Zoom In/Out shortcuts zoom around the pointer over the canvas (#2075)

crates/ui-egui/src/menus/invoke.rs

@@ -151,9 +151,24 @@ pub fn activate_native(app: &mut DesignApp, ctx: &egui::Context, id: &str, param
     if params.is_null() && app.session.wants_text() && matches!(id, "edit.copy" | "edit.cut" | "edit.paste") && forward_to_text_edit(app, ctx, id) {
         return;
     }
+    // Zoom In/Out by key equivalent: the pointer is still in the window. A click in the menu bar
+    // takes it out, so that zooms around the centre.
+    if params.is_null()
+        && let Some(p) = pointer_zoom_params(ctx, id)
+    {
+        activate(app, id, &p);
+        return;
+    }
     activate(app, id, params);
 }
 
+/// Zoom In/Out from a key: the pointer's position (`at`), so the zoom keeps the point under it
+/// when it is over the canvas. `None` for other commands or with no pointer in the window.
+pub(super) fn pointer_zoom_params(ctx: &egui::Context, id: &str) -> Option<Value> {
+    let at = ctx.pointer_hover_pos()?;
+    matches!(id, "view.zoomIn" | "view.zoomOut").then(|| json!({"at": [at.x, at.y]}))
+}
+
 /// The editing commands a focused text field takes from the native menu bar.
 pub(super) const TEXT_FIELD_COMMANDS: [&str; 6] = ["edit.selectAll", "edit.copy", "edit.cut", "edit.paste", "edit.undo", "edit.redo"];
 

crates/ui-egui/src/menus/keys.rs

@@ -1,4 +1,4 @@
-use super::invoke::activate;
+use super::invoke::{activate, pointer_zoom_params};
 use super::{DesignApp, ScreenMode, Value, json};
 
 /// The command a paste event stands for besides plain Paste. egui-winit turns every ⌘+V chord into
@@ -39,7 +39,7 @@ pub fn shortcuts(app: &mut DesignApp, ctx: &egui::Context) {
     }
     let typing = app.session.wants_text();
     let keys = ctx.input_mut(|i| take_keys(app, i, typing));
-    run_keys(app, keys, typing);
+    run_keys(app, ctx, keys, typing);
 }
 
 /// Keys that a floating panel in its own OS window left over (craft-ui's
@@ -59,7 +59,7 @@ pub fn forwarded_shortcuts(app: &mut DesignApp, ctx: &egui::Context, events: Vec
     input.events = events;
     input.modifiers = modifiers;
     let keys = take_keys(app, &mut input, typing);
-    run_keys(app, keys, typing);
+    run_keys(app, ctx, keys, typing);
     crate::canvas::forwarded_keys(app, input.events, modifiers);
 }
 
@@ -112,7 +112,7 @@ fn take_keys(app: &mut DesignApp, input: &mut egui::InputState, typing: bool) ->
 }
 
 /// Runs what [`take_keys`] took, then Esc's return to the Selection tool.
-fn run_keys(app: &mut DesignApp, keys: Keys, typing: bool) {
+fn run_keys(app: &mut DesignApp, ctx: &egui::Context, keys: Keys, typing: bool) {
     for step in keys.presentation {
         match step {
             None => {
@@ -138,7 +138,11 @@ fn run_keys(app: &mut DesignApp, keys: Keys, typing: bool) {
             app.select_tool(&tool);
         } else {
             // Like choosing the menu item: "…" commands open their dialog.
-            activate(app, &hit.command.id, &hit.command.params);
+            // Zoom In/Out by key zoom around the pointer while it is over the canvas.
+            match pointer_zoom_params(ctx, &hit.command.id) {
+                Some(p) => activate(app, &hit.command.id, &p),
+                None => activate(app, &hit.command.id, &hit.command.params),
+            }
         }
     }
     // Esc with no shortcut of its own goes back to the Selection tool.

crates/ui-egui/src/menus/run.rs

@@ -575,7 +575,11 @@ fn run_ui_part3(app: &mut DesignApp, id: &str, p: &Value) -> Option<Result<Value
     Some(match id {
         "view.zoomIn" | "view.zoomOut" => {
             if let Some(r) = rect {
-                crate::canvas::zoom_at(app, r.center(), if id == "view.zoomIn" { 1.5 } else { 1.0 / 1.5 });
+                // A keyboard zoom names the pointer ("at"); it counts only over the canvas.
+                let xy = p.get("at").and_then(Value::as_array).map(|a| a.iter().filter_map(Value::as_f64).collect::<Vec<_>>());
+                let at = xy.filter(|v| v.len() == 2).map(|v| egui::pos2(v[0] as f32, v[1] as f32));
+                let at = at.filter(|at| r.contains(*at)).unwrap_or_else(|| r.center());
+                crate::canvas::zoom_at(app, at, if id == "view.zoomIn" { 1.5 } else { 1.0 / 1.5 });
             }
             Ok(Value::Null)
         }

crates/ui-egui/src/menus/tests.rs

@@ -3152,3 +3152,70 @@ fn file_menu_ends_with_quit_but_the_macos_menu_bar_leaves_it_to_the_app_menu() {
     let file_items = native.iter().find(|(t, _)| *t == "File").map(|(_, e)| e);
     assert!(!matches!(file_items.and_then(|e| e.last()), Some(Item::Sep)), "no separator left at the end of File");
 }
+
+#[test]
+fn zoom_commands_zoom_around_the_pointer_when_it_is_over_the_canvas() {
+    let mut app = crate::DesignApp::new(designcraft_engine::Session::new(), crate::Services::default());
+    app.session.execute("file.new", &json!({})).unwrap();
+    let ctx = egui::Context::default();
+    let frame = |app: &mut crate::DesignApp, events: Vec<egui::Event>| {
+        let input = egui::RawInput {
+            screen_rect: Some(egui::Rect::from_min_size(egui::Pos2::ZERO, egui::vec2(1400.0, 900.0))),
+            events,
+            ..Default::default()
+        };
+        let mut out = ctx.run_ui(input, |ui| {
+            app.logic(&ui.ctx().clone());
+            app.ui(ui);
+        });
+        out.textures_delta.clear();
+    };
+    frame(&mut app, vec![]);
+    frame(&mut app, vec![]);
+    let rect = app.canvas_rect.unwrap();
+    let pointer = rect.center() + egui::vec2(200.0, 120.0);
+    let under = |app: &crate::DesignApp, at: egui::Pos2| crate::canvas::Xf::new(app.canvas_rect.unwrap(), app.view().unwrap()).to_canvas(at);
+    let before = under(&app, pointer);
+    let zoom = app.view().unwrap().zoom;
+
+    // The command with a pointer position keeps the point under it fixed.
+    app.run("view.zoomIn", json!({"at": [pointer.x, pointer.y]})).unwrap();
+    assert!(app.view().unwrap().zoom > zoom);
+    let after = under(&app, pointer);
+    assert!((after.x - before.x).abs() < 1e-3 && (after.y - before.y).abs() < 1e-3);
+    app.run("view.zoomOut", json!({"at": [pointer.x, pointer.y]})).unwrap();
+    let after = under(&app, pointer);
+    assert!((after.x - before.x).abs() < 1e-3 && (after.y - before.y).abs() < 1e-3);
+
+    // A position outside the canvas (or none: the menu) zooms around the centre.
+    let centre = under(&app, rect.center());
+    app.run("view.zoomIn", json!({"at": [-50.0, -50.0]})).unwrap();
+    let kept = under(&app, rect.center());
+    assert!((kept.x - centre.x).abs() < 1e-3 && (kept.y - centre.y).abs() < 1e-3);
+    app.run("view.zoomIn", json!({})).unwrap();
+    let kept = under(&app, rect.center());
+    assert!((kept.x - centre.x).abs() < 1e-3 && (kept.y - centre.y).abs() < 1e-3);
+
+    // The keyboard shortcut uses the pointer.
+    app.run("view.zoom", json!({"zoom": 1.0})).unwrap();
+    let before = under(&app, pointer);
+    frame(&mut app, vec![egui::Event::PointerMoved(pointer)]);
+    let key = egui::Event::Key { key: egui::Key::Equals, physical_key: None, pressed: true, repeat: false, modifiers: egui::Modifiers::COMMAND };
+    frame(&mut app, vec![key]);
+    assert!(app.view().unwrap().zoom > 1.0);
+    let after = under(&app, pointer);
+    assert!((after.x - before.x).abs() < 1e-3 && (after.y - before.y).abs() < 1e-3);
+
+    // The native menu bar's key equivalent (macOS) leaves the pointer in the window and uses it.
+    app.run("view.zoom", json!({"zoom": 1.0})).unwrap();
+    let before = under(&app, pointer);
+    native_frame(&mut app, &ctx, vec![egui::Event::PointerMoved(pointer)], Some("view.zoomIn"));
+    assert!(app.view().unwrap().zoom > 1.0);
+    let after = under(&app, pointer);
+    assert!((after.x - before.x).abs() < 1e-3 && (after.y - before.y).abs() < 1e-3);
+    // A click in the menu bar takes the pointer out of the window: the centre stays.
+    let centre = under(&app, rect.center());
+    native_frame(&mut app, &ctx, vec![egui::Event::PointerGone], Some("view.zoomOut"));
+    let kept = under(&app, rect.center());
+    assert!((kept.x - centre.x).abs() < 1e-3 && (kept.y - centre.y).abs() < 1e-3);
+}

crates/ui-egui/src/menus/ui_commands.rs

@@ -178,8 +178,8 @@ pub const UI_COMMANDS: &[(&str, &str, Option<&str>, &str)] = &[
     ("app.paragraphStylesPanel", "Paragraph Styles", Some("Cmd+F11"), "{} — the Paragraph Styles panel"),
     ("app.insertCurrentPageNumber", "Current Page Number", Some("Cmd+Alt+Shift+N"), "{} — the Current Page Number marker at the insertion point"),
     ("app.storyEditor", "Edit in Story Editor", Some("Cmd+Y"), "{story?}"),
-    ("view.zoomIn", "Zoom In", Some("Cmd+="), "{}"),
-    ("view.zoomOut", "Zoom Out", Some("Cmd+-"), "{}"),
+    ("view.zoomIn", "Zoom In", Some("Cmd+="), "{at?: [x, y] window pixels, kept in place when over the canvas}"),
+    ("view.zoomOut", "Zoom Out", Some("Cmd+-"), "{at?: [x, y] window pixels, kept in place when over the canvas}"),
     ("view.fitPage", "Fit Page in Window", Some("Cmd+0"), "{}"),
     ("view.fitSelection", "Fit Selection in Window", Some("Cmd+Alt+="), "{}"),
     ("view.fitSpread", "Fit Spread in Window", Some("Cmd+Alt+0"), "{}"),