Merge pull request #769 from storytold/fix/740-move-snaps-to-grid

Fix #740: moved art snaps to the grid

ROADMAP.md

@@ -140,7 +140,7 @@ grade by behaviour against `plan/illustrator/`, not by whether a menu item exist
   - **Panel drag and drop:** art dragged off the canvas onto the Symbols panel becomes a symbol, onto the Swatches panel a pattern swatch and onto the Brushes panel an Art brush; a symbol dragged onto the canvas places an instance where it is dropped, and a brush dragged onto a path is applied to it.
   - **Tool double-clicks:** double-clicking a tool's button opens its options: Hand fits the artboard in the window, Zoom shows 100 %, Rotate, Scale, Reflect and Shear open their Object › Transform dialogs, the Selection, Direct Selection and Group Selection tools the Move dialog (Enter opens these seven tools' dialogs too), Gradient, Eyedropper, Blend and the Liquify tools their panels or options, and the Pencil, Paintbrush, Smooth, Blob Brush and Eraser tools their Tool Options (Fidelity, fill, the tolerances, the brush size).
 - **Layers panel:** every layer, sublayer, group and object is a clickable row at any depth: a click highlights it and makes its layer current (new art goes there), Shift-click a range, Ctrl/Cmd-click toggles. Sublayers are no longer treated as objects: clicks, marquees, Select All and the Select menu take the art inside them, and each sublayer selects in its own colour. Selection squares on rows with selected art (click selects a row's art, Shift adds or removes; dragging the square moves the selection to another row, Alt copies), the eye and lock on every row with drag-down-the-column (one undo step), Ctrl/Cmd-click an eye for per-layer Outline, Alt-click an eye or lock to hide or lock the other layers (again: show or unlock them all), triangles with Alt to open or close everything inside, drag and drop rows above, below or into layers and groups with a drop line (Alt copies) and a dimmed copy of the row under the pointer (dropped on the trash rows are deleted, on New Layer duplicated, as in Illustrator), inline rename, Delete key on highlighted rows. Buttons and the full panel menu: New Layer/Sublayer (Alt: options, Ctrl: on top), Duplicate, Delete, Options for Selection, clipping mask, isolation, Locate Object, Merge Selected, Flatten Artwork, Collect in New Layer, Release to Layers (Sequence and Build), Reverse Order, Template, Hide/Outline/Lock Others and Show/Preview/Unlock All, Paste Remembers Layers, Panel Options (row size, thumbnails per kind, Show Layers Only). Layer Options: name, colour (presets, each with a chip of its colour, or custom), Template, Lock, Show, Print, Preview (outline drawing and clicking) and Dim Images to %. Every operation is a command (`layer.move`, `layer.highlight`, `layer.merge`…) with validation against cycles and invalid nesting. A document opens with only its top-level layers open; the rows left open are saved in the native file (nothing is written for the default) and reopen that way. Only the rows scrolled into view are laid out, from a row list made once per change: a layer of 5,000 groups of 10 paths, all open, draws the panel in 0.4 ms a frame instead of about 29 s (#638).
-- **Drawing aids:** Smart Guides and snapping (moving, with the Selection, Group Selection or Direct Selection tool, and resizing by the bounding-box handles with the Selection or Free Transform tool, Shift and Alt too: the dragged corner or side lands on the other objects' anchors and centres ("anchor", "center") or lines up with their edges and centres (a line and "align"); with Smart Guides › Spacing Guides, a moved selection that lines up with nothing along an axis lands as far from its neighbour as two other objects of its row or column are apart, or halfway between its two neighbours, the equal gaps marked; the Rotate, Scale, Shear and Reflect tools drag from the anchor they grab and snap the pointer the same way, so a corner dragged onto another object's anchor scales exactly onto it, #482; anchors dragged with Direct Selection: the one pressed on lands on other anchors, its own path's that stay put among them, on path segments or in line with them, the others following, Shift keeps 45° steps, and with Smart Guides off Snap to Point pulls it onto anchors; the Artboard tool snaps artboards, and their bleed, to other artboards, bleeds and art, the grid or whole pixels while moving, copying and resizing them, and the Transform panel shows and edits the active artboard's X/Y/W/H; drawn points, #506: hovering shows where the press goes, the point lands on the other objects' anchors, centres and paths ("anchor", "center", "path") or lines up with their anchors, edges and centres ("align"), the Pen's on the path being drawn too, near a construction guide through the anchor before it on that guide (Preferences › Smart Guides › Construction Guides and Angles), and with Shift kept to its 45° step or a square's diagonal it slides along that way into line; the targets are gathered once per document state, from the art in the window, and the anchors, centres and lines near the pointer are found by bisection, so hovering never rescans the document), guides dragged out of the rulers (#451: they snap as moved guides do, Shift to the ruler's ticks; with the Artboard tool they are artboard guides, which run across their artboard only and move, copy and delete with it, `guide.add {artboard}`) that the Selection, Direct Selection and Group Selection tools then pick and drag (#414: the selected guides highlight and move together, Alt copies them, Shift snaps the dragged one to the ticks, otherwise it snaps to pixels, the grid or the edges, centres (so the sides' midpoints) and anchors of the art and the artboards, or with Smart Guides off Snap to Point pulls it onto anchors; the arrow keys nudge them, Delete deletes them, dragging one back onto its ruler deletes it, Lock Guides and Hide Guides leave them alone; `guide.list`, `guide.select`, `guide.move` and `guide.remove` reach agents), a right-click on either ruler or the origin box to pick the document's units (the current one checked; `document.setUnits`, one undo step, #528), and Draw Normal / Behind / Inside modes.
+- **Drawing aids:** Smart Guides and snapping (moving, with the Selection, Group Selection or Direct Selection tool, and resizing by the bounding-box handles with the Selection or Free Transform tool, Shift and Alt too: the dragged corner or side lands on the other objects' anchors and centres ("anchor", "center") or lines up with their edges and centres (a line and "align"); with Smart Guides › Spacing Guides, a moved selection that lines up with nothing along an axis lands as far from its neighbour as two other objects of its row or column are apart, or halfway between its two neighbours, the equal gaps marked; with View › Snap to Grid on, a moved selection lands on the grid instead, by whichever of its edges or its centre is nearest a gridline on each axis, #740; the Rotate, Scale, Shear and Reflect tools drag from the anchor they grab and snap the pointer the same way, so a corner dragged onto another object's anchor scales exactly onto it, #482; anchors dragged with Direct Selection: the one pressed on lands on other anchors, its own path's that stay put among them, on path segments or in line with them, the others following, Shift keeps 45° steps, and with Smart Guides off Snap to Point pulls it onto anchors; the Artboard tool snaps artboards, and their bleed, to other artboards, bleeds and art, the grid or whole pixels while moving, copying and resizing them, and the Transform panel shows and edits the active artboard's X/Y/W/H; drawn points, #506: hovering shows where the press goes, the point lands on the other objects' anchors, centres and paths ("anchor", "center", "path") or lines up with their anchors, edges and centres ("align"), the Pen's on the path being drawn too, near a construction guide through the anchor before it on that guide (Preferences › Smart Guides › Construction Guides and Angles), and with Shift kept to its 45° step or a square's diagonal it slides along that way into line; the targets are gathered once per document state, from the art in the window, and the anchors, centres and lines near the pointer are found by bisection, so hovering never rescans the document), guides dragged out of the rulers (#451: they snap as moved guides do, Shift to the ruler's ticks; with the Artboard tool they are artboard guides, which run across their artboard only and move, copy and delete with it, `guide.add {artboard}`) that the Selection, Direct Selection and Group Selection tools then pick and drag (#414: the selected guides highlight and move together, Alt copies them, Shift snaps the dragged one to the ticks, otherwise it snaps to pixels, the grid or the edges, centres (so the sides' midpoints) and anchors of the art and the artboards, or with Smart Guides off Snap to Point pulls it onto anchors; the arrow keys nudge them, Delete deletes them, dragging one back onto its ruler deletes it, Lock Guides and Hide Guides leave them alone; `guide.list`, `guide.select`, `guide.move` and `guide.remove` reach agents), a right-click on either ruler or the origin box to pick the document's units (the current one checked; `document.setUnits`, one undo step, #528), and Draw Normal / Behind / Inside modes.
 - **Views:** the status bar's artboard navigator (first, previous, next, last; `view.goToArtboard`) goes to an artboard and fits it, and Fit Artboard in Window and Actual Size show the navigator's artboard. The Artboards panel highlights that active artboard: clicking a row makes it active (the Artboard tool's too, while it is chosen) as does clicking an artboard with the Artboard tool, double-clicking its number also fits it in the window and double-clicking its name renames it. Duplicate Artboards, or a row dragged onto New Artboard, copies the artboard with its art (#446). Escape leaves Presentation Mode, F from it goes back to Normal Screen Mode, and the screen mode isn't saved with the preferences: the app always starts in Normal Screen Mode with its menus and panels (#472). View › Pixel Preview shows the art as the document pixels it rasterizes to, one per point and hard-edged when magnified, turning with a rotated view (it used to draw the smooth vectors, with only the pixel grid over them).
 - **Geometry and effects:**
   - Pathfinder (10 exact curve booleans), Offset, Outline Stroke, Simplify, Clean Up, Split Into Grid, Divide Objects Below. Object › Path › Remove Anchor Points (`path.removeAnchors`) removes the direct-selected anchors without opening their paths (the Delete key still deletes them with their segments): the neighbours keep their handle directions and their facing handles are refitted so one cubic follows the two old segments, and straight sides stay straight. The Delete Anchor Point tool uses the same refit. The Control bar, the contextual task bar, the Properties quick actions and the canvas context menu offer it when anchors are selected. With anchors selected, the Control bar and the Properties panel also convert them to corner or smooth (`path.convertAnchors`), connect end points (Join) and cut the path at them (`path.cutAtAnchors`, also on the task bar and the context menu): a closed path opens there and an open one becomes one path per piece, each cut leaving one of its two coincident anchors selected so a drag pulls the path apart.
@@ -225,7 +225,7 @@ about 1–1.5 agent-hours each, so the other rows (estimated on the older scale)
 | Image Trace, graphs, image tools | 3 | 70% | graph Design/Column/Marker, Create Object Mosaic, Crop Image polish (an on-canvas crop box), per-feature stroke/fill choice and varying widths in Image Trace's Create Strokes (Vector Halftone and the Image Trace View modes, Palette and Create Strokes are done) | 6–10 |
 | Layers, artboards, document setup | 5 | 82% | Layers panel: a confirmation before deleting layers that hold art, Collect for Export, row context menus, the Layer Options dialog for several rows with mixed values, Paste Remembers Layers for sublayers, drag-scrolling a long panel while dragging rows; artboard preset polish (Rearrange All Artboards, Document Setup, New Document and the rest of the Layers panel are done) | 4–7 |
 | View & navigation | 3 | 70% | New View/Edit Views, multiple windows/arrange, Snap to Pixel/Glyph (print tiling is done) | 9–14 |
-| Guides, grids, smart guides, snapping, rulers | 3 | 85% | global/video rulers, Spacing Guides' distance readouts and spacing for resized or drawn art, Smart Guides' angle and distance readouts while drawing, Alt swapping a ruler guide's orientation, ruler guides selected together with art (marquee, Shift-click), ruler guides as Layers rows with their own lock and hide (#451: Lock Guides locks them all; Make Guides paths are Layers rows already) (dragging existing guides is done, #414; new guides snapping to side midpoints and artboards, and artboard guides, #451; the drawing tools snapping, with Construction Guides, #506; Spacing Guides for moves, #394) | 2–4 |
+| Guides, grids, smart guides, snapping, rulers | 3 | 85% | global/video rulers, Spacing Guides' distance readouts and spacing for resized or drawn art, Smart Guides' angle and distance readouts while drawing, Alt swapping a ruler guide's orientation, ruler guides selected together with art (marquee, Shift-click), ruler guides as Layers rows with their own lock and hide (#451: Lock Guides locks them all; Make Guides paths are Layers rows already) (dragging existing guides is done, #414; new guides snapping to side midpoints and artboards, and artboard guides, #451; the drawing tools snapping, with Construction Guides, #506; Spacing Guides for moves, #394; moves snapping to the grid, #740) | 2–4 |
 | File formats | 6 | 85% | Affinity export, and the rest of Affinity import (effects, adjustments, brushes, master pages, live symbol instances), DWG (no open spec: DXF instead), PSD placement as layers, EPS checked against more real files users send (Inkscape files open as vectors; other generators' constructs are tested with programs written from the PostScript Language Reference only; CID-keyed CJK type and `CCITTFaxDecode` images not read), legacy `.ai` files saved without the prolog that defines their operators (their own operator set isn't read yet), the rest of Illustrator's editing data (area type and type on a path, appearances and live effects, symbols, pattern fills, brushes, placed files: #637), the remaining fidelity polish; EPS, DXF, EMF/WMF, TIFF, BMP, Targa, PSD export, SVGZ, PDF security, PDF/X, PDF layers, presets and Affinity import are done | 6–10 (existing scope; Affinity export unestimated) |
 | Export for Screens, Asset Export, slices, Save for Web | 3 | 85% | polish only (all four are done) | 2–4 |
 | Print, colour management, separations, flattener | 3 | 80% | print preview fidelity (flattener presets in PDF and print, overprint in PDF and composite print, Print dialog, presets, PostScript, marks, separations, Print Tiling, print overprint/flattener/bitmap options and printer profile are done) | 1–2 |

crates/tools/src/select.rs

@@ -73,9 +73,10 @@ pub struct SelectionTool {
     guide: GuideEdit,
 }
 
-/// Snapping for the selection moved as a whole, its targets gathered when the move begins: Smart
-/// Guides line its bounds up with the other art; with them off, View → Snap to Point lands the
-/// point it was grabbed by on an anchor or a ruler guide; Snap to Pixel puts its top-left on whole
+/// Snapping for the selection moved as a whole, its targets gathered when the move begins: View →
+/// Snap to Grid lands its bounds on the grid (#740), taking over from the rest; otherwise Smart
+/// Guides line its bounds up with the other art, and with them off, View → Snap to Point lands the
+/// point it was grabbed by on an anchor or a ruler guide. Snap to Pixel puts its top-left on whole
 /// pixels.
 pub(crate) struct MoveSnap {
     bounds: Option<Rect>,
@@ -87,14 +88,19 @@ impl MoveSnap {
     pub(crate) fn new(cx: &ToolContext) -> Self {
         Self {
             bounds: selection_bounds(cx),
-            targets: cx.smart_guides.then(|| Targets::for_move(cx)),
-            points: Targets::snap_to_point(cx, &cx.selection.objects),
+            targets: (cx.smart_guides && !cx.snap_to_grid).then(|| Targets::for_move(cx)),
+            points: if cx.snap_to_grid { None } else { Targets::snap_to_point(cx, &cx.selection.objects) },
         }
     }
 
     /// The move by `d` of the selection grabbed at `start`, snapped, and its guides.
     pub(crate) fn snap(&self, cx: &ToolContext, start: Point, mut d: Vec2) -> (Vec2, Vec<Overlay>) {
         let mut guides = vec![];
+        if cx.snap_to_grid
+            && let Some(b) = self.bounds
+        {
+            d += grid_pull(b + d, cx.grid_step());
+        }
         if let Some(t) = &self.points {
             let (q, ov) = t.snap_point(start + d, cx.tol(cx.snap_tolerance));
             d = q - start;
@@ -115,6 +121,15 @@ impl MoveSnap {
     }
 }
 
+/// The shift that lands `r` on the grid (a gridline every `step`), on each axis by whichever of its
+/// two edges and its centre is nearest a gridline, however far that is.
+fn grid_pull(r: Rect, step: f64) -> Vec2 {
+    let pull = |vs: [f64; 3]| {
+        vs.iter().map(|v| vectorcraft_geom::snap::snap_to_grid(*v, step, 0.0) - v).min_by(|a, b| a.abs().total_cmp(&b.abs())).unwrap_or(0.0)
+    };
+    Vec2::new(pull([r.x0, r.center().x, r.x1]), pull([r.y0, r.center().y, r.y1]))
+}
+
 pub fn matrix_json(a: Affine) -> Value {
     let c = a.as_coeffs();
     json!([c[0], c[1], c[2], c[3], c[4], c[5]])
@@ -517,6 +532,32 @@ mod tests {
         assert_eq!(a, vec![Action::Commit]);
     }
 
+    /// #740: with Snap to Grid on, a moved object lands on the grid (every 9 pt by default) by
+    /// whichever of its edges or its centre is nearest a gridline, on each axis.
+    #[test]
+    fn a_move_lands_the_nearest_edge_or_centre_on_the_grid() {
+        let (d, id) = doc_with_rect();
+        let mut s = Selection::default();
+        s.add(id);
+        let p = paint();
+        let cx = ToolContext { snap_to_grid: true, smart_guides: true, ..cx(&d, &s, &p) };
+        let moved = |to: (f64, f64)| {
+            let mut t = SelectionTool::default();
+            t.pointer(&cx, &ev(PointerKind::Down, 150.0, 150.0));
+            let a = t.pointer(&cx, &ev(PointerKind::Drag, to.0, to.1));
+            match a.get(1) {
+                Some(Action::Preview(_, v)) => (v["matrix"][4].as_f64().unwrap(), v["matrix"][5].as_f64().unwrap()),
+                other => panic!("{other:?}"),
+            }
+        };
+        // Bounds 100–200 moved by (13, 4): the centres (163, 154) are nearest gridlines (162, 153).
+        let (x, y) = moved((163.0, 154.0));
+        assert!((x - 12.0).abs() < 1e-9 && (y - 3.0).abs() < 1e-9, "{x} {y}");
+        // Moved by (7, 0): the right edge is on a gridline (207) and the top goes up to one (99).
+        let (x, y) = moved((157.0, 150.0));
+        assert!((x - 7.0).abs() < 1e-9 && (y + 1.0).abs() < 1e-9, "{x} {y}");
+    }
+
     #[test]
     fn shift_drag_on_a_selected_object_moves_it_constrained() {
         let (d, id) = doc_with_rect();