Enum Op 

pub enum Op {
    Save,
    SaveLayer {
        paint: Paint,
        mask_composite: Option<MaskKind>,
        scope_bounds: Rect,
        base_slot: u32,
        composite_slot: u32,
        can_elide: bool,
        backdrop_sigma: Option<f32>,
        backdrop_key: Option<u64>,
    },
    Restore,
    Transform(Matrix),
    DrawRect {
        rect: Rect,
        paint: Paint,
        bounds: Rect,
        slot: u32,
    },
    DrawPath {
        path: Arc<Path>,
        fill_rule: FillRule,
        paint: Paint,
        bounds: Rect,
        slot: u32,
    },
    RRectBlur {
        rect: Rect,
        radii: [f32; 4],
        paint: Paint,
        bounds: Rect,
        slot: u32,
    },
    ClipPath {
        path: Arc<Path>,
        fill_rule: FillRule,
        op: ClipOp,
        expiry_slot: u32,
    },
    DrawImage {
        image: Image,
        src: Rect,
        dst: Rect,
        sampling: Sampling,
        paint: Paint,
        bounds: Rect,
        slot: u32,
    },
    GlyphRun {
        font: Arc<Font>,
        size: f32,
        paint: Paint,
        glyphs: Arc<Vec<GlyphPos>>,
        bounds: Rect,
        slot: u32,
    },
    DrawDisplayList {
        list: Arc<DisplayList>,
        bounds: Rect,
        base_slot: u32,
        cache: bool,
    },
}

Op is one recorded display-list command.

Draw and clip operations include the bounds and ordering metadata resolved by crate::DisplayListBuilder at record time.

Variants

Save

SaveLayer

Open an offscreen layer scope, closed by the matching Restore. All oracle fields are backpatched when the scope closes — still record time; replay reads them, never counts.

Fields

paint: Paint

mask_composite: Option<MaskKind>

Set = this layer is a MASK: its composite converts the texture to COVERAGE (luminance or alpha) and multiplies the enclosing layer by it (DstIn over the whole enclosing extent, so content outside the mask’s ink disappears).

scope_bounds: Rect

Children’s union bounds ∩ clip ∩ hint, list-root space — the layer texture’s size and the composite quad’s rect.

base_slot: u32

Slot count when the scope opened. Children continue the SAME depth line as the parent (Impeller’s global numbering, Canvas::current_depth_); the layer’s own pass rebases by subtracting it. Impeller records one span (total_content_depth) and counts during replay; valo’s replay never counts, so it records both ends of the span instead.

composite_slot: u32

The composite draw’s slot — next on the same line, after the children’s span (so the span is composite_slot - base_slot - 1).

can_elide: bool

Alpha-linear + pairwise-disjoint children and a plain-alpha composite: replay may skip the texture entirely and let the alpha ride each child at its own slot (Impeller’s opacity peephole: elision changes nothing about depth).

backdrop_sigma: Option<f32>

Set = the layer OPENS pre-filled with a blur of everything already painted beneath it (σ in local units; replay scales it into device px). Children paint over that glass, and the composite applies group alpha to blur + children as one image — Flutter’s saveLayer(bounds, paint, backdrop). A backdrop layer never elides: the seed needs a texture.

backdrop_key: Option<u64>

Tiles sharing one key reuse the FIRST tile’s blur (and see the scene as of that tile). Meaningful only with backdrop_sigma.

Restore

Transform(Matrix)

Appends to the current transform (canvas semantics: applies to subsequently drawn geometry first).

DrawRect

Fields

rect: Rect

paint: Paint

bounds: Rect

slot: u32

DrawPath

Fields

path: Arc<Path>

fill_rule: FillRule

paint: Paint

bounds: Rect

slot: u32

RRectBlur

A mask-blurred solid (r)rect in CLOSED FORM — one draw, no filter passes; why a box shadow costs one quad (Impeller’s SolidRRectBlurContents). Recorded when a solid paint has mask_blur; radii are per corner, clockwise from top-left ([0.0; 4] = sharp).

Fields

rect: Rect

radii: [f32; 4]

paint: Paint

bounds: Rect

slot: u32

ClipPath

Depth-buffer clip (Impeller’s “new clips”): the renderer stencils the shape, then writes a depth CEILING at expiry_slot — Intersect ceilings the exterior, Difference the interior. Draws below the ceiling fail the depth test there; draws after the scope’s restore sit above it. Expiry is auto — restore renders nothing.

Fields

path: Arc<Path>

fill_rule: FillRule

op: ClipOp

expiry_slot: u32

The slot of the restore that ends this clip’s scope (backpatched by the builder when the scope closes — still record-time).

DrawImage

Textured quad: src (texture px) → dst (local space). Sampling picks filter/tiling; paint contributes tint (color as multiplier), alpha, and blend.

Fields

image: Image

src: Rect

dst: Rect

sampling: Sampling

paint: Paint

bounds: Rect

slot: u32

GlyphRun

Positioned glyphs from a laid-out paragraph — the TextFrame analog (font id + glyph ids + positions, so this crate never depends on the text stack). One op per placed run; y sits on the baseline; the renderer picks bitmap/SDF/path per transform.

Fields

font: Arc<Font>

The font INSTANCE, carried by value to raster (Skia: text blobs hold sk_sp<SkTypeface> — nothing is registered renderer-side). Serialization keeps only the raster identity.

size: f32

paint: Paint

Blend/alpha/mask-blur apply like any draw; paint.color tints mask glyphs (color glyphs keep their palette, alpha only).

glyphs: Arc<Vec<GlyphPos>>

bounds: Rect

slot: u32

DrawDisplayList

Embed another list by reference — the retained-layer composition op.

Fields

list: Arc<DisplayList>

bounds: Rect

base_slot: u32

Child slots are child-relative; replay offsets them by this.

cache: bool

The embedder judges this subtree stable and heavy enough to raster-cache (policy is the caller’s; admission stays in the renderer).

Trait Implementations

impl Clone for Op

fn clone(&self) -> Op

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Op

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.