Change API of `Tooltip` slightly (#7151)

We try to be consistent with our parameter order to reduce surprise for
users.

I also renamed a few things to clarify what is what

CONTRIBUTING.md

@@ -35,7 +35,7 @@ You can test your code locally by running `./scripts/check.sh`.
 There are snapshots test that might need to be updated.
 Run the tests with `UPDATE_SNAPSHOTS=true cargo test --workspace --all-features` to update all of them.
 If CI keeps complaining about snapshots (which could happen if you don't use macOS, snapshots in CI are currently
-rendered with macOS), you can instead run `./scripts/update_snapshots_from_ci.sh` to update your local snapshots from 
+rendered with macOS), you can instead run `./scripts/update_snapshots_from_ci.sh` to update your local snapshots from
 the last CI run of your PR (which will download the `test_results` artefact).
 For more info about the tests see [egui_kittest](./crates/egui_kittest/README.md).
 Snapshots and other big files are stored with git lfs. See [Working with git lfs](#working-with-git-lfs) for more info.
@@ -125,6 +125,7 @@ While using an immediate mode gui is simple, implementing one is a lot more tric
 * Flip `if !condition {} else {}`
 * Sets of things should be lexicographically sorted (e.g. crate dependencies in `Cargo.toml`)
 * Put each type in their own file, unless they are trivial (e.g. a `struct` with no `impl`)
+* Put most generic arguments first (e.g. `Context`), and most specific last
 * Break the above rules when it makes sense
 
 

crates/egui/src/containers/old_popup.rs

@@ -61,7 +61,7 @@ pub fn show_tooltip_at_pointer<R>(
     widget_id: Id,
     add_contents: impl FnOnce(&mut Ui) -> R,
 ) -> Option<R> {
-    Tooltip::new(widget_id, ctx.clone(), PopupAnchor::Pointer, parent_layer)
+    Tooltip::new(ctx.clone(), parent_layer, widget_id, PopupAnchor::Pointer)
         .gap(12.0)
         .show(add_contents)
         .map(|response| response.inner)
@@ -78,7 +78,7 @@ pub fn show_tooltip_for<R>(
     widget_rect: &Rect,
     add_contents: impl FnOnce(&mut Ui) -> R,
 ) -> Option<R> {
-    Tooltip::new(widget_id, ctx.clone(), *widget_rect, parent_layer)
+    Tooltip::new(ctx.clone(), parent_layer, widget_id, *widget_rect)
         .show(add_contents)
         .map(|response| response.inner)
 }
@@ -94,7 +94,7 @@ pub fn show_tooltip_at<R>(
     suggested_position: Pos2,
     add_contents: impl FnOnce(&mut Ui) -> R,
 ) -> Option<R> {
-    Tooltip::new(widget_id, ctx.clone(), suggested_position, parent_layer)
+    Tooltip::new(ctx.clone(), parent_layer, widget_id, suggested_position)
         .show(add_contents)
         .map(|response| response.inner)
 }

crates/egui/src/containers/tooltip.rs

@@ -7,26 +7,31 @@ use emath::Vec2;
 
 pub struct Tooltip<'a> {
     pub popup: Popup<'a>,
-    layer_id: LayerId,
+
-    widget_id: Id,
+    /// The layer of the parent widget.
+    parent_layer: LayerId,
+
+    /// The id of the widget that owns this tooltip.
+    parent_widget: Id,
 }
 
 impl Tooltip<'_> {
-    /// Show a tooltip that is always open
+    /// Show a tooltip that is always open.
     pub fn new(
-        widget_id: Id,
         ctx: Context,
+        parent_layer: LayerId,
+        parent_widget: Id,
         anchor: impl Into<PopupAnchor>,
-        layer_id: LayerId,
     ) -> Self {
+        let width = ctx.style().spacing.tooltip_width;
         Self {
-            // TODO(lucasmerlin): Set width somehow (we're missing context here)
+            popup: Popup::new(parent_widget, ctx, anchor.into(), parent_layer)
-            popup: Popup::new(widget_id, ctx, anchor.into(), layer_id)
                 .kind(PopupKind::Tooltip)
                 .gap(4.0)
+                .width(width)
                 .sense(Sense::hover()),
-            layer_id,
+            parent_layer,
-            widget_id,
+            parent_widget,
         }
     }
 
@@ -39,8 +44,8 @@ impl Tooltip<'_> {
             .sense(Sense::hover());
         Self {
             popup,
-            layer_id: response.layer_id,
+            parent_layer: response.layer_id,
-            widget_id: response.id,
+            parent_widget: response.id,
         }
     }
 
@@ -96,8 +101,8 @@ impl Tooltip<'_> {
     pub fn show<R>(self, content: impl FnOnce(&mut crate::Ui) -> R) -> Option<InnerResponse<R>> {
         let Self {
             mut popup,
-            layer_id: parent_layer,
+            parent_layer,
-            widget_id,
+            parent_widget,
         } = self;
 
         if !popup.is_open() {
@@ -111,11 +116,11 @@ impl Tooltip<'_> {
             fs.layers
                 .entry(parent_layer)
                 .or_default()
-                .widget_with_tooltip = Some(widget_id);
+                .widget_with_tooltip = Some(parent_widget);
 
             fs.tooltips
                 .widget_tooltips
-                .get(&widget_id)
+                .get(&parent_widget)
                 .copied()
                 .unwrap_or(PerWidgetTooltipState {
                     bounding_rect: rect,
@@ -123,7 +128,7 @@ impl Tooltip<'_> {
                 })
         });
 
-        let tooltip_area_id = Self::tooltip_id(widget_id, state.tooltip_count);
+        let tooltip_area_id = Self::tooltip_id(parent_widget, state.tooltip_count);
         popup = popup.anchor(state.bounding_rect).id(tooltip_area_id);
 
         let response = popup.show(|ui| {
@@ -144,7 +149,7 @@ impl Tooltip<'_> {
             response
                 .response
                 .ctx
-                .pass_state_mut(|fs| fs.tooltips.widget_tooltips.insert(widget_id, state));
+                .pass_state_mut(|fs| fs.tooltips.widget_tooltips.insert(parent_widget, state));
             Self::remember_that_tooltip_was_shown(&response.response.ctx);
         }