Add support for reporting cursor selection changes.

egui/src/context.rs

@@ -194,6 +194,7 @@ impl CtxRef {
             is_pointer_button_down_on: false,
             interact_pointer_pos: None,
             changed: false,         // must be set by the widget itself
+            has_widget_info: false, // must be set by the widget itself
         };
 
         if !enabled || !sense.focusable || !layer_id.allow_interaction() {

egui/src/data/output.rs

@@ -43,6 +43,7 @@ impl Output {
                 OutputEvent::Clicked(widget_info)
                 | OutputEvent::DoubleClicked(widget_info)
                 | OutputEvent::FocusGained(widget_info)
+                | OutputEvent::TextSelectionChanged(widget_info)
                 | OutputEvent::ValueChanged(widget_info) => {
                     return widget_info.description();
                 }
@@ -213,6 +214,8 @@ pub enum OutputEvent {
     DoubleClicked(WidgetInfo),
     /// A widget gained keyboard focus (by tab key).
     FocusGained(WidgetInfo),
+    // Text selection was updated.
+    TextSelectionChanged(WidgetInfo),
     // A widget's value changed.
     ValueChanged(WidgetInfo),
 }
@@ -223,6 +226,7 @@ impl std::fmt::Debug for OutputEvent {
             Self::Clicked(wi) => write!(f, "Clicked({:?})", wi),
             Self::DoubleClicked(wi) => write!(f, "DoubleClicked({:?})", wi),
             Self::FocusGained(wi) => write!(f, "FocusGained({:?})", wi),
+            Self::TextSelectionChanged(wi) => write!(f, "TextSelectionChanged({:?})", wi),
             Self::ValueChanged(wi) => write!(f, "ValueChanged({:?})", wi),
         }
     }
@@ -238,11 +242,15 @@ pub struct WidgetInfo {
     /// The contents of some editable text (for `TextEdit` fields).
     pub text_value: Option<String>,
     // The previous text value.
-    prev_text_value: Option<String>,
+    pub prev_text_value: Option<String>,
     /// The current value of checkboxes and radio buttons.
     pub selected: Option<bool>,
     /// The current value of sliders etc.
     pub value: Option<f64>,
+    // Location of primary cursor.
+    pub primary_cursor: Option<usize>,
+    // Location of secondary cursor.
+    pub secondary_cursor: Option<usize>,
 }
 
 impl std::fmt::Debug for WidgetInfo {
@@ -254,6 +262,8 @@ impl std::fmt::Debug for WidgetInfo {
             prev_text_value,
             selected,
             value,
+            primary_cursor,
+            secondary_cursor,
         } = self;
 
         let mut s = f.debug_struct("WidgetInfo");
@@ -275,6 +285,12 @@ impl std::fmt::Debug for WidgetInfo {
         if let Some(value) = value {
             s.field("value", value);
         }
+        if let Some(primary_cursor) = primary_cursor {
+            s.field("primary_cursor", primary_cursor);
+        }
+        if let Some(secondary_cursor) = secondary_cursor {
+            s.field("secondary_cursor", secondary_cursor);
+        }
 
         s.finish()
     }
@@ -289,6 +305,8 @@ impl WidgetInfo {
             prev_text_value: None,
             selected: None,
             value: None,
+            primary_cursor: None,
+            secondary_cursor: None,
         }
     }
 
@@ -336,6 +354,20 @@ impl WidgetInfo {
         }
     }
 
+    #[allow(clippy::needless_pass_by_value)]
+    pub fn text_selection_changed(
+        primary_cursor: usize,
+        secondary_cursor: usize,
+        text_value: impl ToString,
+    ) -> Self {
+        Self {
+            primary_cursor: Some(primary_cursor),
+            secondary_cursor: Some(secondary_cursor),
+            text_value: Some(text_value.to_string()),
+            ..Self::new(WidgetType::TextEdit)
+        }
+    }
+
     /// This can be used by a text-to-speech system to describe the widget.
     pub fn description(&self) -> String {
         let Self {
@@ -345,6 +377,8 @@ impl WidgetInfo {
             prev_text_value: _,
             selected,
             value,
+            primary_cursor: _,
+            secondary_cursor: _,
         } = self;
 
         // TODO: localization

egui/src/response.rs

@@ -65,6 +65,8 @@ pub struct Response {
     /// e.g. the slider was dragged, text was entered in a `TextEdit` etc.
     /// Always `false` for something like a `Button`.
     pub(crate) changed: bool,
+    /// Has a `WidgetInfo` but isn't covered by some other case (E.g. `changed`, `clicked`.)
+    pub(crate) has_widget_info: bool,
 }
 
 impl std::fmt::Debug for Response {
@@ -84,6 +86,7 @@ impl std::fmt::Debug for Response {
             is_pointer_button_down_on,
             interact_pointer_pos,
             changed,
+            has_widget_info,
         } = self;
         f.debug_struct("Response")
             .field("layer_id", layer_id)
@@ -99,6 +102,7 @@ impl std::fmt::Debug for Response {
             .field("is_pointer_button_down_on", is_pointer_button_down_on)
             .field("interact_pointer_pos", interact_pointer_pos)
             .field("changed", changed)
+            .field("has_widget_info", has_widget_info)
             .finish()
     }
 }
@@ -437,6 +441,13 @@ impl Response {
             Some(OutputEvent::FocusGained(make_info()))
         } else if self.changed {
             Some(OutputEvent::ValueChanged(make_info()))
+        } else if self.has_widget_info {
+            let info = make_info();
+            if info.primary_cursor.is_some() && info.secondary_cursor.is_some() {
+                Some(OutputEvent::TextSelectionChanged(info))
+            } else {
+                None
+            }
         } else {
             None
         };
@@ -479,6 +490,7 @@ impl Response {
                 || other.is_pointer_button_down_on,
             interact_pointer_pos: self.interact_pointer_pos.or(other.interact_pointer_pos),
             changed: self.changed || other.changed,
+            has_widget_info: self.has_widget_info || other.has_widget_info,
         }
     }
 }

egui/src/widgets/text_edit.rs

@@ -665,7 +665,18 @@ impl<'t> TextEdit<'t> {
 
         ui.memory().id_data.insert(id, state);
 
+        if response.changed {
             response.widget_info(|| WidgetInfo::text_edit(&*text, &*prev_text));
+        } else if let Some(text_cursor) = text_cursor {
+            response.has_widget_info = true;
+            response.widget_info(|| {
+                WidgetInfo::text_selection_changed(
+                    text_cursor.primary.ccursor.index,
+                    text_cursor.secondary.ccursor.index,
+                    &*text,
+                )
+            });
+        }
         response
     }
 }