Render a ghost stone over the current cursor location

flake.lock

@@ -17,11 +17,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1678972866,
+        "lastModified": 1680122840,
-        "narHash": "sha256-YV8BcNWfNVgS449B6hFYFUg4kwVIQMNehZP+FNDs1LY=",
+        "narHash": "sha256-zCQ/9iFHzCW5JMYkkHMwgK1/1/kTMgCMHq4THPINpAU=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "cd34d6ed7ba7d5c4e44b04a53dc97edb52f2766c",
+        "rev": "a575c243c23e2851b78c00e9fa245232926ec32f",
         "type": "github"
       },
       "original": {
@@ -52,7 +52,7 @@
         "nixpkgs": "nixpkgs_2"
       },
       "locked": {
-        "narHash": "sha256-03Opt2yu4E/AIFjvlgib0/nhMn6B4B/t/nvwS2bzOGw=",
+        "narHash": "sha256-o28gi3WKSsVeXg3wDSR2kGpawrDO5lzGG4eUsLTPglw=",
         "type": "tarball",
         "url": "https://github.com/oxalica/rust-overlay/archive/master.tar.gz"
       },
@@ -70,11 +70,11 @@
     },
     "unstable": {
       "locked": {
-        "lastModified": 1678898370,
+        "lastModified": 1680125544,
-        "narHash": "sha256-xTICr1j+uat5hk9FyuPOFGxpWHdJRibwZC+ATi0RbtE=",
+        "narHash": "sha256-mlqo1r+TZUOuypWdrZHluxWL+E5WzXlUXNZ9Y0WLDFU=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "ac718d02867a84b42522a0ece52d841188208f2c",
+        "rev": "9a6aabc4740790ef3bbb246b86d029ccf6759658",
         "type": "github"
       },
       "original": {

kifu/kifu-core/src/types.rs

@@ -1,12 +1,12 @@
 use std::time::Duration;
 
-#[derive(Clone, Debug)]
+#[derive(Clone, Copy, Debug)]
 pub enum Color {
     Black,
     White,
 }
 
-#[derive(Clone, Debug)]
+#[derive(Clone, Copy, Debug)]
 pub struct Size {
     pub width: u8,
     pub height: u8,

kifu/kifu-gtk/src/ui/goban.rs

@@ -6,11 +6,18 @@ use std::{cell::RefCell, rc::Rc};
 const WIDTH: i32 = 800;
 const HEIGHT: i32 = 800;
 
-#[derive(Default)]
+#[derive(Clone, Default, PartialEq)]
+struct Addr {
+    row: u8,
+    column: u8,
+}
+
 pub struct GobanPrivate {
     drawing_area: gtk::DrawingArea,
 
+    current_player: Rc<RefCell<Color>>,
     goban: Rc<RefCell<GobanElement>>,
+    cursor_location: Rc<RefCell<Addr>>,
 }
 
 #[glib::object_subclass]
@@ -18,6 +25,15 @@ impl ObjectSubclass for GobanPrivate {
     const NAME: &'static str = "Goban";
     type Type = Goban;
     type ParentType = gtk::Grid;
+
+    fn new() -> GobanPrivate {
+        GobanPrivate {
+            drawing_area: Default::default(),
+            current_player: Rc::new(RefCell::new(Color::Black)),
+            goban: Default::default(),
+            cursor_location: Default::default(),
+        }
+    }
 }
 
 impl ObjectImpl for GobanPrivate {
@@ -26,6 +42,8 @@ impl ObjectImpl for GobanPrivate {
         self.drawing_area.set_height_request(HEIGHT);
 
         let goban = self.goban.clone();
+        let cursor_location = self.cursor_location.clone();
+        let current_player = self.current_player.clone();
         self.drawing_area
             .set_draw_func(move |_, context, width, height| {
                 let goban = goban.borrow();
@@ -72,7 +90,36 @@ impl ObjectImpl for GobanPrivate {
                         };
                     })
                 });
+
+                let cursor = cursor_location.borrow();
+                pen.ghost_stone(context, cursor.row, cursor.column, *current_player.borrow());
             });
+
+        let motion_controller = gtk::EventControllerMotion::new();
+        {
+            let goban = self.goban.clone();
+            let cursor = self.cursor_location.clone();
+            let drawing_area = self.drawing_area.clone();
+            motion_controller.connect_motion(move |_, x, y| {
+                let goban = goban.borrow();
+                let mut cursor = cursor.borrow_mut();
+                let hspace_between = ((WIDTH - 40) as f64) / ((goban.size.width - 1) as f64);
+                let vspace_between = ((HEIGHT - 40) as f64) / ((goban.size.height - 1) as f64);
+
+                let addr = Addr {
+                    column: ((x.round() - 20.) / hspace_between).round() as u8,
+                    row: ((y.round() - 20.) / vspace_between).round() as u8,
+                };
+
+                if *cursor != addr {
+                    println!("redrawing with cursor at {} {}", addr.row, addr.column);
+                    *cursor = addr;
+                    drawing_area.queue_draw();
+                }
+            });
+        }
+
+        self.drawing_area.add_controller(motion_controller);
     }
 }
 impl WidgetImpl for GobanPrivate {}
@@ -93,6 +140,10 @@ impl Goban {
         *self.imp().goban.borrow_mut() = goban;
         self.imp().drawing_area.queue_draw();
     }
+
+    pub fn set_current_player(&self, color: Color) {
+        *self.imp().current_player.borrow_mut() = color;
+    }
 }
 
 struct Pen {
@@ -128,4 +179,19 @@ impl Pen {
         );
         let _ = context.fill();
     }
+
+    fn ghost_stone(&self, context: &cairo::Context, row: u8, col: u8, color: Color) {
+        match color {
+            Color::White => context.set_source_rgba(0.9, 0.9, 0.9, 0.5),
+            Color::Black => context.set_source_rgba(0.0, 0.0, 0.0, 0.5),
+        };
+        context.arc(
+            20.0 + (col as f64) * self.hspace_between,
+            20.0 + (row as f64) * self.vspace_between,
+            25.0,
+            0.0,
+            2.0 * std::f64::consts::PI,
+        );
+        let _ = context.fill();
+    }
 }

kifu/kifu-gtk/src/ui/playing_field.rs

@@ -82,6 +82,7 @@ impl PlayingField {
         *s.imp().player_card_white.borrow_mut() = Some(player_card_white);
         *s.imp().player_card_black.borrow_mut() = Some(player_card_black);
         *s.imp().chat.borrow_mut() = Some(chat);
+        s.imp().goban.set_current_player(view.current_player);
 
         s
     }