Add Label::sense so you can make clickable labels

relates to https://github.com/emilk/egui/issues/292

CHANGELOG.md

@@ -7,6 +7,8 @@ NOTE: [`eframe`](eframe/CHANGELOG.md), [`egui_web`](egui_web/CHANGELOG.md) and [
 
 ## Unreleased
 
+### Added ⭐
+* Make labels interactive with `Label::sense(Sense::click())`.
 
 ## 0.11.0 - 2021-04-05 - Optimization, screen reader & new layout logic
 

egui/src/response.rs

@@ -105,6 +105,11 @@ impl std::fmt::Debug for Response {
 
 impl Response {
     /// Returns true if this widget was clicked this frame by the primary button.
+    ///
+    /// Note that the widget must be sensing clicks with [`Sense::click`].
+    /// [`crate::Button`] senses clicks; [`crate::Label`] does not (unless you call [`crate::Label::sense`]).
+    ///
+    /// You can use [`Self::interact`] to sense more things *after* adding a widget.
     #[inline(always)]
     pub fn clicked(&self) -> bool {
         self.clicked[PointerButton::Primary as usize]
@@ -198,6 +203,11 @@ impl Response {
     ///
     /// To find out which button(s), query [`crate::PointerState::button_down`]
     /// (`ui.input().pointer.button_down(…)`).
+    ///
+    /// Note that the widget must be sensing drags with [`Sense::drag`].
+    /// [`crate::DragValue`] senses drags; [`crate::Label`] does not (unless you call [`crate::Label::sense`]).
+    ///
+    /// You can use [`Self::interact`] to sense more things *after* adding a widget.
     #[inline(always)]
     pub fn dragged(&self) -> bool {
         self.dragged
@@ -340,10 +350,13 @@ impl Response {
 
     /// Check for more interactions (e.g. sense clicks on a `Response` returned from a label).
     ///
+    /// Note that this call will not add any hover-effects to the widget, so when possible
+    /// it is better to give the widget a `Sense` instead, e.g. using `[Label::sense]`.
+    ///
     /// ```
     /// # let mut ui = egui::Ui::__test();
     /// let response = ui.label("hello");
-    /// assert!(!response.clicked()); // labels don't sense clicks
+    /// assert!(!response.clicked()); // labels don't sense clicks by default
     /// let response = response.interact(egui::Sense::click());
     /// if response.clicked() { /* … */ }
     /// ```

egui/src/sense.rs

@@ -75,4 +75,9 @@ impl Sense {
             focusable: self.focusable | other.focusable,
         }
     }
+
+    /// Returns true if we sense either clicks or drags.
+    pub fn interactive(&self) -> bool {
+        self.click || self.drag
+    }
 }

egui/src/style.rs

@@ -243,7 +243,9 @@ pub struct Widgets {
 
 impl Widgets {
     pub fn style(&self, response: &Response) -> &WidgetVisuals {
-        if response.is_pointer_button_down_on() || response.has_focus() {
+        if !response.sense.interactive() {
+            &self.noninteractive
+        } else if response.is_pointer_button_down_on() || response.has_focus() {
             &self.active
         } else if response.hovered() {
             &self.hovered

egui/src/widgets/label.rs

@@ -25,6 +25,7 @@ pub struct Label {
     underline: bool,
     italics: bool,
     raised: bool,
+    sense: Sense,
 }
 
 impl Label {
@@ -42,6 +43,7 @@ impl Label {
             underline: false,
             italics: false,
             raised: false,
+            sense: Sense::focusable_noninteractive(),
         }
     }
 
@@ -141,6 +143,24 @@ impl Label {
         self.text_color = Some(text_color.into());
         self
     }
+
+    /// Make the label response to clicks and/or drags.
+    ///
+    /// By default, a label is inert and does not response to click or drags.
+    /// By calling this you can turn the label into a button of sorts.
+    /// This will also give the label the hover-effect of a button, but without the frame.
+    ///
+    /// ``` rust
+    /// # use egui::{Label, Sense};
+    /// # let ui = &mut egui::Ui::__test();
+    /// if ui.add(Label::new("click me").sense(Sense::click())).clicked() {
+    ///     /* … */
+    /// }
+    /// ```
+    pub fn sense(mut self, sense: Sense) -> Self {
+        self.sense = sense;
+        self
+    }
 }
 
 impl Label {
@@ -176,10 +196,17 @@ impl Label {
     // This should be the easiest method of putting text anywhere.
 
     pub fn paint_galley(&self, ui: &mut Ui, pos: Pos2, galley: Arc<Galley>) {
-        self.paint_galley_focus(ui, pos, galley, false)
+        self.paint_galley_impl(ui, pos, galley, false, ui.visuals().text_color())
     }
 
-    fn paint_galley_focus(&self, ui: &mut Ui, pos: Pos2, galley: Arc<Galley>, focus: bool) {
+    fn paint_galley_impl(
+        &self,
+        ui: &mut Ui,
+        pos: Pos2,
+        galley: Arc<Galley>,
+        has_focus: bool,
+        response_color: Color32,
+    ) {
         let Self {
             mut background_color,
             code,
@@ -192,7 +219,7 @@ impl Label {
             ..
         } = *self;
 
-        let underline = underline || focus;
+        let underline = underline || has_focus;
 
         let text_color = if let Some(text_color) = self.text_color {
             text_color
@@ -201,7 +228,7 @@ impl Label {
         } else if weak {
             ui.visuals().weak_text_color()
         } else {
-            ui.visuals().text_color()
+            response_color
         };
 
         if code {
@@ -287,7 +314,7 @@ impl Label {
 
 impl Widget for Label {
     fn ui(self, ui: &mut Ui) -> Response {
-        let sense = Sense::focusable_noninteractive();
+        let sense = self.sense;
 
         if self.should_wrap(ui)
             && ui.layout().main_dir() == Direction::LeftToRight
@@ -339,13 +366,15 @@ impl Widget for Label {
                 response |= ui.allocate_rect(rect, sense);
             }
             response.widget_info(|| WidgetInfo::labeled(WidgetType::Label, &galley.text));
-            self.paint_galley_focus(ui, pos, galley, response.has_focus());
+            let response_color = ui.style().interact(&response).text_color();
+            self.paint_galley_impl(ui, pos, galley, response.has_focus(), response_color);
             response
         } else {
             let galley = self.layout(ui);
             let (rect, response) = ui.allocate_exact_size(galley.size, sense);
             response.widget_info(|| WidgetInfo::labeled(WidgetType::Label, &galley.text));
-            self.paint_galley_focus(ui, rect.min, galley, response.has_focus());
+            let response_color = ui.style().interact(&response).text_color();
+            self.paint_galley_impl(ui, rect.min, galley, response.has_focus(), response_color);
             response
         }
     }