fix(ui-egui): a click under a new page's date starts writing (#148)

crates/ui-egui/src/containers.rs

@@ -308,6 +308,8 @@ pub fn show(
     let mut delete_object: Option<usize> = None;
     // An empty box that was clicked: it has no words to answer a click, so the click starts some.
     let mut start_in: Option<usize> = None;
+    // A new page's box clicked below its date: the words start on a line under the date.
+    let mut start_under_date: Option<usize> = None;
     let right_click = ui.input(|i| i.pointer.secondary_clicked());
     let pointer = ui.ctx().pointer_latest_pos();
     let mut opened_now = false;
@@ -476,6 +478,22 @@ pub fn show(
             filled_bottom = filled_bottom.max(frame.max.y);
         }
 
+        // A new page's box holds only its date and is drawn tall, as OneNote's first note area is.
+        // Below the date there was no block to take a click, so the space looked ready for
+        // writing and swallowed what was typed (issue #148). A click there starts a line under
+        // the date.
+        if range.len() == 1 && pageedit::is_page_stamp(blocks, range.start) {
+            let under_date = Rect::from_min_max(pos2(frame.min.x, child.min_rect().max.y), frame.max);
+            if under_date.height() > 0.0 {
+                let start = ui.interact(under_date, ui.id().with(("container-under-date", i)), Sense::click());
+                if start.hovered() {
+                    ui.ctx().set_cursor_icon(egui::CursorIcon::Text);
+                }
+                if start.clicked() {
+                    start_under_date = Some(i);
+                }
+            }
+        }
         let hovered = ui.rect_contains_pointer(frame);
         // A box with nothing in it has no block under the pointer, so a click inside it went
         // nowhere and no caret appeared. The whole of it, below the handle, is a place to start
@@ -1142,6 +1160,34 @@ pub fn show(
         ui.ctx().request_repaint();
     }
 
+    if let Some(i) = start_under_date
+        && start_in.is_none()
+        && delete_at.is_none()
+        && container::blocks_of(boxes, i).len() == 1
+    {
+        let at = container::blocks_of(boxes, i).end.min(blocks.len());
+        blocks.insert(at, Block::Paragraph(Vec::new()));
+        out.changed.columns |= cols.insert_block(at);
+        out.justified |= justified.insert_block(at);
+        if let Some(c) = boxes.get_mut(i) {
+            c.blocks += 1;
+        }
+        *caret = Some(pageedit::Caret {
+            block: at,
+            text: String::new(),
+            focus: true,
+            selection: (0, 0),
+            place: None,
+            cell: None,
+            span: None,
+            inline: None,
+        });
+        out.changed.blocks = true;
+        out.changed.caret = true;
+        out.boxes = true;
+        ui.ctx().request_repaint();
+    }
+
     // Remove an embedded block after it has been drawn, so the current frame's
     // hit testing and selection affordance remain stable.
     if let Some(block) = delete_object

crates/ui-egui/tests/ui.rs

@@ -607,6 +607,38 @@ fn clicking_a_page_opens_it_and_a_container_toggles() {
     review(&mut h, "markdown_page");
 }
 
+/// Issue #148: on a new page, a click in the blank space under the date line puts a caret
+/// there, and what is typed is kept, in both formats.
+#[test]
+fn a_click_under_a_new_pages_date_starts_writing() {
+    for format in ["html", "cmgfm"] {
+        let (_t, app, s) = sample_app("ui-new-page-click");
+        let mut h = harness(app, LIGHT);
+        h.run();
+        let section = s.md_page.parent().expect("section").to_string_lossy().into_owned();
+        let made = ask(&mut h, "engine.execute", json!({"command": "node.create", "params": {"parent": section, "kind": "page", "format": format}}))
+            .expect("page");
+        let page = made.as_str().expect("a path").to_string();
+        ask(&mut h, "ui.open", json!({"path": page})).expect("open");
+        settle(&mut h);
+        let state = ask(&mut h, "ui.inspect", json!({})).expect("inspect");
+        let origin = state.pointer("/page/origin").and_then(Value::as_array).expect("page origin");
+        let (ox, oy) = (origin[0].as_f64().unwrap_or(0.0), origin[1].as_f64().unwrap_or(0.0));
+
+        for (dx, dy) in [(60.0, 90.0), (200.0, 180.0)] {
+            ask(&mut h, "ui.click", json!({"x": ox + dx, "y": oy + dy})).expect("click under the date");
+            settle(&mut h);
+            let caret = ask(&mut h, "ui.inspect", json!({})).expect("inspect")["page"]["caret"].clone();
+            assert!(!caret.is_null(), "{format}: a click at +{dx},+{dy} under the date puts a caret: {state}");
+        }
+        ask(&mut h, "ui.text", json!({"text": "TEST EMPTY AREA"})).expect("type");
+        settle(&mut h);
+        h.state_mut().save_page_now();
+        let saved = ask(&mut h, "engine.execute", json!({"command": "page.load", "params": {"path": page}})).expect("load");
+        assert!(saved["body"].as_str().is_some_and(|b| b.contains("TEST EMPTY AREA")), "{format}: what was typed is kept: {saved}");
+    }
+}
+
 /// The caret lives in the page: clicking a block and typing changes that block, and the page
 /// is written back in its own format. This is the editor the owner asked for, so it is tested
 /// for both formats.