live-preview: Have the selection popup highlight locations

Have the selection popup actually highlight the hovered
object in the editor.

We did not have this use case before: We used to either
highlight after an update or never at all. Neither semantic
matches what we are doing in the selection popup, so I added
a highlight-now flag.

tools/lsp/preview.rs

@@ -252,7 +252,7 @@ fn add_new_component() {
             drop_data.path,
             drop_data.selection_offset,
             None,
-            true,
+            SelectionNotification::AfterUpdate,
         );
 
         {
@@ -668,7 +668,7 @@ fn drop_component(component_index: i32, x: f32, y: f32) {
             drop_data.path,
             drop_data.selection_offset,
             None,
-            true,
+            SelectionNotification::AfterUpdate,
         );
 
         send_workspace_edit(format!("Add element {}", component_name), edit, false);
@@ -860,7 +860,7 @@ fn move_selected_element(x: f32, y: f32, mouse_x: f32, mouse_y: f32) {
             drop_data.path,
             drop_data.selection_offset,
             None,
-            true,
+            SelectionNotification::AfterUpdate,
         );
 
         send_workspace_edit("Move element".to_string(), edit, false);
@@ -1167,7 +1167,7 @@ async fn reload_timer_function() {
             se.path.clone(),
             se.offset,
             None,
-            false,
+            SelectionNotification::Never,
         );
 
         if notify_editor {
@@ -1411,7 +1411,12 @@ pub fn highlight(url: Option<Url>, offset: TextSize) {
                 // Already selected!
                 return;
             }
-            element_selection::select_element_at_source_code_position(path, offset, None, false);
+            element_selection::select_element_at_source_code_position(
+                path,
+                offset,
+                None,
+                SelectionNotification::Never,
+            );
         });
     }
 }
@@ -1528,10 +1533,17 @@ fn set_drop_mark(mark: &Option<drop_location::DropMark>) {
     })
 }
 
+#[derive(Debug, PartialEq)]
+pub enum SelectionNotification {
+    Never,
+    Now,
+    AfterUpdate,
+}
+
 fn set_selected_element(
     selection: Option<element_selection::ElementSelection>,
     positions: &[i_slint_core::lengths::LogicalRect],
-    notify_editor_about_selection_after_update: bool,
+    editor_notification: SelectionNotification,
 ) {
     let (layout_kind, parent_layout_kind, type_name) = {
         let selection_node = selection.as_ref().and_then(|s| s.as_element_node());
@@ -1553,6 +1565,9 @@ fn set_selected_element(
 
     set_drop_mark(&None);
 
+    let element_node = selection.as_ref().and_then(|s| s.as_element_node());
+    let notify_editor_about_selection_after_update =
+        editor_notification == SelectionNotification::AfterUpdate;
     PREVIEW_STATE.with(move |preview_state| {
         let mut preview_state = preview_state.borrow_mut();
 
@@ -1633,7 +1648,24 @@ fn set_selected_element(
         preview_state.selected = selection;
         preview_state.notify_editor_about_selection_after_update =
             notify_editor_about_selection_after_update;
-    })
+    });
+
+    if editor_notification == SelectionNotification::Now {
+        if let Some(element_node) = element_node {
+            let (path, pos) = element_node.with_element_node(|node| {
+                let sf = &node.source_file;
+                (
+                    sf.path().to_owned(),
+                    util::text_size_to_lsp_position(sf, node.text_range().start()),
+                )
+            });
+            ask_editor_to_show_document(
+                &path.to_string_lossy(),
+                lsp_types::Range::new(pos, pos),
+                false,
+            );
+        }
+    }
 }
 
 fn selected_element() -> Option<ElementSelection> {

tools/lsp/preview/element_selection.rs

@@ -12,7 +12,7 @@ use slint_interpreter::ComponentInstance;
 
 use crate::common;
 
-use super::{ext::ElementRcNodeExt, ui};
+use crate::preview::{ext::ElementRcNodeExt, ui, SelectionNotification};
 
 #[derive(Clone, Debug)]
 pub struct ElementSelection {
@@ -89,14 +89,14 @@ fn element_covers_point(
 }
 
 pub fn unselect_element() {
-    super::set_selected_element(None, &[], false);
+    super::set_selected_element(None, &[], SelectionNotification::Never);
 }
 
 pub fn select_element_at_source_code_position(
     path: PathBuf,
     offset: TextSize,
     position: Option<LogicalPoint>,
-    notify_editor_about_selection_after_update: bool,
+    editor_notification: crate::preview::SelectionNotification,
 ) {
     let Some(component_instance) = super::component_instance() else {
         return;
@@ -106,7 +106,7 @@ pub fn select_element_at_source_code_position(
         path,
         offset,
         position,
-        notify_editor_about_selection_after_update,
+        editor_notification,
     )
 }
 
@@ -115,7 +115,7 @@ fn select_element_at_source_code_position_impl(
     path: PathBuf,
     offset: TextSize,
     position: Option<LogicalPoint>,
-    notify_editor_about_selection_after_update: bool,
+    editor_notification: SelectionNotification,
 ) {
     let positions = component_instance.component_positions(&path, offset.into());
 
@@ -126,7 +126,7 @@ fn select_element_at_source_code_position_impl(
     super::set_selected_element(
         Some(ElementSelection { path, offset, instance_index }),
         &positions,
-        notify_editor_about_selection_after_update,
+        editor_notification,
     );
 }
 
@@ -142,7 +142,7 @@ fn select_element_node(
         path,
         offset,
         position,
-        false, // We update directly;-)
+        SelectionNotification::Never, // We update directly;-)
     );
 
     if let Some(document_position) = lsp_element_node_position(selected_element) {
@@ -525,7 +525,7 @@ pub fn select_element_behind(x: f32, y: f32, enter_component: bool, reverse: boo
 // Called from UI thread!
 pub fn reselect_element() {
     let Some(selected) = super::selected_element() else {
-        super::set_selected_element(None, &[], false);
+        super::set_selected_element(None, &[], SelectionNotification::Never);
         return;
     };
     let Some(component_instance) = super::component_instance() else {
@@ -533,7 +533,7 @@ pub fn reselect_element() {
     };
     let positions = component_instance.component_positions(&selected.path, selected.offset.into());
 
-    super::set_selected_element(Some(selected), &positions, false);
+    super::set_selected_element(Some(selected), &positions, SelectionNotification::Never);
 }
 
 #[cfg(test)]

tools/lsp/preview/ui.rs

@@ -13,7 +13,7 @@ use slint_interpreter::{DiagnosticLevel, PlatformError};
 use smol_str::SmolStr;
 
 use crate::common::{self, ComponentInformation};
-use crate::preview::properties;
+use crate::preview::{properties, SelectionNotification};
 
 #[cfg(target_arch = "wasm32")]
 use crate::wasm_prelude::*;
@@ -80,7 +80,7 @@ pub fn create_ui(style: String, experimental: bool) -> Result<PreviewUi, Platfor
             PathBuf::from(path.to_string()),
             crate::preview::TextSize::from(offset as u32),
             Some(i_slint_core::lengths::LogicalPoint::new(x, y)),
-            true,
+            SelectionNotification::Now,
         );
     });
     api.on_select_behind(super::element_selection::select_element_behind);