Make has_focus reliable.

druid/src/contexts.rs

@@ -270,12 +270,7 @@ impl<'a> EventCtx<'a> {
     ///
     /// [`is_focused`]: struct.EventCtx.html#method.is_focused
     pub fn has_focus(&self) -> bool {
-        // The bloom filter we're checking can return false positives.
-        let is_child = self
-            .focus_widget
-            .map(|id| self.base_state.children.may_contain(&id))
-            .unwrap_or(false);
-        is_child || self.focus_widget == Some(self.widget_id())
+        self.base_state.has_focus
     }
 
     /// Request keyboard focus.
@@ -613,12 +608,7 @@ impl<'a, 'b: 'a> PaintCtx<'a, 'b> {
     /// [`is_focused`]: #method.is_focused
     /// [`EventCtx::is_focused`]: struct.EventCtx.html#method.is_focused
     pub fn has_focus(&self) -> bool {
-        // The bloom filter we're checking can return false positives.
-        let is_child = self
-            .focus_widget
-            .map(|id| self.base_state.children.may_contain(&id))
-            .unwrap_or(false);
-        is_child || self.focus_widget == Some(self.widget_id())
+        self.base_state.has_focus
     }
 
     /// Returns the currently visible [`Region`].

druid/src/core.rs

@@ -86,6 +86,10 @@ pub(crate) struct BaseState {
     /// Any descendant is active.
     has_active: bool,
 
+    /// In the focused path, starting from window and ending at the focused widget.
+    /// Descendants of the focused widget are not in the focused path.
+    pub(crate) has_focus: bool,
+
     /// Any descendant has requested an animation frame.
     pub(crate) request_anim: bool,
 
@@ -514,20 +518,28 @@ impl<T: Data, W: Widget<T>> WidgetPod<T, W> {
                 };
 
                 if let Some(change) = this_changed {
-                    let event = LifeCycle::FocusChanged(change);
-                    self.inner.lifecycle(ctx, &event, data, env);
+                    // Only send FocusChanged in case there's actual change
+                    if old != new {
+                        self.state.has_focus = change;
+                        let event = LifeCycle::FocusChanged(change);
+                        self.inner.lifecycle(ctx, &event, data, env);
+                    }
                     false
                 } else {
+                    self.state.has_focus = false;
                     // Recurse when the target widgets could be our descendants.
                     // The bloom filter we're checking can return false positives.
-                    old.map(|id| self.state.children.may_contain(&id))
-                        .or_else(|| new.map(|id| self.state.children.may_contain(&id)))
-                        .unwrap_or(false)
+                    match (old, new) {
+                        (Some(old), _) if self.state.children.may_contain(old) => true,
+                        (_, Some(new)) if self.state.children.may_contain(new) => true,
+                        _ => false,
+                    }
                 }
             }
             LifeCycle::FocusChanged(_) => {
-                self.state.request_focus = None;
-                true
+                // We are a descendant of a widget that has/had focus.
+                // Descendants don't inherit focus, so don't recurse.
+                false
             }
             #[cfg(test)]
             LifeCycle::DebugRequestState { widget, state_cell } => {
@@ -624,6 +636,7 @@ impl BaseState {
             needs_layout: false,
             is_active: false,
             has_active: false,
+            has_focus: false,
             request_anim: false,
             request_timer: false,
             request_focus: None,
@@ -640,6 +653,7 @@ impl BaseState {
         self.request_anim |= child_state.request_anim;
         self.request_timer |= child_state.request_timer;
         self.has_active |= child_state.has_active;
+        self.has_focus |= child_state.has_focus;
         self.children_changed |= child_state.children_changed;
         self.request_focus = self.request_focus.or(child_state.request_focus);
     }

druid/src/window.rs

@@ -328,22 +328,37 @@ impl<T: Data> Window<T> {
         match focus {
             FocusChange::Resign => None,
             FocusChange::Focus(id) => Some(id),
-            FocusChange::Next => self
-                .focus
-                .and_then(|id| self.focus_chain().iter().position(|i| i == &id))
-                .map(|idx| {
-                    let next_idx = (idx + 1) % self.focus_chain().len();
-                    self.focus_chain()[next_idx]
-                }),
-            FocusChange::Previous => self
-                .focus
-                .and_then(|id| self.focus_chain().iter().position(|i| i == &id))
+            FocusChange::Next => self.widget_from_focus_chain(true),
+            FocusChange::Previous => self.widget_from_focus_chain(false),
+        }
+    }
+
+    fn widget_from_focus_chain(&self, forward: bool) -> Option<WidgetId> {
+        self.focus.and_then(|focus| {
+            self.focus_chain()
+                .iter()
+                // Find where the focused widget is in the focus chain
+                .position(|id| id == &focus)
                 .map(|idx| {
+                    // Return the id that's next to it in the focus chain
                     let len = self.focus_chain().len();
-                    let prev_idx = (idx + len - 1) % len;
-                    self.focus_chain()[prev_idx]
-                }),
-        }
+                    let new_idx = if forward {
+                        (idx + 1) % len
+                    } else {
+                        (idx + len - 1) % len
+                    };
+                    self.focus_chain()[new_idx]
+                })
+                .or_else(|| {
+                    // If the currently focused widget isn't in the focus chain,
+                    // then we'll just return the first/last entry of the chain, if any.
+                    if forward {
+                        self.focus_chain().first().copied()
+                    } else {
+                        self.focus_chain().last().copied()
+                    }
+                })
+        })
     }
 }