib.rs

@@ -134,7 +134,7 @@ pub(crate) struct PaintRect {
     pub rect: emath::Rect,
     /// How rounded the corners are. Use `0.0` for no rounding.
     pub corner_radius: f32,
-    pub fill: Color32,
+    pub fill: Rgba,
     pub stroke: Stroke,
 }
 

epaint/src/mesh.rs

@@ -9,15 +9,15 @@ use emath::*;
 pub struct Vertex {
     /// Logical pixel coordinates (points).
     /// (0,0) is the top left corner of the screen.
-    pub pos: Pos2, // 64 bit
+    pub pos: Pos2, // 2xf32 (64 bit)
 
     /// Normalized texture coordinates.
     /// (0, 0) is the top left corner of the texture.
     /// (1, 1) is the bottom right corner of the texture.
-    pub uv: Pos2, // 64 bit
+    pub uv: Pos2, // 2xf32 (64 bit)
 
-    /// sRGBA with premultiplied alpha
+    /// Linear RGBA with premultiplied alpha
-    pub color: Color32, // 32 bit
+    pub color: Rgba, // 4xf32 (128 bit)
 }
 
 /// Textured triangles in two dimensions.
@@ -93,7 +93,7 @@ impl Mesh {
     }
 
     #[inline(always)]
-    pub fn colored_vertex(&mut self, pos: Pos2, color: Color32) {
+    pub fn colored_vertex(&mut self, pos: Pos2, color: Rgba) {
         crate::epaint_assert!(self.texture_id == TextureId::Egui);
         self.vertices.push(Vertex {
             pos,
@@ -125,7 +125,7 @@ impl Mesh {
     }
 
     /// Rectangle with a texture and color.
-    pub fn add_rect_with_uv(&mut self, rect: Rect, uv: Rect, color: Color32) {
+    pub fn add_rect_with_uv(&mut self, rect: Rect, uv: Rect, color: Rgba) {
         #![allow(clippy::identity_op)]
 
         let idx = self.vertices.len() as u32;
@@ -156,7 +156,7 @@ impl Mesh {
 
     /// Uniformly colored rectangle.
     #[inline(always)]
-    pub fn add_colored_rect(&mut self, rect: Rect, color: Color32) {
+    pub fn add_colored_rect(&mut self, rect: Rect, color: Rgba) {
         crate::epaint_assert!(self.texture_id == TextureId::Egui);
         self.add_rect_with_uv(rect, [WHITE_UV, WHITE_UV].into(), color)
     }

epaint/src/shadow.rs

@@ -10,7 +10,7 @@ pub struct Shadow {
     pub extrusion: f32,
 
     /// Color of the opaque center of the shadow.
-    pub color: Color32,
+    pub color: Rgba,
 }
 
 impl Shadow {
@@ -18,7 +18,7 @@ impl Shadow {
     pub fn small_dark() -> Self {
         Self {
             extrusion: 16.0,
-            color: Color32::from_black_alpha(96),
+            color: Color32::from_black_alpha(96).into(),
         }
     }
 
@@ -26,7 +26,7 @@ impl Shadow {
     pub fn small_light() -> Self {
         Self {
             extrusion: 16.0,
-            color: Color32::from_black_alpha(32),
+            color: Color32::from_black_alpha(32).into(),
         }
     }
 
@@ -34,7 +34,7 @@ impl Shadow {
     pub fn big_dark() -> Self {
         Self {
             extrusion: 32.0,
-            color: Color32::from_black_alpha(96),
+            color: Color32::from_black_alpha(96).into(),
         }
     }
 
@@ -42,7 +42,7 @@ impl Shadow {
     pub fn big_light() -> Self {
         Self {
             extrusion: 32.0,
-            color: Color32::from_black_alpha(40),
+            color: Color32::from_black_alpha(40).into(),
         }
     }
 

epaint/src/shape.rs

@@ -1,6 +1,6 @@
 use crate::{
     text::{Fonts, Galley, TextStyle},
-    Color32, Mesh, Stroke,
+    Mesh, Rgba, Stroke,
 };
 use emath::*;
 
@@ -17,7 +17,7 @@ pub enum Shape {
     Circle {
         center: Pos2,
         radius: f32,
-        fill: Color32,
+        fill: Rgba,
         stroke: Stroke,
     },
     LineSegment {
@@ -30,14 +30,14 @@ pub enum Shape {
         /// This is required if `fill != TRANSPARENT`.
         closed: bool,
         /// Fill is only supported for convex polygons.
-        fill: Color32,
+        fill: Rgba,
         stroke: Stroke,
     },
     Rect {
         rect: Rect,
         /// How rounded the corners are. Use `0.0` for no rounding.
         corner_radius: f32,
-        fill: Color32,
+        fill: Rgba,
         stroke: Stroke,
     },
     Text {
@@ -46,7 +46,7 @@ pub enum Shape {
         /// The layed out text.
         galley: std::sync::Arc<Galley>,
         /// Text color (foreground).
-        color: Color32,
+        color: Rgba,
         /// If true, tilt the letters for a hacky italics effect.
         fake_italics: bool,
     },
@@ -89,7 +89,7 @@ impl Shape {
     /// Turn a line into equally spaced dots.
     pub fn dotted_line(
         points: &[Pos2],
-        color: impl Into<Color32>,
+        color: impl Into<Rgba>,
         spacing: f32,
         radius: f32,
     ) -> Vec<Self> {
@@ -113,7 +113,7 @@ impl Shape {
     /// A convex polygon with a fill and optional stroke.
     pub fn convex_polygon(
         points: Vec<Pos2>,
-        fill: impl Into<Color32>,
+        fill: impl Into<Rgba>,
         stroke: impl Into<Stroke>,
     ) -> Self {
         Self::Path {
@@ -125,11 +125,11 @@ impl Shape {
     }
 
     #[deprecated = "Renamed convex_polygon"]
-    pub fn polygon(points: Vec<Pos2>, fill: impl Into<Color32>, stroke: impl Into<Stroke>) -> Self {
+    pub fn polygon(points: Vec<Pos2>, fill: impl Into<Rgba>, stroke: impl Into<Stroke>) -> Self {
         Self::convex_polygon(points, fill, stroke)
     }
 
-    pub fn circle_filled(center: Pos2, radius: f32, fill_color: impl Into<Color32>) -> Self {
+    pub fn circle_filled(center: Pos2, radius: f32, fill_color: impl Into<Rgba>) -> Self {
         Self::Circle {
             center,
             radius,
@@ -147,7 +147,7 @@ impl Shape {
         }
     }
 
-    pub fn rect_filled(rect: Rect, corner_radius: f32, fill_color: impl Into<Color32>) -> Self {
+    pub fn rect_filled(rect: Rect, corner_radius: f32, fill_color: impl Into<Rgba>) -> Self {
         Self::Rect {
             rect,
             corner_radius,
@@ -172,7 +172,7 @@ impl Shape {
         anchor: Align2,
         text: impl ToString,
         text_style: TextStyle,
-        color: Color32,
+        color: Rgba,
     ) -> Self {
         let galley = fonts.layout_multiline(text_style, text.to_string(), f32::INFINITY);
         let rect = anchor.anchor_rect(Rect::from_min_size(pos, galley.size));
@@ -190,7 +190,7 @@ fn points_from_line(
     line: &[Pos2],
     spacing: f32,
     radius: f32,
-    color: Color32,
+    color: Rgba,
     shapes: &mut Vec<Shape>,
 ) {
     let mut position_on_segment = 0.0;

epaint/src/shape_transform.rs

@@ -1,6 +1,6 @@
 use crate::*;
 
-pub fn adjust_colors(shape: &mut Shape, adjust_color: &impl Fn(&mut Color32)) {
+pub fn adjust_colors(shape: &mut Shape, adjust_color: &impl Fn(&mut Rgba)) {
     #![allow(clippy::match_same_arms)]
     match shape {
         Shape::Noop => {}

epaint/src/stroke.rs

@@ -7,16 +7,16 @@ use super::*;
 #[cfg_attr(feature = "persistence", derive(serde::Deserialize, serde::Serialize))]
 pub struct Stroke {
     pub width: f32,
-    pub color: Color32,
+    pub color: Rgba,
 }
 
 impl Stroke {
     /// Same as [`Stroke::default`].
     pub fn none() -> Self {
-        Self::new(0.0, Color32::TRANSPARENT)
+        Self::new(0.0, Rgba::TRANSPARENT)
     }
 
-    pub fn new(width: impl Into<f32>, color: impl Into<Color32>) -> Self {
+    pub fn new(width: impl Into<f32>, color: impl Into<Rgba>) -> Self {
         Self {
             width: width.into(),
             color: color.into(),
@@ -26,7 +26,7 @@ impl Stroke {
 
 impl<Color> From<(f32, Color)> for Stroke
 where
-    Color: Into<Color32>,
+    Color: Into<Rgba>,
 {
     fn from((width, color): (f32, Color)) -> Stroke {
         Stroke::new(width, color)

epaint/src/tessellator.rs

@@ -272,13 +272,8 @@ impl TessellationOptions {
 }
 
 /// Tessellate the given convex area into a polygon.
-fn fill_closed_path(
+fn fill_closed_path(path: &[PathPoint], color: Rgba, options: TessellationOptions, out: &mut Mesh) {
-    path: &[PathPoint],
+    if color == Rgba::TRANSPARENT {
-    color: Color32,
-    options: TessellationOptions,
-    out: &mut Mesh,
-) {
-    if color == Color32::TRANSPARENT {
         return;
     }
 
@@ -286,7 +281,7 @@ fn fill_closed_path(
     if options.anti_alias {
         out.reserve_triangles(3 * n as usize);
         out.reserve_vertices(2 * n as usize);
-        let color_outer = Color32::TRANSPARENT;
+        let color_outer = Rgba::TRANSPARENT;
         let idx_inner = out.vertices.len() as u32;
         let idx_outer = idx_inner + 1;
         for i in 2..n {
@@ -324,7 +319,7 @@ fn stroke_path(
     options: TessellationOptions,
     out: &mut Mesh,
 ) {
-    if stroke.width <= 0.0 || stroke.color == Color32::TRANSPARENT {
+    if stroke.width <= 0.0 || stroke.color == Rgba::TRANSPARENT {
         return;
     }
 
@@ -333,7 +328,7 @@ fn stroke_path(
 
     if options.anti_alias {
         let color_inner = stroke.color;
-        let color_outer = Color32::TRANSPARENT;
+        let color_outer = Rgba::TRANSPARENT;
 
         let thin_line = stroke.width <= options.aa_size;
         if thin_line {
@@ -346,7 +341,7 @@ fn stroke_path(
 
             // Fade out as it gets thinner:
             let color_inner = mul_color(color_inner, stroke.width / options.aa_size);
-            if color_inner == Color32::TRANSPARENT {
+            if color_inner == Rgba::TRANSPARENT {
                 return;
             }
 
@@ -438,7 +433,7 @@ fn stroke_path(
             // Fade out thin lines rather than making them thinner
             let radius = options.aa_size / 2.0;
             let color = mul_color(stroke.color, stroke.width / options.aa_size);
-            if color == Color32::TRANSPARENT {
+            if color == Rgba::TRANSPARENT {
                 return;
             }
             for p in path {
@@ -455,11 +450,10 @@ fn stroke_path(
     }
 }
 
-fn mul_color(color: Color32, factor: f32) -> Color32 {
+#[inline]
+fn mul_color(color: Rgba, factor: f32) -> Rgba {
     crate::epaint_assert!(0.0 <= factor && factor <= 1.0);
-    // As an unfortunate side-effect of using premultiplied alpha
+    color * factor
-    // we need a somewhat expensive conversion to linear space and back.
-    color.linear_multiply(factor)
 }
 
 // ----------------------------------------------------------------------------
@@ -552,7 +546,7 @@ impl Tessellator {
                         path.add_open_points(&points);
                     }
 
-                    if fill != Color32::TRANSPARENT {
+                    if fill != Rgba::TRANSPARENT {
                         crate::epaint_assert!(
                             closed,
                             "You asked to fill a path that is not closed. That makes no sense."
@@ -634,11 +628,11 @@ impl Tessellator {
         tex_size: [usize; 2],
         pos: Pos2,
         galley: &super::Galley,
-        color: Color32,
+        color: Rgba,
         fake_italics: bool,
         out: &mut Mesh,
     ) {
-        if color == Color32::TRANSPARENT || galley.is_empty() {
+        if color == Rgba::TRANSPARENT || galley.is_empty() {
             return;
         }
         if cfg!(any(