WIP

crates/gpui2/src/app.rs

@@ -11,14 +11,15 @@ use refineable::Refineable;
 use smallvec::SmallVec;
 #[cfg(any(test, feature = "test-support"))]
 pub use test_context::*;
+use uuid::Uuid;
 
 use crate::{
     current_platform, image_cache::ImageCache, Action, AnyBox, AnyView, AnyWindowHandle,
     AppMetadata, AssetSource, ClipboardItem, Context, DispatchPhase, DisplayId, Entity, Executor,
     FocusEvent, FocusHandle, FocusId, KeyBinding, Keymap, LayoutId, MainThread, MainThreadOnly,
-    Pixels, Platform, Point, Render, SharedString, SubscriberSet, Subscription, SvgRenderer, Task,
-    TextStyle, TextStyleRefinement, TextSystem, View, ViewContext, Window, WindowContext,
-    WindowHandle, WindowId,
+    Pixels, Platform, PlatformDisplay, Point, Render, SharedString, SubscriberSet, Subscription,
+    SvgRenderer, Task, TextStyle, TextStyleRefinement, TextSystem, View, ViewContext, Window,
+    WindowContext, WindowHandle, WindowId,
 };
 use anyhow::{anyhow, Result};
 use collections::{HashMap, HashSet, VecDeque};
@@ -32,6 +33,7 @@ use std::{
     mem,
     ops::{Deref, DerefMut},
     path::PathBuf,
+    rc::Rc,
     sync::{atomic::Ordering::SeqCst, Arc, Weak},
     time::Duration,
 };
@@ -847,6 +849,13 @@ where
     pub fn path_for_auxiliary_executable(&self, name: &str) -> Result<PathBuf> {
         self.platform().path_for_auxiliary_executable(name)
     }
+
+    pub fn display_for_uuid(&self, uuid: Uuid) -> Option<Rc<dyn PlatformDisplay>> {
+        self.platform()
+            .displays()
+            .into_iter()
+            .find(|display| display.uuid().ok() == Some(uuid))
+    }
 }
 
 impl MainThread<AppContext> {

crates/gpui2/src/platform.rs

@@ -28,6 +28,7 @@ use std::{
     str::FromStr,
     sync::Arc,
 };
+use uuid::Uuid;
 
 pub use keystroke::*;
 #[cfg(target_os = "macos")]
@@ -106,6 +107,9 @@ pub(crate) trait Platform: 'static {
 
 pub trait PlatformDisplay: Send + Sync + Debug {
     fn id(&self) -> DisplayId;
+    /// Returns a stable identifier for this display that can be persisted and used
+    /// across system restarts.
+    fn uuid(&self) -> Result<Uuid>;
     fn as_any(&self) -> &dyn Any;
     fn bounds(&self) -> Bounds<GlobalPixels>;
 }

crates/gpui2/src/platform/mac/display.rs

@@ -1,9 +1,12 @@
 use crate::{point, size, Bounds, DisplayId, GlobalPixels, PlatformDisplay};
+use anyhow::Result;
+use core_foundation::uuid::{CFUUIDGetUUIDBytes, CFUUIDRef};
 use core_graphics::{
     display::{CGDirectDisplayID, CGDisplayBounds, CGGetActiveDisplayList},
     geometry::{CGPoint, CGRect, CGSize},
 };
 use std::any::Any;
+use uuid::Uuid;
 
 #[derive(Debug)]
 pub struct MacDisplay(pub(crate) CGDirectDisplayID);
@@ -11,17 +14,23 @@ pub struct MacDisplay(pub(crate) CGDirectDisplayID);
 unsafe impl Send for MacDisplay {}
 
 impl MacDisplay {
-    /// Get the screen with the given UUID.
+    /// Get the screen with the given [DisplayId].
     pub fn find_by_id(id: DisplayId) -> Option<Self> {
         Self::all().find(|screen| screen.id() == id)
     }
 
+    /// Get the screen with the given persistent [Uuid].
+    pub fn find_by_uuid(uuid: Uuid) -> Option<Self> {
+        Self::all().find(|screen| screen.uuid().ok() == Some(uuid))
+    }
+
     /// Get the primary screen - the one with the menu bar, and whose bottom left
     /// corner is at the origin of the AppKit coordinate system.
     pub fn primary() -> Self {
         Self::all().next().unwrap()
     }
 
+    /// Obtains an iterator over all currently active system displays.
     pub fn all() -> impl Iterator<Item = Self> {
         unsafe {
             let mut display_count: u32 = 0;
@@ -40,6 +49,11 @@ impl MacDisplay {
     }
 }
 
+#[link(name = "ApplicationServices", kind = "framework")]
+extern "C" {
+    pub fn CGDisplayCreateUUIDFromDisplayID(display: CGDirectDisplayID) -> CFUUIDRef;
+}
+
 /// Convert the given rectangle from CoreGraphics' native coordinate space to GPUI's coordinate space.
 ///
 /// CoreGraphics' coordinate space has its origin at the bottom left of the primary screen,
@@ -88,6 +102,34 @@ impl PlatformDisplay for MacDisplay {
         DisplayId(self.0)
     }
 
+    fn uuid(&self) -> Result<Uuid> {
+        let cfuuid = unsafe { CGDisplayCreateUUIDFromDisplayID(self.0 as CGDirectDisplayID) };
+        anyhow::ensure!(
+            !cfuuid.is_null(),
+            "AppKit returned a null from CGDisplayCreateUUIDFromDisplayID"
+        );
+
+        let bytes = unsafe { CFUUIDGetUUIDBytes(cfuuid) };
+        Ok(Uuid::from_bytes([
+            bytes.byte0,
+            bytes.byte1,
+            bytes.byte2,
+            bytes.byte3,
+            bytes.byte4,
+            bytes.byte5,
+            bytes.byte6,
+            bytes.byte7,
+            bytes.byte8,
+            bytes.byte9,
+            bytes.byte10,
+            bytes.byte11,
+            bytes.byte12,
+            bytes.byte13,
+            bytes.byte14,
+            bytes.byte15,
+        ]))
+    }
+
     fn as_any(&self) -> &dyn Any {
         self
     }