Replace `Id::null()` with `Id::NULL` (#3544)

Shorter and more idiomatic

crates/egui/src/containers/popup.rs

@@ -13,11 +13,11 @@ pub(crate) struct TooltipState {
 
 impl TooltipState {
     pub fn load(ctx: &Context) -> Option<Self> {
-        ctx.data_mut(|d| d.get_temp(Id::null()))
+        ctx.data_mut(|d| d.get_temp(Id::NULL))
     }
 
     fn store(self, ctx: &Context) {
-        ctx.data_mut(|d| d.insert_temp(Id::null(), self));
+        ctx.data_mut(|d| d.insert_temp(Id::NULL, self));
     }
 
     fn individual_tooltip_size(&self, common_id: Id, index: usize) -> Option<Vec2> {

crates/egui/src/id.rs

@@ -35,6 +35,9 @@ impl Id {
     ///
     /// The null [`Id`] is still a valid id to use in all circumstances,
     /// though obviously it will lead to a lot of collisions if you do use it!
+    pub const NULL: Self = Self(0);
+
+    #[deprecated = "Use Id::NULL"]
     pub fn null() -> Self {
         Self(0)
     }

crates/egui/src/widgets/color_picker.rs

@@ -442,5 +442,5 @@ fn color_cache_set(ctx: &Context, rgba: impl Into<Rgba>, hsva: Hsva) {
 
 // To ensure we keep hue slider when `srgba` is gray we store the full [`Hsva`] in a cache:
 fn use_color_cache<R>(ctx: &Context, f: impl FnOnce(&mut FixedCache<Rgba, Hsva>) -> R) -> R {
-    ctx.data_mut(|d| f(d.get_temp_mut_or_default(Id::null())))
+    ctx.data_mut(|d| f(d.get_temp_mut_or_default(Id::NULL)))
 }

crates/egui_extras/src/syntax_highlighting.rs

@@ -248,7 +248,7 @@ impl CodeTheme {
     /// Show UI for changing the color theme.
     pub fn ui(&mut self, ui: &mut egui::Ui) {
         ui.horizontal_top(|ui| {
-            let selected_id = egui::Id::null();
+            let selected_id = egui::Id::NULL;
             let mut selected_tt: TokenType =
                 ui.data_mut(|d| *d.get_persisted_mut_or(selected_id, TokenType::Comment));
 

crates/egui_plot/src/lib.rs

@@ -807,7 +807,7 @@ impl Plot {
             if let Some((name, _)) = linked_axes.as_ref() {
                 ui.memory_mut(|memory| {
                     let link_groups: &mut BoundsLinkGroups =
-                        memory.data.get_temp_mut_or_default(Id::null());
+                        memory.data.get_temp_mut_or_default(Id::NULL);
                     link_groups.0.remove(name);
                 });
             };
@@ -892,7 +892,7 @@ impl Plot {
         // Find the cursors from other plots we need to draw
         let draw_cursors: Vec<Cursor> = if let Some((id, _)) = linked_cursors.as_ref() {
             ui.memory_mut(|memory| {
-                let frames: &mut CursorLinkGroups = memory.data.get_temp_mut_or_default(Id::null());
+                let frames: &mut CursorLinkGroups = memory.data.get_temp_mut_or_default(Id::NULL);
                 let cursors = frames.0.entry(*id).or_default();
 
                 // Look for our previous frame
@@ -921,7 +921,7 @@ impl Plot {
         if let Some((id, axes)) = linked_axes.as_ref() {
             ui.memory_mut(|memory| {
                 let link_groups: &mut BoundsLinkGroups =
-                    memory.data.get_temp_mut_or_default(Id::null());
+                    memory.data.get_temp_mut_or_default(Id::NULL);
                 if let Some(linked_bounds) = link_groups.0.get(id) {
                     if axes.x {
                         bounds.set_x(&linked_bounds.bounds);
@@ -1164,7 +1164,7 @@ impl Plot {
         if let Some((id, _)) = linked_cursors.as_ref() {
             // Push the frame we just drew to the list of frames
             ui.memory_mut(|memory| {
-                let frames: &mut CursorLinkGroups = memory.data.get_temp_mut_or_default(Id::null());
+                let frames: &mut CursorLinkGroups = memory.data.get_temp_mut_or_default(Id::NULL);
                 let cursors = frames.0.entry(*id).or_default();
                 cursors.push(PlotFrameCursors {
                     id: plot_id,
@@ -1177,7 +1177,7 @@ impl Plot {
             // Save the linked bounds.
             ui.memory_mut(|memory| {
                 let link_groups: &mut BoundsLinkGroups =
-                    memory.data.get_temp_mut_or_default(Id::null());
+                    memory.data.get_temp_mut_or_default(Id::NULL);
                 link_groups.0.insert(
                     *id,
                     LinkedBounds {

crates/emath/src/lib.rs

@@ -55,21 +55,15 @@ pub use {
 
 /// Helper trait to implement [`lerp`] and [`remap`].
 pub trait One {
-    fn one() -> Self;
+    const ONE: Self;
 }
 
 impl One for f32 {
-    #[inline(always)]
+    const ONE: Self = 1.0;
-    fn one() -> Self {
-        1.0
-    }
 }
 
 impl One for f64 {
-    #[inline(always)]
+    const ONE: Self = 1.0;
-    fn one() -> Self {
-        1.0
-    }
 }
 
 /// Helper trait to implement [`lerp`] and [`remap`].
@@ -107,7 +101,7 @@ where
     R: Copy + Add<R, Output = R>,
 {
     let range = range.into();
-    (T::one() - t) * *range.start() + t * *range.end()
+    (T::ONE - t) * *range.start() + t * *range.end()
 }
 
 /// Where in the range is this value? Returns 0-1 if within the range.
@@ -174,7 +168,7 @@ where
         crate::emath_assert!(from.start() != from.end());
         let t = (x - *from.start()) / (*from.end() - *from.start());
         // Ensure no numerical inaccuracies sneak in:
-        if T::one() <= t {
+        if T::ONE <= t {
             *to.end()
         } else {
             lerp(to, t)