Propagate events to hidden widgets in Either

CHANGELOG.md

@@ -51,6 +51,7 @@ You can find its changes [documented below](#060---2020-06-01).
 - Widgets can specify a baseline, flex rows can align baselines ([#1295] by [@cmyr])
 - `TextBox::with_text_color` and `TextBox::set_text_color` ([#1320] by [@cmyr])
 - `Checkbox::set_text` to update the label. ([#1346] by [@finnerale])
+- `Event::should_propagate_to_hidden` and `Lifecycle::should_propagate_to_hidden` to determine whether an event should be sent to hidden widgets (e.g. in `Tabs` or `Either`). ([#1351] by [@andrewhickman])
 
 ### Changed
 
@@ -114,6 +115,7 @@ You can find its changes [documented below](#060---2020-06-01).
 - Fix `widget::Either` using the wrong paint insets ([#1299] by [@andrewhickman])
 - Various fixes to cross-platform menus ([#1306] by [@raphlinus])
 - Improve Windows 7 DXGI compatibility ([#1311] by [@raphlinus])
+- Fixed `Either` not passing events to its hidden child correctly. ([#1351] by [@andrewhickman])
 - Don't drop events while showing file dialogs ([#1302], [#1328] by [@jneem])
 
 ### Visual
@@ -520,6 +522,7 @@ Last release without a changelog :(
 [#1326]: https://github.com/linebender/druid/pull/1326
 [#1328]: https://github.com/linebender/druid/pull/1328
 [#1346]: https://github.com/linebender/druid/pull/1346
+[#1351]: https://github.com/linebender/druid/pull/1351
 
 [Unreleased]: https://github.com/linebender/druid/compare/v0.6.0...master
 [0.6.0]: https://github.com/linebender/druid/compare/v0.5.0...v0.6.0

druid/src/core.rs

@@ -550,21 +550,13 @@ impl<T: Data, W: Widget<T>> WidgetPod<T, W> {
         }
 
         // log if we seem not to be laid out when we should be
-        if self.state.layout_rect.is_none() {
-            match event {
-                Event::Internal(_) => (),
-                Event::Timer(_) => (),
-                Event::WindowConnected => (),
-                Event::WindowSize(_) => (),
-                _ => {
-                    log::warn!(
-                        "Widget '{}' received an event ({:?}) without having been laid out. \
-                        This likely indicates a missed call to set_layout_rect.",
-                        self.inner.type_name(),
-                        event,
-                    );
-                }
-            }
+        if self.state.layout_rect.is_none() && !event.should_propagate_to_hidden() {
+            log::warn!(
+                "Widget '{}' received an event ({:?}) without having been laid out. \
+                This likely indicates a missed call to set_layout_rect.",
+                self.inner.type_name(),
+                event,
+            );
         }
 
         // TODO: factor as much logic as possible into monomorphic functions.

druid/src/event.rs

@@ -300,6 +300,38 @@ impl Event {
             _ => Some(self.clone()),
         }
     }
+
+    /// Whether this event should be sent to widgets which are currently not visible
+    /// (for example the hidden tabs in a tabs widget).
+    pub fn should_propagate_to_hidden(&self) -> bool {
+        match self {
+            Event::WindowConnected
+            | Event::WindowSize(_)
+            | Event::Timer(_)
+            | Event::AnimFrame(_)
+            | Event::Command(_)
+            | Event::Internal(_) => true,
+            Event::MouseDown(_)
+            | Event::MouseUp(_)
+            | Event::MouseMove(_)
+            | Event::Wheel(_)
+            | Event::KeyDown(_)
+            | Event::KeyUp(_)
+            | Event::Paste(_)
+            | Event::Zoom(_) => false,
+        }
+    }
+}
+
+impl LifeCycle {
+    /// Whether this event should be sent to widgets which are currently not visible
+    /// (for example the hidden tabs in a tabs widget).
+    pub fn should_propagate_to_hidden(&self) -> bool {
+        match self {
+            LifeCycle::WidgetAdded | LifeCycle::Internal(_) => true,
+            LifeCycle::Size(_) | LifeCycle::HotChanged(_) | LifeCycle::FocusChanged(_) => false,
+        }
+    }
 }
 
 #[cfg(test)]

druid/src/widget/either.rs

@@ -46,19 +46,25 @@ impl<T> Either<T> {
 
 impl<T: Data> Widget<T> for Either<T> {
     fn event(&mut self, ctx: &mut EventCtx, event: &Event, data: &mut T, env: &Env) {
-        if self.current {
-            self.true_branch.event(ctx, event, data, env)
+        if event.should_propagate_to_hidden() {
+            self.true_branch.event(ctx, event, data, env);
+            self.false_branch.event(ctx, event, data, env);
         } else {
-            self.false_branch.event(ctx, event, data, env)
+            self.current_widget().event(ctx, event, data, env)
         }
     }
 
     fn lifecycle(&mut self, ctx: &mut LifeCycleCtx, event: &LifeCycle, data: &T, env: &Env) {
         if let LifeCycle::WidgetAdded = event {
             self.current = (self.closure)(data, env);
         }
-        self.true_branch.lifecycle(ctx, event, data, env);
-        self.false_branch.lifecycle(ctx, event, data, env);
+
+        if event.should_propagate_to_hidden() {
+            self.true_branch.lifecycle(ctx, event, data, env);
+            self.false_branch.lifecycle(ctx, event, data, env);
+        } else {
+            self.current_widget().lifecycle(ctx, event, data, env)
+        }
     }
 
     fn update(&mut self, ctx: &mut UpdateCtx, _old_data: &T, data: &T, env: &Env) {
@@ -67,34 +73,28 @@ impl<T: Data> Widget<T> for Either<T> {
             self.current = current;
             ctx.request_layout();
         }
-        if self.current {
-            self.true_branch.update(ctx, data, env);
-        } else {
-            self.false_branch.update(ctx, data, env);
-        }
+        self.current_widget().update(ctx, data, env)
     }
 
     fn layout(&mut self, ctx: &mut LayoutCtx, bc: &BoxConstraints, data: &T, env: &Env) -> Size {
-        if self.current {
-            let size = self.true_branch.layout(ctx, bc, data, env);
-            self.true_branch
-                .set_layout_rect(ctx, data, env, size.to_rect());
-            ctx.set_paint_insets(self.true_branch.paint_insets());
-            size
-        } else {
-            let size = self.false_branch.layout(ctx, bc, data, env);
-            self.false_branch
-                .set_layout_rect(ctx, data, env, size.to_rect());
-            ctx.set_paint_insets(self.false_branch.paint_insets());
-            size
-        }
+        let current_widget = self.current_widget();
+        let size = current_widget.layout(ctx, bc, data, env);
+        current_widget.set_layout_rect(ctx, data, env, size.to_rect());
+        ctx.set_paint_insets(current_widget.paint_insets());
+        size
     }
 
     fn paint(&mut self, ctx: &mut PaintCtx, data: &T, env: &Env) {
+        self.current_widget().paint(ctx, data, env)
+    }
+}
+
+impl<T> Either<T> {
+    fn current_widget(&mut self) -> &mut WidgetPod<T, Box<dyn Widget<T>>> {
         if self.current {
-            self.true_branch.paint_raw(ctx, data, env);
+            &mut self.true_branch
         } else {
-            self.false_branch.paint_raw(ctx, data, env);
+            &mut self.false_branch
         }
     }
 }

druid/src/widget/tabs.rs

@@ -550,37 +550,9 @@ impl<TP: TabsPolicy> TabsBody<TP> {
     }
 }
 
-/// Possibly should be moved to Event
-fn hidden_should_receive_event(evt: &Event) -> bool {
-    match evt {
-        Event::WindowConnected
-        | Event::WindowSize(_)
-        | Event::Timer(_)
-        | Event::AnimFrame(_)
-        | Event::Command(_)
-        | Event::Internal(_) => true,
-        Event::MouseDown(_)
-        | Event::MouseUp(_)
-        | Event::MouseMove(_)
-        | Event::Wheel(_)
-        | Event::KeyDown(_)
-        | Event::KeyUp(_)
-        | Event::Paste(_)
-        | Event::Zoom(_) => false,
-    }
-}
-
-/// Possibly should be moved to Lifecycle.
-fn hidden_should_receive_lifecycle(lc: &LifeCycle) -> bool {
-    match lc {
-        LifeCycle::WidgetAdded | LifeCycle::Internal(_) => true,
-        LifeCycle::Size(_) | LifeCycle::HotChanged(_) | LifeCycle::FocusChanged(_) => false,
-    }
-}
-
 impl<TP: TabsPolicy> Widget<TabsState<TP>> for TabsBody<TP> {
     fn event(&mut self, ctx: &mut EventCtx, event: &Event, data: &mut TabsState<TP>, env: &Env) {
-        if hidden_should_receive_event(event) {
+        if event.should_propagate_to_hidden() {
             for child in self.child_pods() {
                 child.event(ctx, event, &mut data.inner, env);
             }
@@ -612,7 +584,7 @@ impl<TP: TabsPolicy> Widget<TabsState<TP>> for TabsBody<TP> {
             ctx.request_layout();
         }
 
-        if hidden_should_receive_lifecycle(event) {
+        if event.should_propagate_to_hidden() {
             for child in self.child_pods() {
                 child.lifecycle(ctx, event, &data.inner, env);
             }