43 lines
2.1 KiB
Markdown
43 lines
2.1 KiB
Markdown
# Path editor
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The project-authored path core accepts every SVG path command: `M/m`, `L/l`,
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`H/h`, `V/v`, `C/c`, `S/s`, `Q/q`, `T/t`, `A/a` and `Z/z`, including repeated
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parameter groups, implicit lines after move, packed arc flags, exponents,
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relative forms and multiple subpaths. It rejects non-finite values, malformed
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arity/flags and paths beyond the command limit.
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Segments resolve to absolute geometry while retaining source command/form and
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fragment offsets for the command table. Serialization intentionally normalizes
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edited geometry; no editor metadata is emitted.
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## Controls
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- Every segment endpoint is an anchor.
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- Cubics show both controls. `S` reflects the previous cubic control and marks
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the resulting handle as derived/dashed until edited.
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- Quadratics show their one control. `T` reflects the previous quadratic
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control and marks it derived.
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- Arcs expose endpoint, radii and derived center controls and show rotation,
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large-arc and sweep flags in the command panel.
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- Handle radii and strokes use screen-oriented overlay styling so they remain
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usable across zoom levels.
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The full selected-element/ancestor transform chain maps local path geometry into
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root space. Pointer coordinates use its inverse, including an active preview
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matrix; non-invertible chains disable handles. Dragging commits one transaction
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on release; arrow keys use 1, Shift+10 or Alt+0.1 units and merge safely.
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Segment splitting uses the mathematical midpoint: linear interpolation for
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lines, de Casteljau for quadratic/cubic curves, and arc subdivision preserving
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the ellipse. Path reversal reverses every supported segment/subpath and adjusts
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controls/sweep where required.
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## Current limits
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The 0.1.0 UI supplies drag/nudge, split at 50%, reverse and a read-only numeric
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command table. It does not yet supply node modes, multi-selection, deletion,
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conversion, open/close, join/break/combine, subpath-start changes, arbitrary
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split parameter, pen creation, snapping, simplification or boolean operations.
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Visual editing expands shorthand/relative commands to normalized absolute data;
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the dialog/help discloses that source-form change.
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