Added hover support to OverlayLayer

Cargo.lock

@@ -833,6 +833,7 @@ dependencies = [
  "kludgine",
  "palette",
  "pollster",
+ "rand",
  "tracing",
  "tracing-subscriber",
  "unicode-segmentation",
@@ -1711,6 +1712,12 @@ version = "0.3.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "22686f4785f02a4fcc856d3b3bb19bf6c8160d103f7a99cc258bddd0251dc7f2"
 
+[[package]]
+name = "ppv-lite86"
+version = "0.2.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b40af805b3121feab8a3c29f04d8ad262fa8e0561883e7653e024ae4479e6de"
+
 [[package]]
 name = "presser"
 version = "0.3.1"
@@ -1809,6 +1816,18 @@ version = "0.8.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "34af8d1a0e25924bc5b7c43c079c942339d8f0a8b57c39049bef581b46327404"
 dependencies = [
+ "libc",
+ "rand_chacha",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
+dependencies = [
+ "ppv-lite86",
  "rand_core",
 ]
 
@@ -1817,6 +1836,9 @@ name = "rand_core"
 version = "0.6.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ec0be4795e2f6a28069bec0b5ff3e2ac9bafc99e6a9a7dc3547996c5c816922c"
+dependencies = [
+ "getrandom",
+]
 
 [[package]]
 name = "range-alloc"

Cargo.toml

@@ -48,6 +48,7 @@ opt-level = 2
 
 [dev-dependencies]
 pollster = "0.3.0"
+rand = "0.8.5"
 
 [profile.release]
 debug = true

examples/overlays.rs

@@ -1,65 +1,60 @@
+use std::panic::UnwindSafe;
+
 use gooey::widget::{MakeWidget, MakeWidgetWithId, WidgetTag};
-use gooey::widgets::layers::OverlayLayer;
+use gooey::widgets::layers::{OverlayBuilder, OverlayLayer};
 use gooey::Run;
+use kludgine::Color;
+use rand::{thread_rng, Rng};
 
 fn main() -> gooey::Result {
     let overlay = OverlayLayer::default();
 
-    test_widget(&overlay)
+    test_widget(&overlay, true)
         .centered()
         .and(overlay)
         .into_layers()
         .run()
 }
 
-fn test_widget(overlay: &OverlayLayer) -> impl MakeWidget {
+fn test_widget(overlay: &OverlayLayer, is_root: bool) -> impl MakeWidget {
     let (my_tag, my_id) = WidgetTag::new();
-    let right = "Right".into_button().on_click({
+    let right = show_overlay_button("Right", overlay, move |overlay| overlay.right_of(my_id));
-        let overlay = overlay.clone();
+    let left = show_overlay_button("Left", overlay, move |overlay| overlay.left_of(my_id));
-        move |()| {
+    let up = show_overlay_button("Up", overlay, move |overlay| overlay.above(my_id));
-            overlay
+    let down = show_overlay_button("Down", overlay, move |overlay| overlay.below(my_id));
-                .build_overlay(test_widget(&overlay))
-                .right_of(my_id)
-                .show()
-                .forget();
-        }
-    });
-    let left = "Left".into_button().on_click({
-        let overlay = overlay.clone();
-        move |()| {
-            overlay
-                .build_overlay(test_widget(&overlay))
-                .left_of(my_id)
-                .show()
-                .forget();
-        }
-    });
-    let up = "Up".into_button().on_click({
-        let overlay = overlay.clone();
-        move |()| {
-            overlay
-                .build_overlay(test_widget(&overlay))
-                .above(my_id)
-                .show()
-                .forget();
-        }
-    });
-    let down = "Down".into_button().on_click({
-        let overlay = overlay.clone();
-        move |()| {
-            overlay
-                .build_overlay(test_widget(&overlay))
-                .below(my_id)
-                .show()
-                .forget();
-        }
-    });
 
-    up.centered()
+    let mut buttons = up
+        .centered()
         .and(left.and(right).into_columns())
         .and(down.centered())
         .into_rows()
-        .contain()
+        .contain();
-        .pad()
+
-        .make_with_id(my_tag)
+    if !is_root {
+        buttons = buttons.background_color(Color::new(
+            thread_rng().gen(),
+            thread_rng().gen(),
+            thread_rng().gen(),
+            255,
+        ))
+    }
+
+    buttons.pad().make_with_id(my_tag)
+}
+
+fn show_overlay_button(
+    label: &str,
+    overlay: &OverlayLayer,
+    direction_func: impl for<'a> Fn(OverlayBuilder<'a>) -> OverlayBuilder<'a>
+        + Send
+        + UnwindSafe
+        + 'static,
+) -> impl MakeWidget {
+    let overlay = overlay.clone();
+    label.into_button().on_click(move |()| {
+        direction_func(overlay.build_overlay(test_widget(&overlay, false)))
+            .hide_on_unhover()
+            .show()
+            .forget();
+    })
 }

src/context.rs

@@ -170,7 +170,13 @@ impl<'context, 'window> EventContext<'context, 'window> {
         let mut cursor = None;
         for hover in changes.hovered.into_iter().rev() {
             let mut context = self.for_other(&hover);
-            let widget_cursor = hover.lock().as_widget().hover(location, &mut context);
+            let Some(last_layout) = context.last_layout() else {
+                continue;
+            };
+            let widget_cursor = hover
+                .lock()
+                .as_widget()
+                .hover(location - last_layout.origin, &mut context);
 
             if cursor.is_none() {
                 cursor = widget_cursor;
@@ -330,7 +336,7 @@ impl<'context, 'window> EventContext<'context, 'window> {
                 let relative = location - widget_layout.origin;
 
                 if widget_context.hit_test(relative) {
-                    widget_context.hover(relative);
+                    widget_context.hover(location);
                     drop(widget_context);
                     self.cursor.widget = Some(widget.id());
                     break;

src/value.rs

@@ -536,6 +536,7 @@ impl<T> Dynamic<T> {
         DynamicGuard {
             guard: self.0.state().expect("deadlocked"),
             accessed_mut: false,
+            prevent_notifications: false,
         }
     }
 
@@ -1100,6 +1101,7 @@ impl<T> DerefMut for GenerationalValue<T> {
 pub struct DynamicGuard<'a, T> {
     guard: DynamicMutexGuard<'a, T>,
     accessed_mut: bool,
+    prevent_notifications: bool,
 }
 
 impl<T> DynamicGuard<'_, T> {
@@ -1111,6 +1113,12 @@ impl<T> DynamicGuard<'_, T> {
     pub fn generation(&self) -> Generation {
         self.guard.wrapped.generation
     }
+
+    /// Prevent any access through [`DerefMut`] from triggering change
+    /// notifications.
+    pub fn prevent_notifications(&mut self) {
+        self.prevent_notifications = true;
+    }
 }
 
 impl<'a, T> Deref for DynamicGuard<'a, T> {
@@ -1130,7 +1138,7 @@ impl<'a, T> DerefMut for DynamicGuard<'a, T> {
 
 impl<T> Drop for DynamicGuard<'_, T> {
     fn drop(&mut self) {
-        if self.accessed_mut {
+        if self.accessed_mut && !self.prevent_notifications {
             let mut callbacks = Some(self.guard.note_changed());
             run_in_bg(move || drop(callbacks.take()));
         }

src/widgets/layers.rs

@@ -9,7 +9,7 @@ use kludgine::figures::units::{Px, UPx};
 use kludgine::figures::{IntoSigned, IntoUnsigned, Point, Rect, Size, Zero};
 
 use crate::context::{AsEventContext, EventContext, GraphicsContext, LayoutContext};
-use crate::value::{Dynamic, Generation, IntoValue, Value};
+use crate::value::{Dynamic, DynamicGuard, Generation, IntoValue, Value};
 use crate::widget::{
     Children, MakeWidget, ManagedWidget, OnceCallback, Widget, WidgetId, WidgetRef,
 };
@@ -194,8 +194,7 @@ impl OverlayLayer {
 
 impl Widget for OverlayLayer {
     fn redraw(&mut self, context: &mut GraphicsContext<'_, '_, '_, '_, '_>) {
-        let mut guard = self.state.lock();
+        let state = self.state.lock();
-        let state = &mut *guard;
 
         for child in &state.overlays {
             let WidgetRef::Mounted(mounted) = &child.widget else {
@@ -211,8 +210,8 @@ impl Widget for OverlayLayer {
         available_space: Size<ConstraintLimit>,
         context: &mut LayoutContext<'_, '_, '_, '_, '_>,
     ) -> Size<UPx> {
-        let mut guard = self.state.lock();
+        let mut state = self.state.lock();
-        let state = &mut *guard;
+        state.prevent_notifications();
 
         let available_space = available_space.map(ConstraintLimit::max);
 
@@ -237,7 +236,7 @@ impl Widget for OverlayLayer {
             context.set_child_layout(&widget, layout);
         }
 
-        drop(guard);
+        drop(state);
 
         // Now that we're done mutating state, we can register for invalidation
         // tracking.
@@ -249,15 +248,120 @@ impl Widget for OverlayLayer {
         // when shown.
         Size::ZERO
     }
+
+    fn hit_test(&mut self, location: Point<Px>, context: &mut EventContext<'_, '_>) -> bool {
+        let state = self.state.lock();
+        if let Some(index) = state.test_point(location, false, context) {
+            index > 0
+        } else {
+            !(state.overlays.is_empty() || state.point_is_in_root_relative(location, context))
+        }
+    }
+
+    fn hover(
+        &mut self,
+        location: Point<Px>,
+        context: &mut EventContext<'_, '_>,
+    ) -> Option<kludgine::app::winit::window::CursorIcon> {
+        let mut state = self.state.lock();
+
+        let hovering = state.test_point(location, true, context);
+        if let Some(hovering) = hovering {
+            let should_remove = state.hovering > Some(hovering);
+            state.hovering = Some(hovering);
+            if should_remove {
+                remove_children_after(state, hovering);
+            }
+        } else {
+            state.hovering = None;
+        }
+
+        None
+    }
+
+    fn unhover(&mut self, _context: &mut EventContext<'_, '_>) {
+        let mut state = self.state.lock();
+        state.hovering = None;
+
+        let mut remove_starting_at = None;
+        for (index, overlay) in state.overlays.iter().enumerate() {
+            if overlay.requires_hover {
+                remove_starting_at = Some(index);
+                break;
+            }
+        }
+
+        if let Some(remove_starting_at) = remove_starting_at {
+            remove_children_after(state, remove_starting_at);
+        }
+    }
 }
 
 #[derive(Debug, Eq, PartialEq, Default)]
 struct OverlayState {
     overlays: OrderedLots<OverlayLayout>,
     new_overlays: usize,
+    hovering: Option<usize>,
+}
+
+fn remove_children_after(mut state: DynamicGuard<'_, OverlayState>, remove_starting_at: usize) {
+    let mut removed = Vec::with_capacity(state.overlays.len() - remove_starting_at);
+    while remove_starting_at < state.overlays.len() && !state.overlays.is_empty() {
+        removed.push(state.overlays.pop());
+        state.new_overlays = state.new_overlays.saturating_sub(1);
+    }
+    drop(state);
+    // We delay dropping the removed widgets, as they may contain a
+    // reference to this OverlayLayer.
+    drop(removed);
 }
 
 impl OverlayState {
+    fn test_point(
+        &self,
+        location: Point<Px>,
+        check_original_relative: bool,
+        context: &mut EventContext<'_, '_>,
+    ) -> Option<usize> {
+        for (index, overlay) in self.overlays.iter().enumerate() {
+            if overlay.requires_hover
+                && !overlay
+                    .layout
+                    .map_or(false, |check| !check.contains(location))
+            {
+                return Some(index + 1);
+            }
+        }
+
+        if check_original_relative
+            && !self.overlays.is_empty()
+            && self.point_is_in_root_relative(location, context)
+        {
+            Some(0)
+        } else {
+            None
+        }
+    }
+
+    fn point_is_in_root_relative(
+        &self,
+        location: Point<Px>,
+        context: &mut EventContext<'_, '_>,
+    ) -> bool {
+        if let Some(relative_to) = self
+            .overlays
+            .get_by_index(0)
+            .and_then(|overlay| overlay.relative_to)
+            .and_then(|relative_to| context.widget.for_other(&relative_to))
+            .and_then(|c| c.widget().last_layout())
+        {
+            if !relative_to.contains(location) {
+                return true;
+            }
+        }
+        false
+    }
+
     fn process_new_overlays(&mut self, context: &mut EventContext<'_, '_>) {
         while self.new_overlays > 0 {
             let new_index = self.overlays.len() - self.new_overlays;