Check if TextEdit lost keyboard focus with response.lost_kb_focus

CHANGELOG.md

@@ -6,6 +6,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ## Unreleased
 
+### Added ⭐
+
+* You can now check if a `TextEdit` lost keyboard focus with `response.lost_kb_focus`.
+
 ### Changed 🔧
 
 * Pressing enter in a single-line `TextEdit` will now surrender keyboard focus for it

egui/src/context.rs

@@ -430,6 +430,12 @@ impl Context {
         let hovered = self.contains_mouse(layer_id, clip_rect, interact_rect);
         let has_kb_focus = id.map(|id| self.memory().has_kb_focus(id)).unwrap_or(false);
 
+        // If the the focus is lost after the call to interact,
+        // this will be `false`, so `TextEdit` also sets this manually.
+        let lost_kb_focus = id
+            .map(|id| self.memory().lost_kb_focus(id))
+            .unwrap_or(false);
+
         if id.is_none() || sense == Sense::nothing() || !layer_id.allow_interaction() {
             // Not interested or allowed input:
             return Response {
@@ -441,6 +447,7 @@ impl Context {
                 double_clicked: false,
                 active: false,
                 has_kb_focus,
+                lost_kb_focus,
             };
         }
         let id = id.unwrap();
@@ -466,6 +473,7 @@ impl Context {
                     double_clicked: false,
                     active: false,
                     has_kb_focus,
+                    lost_kb_focus,
                 };
 
                 if sense.click && memory.interaction.click_id.is_none() {
@@ -496,6 +504,7 @@ impl Context {
                     double_clicked: false,
                     active: false,
                     has_kb_focus,
+                    lost_kb_focus,
                 }
             }
         } else if self.input.mouse.released {
@@ -509,6 +518,7 @@ impl Context {
                 double_clicked: clicked && self.input.mouse.double_click,
                 active,
                 has_kb_focus,
+                lost_kb_focus,
             }
         } else if self.input.mouse.down {
             Response {
@@ -520,6 +530,7 @@ impl Context {
                 double_clicked: false,
                 active,
                 has_kb_focus,
+                lost_kb_focus,
             }
         } else {
             Response {
@@ -531,6 +542,7 @@ impl Context {
                 double_clicked: false,
                 active,
                 has_kb_focus,
+                lost_kb_focus,
             }
         }
     }

egui/src/demos/widgets.rs

@@ -133,12 +133,16 @@ impl Widgets {
 
         ui.horizontal(|ui| {
             ui.label("Single line text input:");
-            ui.add(
+            let response = ui.add(
                 TextEdit::new(&mut self.single_line_text_input)
                     .multiline(false)
                     .id_source("single line"),
             );
-        }); // TODO: .on_hover_text("Enter text to edit me")
+
+            if response.lost_kb_focus {
+                // The user pressed enter.
+            }
+        });
 
         ui.label("Multiline text input:");
         ui.add(TextEdit::new(&mut self.multiline_text_input).id_source("multiline"));

egui/src/memory.rs

@@ -71,7 +71,7 @@ pub struct Memory {
 /// If the user releases the button without moving the mouse we register it as a click on `click_id`.
 /// If the cursor moves too much we clear the `click_id` and start passing move events to `drag_id`.
 #[derive(Clone, Debug, Default)]
-pub struct Interaction {
+pub(crate) struct Interaction {
     /// A widget interested in clicks that has a mouse press on it.
     pub click_id: Option<Id>,
 
@@ -81,6 +81,9 @@ pub struct Interaction {
     /// The widget with keyboard focus (i.e. a text input field).
     pub kb_focus_id: Option<Id>,
 
+    /// What had keyboard focus previous frame?
+    pub kb_focus_id_previous_frame: Option<Id>,
+
     /// HACK: windows have low priority on dragging.
     /// This is so that if you drag a slider in a window,
     /// the slider will steal the drag away from the window.
@@ -103,6 +106,7 @@ impl Interaction {
     }
 
     fn begin_frame(&mut self, prev_input: &crate::input::InputState) {
+        self.kb_focus_id_previous_frame = self.kb_focus_id;
         self.click_interest = false;
         self.drag_interest = false;
 
@@ -143,6 +147,11 @@ impl Memory {
         self.areas.layer_id_at(pos, resize_interact_radius_side)
     }
 
+    /// True if the given widget had keyboard focus last frame, but not this one.
+    pub fn lost_kb_focus(&self, id: Id) -> bool {
+        self.interaction.kb_focus_id_previous_frame == Some(id) && !self.has_kb_focus(id)
+    }
+
     pub fn has_kb_focus(&self, id: Id) -> bool {
         self.interaction.kb_focus_id == Some(id)
     }

egui/src/types.rs

@@ -81,18 +81,36 @@ pub struct Response {
 
     /// This widget has the keyboard focus (i.e. is receiving key pressed)
     pub has_kb_focus: bool,
+
+    /// The widget had keyboard focus and lost it,
+    /// perhaps because the user pressed enter.
+    /// This is often a signal to the user to the application
+    /// to make use of the contents of the text field.
+    pub lost_kb_focus: bool,
 }
 
 impl std::fmt::Debug for Response {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        let Self {
+            ctx: _,
+            rect,
+            sense,
+            hovered,
+            clicked,
+            double_clicked,
+            active,
+            has_kb_focus,
+            lost_kb_focus,
+        } = self;
         f.debug_struct("Response")
-            .field("rect", &self.rect)
-            .field("sense", &self.sense)
-            .field("hovered", &self.hovered)
-            .field("clicked", &self.clicked)
-            .field("double_clicked", &self.double_clicked)
-            .field("active", &self.active)
-            .field("has_kb_focus", &self.has_kb_focus)
+            .field("rect", rect)
+            .field("sense", sense)
+            .field("hovered", hovered)
+            .field("clicked", clicked)
+            .field("double_clicked", double_clicked)
+            .field("active", active)
+            .field("has_kb_focus", has_kb_focus)
+            .field("lost_kb_focus", lost_kb_focus)
             .finish()
     }
 }
@@ -133,6 +151,7 @@ impl Response {
             double_clicked: self.double_clicked || other.double_clicked,
             active: self.active || other.active,
             has_kb_focus: self.has_kb_focus || other.has_kb_focus,
+            lost_kb_focus: self.lost_kb_focus || other.lost_kb_focus,
         }
     }
 }

egui/src/widgets/text_edit.rs

@@ -16,8 +16,7 @@ pub(crate) struct State {
 /// # let mut ui = egui::Ui::__test();
 /// # let mut my_string = String::new();
 /// let response = ui.add(egui::TextEdit::new(&mut my_string).multiline(false));
-/// if response.has_kb_focus && ui.input().key_pressed(egui::Key::Enter) {
-///     ui.memory().stop_text_input();
+/// if response.lost_kb_focus {
 ///     // use my_string
 /// }
 /// ```
@@ -240,7 +239,11 @@ impl<'t> Widget for TextEdit<'t> {
             .unwrap_or_else(|| visuals.text_color());
         painter.galley(response.rect.min, galley, text_style, text_color);
         ui.memory().text_edit.insert(id, state);
-        response
+
+        Response {
+            lost_kb_focus: ui.memory().lost_kb_focus(id), // we may have lost it during the course of this function
+            ..response
+        }
     }
 }