Move all crates to a top-level crates folder

Co-Authored-By: Max Brunsfeld <maxbrunsfeld@gmail.com>

crates/gpui/src/elements/event_handler.rs

@@ -0,0 +1,91 @@
+use pathfinder_geometry::rect::RectF;
+use serde_json::json;
+
+use crate::{
+    geometry::vector::Vector2F, DebugContext, Element, ElementBox, Event, EventContext,
+    LayoutContext, PaintContext, SizeConstraint,
+};
+
+pub struct EventHandler {
+    child: ElementBox,
+    mouse_down: Option<Box<dyn FnMut(&mut EventContext) -> bool>>,
+}
+
+impl EventHandler {
+    pub fn new(child: ElementBox) -> Self {
+        Self {
+            child,
+            mouse_down: None,
+        }
+    }
+
+    pub fn on_mouse_down<F>(mut self, callback: F) -> Self
+    where
+        F: 'static + FnMut(&mut EventContext) -> bool,
+    {
+        self.mouse_down = Some(Box::new(callback));
+        self
+    }
+}
+
+impl Element for EventHandler {
+    type LayoutState = ();
+    type PaintState = ();
+
+    fn layout(
+        &mut self,
+        constraint: SizeConstraint,
+        cx: &mut LayoutContext,
+    ) -> (Vector2F, Self::LayoutState) {
+        let size = self.child.layout(constraint, cx);
+        (size, ())
+    }
+
+    fn paint(
+        &mut self,
+        bounds: RectF,
+        visible_bounds: RectF,
+        _: &mut Self::LayoutState,
+        cx: &mut PaintContext,
+    ) -> Self::PaintState {
+        self.child.paint(bounds.origin(), visible_bounds, cx);
+    }
+
+    fn dispatch_event(
+        &mut self,
+        event: &Event,
+        bounds: RectF,
+        _: &mut Self::LayoutState,
+        _: &mut Self::PaintState,
+        cx: &mut EventContext,
+    ) -> bool {
+        if self.child.dispatch_event(event, cx) {
+            true
+        } else {
+            match event {
+                Event::LeftMouseDown { position, .. } => {
+                    if let Some(callback) = self.mouse_down.as_mut() {
+                        if bounds.contains_point(*position) {
+                            return callback(cx);
+                        }
+                    }
+                    false
+                }
+                _ => false,
+            }
+        }
+    }
+
+    fn debug(
+        &self,
+        _: RectF,
+        _: &Self::LayoutState,
+        _: &Self::PaintState,
+        cx: &DebugContext,
+    ) -> serde_json::Value {
+        json!({
+            "type": "EventHandler",
+            "child": self.child.debug(cx),
+        })
+    }
+}