Add ui.set_enabled(false) to disable all widgets in a Ui

Closes https://github.com/emilk/egui/issues/50

CHANGELOG.md

@@ -13,7 +13,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 * Add support for secondary and middle mouse buttons.
 * Add `Label` methods for code, strong, strikethrough, underline and italics.
-* Add `ui.group(|ui| { … })` to visually group some widgets within a frame
+* Add `ui.group(|ui| { … })` to visually group some widgets within a frame.
+* Add `ui.set_enabled(false)` to disable all widgets in a `Ui` (grayed out and non-interactive).
 * Add `TextEdit::hint_text` for showing a weak hint text when empty.
 * `egui::popup::popup_below_widget`: show a popup area below another widget.
 * Add `Slider::clamp_to_range(bool)`: if set, clamp the incoming and outgoing values to the slider range.

egui/src/containers/area.rs

@@ -45,6 +45,7 @@ pub struct Area {
     pub(crate) id: Id,
     movable: bool,
     interactable: bool,
+    enabled: bool,
     order: Order,
     default_pos: Option<Pos2>,
     new_pos: Option<Pos2>,
@@ -56,6 +57,7 @@ impl Area {
             id: Id::new(id_source),
             movable: true,
             interactable: true,
+            enabled: true,
             order: Order::Middle,
             default_pos: None,
             new_pos: None,
@@ -71,6 +73,15 @@ impl Area {
         LayerId::new(self.order, self.id)
     }
 
+    /// If false, no content responds to click
+    /// and widgets will be shown grayed out.
+    /// You won't be able to move the window.
+    /// Default: `true`.
+    pub fn enabled(mut self, enabled: bool) -> Self {
+        self.enabled = enabled;
+        self
+    }
+
     /// moveable by dragging the area?
     pub fn movable(mut self, movable: bool) -> Self {
         self.movable = movable;
@@ -78,8 +89,12 @@ impl Area {
         self
     }
 
+    pub fn is_enabled(&self) -> bool {
+        self.enabled
+    }
+
     pub fn is_movable(&self) -> bool {
-        self.movable
+        self.movable && self.enabled
     }
 
     /// If false, clicks goes straight through to what is behind us.
@@ -121,6 +136,7 @@ pub(crate) struct Prepared {
     layer_id: LayerId,
     state: State,
     movable: bool,
+    enabled: bool,
 }
 
 impl Area {
@@ -130,6 +146,7 @@ impl Area {
             movable,
             order,
             interactable,
+            enabled,
             default_pos,
             new_pos,
         } = self;
@@ -149,6 +166,7 @@ impl Area {
             layer_id,
             state,
             movable,
+            enabled,
         }
     }
 
@@ -214,13 +232,15 @@ impl Prepared {
             clip_rect = clip_rect.intersect(central_area);
         }
 
-        Ui::new(
+        let mut ui = Ui::new(
             ctx.clone(),
             self.layer_id,
             self.layer_id.id,
             max_rect,
             clip_rect,
-        )
+        );
+        ui.set_enabled(self.enabled);
+        ui
     }
 
     #[allow(clippy::needless_pass_by_value)] // intentional to swallow up `content_ui`.
@@ -229,6 +249,7 @@ impl Prepared {
             layer_id,
             mut state,
             movable,
+            enabled,
         } = self;
 
         state.size = content_ui.min_rect().size();
@@ -247,6 +268,7 @@ impl Prepared {
             interact_id,
             state.rect(),
             sense,
+            enabled,
         );
 
         if move_response.dragged() && movable {

egui/src/containers/frame.rs

@@ -23,7 +23,7 @@ impl Frame {
         Self {
             margin: Vec2::new(8.0, 6.0),
             corner_radius: 4.0,
-            stroke: style.visuals.widgets.noninteractive.bg_stroke,
+            stroke: style.visuals.window_stroke(),
             ..Default::default()
         }
     }
@@ -32,8 +32,8 @@ impl Frame {
         Self {
             margin: Vec2::new(8.0, 2.0),
             corner_radius: 0.0,
-            fill: style.visuals.widgets.noninteractive.bg_fill,
-            stroke: style.visuals.widgets.noninteractive.bg_stroke,
+            fill: style.visuals.window_fill(),
+            stroke: style.visuals.window_stroke(),
             ..Default::default()
         }
     }
@@ -42,7 +42,7 @@ impl Frame {
         Self {
             margin: Vec2::new(8.0, 8.0),
             corner_radius: 0.0,
-            fill: style.visuals.widgets.noninteractive.bg_fill,
+            fill: style.visuals.window_fill(),
             stroke: Default::default(),
             ..Default::default()
         }
@@ -53,8 +53,8 @@ impl Frame {
             margin: style.spacing.window_padding,
             corner_radius: style.visuals.window_corner_radius,
             shadow: style.visuals.window_shadow,
-            fill: style.visuals.widgets.noninteractive.bg_fill,
-            stroke: style.visuals.widgets.noninteractive.bg_stroke,
+            fill: style.visuals.window_fill(),
+            stroke: style.visuals.window_stroke(),
         }
     }
 
@@ -63,8 +63,8 @@ impl Frame {
             margin: Vec2::splat(1.0),
             corner_radius: 2.0,
             shadow: Shadow::small(),
-            fill: style.visuals.widgets.noninteractive.bg_fill,
-            stroke: style.visuals.widgets.noninteractive.bg_stroke,
+            fill: style.visuals.window_fill(),
+            stroke: style.visuals.window_stroke(),
         }
     }
 
@@ -73,8 +73,8 @@ impl Frame {
             margin: style.spacing.window_padding,
             corner_radius: 5.0,
             shadow: Shadow::small(),
-            fill: style.visuals.widgets.noninteractive.bg_fill,
-            stroke: style.visuals.widgets.noninteractive.bg_stroke,
+            fill: style.visuals.window_fill(),
+            stroke: style.visuals.window_stroke(),
         }
     }
 
@@ -84,7 +84,7 @@ impl Frame {
             margin: Vec2::new(10.0, 10.0),
             corner_radius: 5.0,
             fill: Color32::from_black_alpha(250),
-            stroke: style.visuals.widgets.noninteractive.bg_stroke,
+            stroke: style.visuals.window_stroke(),
             ..Default::default()
         }
     }

egui/src/containers/window.rs

@@ -70,6 +70,12 @@ impl<'open> Window<'open> {
         self
     }
 
+    /// If `false` the window will be grayed out and non-interactive.
+    pub fn enabled(mut self, enabled: bool) -> Self {
+        self.area = self.area.enabled(enabled);
+        self
+    }
+
     /// Usage: `Window::new(...).mutate(|w| w.resize = w.resize.auto_expand_width(true))`
     /// Not sure this is a good interface for this.
     pub fn mutate(mut self, mutate: impl Fn(&mut Self)) -> Self {
@@ -239,8 +245,8 @@ impl<'open> Window<'open> {
         let is_maximized = !with_title_bar
             || collapsing_header::State::is_open(ctx, collapsing_id).unwrap_or_default();
         let possible = PossibleInteractions {
-            movable: area.is_movable(),
-            resizable: resize.is_resizable() && is_maximized,
+            movable: area.is_enabled() && area.is_movable(),
+            resizable: area.is_enabled() && resize.is_resizable() && is_maximized,
         };
 
         let area = area.movable(false); // We move it manually

egui/src/context.rs

@@ -218,6 +218,7 @@ impl CtxRef {
     // ---------------------------------------------------------------------
 
     /// Use `ui.interact` instead
+    #[allow(clippy::too_many_arguments)]
     pub(crate) fn interact(
         &self,
         clip_rect: Rect,
@@ -226,6 +227,7 @@ impl CtxRef {
         id: Id,
         rect: Rect,
         sense: Sense,
+        enabled: bool,
     ) -> Response {
         let gap = 0.5; // Just to make sure we don't accidentally hover two things at once (a small eps should be sufficient).
         let interact_rect = rect.expand2(
@@ -234,7 +236,7 @@ impl CtxRef {
                 .at_most(Vec2::splat(5.0)),
         ); // make it easier to click
         let hovered = self.rect_contains_pointer(layer_id, clip_rect.intersect(interact_rect));
-        self.interact_with_hovered(layer_id, id, rect, sense, hovered)
+        self.interact_with_hovered(layer_id, id, rect, sense, enabled, hovered)
     }
 
     /// You specify if a thing is hovered, and the function gives a `Response`.
@@ -244,8 +246,11 @@ impl CtxRef {
         id: Id,
         rect: Rect,
         sense: Sense,
+        enabled: bool,
         hovered: bool,
     ) -> Response {
+        let hovered = hovered && enabled; // can't even hover disabled widgets
+
         let has_kb_focus = self.memory().has_kb_focus(id);
         let lost_kb_focus = self.memory().lost_kb_focus(id);
 
@@ -255,6 +260,7 @@ impl CtxRef {
             id,
             rect,
             sense,
+            enabled,
             hovered,
             clicked: Default::default(),
             double_clicked: Default::default(),
@@ -266,7 +272,7 @@ impl CtxRef {
             lost_kb_focus,
         };
 
-        if sense == Sense::hover() || !layer_id.allow_interaction() {
+        if !enabled || sense == Sense::hover() || !layer_id.allow_interaction() {
             // Not interested or allowed input:
             return response;
         }

egui/src/painter.rs

@@ -22,6 +22,10 @@ pub struct Painter {
     /// Everything painted in this `Painter` will be clipped against this.
     /// This means nothing outside of this rectangle will be visible on screen.
     clip_rect: Rect,
+
+    /// 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>,
 }
 
 impl Painter {
@@ -30,6 +34,7 @@ impl Painter {
             ctx,
             layer_id,
             clip_rect,
+            fade_to_color: None,
         }
     }
 
@@ -39,6 +44,7 @@ impl Painter {
             ctx: self.ctx,
             layer_id,
             clip_rect: self.clip_rect,
+            fade_to_color: None,
         }
     }
 
@@ -47,6 +53,11 @@ impl Painter {
         self.layer_id = layer_id;
     }
 
+    /// If set, colors will be modified to look like this
+    pub(crate) fn set_fade_to_color(&mut self, fade_to_color: Option<Color32>) {
+        self.fade_to_color = fade_to_color;
+    }
+
     /// Create a painter for a sub-region of this `Painter`.
     ///
     /// The clip-rect of the returned `Painter` will be the intersection
@@ -106,10 +117,17 @@ impl Painter {
 
 /// ## Low level
 impl Painter {
+    fn transform_shape(&self, shape: &mut Shape) {
+        if let Some(fade_to_color) = self.fade_to_color {
+            tint_shape_towards(shape, fade_to_color);
+        }
+    }
+
     /// It is up to the caller to make sure there is room for this.
     /// Can be used for free painting.
     /// NOTE: all coordinates are screen coordinates!
-    pub fn add(&self, shape: Shape) -> ShapeIdx {
+    pub fn add(&self, mut shape: Shape) -> ShapeIdx {
+        self.transform_shape(&mut shape);
         self.ctx
             .graphics()
             .list(self.layer_id)
@@ -119,8 +137,14 @@ impl Painter {
     /// Add many shapes at once.
     ///
     /// Calling this once is generally faster than calling [`Self::add`] multiple times.
-    pub fn extend(&self, shapes: Vec<Shape>) {
+    pub fn extend(&self, mut shapes: Vec<Shape>) {
         if !shapes.is_empty() {
+            if self.fade_to_color.is_some() {
+                for shape in &mut shapes {
+                    self.transform_shape(shape);
+                }
+            }
+
             self.ctx
                 .graphics()
                 .list(self.layer_id)
@@ -129,7 +153,8 @@ impl Painter {
     }
 
     /// Modify an existing [`Shape`].
-    pub fn set(&self, idx: ShapeIdx, shape: Shape) {
+    pub fn set(&self, idx: ShapeIdx, mut shape: Shape) {
+        self.transform_shape(&mut shape);
         self.ctx
             .graphics()
             .list(self.layer_id)
@@ -294,3 +319,9 @@ impl Painter {
         });
     }
 }
+
+fn tint_shape_towards(shape: &mut Shape, target: Color32) {
+    epaint::shape_transform::adjust_colors(shape, &|color| {
+        *color = crate::color::tint_color_towards(*color, target);
+    });
+}

egui/src/response.rs

@@ -29,6 +29,10 @@ pub struct Response {
     /// The senses (click and/or drag) that the widget was interested in (if any).
     pub sense: Sense,
 
+    /// Was the widget enabled?
+    /// If `false`, there was no interaction attempted (not even hover).
+    pub(crate) enabled: bool,
+
     // OUT:
     /// The pointer is hovering above this widget or the widget was clicked/tapped this frame.
     pub(crate) hovered: bool,
@@ -68,6 +72,7 @@ impl std::fmt::Debug for Response {
             id,
             rect,
             sense,
+            enabled,
             hovered,
             clicked,
             double_clicked,
@@ -83,6 +88,7 @@ impl std::fmt::Debug for Response {
             .field("id", id)
             .field("rect", rect)
             .field("sense", sense)
+            .field("enabled", enabled)
             .field("hovered", hovered)
             .field("clicked", clicked)
             .field("double_clicked", double_clicked)
@@ -117,6 +123,13 @@ impl Response {
         self.double_clicked[PointerButton::Primary as usize]
     }
 
+    /// Was the widget enabled?
+    /// If false, there was no interaction attempted
+    /// and the widget should be drawn in a gray disabled look.
+    pub fn enabled(&self) -> bool {
+        self.enabled
+    }
+
     /// The pointer is hovering above this widget or the widget was clicked/tapped this frame.
     pub fn hovered(&self) -> bool {
         self.hovered
@@ -208,8 +221,14 @@ impl Response {
     /// if response.clicked() { /* … */ }
     /// ```
     pub fn interact(&self, sense: Sense) -> Self {
-        self.ctx
-            .interact_with_hovered(self.layer_id, self.id, self.rect, sense, self.hovered)
+        self.ctx.interact_with_hovered(
+            self.layer_id,
+            self.id,
+            self.rect,
+            sense,
+            self.enabled,
+            self.hovered,
+        )
     }
 
     /// Move the scroll to this UI with the specified alignment.
@@ -247,6 +266,7 @@ impl Response {
             id: self.id,
             rect: self.rect.union(other.rect),
             sense: self.sense.union(other.sense),
+            enabled: self.enabled || other.enabled,
             hovered: self.hovered || other.hovered,
             clicked: [
                 self.clicked[0] || other.clicked[0],

egui/src/style.rs

@@ -184,12 +184,20 @@ impl Visuals {
     }
 
     pub fn weak_text_color(&self) -> Color32 {
-        self.widgets.disabled.text_color()
+        crate::color::tint_color_towards(self.text_color(), self.window_fill())
     }
 
     pub fn strong_text_color(&self) -> Color32 {
         self.widgets.active.text_color()
     }
+
+    pub fn window_fill(&self) -> Color32 {
+        self.widgets.noninteractive.bg_fill
+    }
+
+    pub fn window_stroke(&self) -> Stroke {
+        self.widgets.noninteractive.bg_stroke
+    }
 }
 
 /// Selected text, selected elements etc
@@ -210,8 +218,6 @@ pub struct Widgets {
     /// * `noninteractive.bg_fill` is the background color of windows.
     /// * `noninteractive.fg_stroke` is the normal text color.
     pub noninteractive: WidgetVisuals,
-    /// The style of a disabled button.
-    pub disabled: WidgetVisuals,
     /// The style of an interactive widget, such as a button, at rest.
     pub inactive: WidgetVisuals,
     /// The style of an interactive widget while you hover it.
@@ -224,8 +230,6 @@ impl Widgets {
     pub fn style(&self, response: &Response) -> &WidgetVisuals {
         if response.is_pointer_button_down_on() || response.has_kb_focus {
             &self.active
-        } else if response.sense == crate::Sense::hover() {
-            &self.disabled
         } else if response.hovered() {
             &self.hovered
         } else {
@@ -374,19 +378,12 @@ impl Widgets {
     pub fn dark() -> Self {
         Self {
             noninteractive: WidgetVisuals {
+                bg_fill: Color32::from_gray(30), // window background
                 bg_stroke: Stroke::new(1.0, Color32::from_gray(65)), // window outline
-                bg_fill: Color32::from_gray(30),                     // window background
                 fg_stroke: Stroke::new(1.0, Color32::from_gray(160)), // normal text color
                 corner_radius: 4.0,
                 expansion: 0.0,
             },
-            disabled: WidgetVisuals {
-                bg_fill: Color32::from_gray(40), // Should look grayed out
-                bg_stroke: Stroke::new(1.0, Color32::from_gray(70)),
-                fg_stroke: Stroke::new(1.0, Color32::from_gray(110)), // Should look grayed out. Also used for "weak" text color.
-                corner_radius: 4.0,
-                expansion: 0.0,
-            },
             inactive: WidgetVisuals {
                 bg_fill: Color32::from_gray(70),
                 bg_stroke: Default::default(),
@@ -414,16 +411,9 @@ impl Widgets {
     pub fn light() -> Self {
         Self {
             noninteractive: WidgetVisuals {
+                bg_fill: Color32::from_gray(220), // window background
                 bg_stroke: Stroke::new(1.0, Color32::from_gray(180)), // window outline
-                bg_fill: Color32::from_gray(220),                     // window background
-                fg_stroke: Stroke::new(1.0, Color32::from_gray(70)),  // normal text color
-                corner_radius: 4.0,
-                expansion: 0.0,
-            },
-            disabled: WidgetVisuals {
-                bg_fill: Color32::from_gray(215), // Should look grayed out
-                bg_stroke: Stroke::new(1.0, Color32::from_gray(185)),
-                fg_stroke: Stroke::new(1.0, Color32::from_gray(145)), // Should look grayed out. Also used for "weak" text color.
+                fg_stroke: Stroke::new(1.0, Color32::from_gray(70)), // normal text color
                 corner_radius: 4.0,
                 expansion: 0.0,
             },
@@ -542,7 +532,6 @@ impl Widgets {
             active,
             hovered,
             inactive,
-            disabled,
             noninteractive,
         } = self;
 
@@ -550,10 +539,6 @@ impl Widgets {
             ui.label("The style of a widget that you cannot interact with.");
             noninteractive.ui(ui)
         });
-        ui.collapsing("interactive & disabled", |ui| {
-            ui.label("The style of a disabled button.");
-            disabled.ui(ui)
-        });
         ui.collapsing("interactive & inactive", |ui| {
             ui.label("The style of an interactive widget, such as a button, at rest.");
             inactive.ui(ui)

egui/src/ui.rs

@@ -46,6 +46,10 @@ pub struct Ui {
 
     /// Handles the `Ui` size and the placement of new widgets.
     placer: Placer,
+
+    /// If false we are unresponsive to input,
+    /// and all widgets will assume a gray style.
+    enabled: bool,
 }
 
 impl Ui {
@@ -60,6 +64,7 @@ impl Ui {
             painter: Painter::new(ctx, layer_id, clip_rect),
             style,
             placer: Placer::new(max_rect, Layout::default()),
+            enabled: true,
         }
     }
 
@@ -72,6 +77,7 @@ impl Ui {
             painter: self.painter.clone(),
             style: self.style.clone(),
             placer: Placer::new(max_rect, layout),
+            enabled: self.enabled,
         }
     }
 
@@ -166,6 +172,39 @@ impl Ui {
         &self.painter
     }
 
+    /// If `false`, the `Ui` does not allow any interaction and
+    /// the widgets in it will draw with a gray look.
+    pub fn enabled(&self) -> bool {
+        self.enabled
+    }
+
+    /// Calling `set_enabled(false)` will cause the `Ui` to deny all future interaction
+    /// and all the widgets will draw with a gray look.
+    ///
+    /// Calling `set_enabled(true)` has no effect - it will NOT re-enable the `Ui` once disabled.
+    ///
+    /// ### Example
+    /// ```
+    /// # let ui = &mut egui::Ui::__test();
+    /// # let mut enabled = true;
+    /// ui.group(|ui|{
+    ///     ui.checkbox(&mut enabled, "Enable subsection");
+    ///     ui.set_enabled(enabled);
+    ///     if ui.button("Button that is not always clickable").clicked() {
+    ///         /* … */
+    ///     }
+    /// });
+    /// ```
+    pub fn set_enabled(&mut self, enabled: bool) {
+        self.enabled &= enabled;
+        if self.enabled {
+            self.painter.set_fade_to_color(None);
+        } else {
+            self.painter
+                .set_fade_to_color(Some(self.visuals().window_fill()));
+        }
+    }
+
     pub fn layout(&self) -> &Layout {
         self.placer.layout()
     }
@@ -427,6 +466,7 @@ impl Ui {
             id,
             rect,
             sense,
+            self.enabled,
         )
     }
 

egui/src/widgets/button.rs

@@ -68,6 +68,8 @@ impl Button {
 
     /// If you set this to `false`, the button will be grayed out and un-clickable.
     /// `enabled(false)` has the same effect as calling `sense(Sense::hover())`.
+    ///
+    /// This is a convenience for [`Ui::set_enabled`].
     pub fn enabled(mut self, enabled: bool) -> Self {
         if !enabled {
             self.sense = Sense::hover();
@@ -76,8 +78,8 @@ impl Button {
     }
 }
 
-impl Widget for Button {
-    fn ui(self, ui: &mut Ui) -> Response {
+impl Button {
+    fn enabled_ui(self, ui: &mut Ui) -> Response {
         let Button {
             text,
             text_color,
@@ -136,6 +138,22 @@ impl Widget for Button {
     }
 }
 
+impl Widget for Button {
+    fn ui(self, ui: &mut Ui) -> Response {
+        let button_enabled = self.sense != Sense::hover();
+        if button_enabled || !ui.enabled() {
+            self.enabled_ui(ui)
+        } else {
+            // We need get a temporary disabled `Ui` to get that grayed out look:
+            ui.wrap(|ui| {
+                ui.set_enabled(false);
+                self.enabled_ui(ui)
+            })
+            .0
+        }
+    }
+}
+
 // ----------------------------------------------------------------------------
 
 // TODO: allow checkbox without a text label

egui/src/widgets/label.rs

@@ -160,15 +160,15 @@ impl Label {
             ..
         } = *self;
 
-        let text_color = self.text_color.unwrap_or_else(|| {
-            if strong {
-                ui.visuals().strong_text_color()
-            } else if weak {
-                ui.visuals().weak_text_color()
-            } else {
-                ui.visuals().text_color()
-            }
-        });
+        let text_color = if let Some(text_color) = self.text_color {
+            text_color
+        } else if strong {
+            ui.visuals().strong_text_color()
+        } else if weak {
+            ui.visuals().weak_text_color()
+        } else {
+            ui.visuals().text_color()
+        };
 
         if code {
             background_color = ui.visuals().code_bg_color;

egui/src/widgets/selected_label.rs

@@ -48,16 +48,19 @@ impl Widget for SelectableLabel {
 
         if selected || response.hovered() {
             let rect = rect.expand(visuals.expansion);
+
             let fill = if selected {
                 ui.visuals().selection.bg_fill
             } else {
                 Default::default()
             };
+
             let stroke = if selected {
                 ui.visuals().selection.stroke
             } else {
                 visuals.bg_stroke
             };
+
             let corner_radius = 2.0;
             ui.painter().rect(rect, corner_radius, fill, stroke);
         }

egui_demo_lib/src/apps/demo/drag_and_drop.rs

@@ -51,20 +51,24 @@ pub fn drop_target<R>(
 
     let style = if is_being_dragged && can_accept_what_is_being_dragged && response.hovered() {
         ui.visuals().widgets.active
-    } else if is_being_dragged && can_accept_what_is_being_dragged {
-        ui.visuals().widgets.inactive
-    } else if is_being_dragged && !can_accept_what_is_being_dragged {
-        ui.visuals().widgets.disabled
     } else {
         ui.visuals().widgets.inactive
     };
 
+    let mut fill = style.bg_fill;
+    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());
+        stroke.color = color::tint_color_towards(stroke.color, ui.visuals().window_fill());
+    }
+
     ui.painter().set(
         where_to_put_background,
         Shape::Rect {
             corner_radius: style.corner_radius,
-            fill: style.bg_fill,
-            stroke: style.bg_stroke,
+            fill,
+            stroke,
             rect,
         },
     );

egui_demo_lib/src/apps/demo/toggle_switch.rs

@@ -83,9 +83,12 @@ fn toggle_compact(ui: &mut egui::Ui, on: &mut bool) -> egui::Response {
 
 pub fn demo(ui: &mut egui::Ui, on: &mut bool) {
     ui.horizontal_wrapped_for_text(egui::TextStyle::Button, |ui| {
-        ui.label("It's easy to create your own widgets!");
-        ui.label("This toggle switch is just one function and 15 lines of code:");
         toggle(ui, on).on_hover_text("Click to toggle");
         ui.add(crate::__egui_github_link_file!());
-    });
+    })
+    .1
+    .on_hover_text(
+        "It's easy to create your own widgets!\n\
+        This toggle switch is just one function and 20 lines of code.",
+    );
 }

egui_demo_lib/src/apps/demo/widget_gallery.rs

@@ -8,6 +8,7 @@ enum Enum {
 
 #[cfg_attr(feature = "persistence", derive(serde::Deserialize, serde::Serialize))]
 pub struct WidgetGallery {
+    enabled: bool,
     boolean: bool,
     radio: Enum,
     scalar: f32,
@@ -18,6 +19,7 @@ pub struct WidgetGallery {
 impl Default for WidgetGallery {
     fn default() -> Self {
         Self {
+            enabled: true,
             boolean: false,
             radio: Enum::First,
             scalar: 42.0,
@@ -46,6 +48,7 @@ impl super::Demo for WidgetGallery {
 impl super::View for WidgetGallery {
     fn ui(&mut self, ui: &mut egui::Ui) {
         let Self {
+            enabled,
             boolean,
             radio,
             scalar,
@@ -53,6 +56,12 @@ impl super::View for WidgetGallery {
             color,
         } = self;
 
+        ui.horizontal(|ui| {
+            ui.radio_value(enabled, true, "Enabled");
+            ui.radio_value(enabled, false, "Disabled");
+        });
+        ui.set_enabled(*enabled);
+
         let grid = egui::Grid::new("my_grid")
             .striped(true)
             .spacing([40.0, 4.0]);
@@ -65,7 +74,7 @@ impl super::View for WidgetGallery {
             ui.add(egui::Hyperlink::new("https://github.com/emilk/egui").text(" egui home page"));
             ui.end_row();
 
-            ui.label("Text Input:");
+            ui.label("TextEdit:");
             ui.add(egui::TextEdit::singleline(string).hint_text("Write something here"));
             ui.end_row();
 
@@ -73,7 +82,7 @@ impl super::View for WidgetGallery {
             ui.checkbox(boolean, "Checkbox");
             ui.end_row();
 
-            ui.label("Radio buttons:");
+            ui.label("RadioButton:");
             ui.horizontal(|ui| {
                 ui.radio_value(radio, Enum::First, "First");
                 ui.radio_value(radio, Enum::Second, "Second");
@@ -143,6 +152,10 @@ impl super::View for WidgetGallery {
                 });
             });
             ui.end_row();
+
+            ui.label("Custom widget");
+            super::toggle_switch::demo(ui, boolean);
+            ui.end_row();
         });
 
         ui.separator();

egui_demo_lib/src/apps/demo/widgets.rs

@@ -134,8 +134,5 @@ impl Widgets {
 
         ui.label("Multiline text input:");
         ui.text_edit_multiline(&mut self.multiline_text_input);
-
-        ui.separator();
-        super::toggle_switch::demo(ui, &mut self.toggle_switch);
     }
 }

egui_demo_lib/src/apps/demo/window_options.rs

@@ -7,6 +7,7 @@ pub struct WindowOptions {
     collapsible: bool,
     resizable: bool,
     scroll: bool,
+    disabled_time: f64,
 }
 
 impl Default for WindowOptions {
@@ -18,6 +19,7 @@ impl Default for WindowOptions {
             collapsible: true,
             resizable: true,
             scroll: false,
+            disabled_time: f64::NEG_INFINITY,
         }
     }
 }
@@ -36,15 +38,22 @@ impl super::Demo for WindowOptions {
             collapsible,
             resizable,
             scroll,
+            disabled_time,
         } = self.clone();
 
+        let enabled = ctx.input().time - disabled_time > 2.0;
+        if !enabled {
+            ctx.request_repaint();
+        }
+
         use super::View;
         let mut window = egui::Window::new(title)
             .id(egui::Id::new("demo_window_options")) // required since we change the title
             .resizable(resizable)
             .collapsible(collapsible)
             .title_bar(title_bar)
-            .scroll(scroll);
+            .scroll(scroll)
+            .enabled(enabled);
         if closable {
             window = window.open(open);
         }
@@ -63,6 +72,7 @@ impl super::View for WindowOptions {
             collapsible,
             resizable,
             scroll,
+            disabled_time,
         } = self;
 
         ui.horizontal(|ui| {
@@ -77,5 +87,9 @@ impl super::View for WindowOptions {
         ui.vertical_centered(|ui| {
             ui.add(crate::__egui_github_link_file!());
         });
+
+        if ui.button("Disable for 2 seconds").clicked() {
+            *disabled_time = ui.input().time;
+        }
     }
 }

epaint/src/color.rs

@@ -682,3 +682,30 @@ 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 {
+    let [mut r, mut g, mut b, mut a] = color.to_array();
+
+    if a == 0 {
+        r /= 2;
+        g /= 2;
+        b /= 2;
+    } else if a < 170 {
+        // Cheapish and looks ok.
+        // Works for e.g. grid stripes.
+        let div = (2 * 255 / a as i32) as u8;
+        r = r / 2 + target.r() / div;
+        g = g / 2 + target.g() / div;
+        b = b / 2 + target.b() / div;
+        a /= 2;
+    } else {
+        r = r / 2 + target.r() / 2;
+        g = g / 2 + target.g() / 2;
+        b = b / 2 + target.b() / 2;
+    }
+    Color32::from_rgba_premultiplied(r, g, b, a)
+}

epaint/src/lib.rs

@@ -49,6 +49,7 @@ mod mesh;
 pub mod mutex;
 mod shadow;
 mod shape;
+pub mod shape_transform;
 pub mod stats;
 mod stroke;
 pub mod tessellator;

epaint/src/shape_transform.rs

@@ -0,0 +1,35 @@
+use crate::*;
+
+pub fn adjust_colors(shape: &mut Shape, adjust_color: &impl Fn(&mut Color32)) {
+    match shape {
+        Shape::Noop => {}
+        Shape::Vec(shapes) => {
+            for shape in shapes {
+                adjust_colors(shape, adjust_color)
+            }
+        }
+        Shape::Circle { fill, stroke, .. } => {
+            adjust_color(fill);
+            adjust_color(&mut stroke.color);
+        }
+        Shape::LineSegment { stroke, .. } => {
+            adjust_color(&mut stroke.color);
+        }
+        Shape::Path { fill, stroke, .. } => {
+            adjust_color(fill);
+            adjust_color(&mut stroke.color);
+        }
+        Shape::Rect { fill, stroke, .. } => {
+            adjust_color(fill);
+            adjust_color(&mut stroke.color);
+        }
+        Shape::Text { color, .. } => {
+            adjust_color(color);
+        }
+        Shape::Mesh(mesh) => {
+            for v in &mut mesh.vertices {
+                adjust_color(&mut v.color);
+            }
+        }
+    }
+}