Add AsId and IdSalt (#8184)

## Related * https://github.com/emilk/egui/pull/5851 * https://github.com/emilk/egui/pull/7988 ## What We want to make it easier to understand the lineage of a `Id` (which is the parent `Id`, and the parent of that, etc?) As a first step of that, we want to clarify the different between a globally unique `Id`, and an `IdSalt` I also introduced the `AsId` and `AsIdSalt` traits, which are implemented of anything that implements `Hash` and `Debug`. The `Debug` half of that is unused here, but will later be used in `Debug` builds to produce a proper tree.
2026-06-26 14:49:06 -04:00 · 2026-05-22 15:19:55 +02:00
parent bea47a2ce7
commit 3888087dc5
14 changed files with 174 additions and 111 deletions
--- a/crates/egui/src/containers/collapsing_header.rs
+++ b/crates/egui/src/containers/collapsing_header.rs
@@ -1,9 +1,7 @@
-use std::hash::Hash;
-
 use crate::{
-    Context, Id, InnerResponse, NumExt as _, Rect, Response, Sense, Stroke, TextStyle,
-    TextWrapMode, Ui, UiBuilder, UiKind, UiStackInfo, WidgetInfo, WidgetText, WidgetType, emath,
-    epaint, pos2, remap, remap_clamp, vec2,
+    AsIdSalt, Context, Id, IdSalt, InnerResponse, NumExt as _, Rect, Response, Sense, Stroke,
+    TextStyle, TextWrapMode, Ui, UiBuilder, UiKind, UiStackInfo, WidgetInfo, WidgetText,
+    WidgetType, emath, epaint, pos2, remap, remap_clamp, vec2,
 };
 use emath::GuiRounding as _;
 use epaint::{Shape, StrokeKind};
@@ -371,7 +369,7 @@ pub struct CollapsingHeader {
    text: WidgetText,
    default_open: bool,
    open: Option<bool>,
-    id_salt: Id,
+    id_salt: IdSalt,
    enabled: bool,
    selectable: bool,
    selected: bool,
@@ -388,7 +386,7 @@ impl CollapsingHeader {
    /// you need to provide a unique id source with [`Self::id_salt`].
    pub fn new(text: impl Into<WidgetText>) -> Self {
        let text = text.into();
-        let id_salt = Id::new(text.text());
+        let id_salt = IdSalt::new(text.text());
        Self {
            text,
            default_open: false,
@@ -424,8 +422,8 @@ impl CollapsingHeader {
    /// Explicitly set the source of the [`Id`] of this widget, instead of using title label.
    /// This is useful if the title label is dynamic or not unique.
    #[inline]
-    pub fn id_salt(mut self, id_salt: impl Hash) -> Self {
-        self.id_salt = Id::new(id_salt);
+    pub fn id_salt(mut self, id_salt: impl AsIdSalt) -> Self {
+        self.id_salt = IdSalt::new(id_salt);
        self
    }

--- a/crates/egui/src/containers/combo_box.rs
+++ b/crates/egui/src/containers/combo_box.rs
@@ -1,9 +1,11 @@
 use epaint::Shape;

 use crate::{
-    Align2, Context, Id, InnerResponse, NumExt as _, Painter, Popup, PopupCloseBehavior, Rect,
-    Response, ScrollArea, Sense, Stroke, TextStyle, TextWrapMode, Ui, UiBuilder, Vec2, WidgetInfo,
-    WidgetText, WidgetType, epaint, style::StyleModifier, style::WidgetVisuals, vec2,
+    Align2, AsIdSalt, Context, Id, IdSalt, InnerResponse, NumExt as _, Painter, Popup,
+    PopupCloseBehavior, Rect, Response, ScrollArea, Sense, Stroke, TextStyle, TextWrapMode, Ui,
+    UiBuilder, Vec2, WidgetInfo, WidgetText, WidgetType, epaint,
+    style::{StyleModifier, WidgetVisuals},
+    vec2,
 };

 #[expect(unused_imports)] // Documentation
@@ -36,7 +38,7 @@ pub type IconPainter = Box<dyn FnOnce(&Ui, Rect, &WidgetVisuals, bool)>;
 /// ```
 #[must_use = "You should call .show*"]
 pub struct ComboBox {
-    id_salt: Id,
+    id_salt: IdSalt,
    label: Option<WidgetText>,
    selected_text: WidgetText,
    width: Option<f32>,
@@ -49,9 +51,9 @@ pub struct ComboBox {

 impl ComboBox {
    /// Create new [`ComboBox`] with id and label
-    pub fn new(id_salt: impl std::hash::Hash, label: impl Into<WidgetText>) -> Self {
+    pub fn new(id_salt: impl AsIdSalt, label: impl Into<WidgetText>) -> Self {
        Self {
-            id_salt: Id::new(id_salt),
+            id_salt: IdSalt::new(id_salt),
            label: Some(label.into()),
            selected_text: Default::default(),
            width: None,
@@ -67,7 +69,7 @@ impl ComboBox {
    pub fn from_label(label: impl Into<WidgetText>) -> Self {
        let label = label.into();
        Self {
-            id_salt: Id::new(label.text()),
+            id_salt: IdSalt::new(label.text()),
            label: Some(label),
            selected_text: Default::default(),
            width: None,
@@ -80,9 +82,9 @@ impl ComboBox {
    }

    /// Without label.
-    pub fn from_id_salt(id_salt: impl std::hash::Hash) -> Self {
+    pub fn from_id_salt(id_salt: impl AsIdSalt) -> Self {
        Self {
-            id_salt: Id::new(id_salt),
+            id_salt: IdSalt::new(id_salt),
            label: Default::default(),
            selected_text: Default::default(),
            width: None,
--- a/crates/egui/src/containers/resize.rs
+++ b/crates/egui/src/containers/resize.rs
@@ -1,6 +1,6 @@
 use crate::{
-    Align2, Color32, Context, CursorIcon, Id, NumExt as _, Rect, Response, Sense, Shape, Ui,
-    UiBuilder, UiKind, UiStackInfo, Vec2, Vec2b, pos2, vec2,
+    Align2, AsIdSalt, Color32, Context, CursorIcon, Id, IdSalt, NumExt as _, Rect, Response, Sense,
+    Shape, Ui, UiBuilder, UiKind, UiStackInfo, Vec2, Vec2b, pos2, vec2,
 };

 #[derive(Clone, Copy, Debug)]
@@ -41,7 +41,7 @@ impl State {
 #[must_use = "You should call .show()"]
 pub struct Resize {
    id: Option<Id>,
-    id_salt: Option<Id>,
+    id_salt: Option<IdSalt>,

    /// If false, we are no enabled
    resizable: Vec2b,
@@ -78,8 +78,8 @@ impl Resize {

    /// A source for the unique [`Id`], e.g. `.id_salt("second_resize_area")` or `.id_salt(loop_index)`.
    #[inline]
-    pub fn id_salt(mut self, id_salt: impl std::hash::Hash) -> Self {
-        self.id_salt = Some(Id::new(id_salt));
+    pub fn id_salt(mut self, id_salt: impl AsIdSalt) -> Self {
+        self.id_salt = Some(IdSalt::new(id_salt));
        self
    }

@@ -209,7 +209,7 @@ impl Resize {
    fn begin(&self, ui: &mut Ui) -> Prepared {
        let position = ui.available_rect_before_wrap().min;
        let id = self.id.unwrap_or_else(|| {
-            let id_salt = self.id_salt.unwrap_or_else(|| Id::new("resize"));
+            let id_salt = self.id_salt.unwrap_or_else(|| IdSalt::new("resize"));
            ui.make_persistent_id(id_salt)
        });

--- a/crates/egui/src/containers/scroll_area.rs
+++ b/crates/egui/src/containers/scroll_area.rs
@@ -8,9 +8,9 @@ use emath::GuiRounding as _;
 use epaint::{Color32, Direction, Margin, Shape};

 use crate::{
-    Context, CursorIcon, Id, NumExt as _, Pos2, Rangef, Rect, Response, Sense, Ui, UiBuilder,
-    UiKind, UiStackInfo, Vec2, Vec2b, WidgetInfo, emath, epaint, lerp, pass_state, pos2, remap,
-    remap_clamp,
+    AsIdSalt, Context, CursorIcon, Id, IdSalt, NumExt as _, Pos2, Rangef, Rect, Response, Sense,
+    Ui, UiBuilder, UiKind, UiStackInfo, Vec2, Vec2b, WidgetInfo, emath, epaint, lerp, pass_state,
+    pos2, remap, remap_clamp,
 };

 #[derive(Clone, Copy, Debug)]
@@ -344,7 +344,7 @@ pub struct ScrollArea {
    min_scrolled_size: Vec2,
    scroll_bar_visibility: ScrollBarVisibility,
    scroll_bar_rect: Option<Rect>,
-    id_salt: Option<Id>,
+    id_salt: Option<IdSalt>,
    offset_x: Option<f32>,
    offset_y: Option<f32>,
    on_hover_cursor: Option<CursorIcon>,
@@ -479,8 +479,8 @@ impl ScrollArea {

    /// A source for the unique [`Id`], e.g. `.id_salt("second_scroll_area")` or `.id_salt(loop_index)`.
    #[inline]
-    pub fn id_salt(mut self, id_salt: impl std::hash::Hash) -> Self {
-        self.id_salt = Some(Id::new(id_salt));
+    pub fn id_salt(mut self, id_salt: impl AsIdSalt) -> Self {
+        self.id_salt = Some(IdSalt::new(id_salt));
        self
    }

@@ -730,7 +730,7 @@ impl ScrollArea {

        let ctx = ui.ctx().clone();

-        let id_salt = id_salt.unwrap_or_else(|| Id::new("scroll_area"));
+        let id_salt = id_salt.unwrap_or_else(|| IdSalt::new("scroll_area"));
        let id = ui.make_persistent_id(id_salt);
        ctx.check_for_id_clash(
            id,
--- a/crates/egui/src/grid.rs
+++ b/crates/egui/src/grid.rs
@@ -3,8 +3,8 @@ use std::sync::Arc;
 use emath::GuiRounding as _;

 use crate::{
-    Align2, Color32, Context, Id, InnerResponse, NumExt as _, Painter, Rect, Region, Style, Ui,
-    UiBuilder, Vec2, vec2,
+    Align2, AsIdSalt, Color32, Context, Id, IdSalt, InnerResponse, NumExt as _, Painter, Rect,
+    Region, Style, Ui, UiBuilder, Vec2, vec2,
 };

 #[cfg(debug_assertions)]
@@ -312,7 +312,7 @@ impl GridLayout {
 /// ```
 #[must_use = "You should call .show()"]
 pub struct Grid {
-    id_salt: Id,
+    id_salt: IdSalt,
    num_columns: Option<usize>,
    min_col_width: Option<f32>,
    min_row_height: Option<f32>,
@@ -324,9 +324,9 @@ pub struct Grid {

 impl Grid {
    /// Create a new [`Grid`] with a locally unique identifier.
-    pub fn new(id_salt: impl std::hash::Hash) -> Self {
+    pub fn new(id_salt: impl AsIdSalt) -> Self {
        Self {
-            id_salt: Id::new(id_salt),
+            id_salt: IdSalt::new(id_salt),
            num_columns: None,
            min_col_width: None,
            min_row_height: None,
--- a/crates/egui/src/id.rs
+++ b/crates/egui/src/id.rs
@@ -2,6 +2,16 @@

 use std::num::NonZeroU64;

+use crate::{AsIdSalt, IdSalt};
+
+/// Types that can be converted to an [`Id`].
+///
+/// This is all types implementing `Hash` and `Debug`,
+/// which includes things like string, integers, tuples of those, etc.
+pub trait AsId: std::hash::Hash + std::fmt::Debug {}
+
+impl<T: std::hash::Hash + std::fmt::Debug> AsId for T {}
+
 /// egui tracks widgets frame-to-frame using [`Id`]s.
 ///
 /// For instance, if you start dragging a slider one frame, egui stores
@@ -43,6 +53,7 @@ impl Id {
    /// though obviously it will lead to a lot of collisions if you do use it!
    pub const NULL: Self = Self(NonZeroU64::MAX);

+    /// Create a new root [`Id`] from a high-entropy hash.
    #[inline]
    const fn from_hash(hash: u64) -> Self {
        if let Some(nonzero) = NonZeroU64::new(hash) {
@@ -52,17 +63,17 @@ impl Id {
        }
    }

-    /// Generate a new [`Id`] by hashing some source (e.g. a string or integer).
-    pub fn new(source: impl std::hash::Hash) -> Self {
+    /// Generate a new root [`Id`] by hashing some source (e.g. a string or integer).
+    pub fn new(source: impl AsId) -> Self {
        Self::from_hash(ahash::RandomState::with_seeds(1, 2, 3, 4).hash_one(source))
    }

-    /// Generate a new [`Id`] by hashing the parent [`Id`] and the given argument.
-    pub fn with(self, child: impl std::hash::Hash) -> Self {
+    /// Generate a child [`Id`] by salting the parent [`Id`] with the given argument.
+    pub fn with(self, salt: impl AsIdSalt) -> Self {
        use std::hash::{BuildHasher as _, Hasher as _};
        let mut hasher = ahash::RandomState::with_seeds(1, 2, 3, 4).build_hasher();
-        hasher.write_u64(self.0.get());
-        child.hash(&mut hasher);
+        hasher.write_u64(self.value());
+        hasher.write_u64(IdSalt::new(salt).value());
        Self::from_hash(hasher.finish())
    }

--- a/crates/egui/src/id_salt.rs
+++ b/crates/egui/src/id_salt.rs
@@ -0,0 +1,59 @@
+use std::num::NonZeroU64;
+
+/// Types that can be converted to an [`IdSalt`].
+///
+/// This is all types implementing `Hash` and `Debug`,
+/// which includes things like string, integers, tuples of those, etc.
+pub trait AsIdSalt: std::hash::Hash + std::fmt::Debug {}
+
+impl<T: std::hash::Hash + std::fmt::Debug> AsIdSalt for T {}
+
+/// Uniquely identifies a child widget within a parent widget.
+///
+/// An [`IdSalt`] is only unique within a parent [`crate::Id`].
+/// An [`IdSalt`] is NOT globally unique.
+///
+/// You combine a parent [`crate::Id`] with an [`IdSalt`] to get a child [`crate::Id`],
+/// using [`crate::Id::with`].
+///
+/// An [`IdSalt`] is usually a string, an integer, or similar.
+///
+/// An [`IdSalt`] should NOT be produced from an [`crate::Id`].
+///
+/// This is niche-optimized to that `Option<IdSalt>` is the same size as `IdSalt`.
+#[derive(Clone, Copy, Hash, Eq, PartialEq)]
+#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
+pub struct IdSalt(NonZeroU64);
+
+impl nohash_hasher::IsEnabled for IdSalt {}
+
+impl IdSalt {
+    /// Create a new [`IdSalt`] by hashing some source (e.g. a string or integer).
+    pub fn new(source: impl AsIdSalt) -> Self {
+        Self::from_hash(ahash::RandomState::with_seeds(1, 2, 3, 4).hash_one(source))
+    }
+
+    /// Create a new root [`IdSalt`] from a high-entropy hash.
+    #[inline]
+    const fn from_hash(hash: u64) -> Self {
+        if let Some(nonzero) = NonZeroU64::new(hash) {
+            Self(nonzero)
+        } else {
+            Self(NonZeroU64::MIN) // The hash was exactly zero
+        }
+    }
+
+    /// The inner value of the [`IdSalt`].
+    ///
+    /// This is a high-entropy hash.
+    #[inline(always)]
+    pub fn value(&self) -> u64 {
+        self.0.get()
+    }
+}
+
+impl std::fmt::Debug for IdSalt {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "salt_{:04X}", self.value() as u16)
+    }
+}
--- a/crates/egui/src/lib.rs
+++ b/crates/egui/src/lib.rs
@@ -400,6 +400,7 @@ pub(crate) mod grid;
 pub mod gui_zoom;
 mod hit_test;
 mod id;
+mod id_salt;
 mod input_state;
 mod interaction;
 pub mod introspection;
@@ -473,7 +474,8 @@ pub use self::{
    drag_and_drop::DragAndDrop,
    epaint::text::TextWrapMode,
    grid::Grid,
-    id::{Id, IdMap, IdSet},
+    id::{AsId, Id, IdMap, IdSet},
+    id_salt::{AsIdSalt, IdSalt},
    input_state::{InputOptions, InputState, MultiTouchInfo, PointerState, SurrenderFocusOn},
    layers::{LayerId, Order},
    layout::*,
@@ -486,7 +488,7 @@ pub use self::{
    style::{FontSelection, Spacing, Style, TextStyle, Visuals},
    text::{Galley, TextFormat},
    ui::Ui,
-    ui_builder::UiBuilder,
+    ui_builder::{IdSource, UiBuilder},
    ui_stack::*,
    viewport::*,
    widget_rect::{InteractOptions, WidgetRect, WidgetRects},
--- a/crates/egui/src/ui.rs
+++ b/crates/egui/src/ui.rs
@@ -1,12 +1,13 @@
 #![warn(missing_docs)] // Let's keep `Ui` well-documented.
 #![expect(clippy::use_self)]

-use std::{any::Any, hash::Hash, ops::Deref, sync::Arc};
+use std::{any::Any, ops::Deref, sync::Arc};

 use crate::containers::menu;
 use crate::widget_style::{HasClasses as _, ROOT_CLASS};
-use crate::{containers::*, ecolor::*, layout::*, placer::Placer, widgets::*, *};
+use crate::{IdSource, containers::*, ecolor::*, layout::*, placer::Placer, widgets::*, *};
 use emath::GuiRounding as _;
+
 // ----------------------------------------------------------------------------

 /// This is what you use to place widgets.
@@ -106,8 +107,7 @@ impl Ui {
    /// [`crate::Panel`], [`crate::CentralPanel`], [`crate::Window`] or [`crate::Area`].
    pub fn new(ctx: Context, id: Id, ui_builder: UiBuilder) -> Self {
        let UiBuilder {
-            id_salt,
-            global_scope: _,
+            id_source,
            ui_stack_info,
            layer_id,
            max_rect,
@@ -124,8 +124,8 @@ impl Ui {
        let layer_id = layer_id.unwrap_or_else(LayerId::background);

        debug_assert!(
-            id_salt.is_none(),
-            "Top-level Ui:s should not have an id_salt"
+            id_source.is_none(),
+            "Top-level Ui:s should not have an UiBuilder::id_source"
        );

        let max_rect = max_rect.unwrap_or_else(|| ctx.content_rect());
@@ -207,8 +207,7 @@ impl Ui {
    /// [`Ui::advance_cursor_after_rect`].
    pub fn new_child(&mut self, ui_builder: UiBuilder) -> Self {
        let UiBuilder {
-            id_salt,
-            global_scope,
+            id_source,
            ui_stack_info,
            layer_id,
            max_rect,
@@ -224,7 +223,6 @@ impl Ui {

        let mut painter = self.painter.clone();

-        let id_salt = id_salt.unwrap_or_else(|| Id::from("child"));
        let max_rect = max_rect.unwrap_or_else(|| self.available_rect_before_wrap());
        let mut layout = layout.unwrap_or_else(|| *self.layout());
        let enabled = self.enabled && !disabled && !invisible;
@@ -248,13 +246,15 @@ impl Ui {
        }

        debug_assert!(!max_rect.any_nan(), "max_rect is NaN: {max_rect:?}");
-        let (stable_id, unique_id) = if global_scope {
-            (id_salt, id_salt)
-        } else {
-            let stable_id = self.id.with(id_salt);
-            let unique_id = stable_id.with(self.next_auto_id_salt);

-            (stable_id, unique_id)
+        let id_source = id_source.unwrap_or_else(|| IdSource::Child(IdSalt::new("child")));
+        let (stable_id, unique_id) = match id_source {
+            IdSource::Explicit(id) => (id, id),
+            IdSource::Child(id_salt) => {
+                let stable_id = self.id.with(id_salt);
+                let unique_id = stable_id.with(self.next_auto_id_salt);
+                (stable_id, unique_id)
+            }
        };
        let next_auto_id_salt = unique_id.value().wrapping_add(1);

@@ -880,11 +880,8 @@ impl Ui {
 /// # [`Id`] creation
 impl Ui {
    /// Use this to generate widget ids for widgets that have persistent state in [`Memory`].
-    pub fn make_persistent_id<IdSource>(&self, id_salt: IdSource) -> Id
-    where
-        IdSource: Hash,
-    {
-        self.id.with(&id_salt)
+    pub fn make_persistent_id(&self, id_salt: impl AsIdSalt) -> Id {
+        self.id.with(id_salt)
    }

    /// This is the `Id` that will be assigned to the next widget added to this `Ui`.
@@ -893,10 +890,7 @@ impl Ui {
    }

    /// Same as `ui.next_auto_id().with(id_salt)`
-    pub fn auto_id_with<IdSource>(&self, id_salt: IdSource) -> Id
-    where
-        IdSource: Hash,
-    {
+    pub fn auto_id_with(&self, id_salt: impl AsIdSalt) -> Id {
        Id::new(self.next_auto_id_salt).with(id_salt)
    }

@@ -2168,7 +2162,7 @@ impl Ui {
    /// ```
    pub fn push_id<R>(
        &mut self,
-        id_salt: impl Hash,
+        id_salt: impl AsIdSalt,
        add_contents: impl FnOnce(&mut Ui) -> R,
    ) -> InnerResponse<R> {
        self.scope_dyn(UiBuilder::new().id_salt(id_salt), Box::new(add_contents))
@@ -2233,7 +2227,7 @@ impl Ui {
    #[inline]
    pub fn indent<R>(
        &mut self,
-        id_salt: impl Hash,
+        id_salt: impl AsIdSalt,
        add_contents: impl FnOnce(&mut Ui) -> R,
    ) -> InnerResponse<R> {
        self.indent_dyn(id_salt, Box::new(add_contents))
@@ -2241,7 +2235,7 @@ impl Ui {

    fn indent_dyn<'c, R>(
        &mut self,
-        id_salt: impl Hash,
+        id_salt: impl AsIdSalt,
        add_contents: Box<dyn FnOnce(&mut Ui) -> R + 'c>,
    ) -> InnerResponse<R> {
        assert!(
--- a/crates/egui/src/ui_builder.rs
+++ b/crates/egui/src/ui_builder.rs
@@ -1,10 +1,11 @@
-use std::{hash::Hash, sync::Arc};
+use std::sync::Arc;

 #[expect(unused_imports)] // Used for doclinks
 use crate::Ui;
-use crate::widget_style::HasClasses;
-use crate::{ClosableTag, widget_style::Classes};
-use crate::{Id, LayerId, Layout, Rect, Sense, Style, UiStackInfo};
+use crate::{
+    AsIdSalt, ClosableTag, Id, IdSalt, LayerId, Layout, Rect, Sense, Style, UiStackInfo,
+    widget_style::{Classes, HasClasses},
+};

 /// Build a [`Ui`] as the child of another [`Ui`].
 ///
@@ -14,8 +15,7 @@ use crate::{Id, LayerId, Layout, Rect, Sense, Style, UiStackInfo};
 #[must_use]
 #[derive(Clone, Default)]
 pub struct UiBuilder {
-    pub id_salt: Option<Id>,
-    pub global_scope: bool,
+    pub id_source: Option<IdSource>,
    pub ui_stack_info: UiStackInfo,
    pub layer_id: Option<LayerId>,
    pub max_rect: Option<Rect>,
@@ -29,6 +29,16 @@ pub struct UiBuilder {
    pub classes: Classes,
 }

+/// Is this [`Ui`] a root or a child of another [`Ui`]?
+#[derive(Clone)]
+pub enum IdSource {
+    /// Explicitly use this [`Id`]
+    Explicit(Id),
+
+    /// Salt the parent [`Id`] with this.
+    Child(IdSalt),
+}
+
 impl UiBuilder {
    #[inline]
    pub fn new() -> Self {
@@ -41,8 +51,8 @@ impl UiBuilder {
    /// You should give each [`Ui`] an `id_salt` that is unique
    /// within the parent, or give it none at all.
    #[inline]
-    pub fn id_salt(mut self, id_salt: impl Hash) -> Self {
-        self.id_salt = Some(Id::new(id_salt));
+    pub fn id_salt(mut self, id_salt: impl AsIdSalt) -> Self {
+        self.id_source = Some(IdSource::Child(IdSalt::new(id_salt)));
        self
    }

@@ -57,20 +67,7 @@ impl UiBuilder {
    /// This is a shortcut for `.id_salt(my_id).global_scope(true)`.
    #[inline]
    pub fn id(mut self, id: Id) -> Self {
-        self.id_salt = Some(id);
-        self.global_scope = true;
-        self
-    }
-
-    /// Make the new `Ui` child ids independent of the parent `Ui`.
-    /// This way child widgets can be moved in the ui tree without losing state.
-    /// You have to ensure that in a frame the child widgets do not get rendered in multiple places.
-    ///
-    /// You should set the same globally unique `id_salt` at every place in the ui tree where you want the
-    /// child widgets to share state.
-    #[inline]
-    pub fn global_scope(mut self, global_scope: bool) -> Self {
-        self.global_scope = global_scope;
+        self.id_source = Some(IdSource::Explicit(id));
        self
    }

--- a/crates/egui/src/viewport.rs
+++ b/crates/egui/src/viewport.rs
@@ -73,7 +73,7 @@ use std::sync::Arc;

 use epaint::{Pos2, Vec2};

-use crate::{Context, Id, Ui};
+use crate::{AsId, Context, Id, Ui};

 // ----------------------------------------------------------------------------

@@ -150,7 +150,7 @@ impl ViewportId {
    pub const ROOT: Self = Self(Id::NULL);

    #[inline]
-    pub fn from_hash_of(source: impl std::hash::Hash) -> Self {
+    pub fn from_hash_of(source: impl AsId) -> Self {
        Self(Id::new(source))
    }
 }
--- a/crates/egui/src/widgets/text_edit/builder.rs
+++ b/crates/egui/src/widgets/text_edit/builder.rs
@@ -4,10 +4,10 @@ use emath::{Rect, TSTransform};
 use epaint::text::{Galley, LayoutJob, TextWrapMode, cursor::CCursor};

 use crate::{
-    Align, Align2, AtomExt as _, AtomKind, AtomLayout, Atoms, Color32, Context, CursorIcon, Event,
-    EventFilter, FontSelection, Frame, Id, ImeEvent, IntoAtoms, IntoSizedResult, Key,
-    KeyboardShortcut, Margin, Modifiers, NumExt as _, Response, Sense, SizedAtomKind, TextBuffer,
-    TextStyle, Ui, Vec2, Widget, WidgetInfo, WidgetWithState, epaint,
+    Align, Align2, AsIdSalt, AtomExt as _, AtomKind, AtomLayout, Atoms, Color32, Context,
+    CursorIcon, Event, EventFilter, FontSelection, Frame, Id, IdSalt, ImeEvent, IntoAtoms,
+    IntoSizedResult, Key, KeyboardShortcut, Margin, Modifiers, NumExt as _, Response, Sense,
+    SizedAtomKind, TextBuffer, TextStyle, Ui, Vec2, Widget, WidgetInfo, WidgetWithState, epaint,
    os::OperatingSystem,
    output::OutputEvent,
    response,
@@ -72,7 +72,7 @@ pub struct TextEdit<'t> {
    suffix: Atoms<'static>,
    hint_text: Atoms<'static>,
    id: Option<Id>,
-    id_salt: Option<Id>,
+    id_salt: Option<IdSalt>,
    font_selection: FontSelection,
    text_color: Option<Color32>,
    layouter: Option<LayouterFn<'t>>,
@@ -171,14 +171,14 @@ impl<'t> TextEdit<'t> {

    /// A source for the unique [`Id`], e.g. `.id_source("second_text_edit_field")` or `.id_source(loop_index)`.
    #[inline]
-    pub fn id_source(self, id_salt: impl std::hash::Hash) -> Self {
+    pub fn id_source(self, id_salt: impl AsIdSalt) -> Self {
        self.id_salt(id_salt)
    }

    /// A source for the unique [`Id`], e.g. `.id_salt("second_text_edit_field")` or `.id_salt(loop_index)`.
    #[inline]
-    pub fn id_salt(mut self, id_salt: impl std::hash::Hash) -> Self {
-        self.id_salt = Some(Id::new(id_salt));
+    pub fn id_salt(mut self, id_salt: impl AsIdSalt) -> Self {
+        self.id_salt = Some(IdSalt::new(id_salt));
        self
    }

--- a/crates/egui_demo_lib/tests/snapshots/demos/ID
+++ b/crates/egui_demo_lib/tests/snapshots/demos/ID
@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:d14571fdd7602ea4924d04725008433e1bb53596d8a279f310ddc6c3231b6d32
-size 114106
+oid sha256:c9b497aa9b2b92843937c84a6ff8901f248501d5d4a89c2fb1237008a44fcad1
+size 114038
--- a/crates/egui_extras/src/table.rs
+++ b/crates/egui_extras/src/table.rs
@@ -4,7 +4,7 @@
 //! Takes all available height, so if you want something below the table, put it in a strip.

 use egui::{
-    Align, Id, NumExt as _, Rangef, Rect, Response, ScrollArea, Ui, Vec2, Vec2b,
+    Align, AsIdSalt, IdSalt, NumExt as _, Rangef, Rect, Response, ScrollArea, Ui, Vec2, Vec2b,
    scroll_area::{DragScroll, ScrollAreaOutput, ScrollBarVisibility, ScrollSource},
 };

@@ -246,7 +246,7 @@ impl Default for TableScrollOptions {
 /// ```
 pub struct TableBuilder<'a> {
    ui: &'a mut Ui,
-    id_salt: Id,
+    id_salt: IdSalt,
    columns: Vec<Column>,
    striped: Option<bool>,
    resizable: bool,
@@ -260,7 +260,7 @@ impl<'a> TableBuilder<'a> {
        let cell_layout = *ui.layout();
        Self {
            ui,
-            id_salt: Id::new("__table_state"),
+            id_salt: IdSalt::new("__table_state"),
            columns: Default::default(),
            striped: None,
            resizable: false,
@@ -270,12 +270,12 @@ impl<'a> TableBuilder<'a> {
        }
    }

-    /// Give this table a unique id within the parent [`Ui`].
+    /// Give this table a unique salt within the parent [`Ui`].
    ///
    /// This is required if you have multiple tables in the same [`Ui`].
    #[inline]
-    pub fn id_salt(mut self, id_salt: impl std::hash::Hash) -> Self {
-        self.id_salt = Id::new(id_salt);
+    pub fn id_salt(mut self, id_salt: impl AsIdSalt) -> Self {
+        self.id_salt = IdSalt::new(id_salt);
        self
    }