Enum DisplayListItem 

pub enum DisplayListItem {
    Rect {
        bounds: WindowLogicalRect,
        color: ColorU,
        border_radius: BorderRadius,
    },
    SelectionRect {
        bounds: WindowLogicalRect,
        border_radius: BorderRadius,
        color: ColorU,
    },
    CursorRect {
        bounds: WindowLogicalRect,
        color: ColorU,
    },
    Border {
        bounds: WindowLogicalRect,
        widths: StyleBorderWidths,
        colors: StyleBorderColors,
        styles: StyleBorderStyles,
        border_radius: StyleBorderRadius,
    },
    TextLayout {
        layout: Arc<dyn Any + Send + Sync>,
        bounds: WindowLogicalRect,
        font_hash: FontHash,
        font_size_px: f32,
        color: ColorU,
    },
    Text {
        glyphs: Vec<GlyphInstance>,
        font_hash: FontHash,
        font_size_px: f32,
        color: ColorU,
        clip_rect: WindowLogicalRect,
        source_node_index: Option<usize>,
    },
    Underline {
        bounds: WindowLogicalRect,
        color: ColorU,
        thickness: f32,
    },
    Strikethrough {
        bounds: WindowLogicalRect,
        color: ColorU,
        thickness: f32,
    },
    Overline {
        bounds: WindowLogicalRect,
        color: ColorU,
        thickness: f32,
    },
    Image {
        bounds: WindowLogicalRect,
        image: ImageRef,
        border_radius: BorderRadius,
    },
    ScrollBar {
        bounds: WindowLogicalRect,
        color: ColorU,
        orientation: ScrollbarOrientation,
        opacity_key: Option<OpacityKey>,
        hit_id: Option<ScrollbarHitId>,
    },
    ScrollBarStyled {
        info: Box<ScrollbarDrawInfo>,
    },
    VirtualView {
        child_dom_id: DomId,
        bounds: WindowLogicalRect,
        clip_rect: WindowLogicalRect,
    },
    VirtualViewPlaceholder {
        node_id: NodeId,
        bounds: WindowLogicalRect,
        clip_rect: WindowLogicalRect,
    },
    PushClip {
        bounds: WindowLogicalRect,
        border_radius: BorderRadius,
    },
    PopClip,
    PushImageMaskClip {
        bounds: WindowLogicalRect,
        mask_image: ImageRef,
        mask_rect: WindowLogicalRect,
    },
    PopImageMaskClip,
    PushScrollFrame {
        clip_bounds: WindowLogicalRect,
        content_size: LogicalSize,
        scroll_id: LocalScrollId,
    },
    PopScrollFrame,
    PushStackingContext {
        z_index: i32,
        bounds: WindowLogicalRect,
    },
    PopStackingContext,
    PushReferenceFrame {
        transform_key: TransformKey,
        initial_transform: ComputedTransform3D,
        bounds: WindowLogicalRect,
    },
    PopReferenceFrame,
    HitTestArea {
        bounds: WindowLogicalRect,
        tag: DisplayListTagId,
    },
    LinearGradient {
        bounds: WindowLogicalRect,
        gradient: LinearGradient,
        border_radius: BorderRadius,
    },
    RadialGradient {
        bounds: WindowLogicalRect,
        gradient: RadialGradient,
        border_radius: BorderRadius,
    },
    ConicGradient {
        bounds: WindowLogicalRect,
        gradient: ConicGradient,
        border_radius: BorderRadius,
    },
    BoxShadow {
        bounds: WindowLogicalRect,
        shadow: StyleBoxShadow,
        border_radius: BorderRadius,
    },
    PushFilter {
        bounds: WindowLogicalRect,
        filters: Vec<StyleFilter>,
    },
    PopFilter,
    PushBackdropFilter {
        bounds: WindowLogicalRect,
        filters: Vec<StyleFilter>,
    },
    PopBackdropFilter,
    PushOpacity {
        bounds: WindowLogicalRect,
        opacity: f32,
    },
    PopOpacity,
    PushTextShadow {
        shadow: StyleBoxShadow,
    },
    PopTextShadow,
}

A command in the display list. Can be either a drawing primitive or a state-management instruction for the renderer’s graphics context.

Variants

Rect

A filled rectangle with optional rounded corners. Used for backgrounds, colored boxes, and other solid fills.

Fields

bounds: WindowLogicalRect

The rectangle bounds in absolute window coordinates

color: ColorU

The fill color (RGBA)

border_radius: BorderRadius

Corner radii for rounded rectangles

SelectionRect

A selection highlight rectangle (e.g., for text selection). Rendered behind text to show selected regions.

Fields

bounds: WindowLogicalRect

The rectangle bounds in absolute window coordinates

border_radius: BorderRadius

Corner radii for rounded selection

color: ColorU

The selection highlight color (typically semi-transparent)

CursorRect

A text cursor (caret) rectangle. Typically a thin vertical line indicating text insertion point.

Fields

bounds: WindowLogicalRect

The cursor bounds (usually narrow width)

color: ColorU

The cursor color

Border

A CSS border with per-side widths, colors, and styles. Supports different styles per side (solid, dashed, dotted, etc.).

Fields

bounds: WindowLogicalRect

The border-box bounds

widths: StyleBorderWidths

Border widths for each side

colors: StyleBorderColors

Border colors for each side

styles: StyleBorderStyles

Border styles for each side (solid, dashed, etc.)

border_radius: StyleBorderRadius

Corner radii for rounded borders

TextLayout

Text layout with full metadata (for PDF, accessibility, etc.) This is pushed BEFORE the individual Text items and contains the original text, glyph-to-unicode mapping, and positioning info

Fields

layout: Arc<dyn Any + Send + Sync>

bounds: WindowLogicalRect

font_hash: FontHash

font_size_px: f32

color: ColorU

Text

Text rendered with individual glyph positioning (for simple renderers)

Fields

glyphs: Vec<GlyphInstance>

font_hash: FontHash

font_size_px: f32

color: ColorU

clip_rect: WindowLogicalRect

source_node_index: Option<usize>

Layout node index that produced this text run. Enables patching glyphs without full display list regeneration.

Underline

Underline decoration for text (CSS text-decoration: underline)

Fields

bounds: WindowLogicalRect

color: ColorU

thickness: f32

Strikethrough

Strikethrough decoration for text (CSS text-decoration: line-through)

Fields

bounds: WindowLogicalRect

color: ColorU

thickness: f32

Overline

Overline decoration for text (CSS text-decoration: overline)

Fields

bounds: WindowLogicalRect

color: ColorU

thickness: f32

Image

Fields

bounds: WindowLogicalRect

image: ImageRef

border_radius: BorderRadius

ScrollBar

A dedicated primitive for a scrollbar with optional GPU-animated opacity. This is a simple single-color scrollbar used for basic rendering.

Fields

bounds: WindowLogicalRect

color: ColorU

orientation: ScrollbarOrientation

opacity_key: Option<OpacityKey>

Optional opacity key for GPU-side fading animation. If present, the renderer will use this key to look up dynamic opacity. If None, the alpha channel of color is used directly.

hit_id: Option<ScrollbarHitId>

Optional hit-test ID for WebRender hit-testing. If present, allows event handlers to identify which scrollbar component was clicked.

ScrollBarStyled

A fully styled scrollbar with separate track, thumb, and optional buttons. Used when CSS scrollbar properties are specified.

Fields

info: Box<ScrollbarDrawInfo>

Complete drawing information for all scrollbar components

VirtualView

An embedded VirtualView that references a child DOM with its own display list. The renderer will look up the child display list by child_dom_id and render it within the bounds. The VirtualView viewport is rendered in parent coordinate space (NOT inside a scroll frame) so it stays stationary. Scroll offset is communicated to the VirtualView callback, not via WebRender.

Fields

child_dom_id: DomId

The DomId of the child DOM (similar to webrender’s pipeline_id)

bounds: WindowLogicalRect

The bounds where the VirtualView should be rendered

clip_rect: WindowLogicalRect

The clip rect for the VirtualView content

VirtualViewPlaceholder

Placeholder emitted during display list generation for VirtualView nodes. window.rs replaces this with a real VirtualView item after invoking the VirtualView callback. This avoids the need for post-hoc scroll frame scanning — window.rs simply finds the placeholder by node_id.

Unlike regular scrollable nodes, VirtualView nodes do NOT get a PushScrollFrame/PopScrollFrame pair. Scroll state is managed by ScrollManager and passed to the VirtualView callback as scroll_offset.

Fields

node_id: NodeId

The DOM NodeId of the VirtualView element in the parent DOM

bounds: WindowLogicalRect

The layout bounds of the VirtualView container

clip_rect: WindowLogicalRect

The clip rect (same as bounds initially, may be adjusted)

PushClip

Pushes a new clipping rectangle onto the renderer’s clip stack. All subsequent primitives will be clipped by this rect until a PopClip.

Fields

bounds: WindowLogicalRect

border_radius: BorderRadius

PopClip

Pops the current clip from the renderer’s clip stack.

PushImageMaskClip

Pushes an image-based clip mask onto the renderer’s clip stack. The mask image should be R8 format: white (255) = visible, black (0) = clipped. All subsequent primitives will be masked until PopImageMaskClip.

Fields

bounds: WindowLogicalRect

The bounds of the element being clipped

mask_image: ImageRef

The mask image (R8 format)

mask_rect: WindowLogicalRect

The rect within which the mask is applied

PopImageMaskClip

Pops the current image mask clip from the renderer’s clip stack.

PushScrollFrame

Defines a scrollable area. This is a specialized clip that also establishes a new coordinate system for its children, which can be offset.

Fields

clip_bounds: WindowLogicalRect

The clip rect in the parent’s coordinate space.

content_size: LogicalSize

The total size of the scrollable content.

scroll_id: LocalScrollId

An ID for the renderer to track this scrollable area between frames.

PopScrollFrame

Pops the current scroll frame.

PushStackingContext

Pushes a new stacking context for proper z-index layering. All subsequent primitives until PopStackingContext will be in this stacking context.

Fields

z_index: i32

The z-index for this stacking context (for debugging/validation)

bounds: WindowLogicalRect

The bounds of the stacking context root element

PopStackingContext

Pops the current stacking context.

PushReferenceFrame

Pushes a reference frame with a GPU-accelerated transform. Used for CSS transforms and drag visual offsets. Creates a new spatial coordinate system for all children.

Fields

transform_key: TransformKey

The transform key for GPU-animated property binding

initial_transform: ComputedTransform3D

The initial transform value (identity for drag, computed for CSS transform)

bounds: WindowLogicalRect

The bounds of the reference frame (origin = transform origin)

PopReferenceFrame

Pops the current reference frame.

HitTestArea

Defines a region for hit-testing.

Fields

bounds: WindowLogicalRect

tag: DisplayListTagId

LinearGradient

A linear gradient fill.

Fields

bounds: WindowLogicalRect

gradient: LinearGradient

border_radius: BorderRadius

RadialGradient

A radial gradient fill.

Fields

bounds: WindowLogicalRect

gradient: RadialGradient

border_radius: BorderRadius

ConicGradient

A conic (angular) gradient fill.

Fields

bounds: WindowLogicalRect

gradient: ConicGradient

border_radius: BorderRadius

BoxShadow

A box shadow (either outset or inset).

Fields

bounds: WindowLogicalRect

shadow: StyleBoxShadow

border_radius: BorderRadius

PushFilter

Push a filter effect that applies to subsequent content.

Fields

bounds: WindowLogicalRect

filters: Vec<StyleFilter>

PopFilter

Pop a previously pushed filter.

PushBackdropFilter

Push a backdrop filter (applies to content behind the element).

Fields

bounds: WindowLogicalRect

filters: Vec<StyleFilter>

PopBackdropFilter

Pop a previously pushed backdrop filter.

PushOpacity

Push an opacity layer.

Fields

bounds: WindowLogicalRect

opacity: f32

PopOpacity

Pop an opacity layer.

PushTextShadow

Push a text shadow that applies to subsequent text content.

Fields

shadow: StyleBoxShadow

PopTextShadow

Pop all text shadows.

Implementations

impl DisplayListItem

pub fn is_visually_equal(&self, other: &Self) -> bool

Compare two display list items for visual equality (same appearance when rendered). Used by damage computation to detect content changes within the same bounds. Conservative: returns false (assumes different) for complex types like Arc.

pub fn is_state_management(&self) -> bool

Returns true if this item is a state-management command (Push/Pop) that must always be processed to maintain correct stacks.

pub fn visual_bounds(&self) -> Option<LogicalRect>

Return the visual bounding rect including effects that extend beyond content bounds (e.g. box-shadow spread/blur/offset). Used for damage rect computation where we need the full repaint area.

pub fn bounds(&self) -> Option<LogicalRect>

Return the bounding rect of this item, or None for push/pop commands that don’t have their own visual bounds.

Trait Implementations

impl Clone for DisplayListItem

fn clone(&self) -> DisplayListItem

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for DisplayListItem

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

Formats the value using the given formatter.