photocraft/docs/brush-parity.md

Brush and painting parity

Last reviewed: 2026-10-10 · Last updated: 2026-10-14 · Change: minor (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) · 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
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
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
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	missing	TOOL-213-7
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	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)	partial	"incomplete" (#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
2026-10-13	minor	Stale "missing tool" row corrected against main: Color Replacement (paint.colorReplacement) is a live toolbar tool; no brush-feel estimate changed
2026-10-10	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	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.