feat(ui-egui): Insert Space drags room into the page (#164)

crates/ui-egui/src/app.rs

@@ -279,6 +279,51 @@ fn shown(p: &Path) -> String {
     notecraft_store::tree::display_path(p)
 }
 
+/// The Insert Space tool's own layer over the visible page (issue #164): a vertical-resize
+/// pointer, a guide at the pointer's height, and while it is dragged, the band of room being
+/// added (below the start) or taken away (above it). Returns where the drag began and how far it
+/// went, in screen points, on the frame it is let go.
+fn insert_space_overlay(ctx: &Context, visible: egui::Rect, t: &Tokens) -> Option<(f32, f32)> {
+    let id = Id::new("insert-space-tool");
+    let from_id = id.with("from");
+    let mut done = None;
+    egui::Area::new(id).order(egui::Order::Foreground).fixed_pos(visible.min).constrain(false).movable(false).show(ctx, |ui| {
+        let (rect, resp) = ui.allocate_exact_size(visible.size(), Sense::drag());
+        resp.widget_info(|| egui::WidgetInfo::labeled(egui::WidgetType::Button, true, crate::tl_id!("ui.insert_space_how")));
+        if resp.hovered() || resp.dragged() {
+            ui.ctx().set_cursor_icon(egui::CursorIcon::ResizeVertical);
+        }
+        if resp.drag_started()
+            && let Some(p) = resp.interact_pointer_pos()
+        {
+            ui.data_mut(|d| d.insert_temp(from_id, p.y));
+        }
+        let from = ui.data(|d| d.get_temp::<f32>(from_id));
+        let now = ui.ctx().pointer_latest_pos().filter(|p| rect.contains(*p) || resp.dragged()).map(|p| p.y.clamp(rect.min.y, rect.max.y));
+        let painter = ui.painter();
+        let line = egui::Stroke::new(1.5, t.accent);
+        match (from, now) {
+            (Some(a), Some(b)) => {
+                let band = egui::Rect::from_x_y_ranges(rect.x_range(), egui::Rangef::new(a.min(b), a.max(b)));
+                painter.rect_filled(band, 0.0, t.accent.gamma_multiply(0.12));
+                painter.hline(rect.x_range(), a, line);
+                painter.hline(rect.x_range(), b, egui::Stroke::new(1.0, t.accent.gamma_multiply(0.7)));
+            }
+            (None, Some(y)) => {
+                painter.hline(rect.x_range(), y, line);
+            }
+            _ => {}
+        }
+        if resp.drag_stopped() {
+            if let (Some(a), Some(p)) = (from, resp.interact_pointer_pos()) {
+                done = Some((a, p.y.clamp(rect.min.y, rect.max.y) - a));
+            }
+            ui.data_mut(|d| d.remove::<f32>(from_id));
+        }
+    });
+    done
+}
+
 fn notebook_for(path: &Path) -> Option<PathBuf> {
     let mut current = path;
     loop {
@@ -876,6 +921,8 @@ pub struct NoteCraftApp {
     canvas_drag: Option<egui::Pos2>,
     /// The page's sideways scroll bar and its thumb, when one was drawn last frame (issue #188).
     page_hbar: Option<(egui::Rect, egui::Rect)>,
+    /// True while Insert Space is in hand: the next drag on the page adds or takes away room.
+    space_tool: bool,
     /// What the pointer does on the page (the Draw tab).
     pointer: ribbon::Pointer,
     /// The tools on the rack, as the owner has arranged them, and which is in hand. Both
@@ -1038,6 +1085,7 @@ impl NoteCraftApp {
             page_rect: None,
             canvas_pan: egui::Vec2::ZERO,
             page_hbar: None,
+            space_tool: false,
             canvas_drag: None,
             pointer: ribbon::Pointer::Write,
             rack,
@@ -3430,6 +3478,7 @@ impl NoteCraftApp {
             rack: &self.rack,
             nib: self.nib,
             in_table: self.caret_in_table(),
+            space_tool: self.space_tool,
             table_borders: self.caret_table_has_borders(),
             table_align: self.caret_cells_align(),
             table_shade: self.caret_cells_shade(),
@@ -3852,6 +3901,17 @@ impl NoteCraftApp {
             }
             ribbon::Act::PageWidth => self.fit_page_width = true,
             ribbon::Act::FormatPainter(sticky) => self.pick_up_formatting(sticky),
+            ribbon::Act::InsertSpaceTool => {
+                if self.editor.is_none() {
+                    self.say(crate::tl_id!("ui.open_a_page_first"));
+                    return;
+                }
+                self.space_tool = !self.space_tool;
+                if self.space_tool {
+                    self.pointer = ribbon::Pointer::Write;
+                    self.say(crate::tl_id!("ui.insert_space_how"));
+                }
+            }
             ribbon::Act::FindTags => {
                 // OneNote looks in the section first; with no page open there is no section.
                 let scope = self.tags_pane.as_ref().map_or(if self.editor.is_some() { TagScope::Section } else { TagScope::All }, |p| p.scope);
@@ -6502,6 +6562,9 @@ impl NoteCraftApp {
         let mut hbar = crate::hscroll::Shown::default();
         // What the page's right-click menu asked for, run once the page's borrow is over.
         let mut page_acts: Vec<ribbon::Act> = Vec::new();
+        // Insert Space: in hand this frame, and whether it was used or put down.
+        let space_on = self.space_tool && self.pointer == ribbon::Pointer::Write;
+        let mut space_over = false;
         {
             let Some(ed) = self.editor.as_mut() else { return };
             let missing_fonts = crate::fonts::ensure_page_fonts(ui.ctx(), &crate::fonts::page_families(&ed.blocks));
@@ -6685,6 +6748,35 @@ impl NoteCraftApp {
                                 }
                                 page_span = Some(span);
                             }
+                            // Insert Space (issue #164): a drag down the page pushes everything that
+                            // starts below where it began, boxes and ink together, down by as far as
+                            // it went; a drag up pulls it back up. One drag, then the tool is put down.
+                            if space_on {
+                                let visible = ui.clip_rect().intersect(viewport.with_max_y(viewport.max.y.max(ui.clip_rect().max.y)));
+                                if let Some((from, by)) = insert_space_overlay(ui.ctx(), visible, &tokens) {
+                                    let z = zoom_scale.max(0.01);
+                                    let (at, by) = ((from - moved.origin.y) / z, by / z);
+                                    let below: Vec<usize> = (0..ed.boxes.len()).filter(|i| ed.boxes.get(*i).is_some_and(|b| b.y >= at)).collect();
+                                    // Room taken away never pulls anything above the top of the page.
+                                    let highest = below.iter().filter_map(|i| ed.boxes.get(*i)).map(|b| b.y).fold(f32::INFINITY, f32::min);
+                                    let by = if by < 0.0 && highest.is_finite() { by.max(-highest) } else { by };
+                                    for i in &below {
+                                        if let Some(b) = ed.boxes.get_mut(*i) {
+                                            *b = notecraft_model::container::Container::new(b.x, b.y + by, b.width, b.blocks);
+                                        }
+                                    }
+                                    if !below.is_empty() && by != 0.0 {
+                                        moved.boxes = true;
+                                    }
+                                    if let Some(pad) = pad.as_mut() {
+                                        ink_changed |= pad.shift_below(at, by);
+                                    }
+                                    space_over = true;
+                                }
+                                if ui.input(|i| i.key_pressed(egui::Key::Escape)) {
+                                    space_over = true;
+                                }
+                            }
                             // The selection box takes ink as well as boxes, as in OneNote, and what
                             // it took moves together: boxes dragged take the ink with them, ink
                             // dragged takes the boxes.
@@ -6944,6 +7036,9 @@ impl NoteCraftApp {
             self.canvas_pan.x = (self.canvas_pan.x + hbar.pan).clamp(-1.0e6, 1.0e6);
             ui.ctx().request_repaint();
         }
+        if space_over {
+            self.space_tool = false;
+        }
         for act in page_acts {
             self.ribbon_act(act);
         }
@@ -8402,6 +8497,8 @@ impl NoteCraftApp {
                 // [left, top, right, bottom] in screen points, or null when everything fits.
                 "horizontalBar": self.page_hbar.map(|(track, _)| [track.min.x, track.min.y, track.max.x, track.max.y]),
                 "horizontalThumb": self.page_hbar.map(|(_, thumb)| [thumb.min.x, thumb.min.y, thumb.max.x, thumb.max.y]),
+                // True while Insert Space is in hand (issue #164).
+                "insertSpace": self.space_tool,
             },
             // How the side panel is arranged: one tree, or the organisers and the pages in
             // columns of their own, with the first one hidden or not.

crates/ui-egui/src/inkpad.rs

@@ -362,6 +362,23 @@ impl Pad {
         (shift != (0.0, 0.0)).then_some(shift)
     }
 
+    /// Insert Space (issue #164): every stroke whose top is at or below `y`, in page points,
+    /// moves down by `dy`, or up when `dy` is negative. True when any moved.
+    pub fn shift_below(&mut self, y: f32, dy: f32) -> bool {
+        if dy == 0.0 || !dy.is_finite() {
+            return false;
+        }
+        let below: Vec<usize> =
+            (0..self.drawing.strokes.len()).filter(|i| pick::bounds(&self.drawing, &[*i]).is_some_and(|(_, top, _, _)| top >= y)).collect();
+        if below.is_empty() {
+            return false;
+        }
+        pick::move_by(&mut self.drawing, &below, 0.0, dy);
+        self.dirty = true;
+        self.touched = true;
+        true
+    }
+
     /// The box round all the ink on the page, in page points.
     pub fn bounds(&self) -> Option<[f32; 4]> {
         let all: Vec<usize> = (0..self.drawing.strokes.len()).collect();

crates/ui-egui/src/ribbon.rs

@@ -101,6 +101,8 @@ pub enum Act {
     ClearFormatting,
     /// Put a tag on the line the caret is in, or take it off again.
     Tag(Tag),
+    /// Take up the Insert Space tool, or put it down (issue #164).
+    InsertSpaceTool,
     /// Open the Tags Summary: the tagged notes, and a way to each of them (issue #166).
     FindTags,
     /// Something OneNote has that NoteCraft does not: say so plainly.
@@ -426,6 +428,8 @@ pub struct View<'a> {
     /// The tools on the rack, and which of them is in hand.
     pub rack: &'a [Nib],
     pub nib: usize,
+    /// True while the Insert Space tool is in hand.
+    pub space_tool: bool,
     /// True while the caret is in a table, which is when the Table tab is offered.
     pub in_table: bool,
     /// Whether the table the caret is in is drawn with lines round its cells.
@@ -1597,8 +1601,9 @@ fn mark_button(ui: &mut Ui, mark: Mark, label: &str, tip: &str, on: bool, t: &To
 /// work is rather than a short list of what happens to exist.
 fn insert_tab(ui: &mut Ui, view: &View<'_>, t: &Tokens, acts: &mut Vec<Act>) {
     group(ui, crate::tl_id!("ui.insert"), t, |ui| {
-        if big(ui, Icon::InsertSpace, crate::tl_id!("ui.insert_space_2"), crate::tl_id!("ui.add_a_blank_paragraph_at_the_caret"), t).clicked() {
-            acts.push(Act::Insert("space"));
+        // OneNote's tool: a drag on the page adds room there, or takes it away (issue #164).
+        if big_on(ui, Icon::InsertSpace, crate::tl_id!("ui.insert_space_2"), crate::tl_id!("ui.insert_space_tip"), view.space_tool, t).clicked() {
+            acts.push(Act::InsertSpaceTool);
         }
     });
     group(ui, crate::tl_id!("ui.tables"), t, |ui| {

crates/ui-egui/tests/ui.rs

@@ -9552,6 +9552,87 @@ fn content_wider_than_the_view_gets_a_horizontal_scroll_bar() {
     }
 }
 
+/// Issue #164: Insert > Insert Space is OneNote's tool. A drag down the page pushes the boxes
+/// and the ink below where it began down by as far as it went; a drag up takes room away; Esc
+/// puts the tool down; Undo puts the boxes back.
+#[test]
+fn insert_space_drags_room_into_the_page_and_out_again() {
+    let (_t, mut app, s) = sample_app("ui-insert-space");
+    let page = s.md_page.to_string_lossy().to_string();
+    app.open_path(&page);
+    let mut h = sized_harness(app, LIGHT, egui::vec2(1400.0, 1000.0));
+    settle(&mut h);
+    let blocks = ask(&mut h, "ui.inspect", json!({})).expect("inspect").pointer("/page/blocks").and_then(Value::as_u64).unwrap_or(0);
+    assert!(blocks > 3, "the sample page has blocks to split: {blocks}");
+    ask(
+        &mut h,
+        "engine.execute",
+        json!({"command": "page.containers", "params": {"path": page.clone(), "boxes": format!("40,20,320,3;40,500,320,{}", blocks - 3)}}),
+    )
+    .expect("two boxes");
+    ask(&mut h, "ui.open", json!({"path": page.clone()})).expect("open");
+    settle(&mut h);
+    let boxes = |h: &mut Harness<'_, NoteCraftApp>| {
+        let v = ask(h, "ui.inspect", json!({})).expect("inspect");
+        let y = |i: usize| v.pointer(&format!("/page/containers/{i}/y")).and_then(Value::as_f64).unwrap_or(-1.0);
+        (y(0), y(1))
+    };
+    let tool =
+        |h: &mut Harness<'_, NoteCraftApp>| ask(h, "ui.inspect", json!({})).expect("inspect").pointer("/canvas/insertSpace").and_then(Value::as_bool);
+    assert_eq!(boxes(&mut h), (20.0, 500.0));
+    let origin = page_origin(&mut h);
+
+    // Ink under the line moves with the boxes; the pen is put down again before the tool.
+    h.get_by_label("Draw").click();
+    settle(&mut h);
+    h.get_by_label("Pen red").click();
+    settle(&mut h);
+    drag_by(&mut h, origin + egui::vec2(500.0, 420.0), egui::vec2(80.0, 0.0));
+    let ink_top = |h: &mut Harness<'_, NoteCraftApp>| {
+        ask(h, "ui.inspect", json!({})).expect("inspect").pointer("/ink/bounds/1").and_then(Value::as_f64).expect("ink bounds")
+    };
+    let ink_before = ink_top(&mut h);
+    h.get_by_label("Insert").click();
+    settle(&mut h);
+    assert_eq!(tool(&mut h), Some(false));
+    h.get_by_label("Insert Space").click();
+    settle(&mut h);
+    assert_eq!(tool(&mut h), Some(true), "the tool is in hand");
+    assert_eq!(ask(&mut h, "ui.inspect", json!({})).expect("inspect").pointer("/ink/pointer").and_then(Value::as_str), Some("write"));
+
+    // Down 100 points from between the boxes: the lower box and the ink move, the upper box stays.
+    drag_by(&mut h, origin + egui::vec2(600.0, 300.0), egui::vec2(0.0, 100.0));
+    assert_eq!(boxes(&mut h), (20.0, 600.0), "room was added above the lower box");
+    assert!((ink_top(&mut h) - (ink_before + 100.0)).abs() < 1.0, "the ink below moved with it");
+    assert_eq!(tool(&mut h), Some(false), "one drag, then the tool is put down");
+    review(&mut h, "insert_space_added");
+    let kept = ask(&mut h, "engine.execute", json!({"command": "page.containers", "params": {"path": page.clone()}})).expect("layout");
+    assert!(kept.as_str().unwrap_or_default().contains("40,600,320"), "the page keeps the new place: {kept}");
+
+    // Undo puts the box back where it was.
+    ask(&mut h, "ui.undo", json!({})).expect("undo");
+    settle(&mut h);
+    assert_eq!(boxes(&mut h).1, 500.0, "undo takes the room back out");
+    ask(&mut h, "ui.redo", json!({})).expect("redo");
+    settle(&mut h);
+    assert_eq!(boxes(&mut h).1, 600.0);
+
+    // Up 150 points from just above the lower box: the room is taken away again.
+    h.get_by_label("Insert Space").click();
+    settle(&mut h);
+    drag_by(&mut h, origin + egui::vec2(600.0, 590.0), egui::vec2(0.0, -150.0));
+    assert_eq!(boxes(&mut h), (20.0, 450.0), "room was taken away");
+
+    // Esc puts the tool down without changing anything.
+    h.get_by_label("Insert Space").click();
+    settle(&mut h);
+    assert_eq!(tool(&mut h), Some(true));
+    ask(&mut h, "ui.key", json!({"key": "Escape"})).expect("Escape");
+    settle(&mut h);
+    assert_eq!(tool(&mut h), Some(false), "Esc puts the tool down");
+    assert_eq!(boxes(&mut h), (20.0, 450.0));
+}
+
 /// Issue #44: Alt and a number pick up that pen on the rack, from anywhere, so a tablet's express
 /// keys can be bound to pens; Alt+0 goes back to typing. A Mac's Option+digit character is not
 /// typed into the note.

docs/gaps.md

@@ -465,7 +465,12 @@ Playground hosts with the Files API continue using their existing persistence pa
   picture, a link, the three time stamps, an equation, a symbol picker, insert space, and
   NoteCraft's own Mermaid diagram. File printout, screen clipping, online video,
   transcription, recording, page templates and stickers remain unbuilt. Spreadsheet is
-  available through the existing GridCraft integration when installed.
+  available through the existing GridCraft integration when installed. Insert Space is
+  OneNote's tool: with it in hand, a drag down the page moves every box and every stroke of
+  ink that starts below where the drag began down by as far as it went, and a drag up moves
+  them up, never past the top of the page; a guide shows the line and the band of room, Esc
+  puts the tool down, and one drag is one step of Undo. It moves boxes, as OneNote moves its
+  containers: it does not open a gap between two lines inside one box.
 - **Unread and author history** are not built. Page version
   history stores snapshots of the page's main file; changes to attached files and drawings
   are not captured by those snapshots. (Tags are: to-do boxes and the other familiar marks,

i18n/ar-XB.tsv

@@ -882,5 +882,7 @@
 @id	ui.no_tagged_notes_here	[[RLI]]$$$No tagged notes here.@@@[[PDI]]
 @id	ui.tags_empty_line	[[RLI]]$$$(an empty line)@@@[[PDI]]
 @id	ui.scroll_the_page_sideways	[[RLI]]$$$Scroll the page sideways@@@[[PDI]]
+@id	ui.insert_space_tip	[[RLI]]$$$Drag down the page to add room, or up to take it away@@@[[PDI]]
+@id	ui.insert_space_how	[[RLI]]$$$Drag down where you want more room, or up to take room away. Esc puts the tool down.@@@[[PDI]]
 @id	ui.pen_keys_typing	[[RLI]]$$$Typing (Alt+0)@@@[[PDI]]
 @id	ui.pen_keys_picked	[[RLI]]$$$Pen {number} (Alt+{number})@@@[[PDI]]

i18n/en-XA.tsv

@@ -882,5 +882,7 @@
 @id	ui.no_tagged_notes_here	$$$No tagged notes here.@@@
 @id	ui.tags_empty_line	$$$(an empty line)@@@
 @id	ui.scroll_the_page_sideways	$$$Scroll the page sideways@@@
+@id	ui.insert_space_tip	$$$Drag down the page to add room, or up to take it away@@@
+@id	ui.insert_space_how	$$$Drag down where you want more room, or up to take room away. Esc puts the tool down.@@@
 @id	ui.pen_keys_typing	$$$Typing (Alt+0)@@@
 @id	ui.pen_keys_picked	$$$Pen {number} (Alt+{number})@@@

i18n/en.tsv

@@ -882,5 +882,7 @@
 @id	ui.no_tagged_notes_here	No tagged notes here.
 @id	ui.tags_empty_line	(an empty line)
 @id	ui.scroll_the_page_sideways	Scroll the page sideways
+@id	ui.insert_space_tip	Drag down the page to add room, or up to take it away
+@id	ui.insert_space_how	Drag down where you want more room, or up to take room away. Esc puts the tool down.
 @id	ui.pen_keys_typing	Typing (Alt+0)
 @id	ui.pen_keys_picked	Pen {number} (Alt+{number})