Fix hover state when element is occluded

crates/gpui2/src/window.rs

@@ -12,7 +12,7 @@ use crate::{
     VisualContext, WeakView, WindowBounds, WindowOptions, SUBPIXEL_VARIANTS,
 };
 use anyhow::{anyhow, Context as _, Result};
-use collections::HashMap;
+use collections::{BTreeMap, HashMap};
 use derive_more::{Deref, DerefMut};
 use futures::{
     channel::{mpsc, oneshot},
@@ -39,8 +39,8 @@ use util::ResultExt;
 
 /// A global stacking order, which is created by stacking successive z-index values.
 /// Each z-index will always be interpreted in the context of its parent z-index.
-#[derive(Deref, DerefMut, Ord, PartialOrd, Eq, PartialEq, Clone, Default)]
-pub(crate) struct StackingOrder(pub(crate) SmallVec<[u32; 16]>);
+#[derive(Deref, DerefMut, Ord, PartialOrd, Eq, PartialEq, Clone, Default, Debug)]
+pub struct StackingOrder(pub(crate) SmallVec<[u32; 16]>);
 
 /// Represents the two different phases when dispatching events.
 #[derive(Default, Copy, Clone, Debug, Eq, PartialEq)]
@@ -243,7 +243,8 @@ pub(crate) struct Frame {
     pub(crate) dispatch_tree: DispatchTree,
     pub(crate) focus_listeners: Vec<AnyFocusListener>,
     pub(crate) scene_builder: SceneBuilder,
-    z_index_stack: StackingOrder,
+    pub(crate) depth_map: BTreeMap<StackingOrder, Bounds<Pixels>>,
+    pub(crate) z_index_stack: StackingOrder,
     content_mask_stack: Vec<ContentMask<Pixels>>,
     element_offset_stack: Vec<Point<Pixels>>,
 }
@@ -257,6 +258,7 @@ impl Frame {
             focus_listeners: Vec::new(),
             scene_builder: SceneBuilder::default(),
             z_index_stack: StackingOrder::default(),
+            depth_map: Default::default(),
             content_mask_stack: Vec::new(),
             element_offset_stack: Vec::new(),
         }
@@ -806,6 +808,32 @@ impl<'a> WindowContext<'a> {
         result
     }
 
+    /// Called during painting to track which z-index is on top at each pixel position
+    pub fn add_opaque_layer(&mut self, bounds: Bounds<Pixels>) {
+        let stacking_order = self.window.current_frame.z_index_stack.clone();
+        self.window
+            .current_frame
+            .depth_map
+            .insert(stacking_order, bounds);
+    }
+
+    /// Returns true if the top-most opaque layer painted over this point was part of the
+    /// same layer as the given stacking order.
+    pub fn was_top_layer(&self, point: &Point<Pixels>, level: &StackingOrder) -> bool {
+        for (stack, bounds) in self.window.previous_frame.depth_map.iter() {
+            if bounds.contains_point(point) {
+                return level.starts_with(stack) || stack.starts_with(level);
+            }
+        }
+
+        false
+    }
+
+    /// Called during painting to get the current stacking order.
+    pub fn stacking_order(&self) -> &StackingOrder {
+        &self.window.current_frame.z_index_stack
+    }
+
     /// Paint one or more drop shadows into the scene for the current frame at the current z-index.
     pub fn paint_shadows(
         &mut self,
@@ -1153,6 +1181,7 @@ impl<'a> WindowContext<'a> {
         frame.mouse_listeners.values_mut().for_each(Vec::clear);
         frame.focus_listeners.clear();
         frame.dispatch_tree.clear();
+        frame.depth_map.clear();
     }
 
     /// Dispatch a mouse or keyboard event on the window.