feat: ruler tool - #1796
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A draggable, rotatable straight-edge for the brush pen. Brush strokes within a configurable snap zone of the ruler's long edge get projected onto that edge, so users can draw straight lines along the ruler. User-facing behavior: - Toggle in the brush sidebar shows/hides the ruler; the band stays fixed relative to the window (not the document) as the canvas is panned or zoomed. - One-finger / mouse / stylus drag on the body translates the ruler. - Two-finger gesture rotates around the projected centroid and can pan via centroid drift. - Scroll wheel / trackpad over the body rotates around the pointer. - Strokes that start within the snap zone "lock" to the ruler edge for the rest of the stroke; strokes that start outside never snap. - Angle dial (with world-aligned tick markings and red direction indicators) sits at the rotation pivot and shows the current angle. - Optional snap-to-common-angles (0/+-45/+-90) during rotation. - Ruler colors flip automatically based on the page background's luminance so the ruler is visible on light and dark backgrounds. Settings exposed in the brush sidebar popover: - Show ruler toggle - Snap distance (% of ruler width) - Snap to common angles toggle - Show angle dial toggle - Ruler width, tick spacing, body opacity - Scroll rotation sensitivity Implementation notes: - New RulerConfig under brush_config holds all persisted ruler state; position/dial/angle are session-only (#[serde(skip)]). - New pens/ruler.rs draws the band, ticks and dial on top of the active pen via PenHolder::draw_on_doc, so the ruler shows regardless of which pen is selected. - Position is stored in scroller (window-relative) pixel coordinates and converted to doc coords at render/snap time via the camera transform. - Brush.rs gains a DraggingRuler state and a sticky ruler_snap_side on BrushState::Drawing so the snap decision is taken once per stroke. - Two-finger handling lives in CanvasWrapper alongside the existing zoom gesture; scroll-rotate uses a short-lived "session" so the pivot is locked for the duration of a gesture rather than being recomputed per event.
- Reorder ruler settings: angle snap, show dial, width, opacity, tick
spacing, snap distance, scroll sensitivity.
- Strip unit suffixes from titles ("Body Opacity (%)" -> "Body Opacity",
etc.) and ensure the descriptions cover the units instead.
- Drop angle snap from scroll rotation; keep it only for the two-finger
gesture. Snap on a discrete wheel device was hard to escape: a single
click stayed within the snap threshold and instantly re-snapped.
- Add a speed-adaptive multiplier for mouse-wheel scroll: precise when
the user rolls slowly, faster when they roll quickly. Multiplier is
clamp(200ms / dt, 0.4, 3.0). Trackpad ('Surface') events are left
as-is because they already encode speed in |dy|.
- Add a dead zone to the scroll-rotation session: when the session
times out, if the pointer is still within one body_half_width of the
previous pivot, revive that pivot instead of recomputing. Stops the
dial from drifting along the ruler when the user scrolls slowly and
the inter-event gap exceeds the session timeout.
- Update the 'Snap to Common Angles' subtitle to clarify the toggle
applies to two-finger rotation only.
- Add hysteresis to the two-finger snap (narrow 'leave' threshold once
locked on a target) so finger jitter doesn't keep the ruler stuck.
…display - Switch scroll controller to Capture phase so the canvas's Scrollable machinery can't consume a scroll mid-rotation and cause the rotation to slip into a canvas pan. - Add a longer revival window (3s): if pointer_pos is momentarily None but a recent session exists, keep rotating around the locked pivot instead of returning false and letting the scroll propagate. - Prime pointer_pos on the motion controller's `enter` signal too, so it's set the instant the pointer enters the widget rather than only on the next motion event. - Two-finger snap hysteresis: apply the narrow leave threshold only to the target the ruler is currently locked on; other targets keep the normal 3° enter threshold. Previously, locking on (say) 90° narrowed the window for every target, so gestures glided past 0° and ±45°. - Display: a rounded -90° now shows as 90° (same physical orientation, and the displayable range is (-90°, 90°]).
Brings in upstream changes through f3f7efd, including: - Real-size zoom button (flxzt#1735) - CI / cargo-deny / licenses - nalgebra -> glam math migration Ported the ruler additions to the new math API: - na::Vector2<f64> -> p2d::math::Vector2 - na::vector![x, y] -> Vector2::new(x, y) - na::vector![0.0, 0.0] -> Vector2::ZERO - v.dot(&w) -> v.dot(w) - v.norm() -> v.length() - Aabb::new(na::point!{...}, ...) -> Aabb::new(Vector2::new(...), ...) - extents().norm() -> extents().length() Also dropped the unused AabbExt import in ruler.rs.
- Validate the cached scroll-session pivot against the current ruler centerline before reusing it. If another operation (e.g. a two-finger rotation) moved/rotated the ruler in between, the cached pivot may be off the line; using it would rotate around an off-line point and put the dial outside the band. Filter expired in that case. - Apply the same dead zone on the very first scroll: if the cursor is within 1.5x body_half_width of the current dial_pos (and the dial is on the line), reuse the dial position as the pivot instead of jumping it to a freshly-projected cursor spot. - Only enter touch-style two-finger ruler manipulation when the event source is an actual touchscreen. Trackpad pinch/rotate gestures also fire GestureZoom/GestureRotate; they should fall through to canvas zoom rather than putting the user into the touch-only ruler mode. - Consume horizontal scroll while rotating the ruler. The scroll controller now listens on both axes so a trackpad scroll with a sideways component doesn't bleed into a canvas pan; the handler returns Propagation::Stop on success, consuming the whole event.
Interpolate the ruler body color against `body_opacity` so the body stays visible at low opacity (contrasting the canvas) and gives enough contrast to the tick/text markings at high opacity.
When touch-drawing is off, the one-finger ruler drag goes through canvas_drag_gesture. Without intervention the ScrolledWindow's kinetic scroll steals the touch sequence once the finger crosses its drag threshold, so the ruler "moves a bit and then the canvas pans". Disable kinetic scrolling for the duration of a ruler drag (restored on drag_end). The touch sequence is intentionally left unclaimed so canvas_zoom_gesture can still grab a second finger for rotation.
Two-finger ruler manipulation was using the touch centroid for its hit-test, so fingers placed on opposite sides of the ruler with neither on the body would still pass (the midpoint lands on the centerline). Check each touch position individually instead; every active touch must lie inside the body strip for the gesture to enter ruler mode.
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Add a OneNote-style ruler tool
Summary
This adds an on-canvas ruler (straight-edge) to the brush tool, the first of the helper tools requested in #147. When enabled, a translucent ruler spans the viewport; brush strokes drawn along its edge are snapped to a perfectly straight line, and the ruler can be freely repositioned and rotated with pen, touch, or mouse.
Addresses #147 (ruler portion; the protractor is left for a follow-up).
Motivation
Rnote had no way to draw a clean straight line freehand. A ruler is the most-requested helper tool in #147 and mirrors a familiar workflow from OneNote, making technical and mathematical sketches practical directly on the canvas.
What's included
Implementation notes
RulerConfig(crates/rnote-engine/src/pens/pensconfig/rulerconfig.rs) holds both the persisted preferences and the in-session runtime state, plus the coordinate conversions and snap math.crates/rnote-engine/src/pens/ruler.rs.crates/rnote-engine/src/pens/brush.rs) gains aDraggingRulerstate and the per-stroke snap logic.rnote-ui(penssidebar/brushpage.rs+.ui), and the gesture handling (drag / two-finger rotate / scroll-rotate) is incrates/rnote-ui/src/canvaswrapper.rs.Checks
cargo fmt --check– cleanui-cargo-clippy/cli-cargo-clippy– no warningscargo-test(nextest) – all passingScreencast
Screencast_20260706_214039.webm
AI disclosure
This contribution was developed with the assistance of LLM/GenAI tools.