feat(joint-core): add Paper#setDragging / Paper#isDragging API#3321
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Geliogabalus merged 4 commits intoMay 19, 2026
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New public methods on `dia.Paper` for marking and reading the active-drag state on an event:
- `paper.setDragging(evt, value = true)` — stash the drag flag on the event's per-paper `eventData` bag (defaults to `true`).
- `paper.isDragging(evt)` — boolean read of the same flag.
Joint-core itself sets the flag from every action-confirmed drag-start branch:
- `ElementView.dragStart` — element move (after `can('elementMove')`).
- `LinkView.dragStart` — link move (after `can('linkMove')`).
- `LinkView.dragLabelStart` — label move (inside `can('labelMove')` block).
- `LinkView.dragArrowheadStart` — arrowhead move (after `can('arrowheadMove')`).
- `CellView.dragLinkStart` — magnet→link transition (when the link is actually created, which may be deferred under `magnetThreshold: 'onleave'`).
External consumers (plugins / hosts) can now ask "is a drag actually happening?" without inspecting view-level eventData internals. Useful for capture-on-drag, custom cursors, drag-aware UI overlays, etc.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Always sets to true. The optional value parameter was unused code for a hypothetical reset use case. YAGNI — easy to add later if needed. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Adds a QUnit module that verifies:
- direct API round-trip (set then read);
- `isDragging` defaults to false on fresh events;
- `ElementView.dragStart` flips the flag after `can('elementMove')` passes;
- `isDragging` stays false when `elementMove` is denied;
- `LinkView.dragStart` flips the flag after `can('linkMove')`.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
…ging signatures `dia.Event` was unresolved inside dia.d.ts itself; the file declares `export type Event = mvc.TriggeredEvent` and other methods reference `Event` directly. Match the convention. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Geliogabalus
approved these changes
May 19, 2026
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Summary
Adds two public methods on
dia.Paperfor marking and reading the active-drag state on an event:paper.setDragging(evt, value = true)— stash the drag flag on the event's per-papereventDatabag (defaults totrue).paper.isDragging(evt)— boolean read of the same flag.Joint-core itself sets the flag from every action-confirmed drag-start branch:
dia/ElementView.mjsdragStartcan('elementMove')dia/LinkView.mjsdragStartcan('linkMove')dia/LinkView.mjsdragLabelStartcan('labelMove')blockdia/LinkView.mjsdragArrowheadStartcan('arrowheadMove')dia/CellView.mjsdragLinkStartThe magnet path notably waits until
CellView.dragLinkStartruns (which may be deferred undermagnetThreshold: 'onleave'), so a magnet pointerdown alone doesn't trip the flag — only when the link actually starts.Motivation
External consumers (plugins, embedding hosts) currently have to inspect view-level
eventData(action,linkView, etc) to determine whether a drag is actually in progress, which means leaking joint-core internals across the API boundary. With these two methods, the question "is a drag actually happening?" becomes a one-call public API.Use cases:
setPointerCaptureonly after a drag is confirmed — i.e. not on every pointerdown).pointermoveand want to gate their work on real drag state.A follow-up PR in
@joint/reactuses this API to drivesetPointerCapture+ ajj-is-draggingCSS class.Changes
packages/joint-core/src/dia/Paper.mjs— definesetDraggingandisDragging.packages/joint-core/src/dia/ElementView.mjs— callpaper.setDragging(evt)aftercan('elementMove').packages/joint-core/src/dia/LinkView.mjs— callpaper.setDragging(evt)indragStart,dragLabelStart,dragArrowheadStart.packages/joint-core/src/dia/CellView.mjs— callpaper.setDragging(evt)at the end ofdragLinkStart.packages/joint-core/types/dia.d.ts— declarations for both methods.Test plan
yarn workspace @joint/core test— full QUnit suite (server + client).grunt test:server --file=test/jointjs/paper.js— Paper-specific.paper.on('pointermove', evt => console.log(paper.isDragging(evt)))— expecttrueonly after a drag-start gate has passed (drag the element / link / label / arrowhead, or magnet-to-link).🤖 Generated with Claude Code