Define a fast ViewportMap type

crates/egui/src/context.rs

@@ -59,13 +59,13 @@ struct Repaint {
     /// The current frame number.
     ///
     /// Incremented at the end of each frame.
-    viewports_frame_nr: HashMap<ViewportId, u64>,
+    viewports_frame_nr: ViewportMap<u64>,
 
     /// While positive, keep requesting repaints. Decrement at the start of each frame.
-    repaint_request: HashMap<ViewportId, u8>,
+    repaint_request: ViewportMap<u8>,
     request_repaint_callback: Option<Box<dyn Fn(RequestRepaintInfo) + Send + Sync>>,
 
-    requested_repaint_last_frame: HashMap<ViewportId, bool>,
+    requested_repaint_last_frame: ViewportMap<bool>,
 }
 
 impl Repaint {
@@ -154,23 +154,23 @@ struct ContextImpl {
 
     os: OperatingSystem,
 
-    input: HashMap<ViewportId, InputState>,
+    input: ViewportMap<InputState>,
 
     /// State that is collected during a frame and then cleared
-    frame_state: HashMap<ViewportId, FrameState>,
+    frame_state: ViewportMap<FrameState>,
 
     /// How deeply nested are we?
     viewport_stack: Vec<ViewportIdPair>,
 
     // The output of a frame:
-    graphics: HashMap<ViewportId, GraphicLayers>,
-    output: HashMap<ViewportId, PlatformOutput>,
+    graphics: ViewportMap<GraphicLayers>,
+    output: ViewportMap<PlatformOutput>,
 
     paint_stats: PaintStats,
 
     repaint: Repaint,
 
-    viewports: HashMap<ViewportId, Viewport>,
+    viewports: ViewportMap<Viewport>,
     viewport_commands: Vec<(ViewportId, ViewportCommand)>,
 
     is_desktop: bool,
@@ -178,11 +178,11 @@ struct ContextImpl {
 
     /// Written to during the frame.
     layer_rects_this_frame: ahash::HashMap<LayerId, Vec<(Id, Rect)>>,
-    layer_rects_this_viewports: HashMap<ViewportId, HashMap<LayerId, Vec<(Id, Rect)>>>,
+    layer_rects_this_viewports: ViewportMap<HashMap<LayerId, Vec<(Id, Rect)>>>,
 
     /// Read
     layer_rects_prev_frame: ahash::HashMap<LayerId, Vec<(Id, Rect)>>,
-    layer_rects_prev_viewports: HashMap<ViewportId, HashMap<LayerId, Vec<(Id, Rect)>>>,
+    layer_rects_prev_viewports: ViewportMap<HashMap<LayerId, Vec<(Id, Rect)>>>,
 
     #[cfg(feature = "accesskit")]
     is_accesskit_enabled: bool,

crates/egui/src/memory.rs

@@ -1,10 +1,11 @@
 #![warn(missing_docs)] // Let's keep this file well-documented.` to memory.rs
 
+use epaint::{emath::Rangef, vec2, Vec2};
+
 use crate::{
     area, window, EventFilter, Id, IdMap, InputState, LayerId, Pos2, Rect, Style, ViewportId,
+    ViewportMap,
 };
-use ahash::HashMap;
-use epaint::{emath::Rangef, vec2, Vec2};
 
 // ----------------------------------------------------------------------------
 
@@ -77,7 +78,7 @@ pub struct Memory {
     pub(crate) new_font_definitions: Option<epaint::text::FontDefinitions>,
 
     #[cfg_attr(feature = "persistence", serde(skip))]
-    pub(crate) interactions: HashMap<ViewportId, Interaction>,
+    pub(crate) interactions: ViewportMap<Interaction>,
 
     #[cfg_attr(feature = "persistence", serde(skip))]
     pub(crate) interaction: Interaction,
@@ -90,7 +91,7 @@ pub struct Memory {
     pub(crate) window_interaction: Option<window::WindowInteraction>,
 
     #[cfg_attr(feature = "persistence", serde(skip))]
-    pub(crate) window_interactions: HashMap<ViewportId, window::WindowInteraction>,
+    pub(crate) window_interactions: ViewportMap<window::WindowInteraction>,
 
     #[cfg_attr(feature = "persistence", serde(skip))]
     pub(crate) drag_value: crate::widgets::drag_value::MonoState,
@@ -99,7 +100,7 @@ pub struct Memory {
     pub(crate) areas: Areas,
 
     #[cfg_attr(feature = "persistence", serde(skip))]
-    pub(crate) viewports_areas: HashMap<ViewportId, Areas>,
+    pub(crate) viewports_areas: ViewportMap<Areas>,
 
     /// Which popup-window is open (if any)?
     /// Could be a combo box, color picker, menu etc.

crates/egui/src/viewport.rs

@@ -49,6 +49,11 @@ impl From<ViewportId> for Id {
     }
 }
 
+impl nohash_hasher::IsEnabled for ViewportId {}
+
+/// A fast hash map from [`ViewportId`] to `T`.
+pub type ViewportMap<T> = nohash_hasher::IntMap<ViewportId, T>;
+
 // ----------------------------------------------------------------------------
 
 /// This will deref to [`Self::this`].