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Class

PaintLayerModifier

abstract
Inherits:EffectModifier
Implements:IHasPaintProviderIModifierCommitChanges

Shared engine for paint layers (fill, stroke, shadow, glow, inner-shadow). Resolves a TextPaint from the parameter, precomputes gradient/texture mapping per styled range, and stamps coverage quads through CoverageQuadOps. Thin subclasses only pick a coverage mode and parse their geometry params — all paint/mapping logic lives here once.

Remarks

Parameter grammar: paint, then the subclass's layer-geometry tokens (ParseExtra), then the shared projection overrides [,mapping][,shape][,fit][,angle][,scale][,offset][,corners][,miterLimit][,tint][,blend][,spread]. Projection values affect gradient/texture paints; tint multiplies every paint kind. The paint slot is optional-with-rewind: only a genuine paint token (colour literal or known swatch name) is consumed; anything else rewinds to the geometry slots, so <stroke=2px> reads as a width. Each projection value resolves through the override hierarchy, weakest → strongest: swatch → modifier field → default parameters → tag attribute (TextPaint.ApplyProjection).

Derived Types(5)

Types that inherit from PaintLayerModifier.

C
FillModifier
Fills the glyph interior with a colour, gradient, or texture. The first fill on a glyph claims the (default-suppressed) base quad; additional fills stack above it. Any fill present suppresses the implicit default fill. A colour glyph the fill leaves untouched is drawn as its own picture at the fill's position, even above a lower fill that painted its silhouette; with several such fills the picture takes the topmost position.
C
GlowModifier
Soft halo around the glyph (a shadow with no offset and a wide soft edge), with a colour, gradient, or texture.
C
InnerShadowModifier
Inset shadow that hugs the inner edge of the glyph, with a colour, gradient, or texture. The offset is a shader parameter (second SDF tap), not a quad displacement.
C
ShadowModifier
Drop shadow behind the glyph — an offset, blurred duplicate with a colour, gradient, or texture paint.
C
StrokeModifier
Draws a real outline (a rim band around the glyph edge, not a filled blob) with a colour, gradient, or texture. Works with the fill off (stroke-only).

Nested Types

E
CornerStyle
How a layer's offset iso-lines treat glyph corners.
public IPaintProvider Provider{ get; set }

Source of named paint swatches this layer resolves (e.g. <fill=ember>, <stroke=gold>). null disables swatch resolution, leaving only inline colour tokens. A gradient or texture paint is only reachable through a swatch, so set this to give the layer a gradient/texture from code.

public PaintMapping Mapping{ get; set }

How a gradient/texture paint spreads over the text (whole block, per line, per glyph, or per range). Inherit (default) uses the swatch's value; a per-range value overrides both.

public PaintProjectionKind Shape{ get; set }

Gradient geometry (linear, radial, angular). Inherit (default) uses the swatch's value; a per-range value overrides both.

public PaintFit Fit{ get; set }

How a texture paint fits its mapping frame. Inherit (default) uses the swatch's value; a per-range value overrides both.

public float Angle{ get; set }

Rotation of the gradient/texture mapping, in degrees. NaN (default) uses the swatch's angle; a per-range value overrides both.

public float Scale{ get; set }

Uniform zoom of the mapping frame; non-positive is treated as 1. NaN (default) uses the swatch's scale; a per-range value overrides both.

public Vector2 PaintOffset{ get; set }

Pan of the paint's sample origin in normalized frame units. NaN per axis uses the swatch's offset; a per-range value overrides both.

public PaintLayerModifier.CornerStyle Corners{ get; set }

Corner treatment of this layer's offset iso-lines (outline rim, shadow spread). Round is artifact-free at any width; Sharp keeps mitered corners up to MiterLimit. Single-channel SDF mode has no perpendicular field — Sharp renders as Round there.

public float MiterLimit{ get; set }

Sharp-corner miter limit as a multiple of the offset width (SVG stroke-miterlimit semantics); corners spikier than this are clipped.

public Color32 Tint{ get; set }

Colour multiplied with the resolved solid, gradient, or texture paint.

protected PaintRef PaintField{ get }

The subclass's own [Parameter] paint, used as the default when the markup carries no paint value.

protected float CoverageModeValue{ get }

Coverage mode written to TEXCOORD2.x (see CoverageMode).

protected Color32 DefaultPaintColor{ get }

Solid colour applied when the paint token is omitted entirely. White for the face/fill; dark layers (stroke, shadow) override so a bare tag still renders sensibly without a paint provider. A present-but-unresolved name still falls back to white, not this.

protected bool ClaimsBase{ get }

When true, the first hit on a glyph recolours the suppressed default base quad instead of emitting a duplicate (fill behaviour).

protected virtual void ParseExtra(ref ParameterReader reader, in RangeApplyContext context, ref PaintLayerModifier.LayerGeometry g)

Parses layer-specific tokens after the optional paint and before shared projection values into coverage parameters and an optional quad offset. Read scalars with ParameterReader.NextUnitFloat and vectors with ParameterReader.NextUnitVector2; set the matching *Px flag from the unit (UnitKind.Absolute = px), so the value resolves to em at emit.

protected override void OnEnable()
protected override void OnDisable()
protected override void OnDestroy()
protected override void ResetOwnRequests()
protected override void BeforeApply()

Clears the range accumulator AND releases the emitter's held gradient ramp rows — the re-run OnApply re-acquires them immediately, so an animated parameter never leaks a row reference per frame (the atlas sweep's grace period protects the currently displayed mesh). The winner buffer is zeroed here too: a granular re-apply replays without the clear a parse gives every attribute buffer, and stale winner indices would point into the freshly reset ranges list.

protected override void OnApply(in RangeApplyContext context)

Resolves the range's paint and geometry, then stamps the per-codepoint winner-index buffer: overlapping ranges of one modifier resolve innermost-wins ONCE here (an IsInner compare against the current holder), so the per-glyph hook reads a single buffer slot instead of scanning ranges. The buffer indexes at most 255 applied ranges per layer instance; ranges beyond that keep the earlier winner.

protected override void OnGlyphEffect()

O(1) per glyph: the winning range comes from the per-codepoint winner buffer resolved at apply time; no range scan happens here.

protected override void OnFlush()
protected override void OnEmitQuad(int sourceBaseIdx, int destBaseIdx, int payload)
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