Replace grid BG with dots

src/app.rs

@@ -635,7 +635,6 @@ impl App {
                     self.view.zoom_to_selection(&self.doc.canvas);
                 }
                 ui.separator();
-                ui.checkbox(&mut self.view.show_grid, "Show grid");
                 ui.checkbox(&mut self.view.snap_to_grid, "Snap to grid");
                 ui.checkbox(&mut self.show_inspector, "Inspector");
                 ui.checkbox(&mut self.dark_mode, "Dark mode");
@@ -715,7 +714,6 @@ impl App {
             ui.with_layout(egui::Layout::right_to_left(egui::Align::Center), |ui| {
                 ui.toggle_value(&mut self.show_inspector, "Inspector");
                 ui.toggle_value(&mut self.view.snap_to_grid, "Snap");
-                ui.toggle_value(&mut self.view.show_grid, "Grid");
                 let icon = if self.dark_mode { "Light theme" } else { "Dark theme" };
                 if ui.button(icon).on_hover_text("Switch theme").clicked() {
                     self.dark_mode = !self.dark_mode;

src/view.rs

@@ -26,6 +26,12 @@ const MIN_ZOOM: f32 = 0.05;
 const MAX_ZOOM: f32 = 3.0;
 /// Spacing of the background grid, in canvas units.
 const GRID: f32 = 20.0;
+/// Every this many dots the background gets a heavier one.
+const MAJOR: f32 = 5.0;
+/// Radius of a background dot, in screen pixels.
+const DOT_RADIUS: f32 = 0.9;
+/// Radius of a heavier background dot, in screen pixels.
+const DOT_RADIUS_MAJOR: f32 = 1.5;
 /// How close the pointer has to be to an edge to hit it, in screen pixels.
 const EDGE_HIT_RADIUS: f32 = 8.0;
 /// Size of the resize/connect handles, in screen pixels.
@@ -239,7 +245,6 @@ pub struct CanvasView {
     hovered_node: Option<String>,
     /// Node whose connect handles are on screen, held still during a drag.
     connect_target: Option<String>,
-    pub show_grid: bool,
     pub snap_to_grid: bool,
     pub previews: PreviewCache,
     /// How far each node's contents are scrolled, and how far they can go.
@@ -287,7 +292,6 @@ impl CanvasView {
             hovered_edge: None,
             hovered_node: None,
             connect_target: None,
-            show_grid: true,
             snap_to_grid: false,
             previews: PreviewCache::default(),
             body_scroll: HashMap::new(),
@@ -615,9 +619,7 @@ impl CanvasView {
 
         ui.ctx().set_transform_layer(layer, self.to_global);
 
-        if self.show_grid {
-            self.paint_grid(&scene, visible, palette);
-        }
+        self.paint_grid(&scene, visible, palette);
         // Groups are painted first so they cannot cover the edges, which in
         // turn run underneath the nodes they connect.
         let mut interactions =
@@ -710,33 +712,37 @@ impl CanvasView {
     // -- painting ---------------------------------------------------------
 
     fn paint_grid(&self, ui: &egui::Ui, visible: Rect, palette: &Palette) {
-        // Below this the grid turns into noise, so it is skipped.
-        if self.to_global.scaling < 0.35 {
+        // Zoomed out far enough the dots crowd into noise, so only every fifth
+        // one is kept; below that they are dropped altogether.
+        let scale = self.to_global.scaling;
+        let step = if GRID * scale < 10.0 { GRID * MAJOR } else { GRID };
+        if step * scale < 6.0 {
             return;
         }
         let painter = ui.painter();
-        let thin = Stroke::new(1.0 / self.to_global.scaling, palette.grid);
-        let thick = Stroke::new(1.0 / self.to_global.scaling, palette.grid_strong);
+        // The dots keep the same size on screen whatever the zoom is.
+        let radius = DOT_RADIUS / scale;
+        let radius_major = DOT_RADIUS_MAJOR / scale;
+        // A dot lands on a multiple of this wherever the paper is emphasised.
+        let major = GRID * MAJOR;
+        let on_major = |v: f32| (v / major).fract().abs() < 1e-3;
 
-        let first_x = (visible.left() / GRID).floor() * GRID;
+        let first_x = (visible.left() / step).floor() * step;
+        let first_y = (visible.top() / step).floor() * step;
         let mut x = first_x;
         while x <= visible.right() {
-            let stroke = if (x / (GRID * 5.0)).fract().abs() < 1e-3 { thick } else { thin };
-            painter.line_segment(
-                [pos2(x, visible.top()), pos2(x, visible.bottom())],
-                stroke,
-            );
-            x += GRID;
-        }
-        let first_y = (visible.top() / GRID).floor() * GRID;
-        let mut y = first_y;
-        while y <= visible.bottom() {
-            let stroke = if (y / (GRID * 5.0)).fract().abs() < 1e-3 { thick } else { thin };
-            painter.line_segment(
-                [pos2(visible.left(), y), pos2(visible.right(), y)],
-                stroke,
-            );
-            y += GRID;
+            let major_x = on_major(x);
+            let mut y = first_y;
+            while y <= visible.bottom() {
+                let (radius, color) = if major_x && on_major(y) {
+                    (radius_major, palette.grid_strong)
+                } else {
+                    (radius, palette.grid)
+                };
+                painter.circle_filled(pos2(x, y), radius, color);
+                y += step;
+            }
+            x += step;
         }
     }