Allow hovered and clicked mouse regions to be tracked in the presenter

crates/gpui/src/gpui.rs

@@ -16,7 +16,7 @@ pub mod fonts;
 pub mod geometry;
 mod presenter;
 mod scene;
-pub use scene::{Border, CursorRegion, Quad, Scene};
+pub use scene::{Border, CursorRegion, MouseRegion, MouseRegionId, Quad, Scene};
 pub mod text_layout;
 pub use text_layout::TextLayoutCache;
 mod util;

crates/gpui/src/presenter.rs

@@ -8,8 +8,9 @@ use crate::{
     scene::CursorRegion,
     text_layout::TextLayoutCache,
     Action, AnyModelHandle, AnyViewHandle, AnyWeakModelHandle, AssetCache, ElementBox,
-    ElementStateContext, Entity, FontSystem, ModelHandle, ReadModel, ReadView, Scene,
-    UpgradeModelHandle, UpgradeViewHandle, View, ViewHandle, WeakModelHandle, WeakViewHandle,
+    ElementStateContext, Entity, FontSystem, ModelHandle, MouseRegion, MouseRegionId, ReadModel,
+    ReadView, Scene, UpgradeModelHandle, UpgradeViewHandle, View, ViewHandle, WeakModelHandle,
+    WeakViewHandle,
 };
 use pathfinder_geometry::vector::{vec2f, Vector2F};
 use serde_json::json;
@@ -24,10 +25,13 @@ pub struct Presenter {
     pub(crate) rendered_views: HashMap<usize, ElementBox>,
     parents: HashMap<usize, usize>,
     cursor_regions: Vec<CursorRegion>,
+    mouse_regions: Vec<MouseRegion>,
     font_cache: Arc<FontCache>,
     text_layout_cache: TextLayoutCache,
     asset_cache: Arc<AssetCache>,
     last_mouse_moved_event: Option<Event>,
+    hovered_region_id: Option<MouseRegionId>,
+    clicked_region: Option<MouseRegion>,
     titlebar_height: f32,
 }
 
@@ -45,10 +49,13 @@ impl Presenter {
             rendered_views: cx.render_views(window_id, titlebar_height),
             parents: HashMap::new(),
             cursor_regions: Default::default(),
+            mouse_regions: Default::default(),
             font_cache,
             text_layout_cache,
             asset_cache,
             last_mouse_moved_event: None,
+            hovered_region_id: None,
+            clicked_region: None,
             titlebar_height,
         }
     }
@@ -122,6 +129,7 @@ impl Presenter {
             );
             self.text_layout_cache.finish_frame();
             self.cursor_regions = scene.cursor_regions();
+            self.mouse_regions = scene.mouse_regions();
 
             if cx.window_is_active(self.window_id) {
                 if let Some(event) = self.last_mouse_moved_event.clone() {
@@ -176,7 +184,30 @@ impl Presenter {
 
     pub fn dispatch_event(&mut self, event: Event, cx: &mut MutableAppContext) {
         if let Some(root_view_id) = cx.root_view_id(self.window_id) {
+            let mut unhovered_region = None;
+            let mut hovered_region = None;
+            let mut clicked_region = None;
+
             match event {
+                Event::LeftMouseDown { position, .. } => {
+                    for region in self.mouse_regions.iter().rev() {
+                        if region.bounds.contains_point(position) {
+                            self.clicked_region = Some(region.clone());
+                            break;
+                        }
+                    }
+                }
+                Event::LeftMouseUp {
+                    position,
+                    click_count,
+                    ..
+                } => {
+                    if let Some(region) = self.clicked_region.take() {
+                        if region.bounds.contains_point(position) {
+                            clicked_region = Some((region, position, click_count));
+                        }
+                    }
+                }
                 Event::MouseMoved {
                     position,
                     left_mouse_down,
@@ -192,6 +223,18 @@ impl Presenter {
                             }
                         }
                         cx.platform().set_cursor_style(style_to_assign);
+
+                        for region in self.mouse_regions.iter().rev() {
+                            if region.bounds.contains_point(position) {
+                                if hovered_region.is_none() {
+                                    hovered_region = Some(region.clone());
+                                }
+                            } else {
+                                if self.hovered_region_id == Some(region.id()) {
+                                    unhovered_region = Some(region.clone())
+                                }
+                            }
+                        }
                     }
                 }
                 Event::LeftMouseDragged { position } => {
@@ -203,7 +246,33 @@ impl Presenter {
                 _ => {}
             }
 
+            self.hovered_region_id = hovered_region.as_ref().map(MouseRegion::id);
+
             let mut event_cx = self.build_event_context(cx);
+            if let Some(unhovered_region) = unhovered_region {
+                if let Some(hover_callback) = unhovered_region.hover {
+                    event_cx.with_current_view(unhovered_region.view_id, |event_cx| {
+                        hover_callback(false, event_cx)
+                    })
+                }
+            }
+
+            if let Some(hovered_region) = hovered_region {
+                if let Some(hover_callback) = hovered_region.hover {
+                    event_cx.with_current_view(hovered_region.view_id, |event_cx| {
+                        hover_callback(true, event_cx)
+                    })
+                }
+            }
+
+            if let Some((clicked_region, position, click_count)) = clicked_region {
+                if let Some(click_callback) = clicked_region.click {
+                    event_cx.with_current_view(clicked_region.view_id, |event_cx| {
+                        click_callback(position, click_count, event_cx)
+                    })
+                }
+            }
+
             event_cx.dispatch_event(root_view_id, &event);
 
             let invalidated_views = event_cx.invalidated_views;
@@ -379,9 +448,8 @@ pub struct EventContext<'a> {
 impl<'a> EventContext<'a> {
     fn dispatch_event(&mut self, view_id: usize, event: &Event) -> bool {
         if let Some(mut element) = self.rendered_views.remove(&view_id) {
-            self.view_stack.push(view_id);
-            let result = element.dispatch_event(event, self);
-            self.view_stack.pop();
+            let result =
+                self.with_current_view(view_id, |this| element.dispatch_event(event, this));
             self.rendered_views.insert(view_id, element);
             result
         } else {
@@ -389,6 +457,16 @@ impl<'a> EventContext<'a> {
         }
     }
 
+    fn with_current_view<F, T>(&mut self, view_id: usize, f: F) -> T
+    where
+        F: FnOnce(&mut Self) -> T,
+    {
+        self.view_stack.push(view_id);
+        let result = f(self);
+        self.view_stack.pop();
+        result
+    }
+
     pub fn dispatch_any_action(&mut self, action: Box<dyn Action>) {
         self.dispatched_actions.push(DispatchDirective {
             path: self.view_stack.clone(),

crates/gpui/src/scene.rs

@@ -1,6 +1,6 @@
 use serde::Deserialize;
 use serde_json::json;
-use std::{borrow::Cow, sync::Arc};
+use std::{any::TypeId, borrow::Cow, rc::Rc, sync::Arc};
 
 use crate::{
     color::Color,
@@ -8,7 +8,7 @@ use crate::{
     geometry::{rect::RectF, vector::Vector2F},
     json::ToJson,
     platform::CursorStyle,
-    ImageData,
+    EventContext, ImageData,
 };
 
 pub struct Scene {
@@ -34,6 +34,7 @@ pub struct Layer {
     icons: Vec<Icon>,
     paths: Vec<Path>,
     cursor_regions: Vec<CursorRegion>,
+    mouse_regions: Vec<MouseRegion>,
 }
 
 #[derive(Copy, Clone)]
@@ -42,6 +43,23 @@ pub struct CursorRegion {
     pub style: CursorStyle,
 }
 
+#[derive(Clone)]
+pub struct MouseRegion {
+    pub view_id: usize,
+    pub tag: TypeId,
+    pub region_id: usize,
+    pub bounds: RectF,
+    pub hover: Option<Rc<dyn Fn(bool, &mut EventContext)>>,
+    pub click: Option<Rc<dyn Fn(Vector2F, usize, &mut EventContext)>>,
+}
+
+#[derive(Copy, Clone, Eq, PartialEq)]
+pub struct MouseRegionId {
+    pub view_id: usize,
+    pub tag: TypeId,
+    pub region_id: usize,
+}
+
 #[derive(Default, Debug)]
 pub struct Quad {
     pub bounds: RectF,
@@ -188,6 +206,13 @@ impl Scene {
             .collect()
     }
 
+    pub fn mouse_regions(&self) -> Vec<MouseRegion> {
+        self.layers()
+            .flat_map(|layer| &layer.mouse_regions)
+            .cloned()
+            .collect()
+    }
+
     pub fn push_stacking_context(&mut self, clip_bounds: Option<RectF>) {
         self.active_stacking_context_stack
             .push(self.stacking_contexts.len());
@@ -305,6 +330,7 @@ impl Layer {
             icons: Default::default(),
             paths: Default::default(),
             cursor_regions: Default::default(),
+            mouse_regions: Default::default(),
         }
     }
 
@@ -333,6 +359,17 @@ impl Layer {
         }
     }
 
+    fn push_mouse_region(&mut self, region: MouseRegion) {
+        if let Some(bounds) = region
+            .bounds
+            .intersection(self.clip_bounds.unwrap_or(region.bounds))
+        {
+            if can_draw(bounds) {
+                self.mouse_regions.push(region);
+            }
+        }
+    }
+
     fn push_underline(&mut self, underline: Underline) {
         if underline.width > 0. {
             self.underlines.push(underline);
@@ -493,6 +530,16 @@ impl ToJson for Border {
     }
 }
 
+impl MouseRegion {
+    pub fn id(&self) -> MouseRegionId {
+        MouseRegionId {
+            view_id: self.view_id,
+            tag: self.tag,
+            region_id: self.region_id,
+        }
+    }
+}
+
 fn can_draw(bounds: RectF) -> bool {
     let size = bounds.size();
     size.x() > 0. && size.y() > 0.