photocraft/docs/brush-parity.md

Brush and painting parity

Last reviewed: 2026-10-10 · Last updated: 2026-10-16 · Change: minor (named, stateful Brush Settings locks and visible keyboard focus; independent Brush Pose tilt-axis overrides; Transfer Wetness/Mix tool applicability; dragged preset tip preview; Hue Jitter amount track; Brush Settings minimum fields follow their Control; checkbox-only rows and non-destructive Smoothing switch; shaped-tip cursor follows the view; Color Replacement is a live toolbar tool; no brush-feel estimate changed; 2026-10-11: Pattern Stamp and Background Eraser draw live, TOOL-213-7) · Target: Adobe Photoshop 2026

Painting is where Photoshop users notice differences first, so it gets its own checklist: the brush engine (crates/paint/src/brush.rs), the Brush Settings UI (crates/ui-egui/src/brush_sections.rs), the live stroke renderer, pen input (hardware-parity.md), and the brush-based tools. Status words as in ui-parity.md.

Summary (estimated): breadth ~90% (every Brush Settings section and option exists), ready for real work ~55%. The engine models what Photoshop models; the gaps are feel (latency, pressure response, edge quality, smoothing), a few missing options, and live previews for retouch tools. Remaining: 100–180 h (gap G4 in gaps.md). Human: feel must be checked on real tablets against Photoshop side by side.

Brush Settings sections

Section	Status	Evidence
Brush Tip Shape: size, angle, roundness, hardness, spacing, flip X/Y	done	brush.rs
Shape Dynamics (size/angle/roundness jitter, pen pressure/tilt/rotation/wheel controls, minimums, flip jitter, brush projection)	done	#174
Scattering (both axes, count, count jitter)	done
Texture (pattern, scale, brightness, contrast, mode, depth, each tip)	done
Dual Brush	done
Color Dynamics (FG/BG, hue/sat/brightness jitter, purity, per tip)	done
Hue Jitter uses a standard percentage-amount track instead of a hue spectrum	done	#3825 (Hue Jitter appearance only); rendered track checked in all 14 themes; numeric and pointer edits retain percentage units and engine command routing.
Transfer (opacity/flow/wetness/mix jitter and controls)	done
Transfer Wetness/Mix blocks disabled outside Mixer Brush, retaining their settings	done	#3825 (tool applicability only); UI regressions cover all 14 themes and 67 tools, disabled input, section/Control Off, command routing and per-tool settings
Shape Dynamics and Transfer minimum fields disabled when their Control is Off, retaining their values	done	#3825 (minimum-field interaction only); brush_sections.rs UI regressions cover all six fields, reactivation and disabled input
Brush Pose (tilt, rotation, pressure overrides)	done
Brush Pose: separate Override Tilt X/Y flags, preserved through ABR import, presets and commands	done	#3825 (axis overrides only); imported single-axis flags retain the other live stylus component; dab/pixel tests cover 8/16/32-bit RGBA; legacy combined inputs migrate and command deltas contain only the edited axis.
Noise, Wet Edges, Build-up, Protect Texture	done
Smoothing: amount, Pulled String, Stroke Catch-up, Catch-up on End, Adjust for Zoom	done	brush.rs:428-438
Section locks	done	#174; brush_panel_tests.rs verifies section-specific accessible names and locked state for all 12 controls in 14 themes, plus visible themed focus, Tab blur, Space activation, minimal command patches and replay without selecting or enabling a section.
Noise, Wet Edges, Build-up, Smoothing and Protect Texture: checkbox-only rows keep the selected controls open	done	brush_panel_tests.rs, #4283; Smoothing enable/disable preserves its amount and options, including imported ABR tool settings
Brush tip from an image file	missing	TOOL-213-12
Erodible, Airbrush and Bristle tips (Photoshop's special tips)	partial	not audited in detail; "3D-based brushes don't work" (#1660)
Anti-aliasing off for brushes	missing	#1666 (Pencil is the aliased path)

Pressure and pen

Behaviour	Status	Evidence
Pressure drives size/opacity/flow per sample (no shared pressure within a frame)	done	#2112
Global pressure curve in Preferences	done	#2195
Per-control pressure curves	missing	TOOL-213-11
Quick taps keep their pressure	partial	#1967 fixed one case; tap paints a full blob (#1798), tap sensitivity (#1933)
Smooth pressure on Windows	partial	"jumpy" (#2046)
Tilt and rotation drive angle/roundness	partial	macOS, X11, web; not Windows; rotation not applied (#1301)
Eraser end of the pen switches to Eraser	partial	macOS; flipped Wacom on Windows not (#2285)

Stroke quality and feel

Behaviour	Status	Evidence
No seams, hard edges stay hard, zero-scatter defaults, ABR tips never black	done	TOOL-213-13
Smooth line weight along a pressure ramp	partial	stair-steps (#1776)
Interpolation and smoothing match Photoshop	partial	#2138, #2057
Soft-edge falloff matches Photoshop's curve	partial	#2149, #1619
Brush preview and cursor crisp, not pixelated	partial	#1433
Cursor outline equals the painted footprint at every zoom	partial	#1761, #2364; shaped tips trace their outline (#3467), turned and flipped with a rotated or flipped view
Latency: dab to screen within a frame	partial	budgets P13/P16/P33 over (scorecard); big-brush lag #2619, #1994; cursor lag #2566, #1343
No hitch at mouse-up on a long stroke	not measurable	P32 needs a frame harness
Live stroke for Brush and Eraser	done
Live stroke for every brush-based retouch tool	partial	TOOL-213-7: all live but the Mixer Brush (PR #3627); Spot Healing shows the area it heals and heals on release, as Photoshop does
No OS arrow cursor over the canvas with a pen	partial	TOOL-213-14

Gestures and cursors

Behaviour	Status	Evidence
⌃⌥-drag (macOS) / Alt+right-drag (Windows) resizes and changes hardness with a readout	done	TOOL-213-10
[ ] size, ⇧[ ⇧] hardness, number keys opacity, ⇧+numbers flow (swapped when build-up is on)	done	2026-10-07
⌥-click samples a colour with painting tools; Eyedropper comparison ring	done	TOOL-213-9
⇧-click draws a straight line from the last point	done
Hold ~ with the Brush or Pencil to erase with its brush: Clear mode while held (rebindable under Tools › Temporary)	done	hold_keys.rs, #3439
Clear painting mode in the Brush and Pencil Mode menus	done	paint_mode_dropdown in panels.rs, "mode": "clear", #3439
Right-click opens the Brush Preset picker	done	context-menu-parity.md; XP-Pen right-click not (#1980), macOS issue #2360
Precise / normal / full-size tip cursors, crosshair in the tip	partial	Caps Lock precise cursor not audited; round Pencil cursor requested (#2662, #1057)
Brush choice kept per tool (Brush, Eraser, Blur each their own)	partial	#2542

Symmetry

Mode	Status
Vertical, Horizontal, Dual axis, Diagonal	done
From a path (Make Symmetry Path)	done
Wavy, Circle, Spiral, Parallel Lines, Radial, Mandala	missing (#2659)

Brush-based tools

Tool	Status	Notes
Brush, Pencil (aliased, Auto Erase), Eraser (Brush/Pencil/Block)	done	Pencil 1 px quality #2139
Mixer Brush (Wet, Load, Mix, Flow, Sample All Layers, Current Brush Load with Load Brush and Clean Brush, automatic Load and Clean)	partial	No live result while dragging, no Alt-click loading (#2247)
Clone Stamp (opacity, flow, aligned, sample, overlay)	partial	Clone Source W/H link and Alt target cursor (TOOL-213-8)
Pattern Stamp (aligned, impressionist)	done
History Brush	done	Art History Brush missing
Spot Healing, Healing	partial	grain not matched on flat colour (#2104), "horrible in general" (#1092), stops responding after switching (#1751)
Blur, Sharpen, Smudge (premultiplied, Sample All Layers, spacing)	done	BUG-207-2/3, #2171
Dodge, Burn, Sponge	done
Background Eraser, Magic Eraser	done
Color Replacement	done
Quick Selection (brush-driven)	done

Presets

Behaviour	Status	Evidence
.abr import (v1/v2/v6) and export, persistent presets, folders	done	psd/src/abr.rs
Brushes panel: drag a folder into a folder	missing	#2014
Dragged brush preset preview	done	Cached, translucent tip thumbnail plus name in panel list/grid and the preset picker; ui-egui/src/brushes_tab.rs, real pointer-drag test in brushes_tab_tests.rs (#4225, partial)
Tool presets (.tpl)	partial	Tool Presets panel exists; .tpl import not found
Import 500 brushes without blocking the UI	not run	P24

Revision history

Date	Change	Summary
2026-10-14	minor	Brush Pose tilt overrides are independent end to end (#3825 partial); ABR flags, legacy JSON/commands, presets and three pixel depths covered; no readiness percentage or estimate changed
2026-10-13	minor	Stale "missing tool" row corrected against main: Color Replacement (paint.colorReplacement) is a live toolbar tool; no brush-feel estimate changed
2026-10-11	minor	Pattern Stamp and Background Eraser draw live (#3754); live retouch row now partial (Mixer Brush left)
2026-10-10	major	First version, from a source audit and the open issues
2026-10-11	minor	~ held with the Brush or Pencil erases with that tool's brush, and Clear joins their Mode menus (#3439)
2026-10-12	minor	Five Brush Settings switch rows toggle without selecting a properties pane; Smoothing has a default-on switch and retains its settings while disabled (#4283). No brush-feel estimate changed.
2026-10-12	minor	A shaped tip's cursor outline turns and flips with a rotated or flipped view, and follows pixel aspect correction
2026-10-13	minor	Shape Dynamics and Transfer minimum inputs follow their Control and retain their values while disabled (#3825, partial). No brush-feel estimate changed.
2026-10-13	minor	Hue Jitter uses the same themed amount slider as other jitter controls (#3825, partial). No brush-feel estimate changed.
2026-10-13	minor	Transfer Wetness/Mix controls follow the active tool and retain their settings while disabled (#3825, partial). No brush-feel estimate changed.
2026-10-14	minor	The 12 existing Brush Settings section locks expose translated names and locked state to AccessKit and show themed keyboard focus (#3477 workflow); icons, hit targets and command behavior retained. No brush-feel estimate changed.
2026-10-13	minor	Dragging a brush preset shows its cached tip thumbnail and name in the Brushes panel and preset picker (#4225, partial). No brush-feel estimate changed.