Struct Modifier 

pub struct Modifier { /* private fields */ }

A modifier chain that can be applied to composable elements.

Modifiers allow you to decorate or augment a composable. Common operations include:

• Adjusting layout (e.g., padding, fill_max_size)
• Adding behavior (e.g., clickable, scrollable)
• Drawing (e.g., background, border)

Modifiers are immutable and form a chain using the builder pattern. The order of modifiers matters: previous modifiers wrap subsequent ones.

Example

Modifier::padding(16.0)     // Applied first (outer)
    .background(Color::Red) // Applied second
    .clickable(|| println!("Clicked")) // Applied last (inner)

Implementations

impl Modifier

pub fn align(self, alignment: Alignment) -> Self

pub fn alignInBox(self, alignment: Alignment) -> Self

pub fn alignInColumn(self, alignment: HorizontalAlignment) -> Self

pub fn alignInRow(self, alignment: VerticalAlignment) -> Self

impl Modifier

pub fn background(self, color: Color) -> Self

Set the background color.

Example: Modifier::empty().background(Color::rgb(1.0, 0.0, 0.0))

pub fn rounded_corners(self, radius: f32) -> Self

Add rounded corners with uniform radius.

Example: Modifier::empty().rounded_corners(8.0)

pub fn rounded_corner_shape(self, shape: RoundedCornerShape) -> Self

Add rounded corners with a custom shape.

Example: Modifier::empty().rounded_corner_shape(shape)

impl Modifier

pub fn blur(self, radius: Dp) -> Self

Apply a Gaussian blur effect to this composable’s rendered content.

radius is expressed in Dp and converted to px using the current render density when modifier slices are evaluated.

Compose parity: this defaults to bounded rectangular edge treatment.

pub fn blur_with_edge_treatment( self, radius: Dp, edge_treatment: BlurredEdgeTreatment, ) -> Self

Apply an isotropic Gaussian blur with explicit edge treatment.

Compose parity:

• bounded treatment clips to shape and uses clamp sampling
• unbounded treatment disables clip and uses decal sampling

pub fn blur_xy( self, radius_x: Dp, radius_y: Dp, edge_treatment: BlurredEdgeTreatment, ) -> Self

Apply a Gaussian blur effect with separate horizontal and vertical radii.

Radii are expressed in Dp and converted to px at evaluation time.

impl Modifier

pub fn clickable(self, handler: impl Fn(Point) + 'static) -> Self

Make the component clickable.

Example: Modifier::empty().clickable(|pt| println!("Clicked at {:?}", pt))

impl Modifier

pub fn draw_with_content(self, f: impl Fn(&mut dyn DrawScope) + 'static) -> Self

Draw around content.

draw_content() splits drawing into behind (before) and overlay (after) phases. If draw_content() is never called, primitives are treated as overlay for backward compatibility.

Example: Modifier::empty().draw_with_content(|scope| { ... })

pub fn draw_behind(self, f: impl Fn(&mut dyn DrawScope) + 'static) -> Self

Draw content behind.

Example: Modifier::empty().draw_behind(|scope| { ... })

pub fn draw_with_cache(self, build: impl FnOnce(&mut DrawCacheBuilder)) -> Self

Draw with cache.

Example: Modifier::empty().draw_with_cache(|builder| { ... })

impl Modifier

pub fn fill_max_width(self) -> Self

Have the content fill the maximum available width.

The [fraction] parameter allows filling only a portion of the available width (0.0 to 1.0).

Matches Kotlin: Modifier.fillMaxWidth(fraction: Float)

Example: Modifier::empty().fill_max_width()

pub fn fill_max_width_fraction(self, fraction: f32) -> Self

Fill a fraction of the maximum available width.

Example: Modifier::empty().fill_max_width_fraction(0.5)

pub fn fill_max_height(self) -> Self

Have the content fill the maximum available height.

The [fraction] parameter allows filling only a portion of the available height (0.0 to 1.0).

Matches Kotlin: Modifier.fillMaxHeight(fraction: Float)

Example: Modifier::empty().fill_max_height()

pub fn fill_max_height_fraction(self, fraction: f32) -> Self

Fill a fraction of the maximum available height.

Example: Modifier::empty().fill_max_height_fraction(0.5)

pub fn fill_max_size(self) -> Self

Have the content fill the maximum available size (both width and height).

The [fraction] parameter allows filling only a portion of the available size (0.0 to 1.0).

Matches Kotlin: Modifier.fillMaxSize(fraction: Float)

Example: Modifier::empty().fill_max_size()

pub fn fill_max_size_fraction(self, fraction: f32) -> Self

Fill a fraction of the maximum available size.

Example: Modifier::empty().fill_max_size_fraction(0.8)

impl Modifier

pub fn graphics_layer(self, layer: impl Fn() -> GraphicsLayer + 'static) -> Self

Apply a lazily evaluated graphics layer.

The closure is evaluated during scene building, not composition, which lets layer properties update without forcing recomposition.

Example: Modifier::empty().graphics_layer(|| GraphicsLayer { alpha: 0.5, ..Default::default() })

pub fn graphics_layer_value(self, layer: GraphicsLayer) -> Self

Apply a concrete graphics layer snapshot.

This is useful for parameter-style wrappers that already build a fixed GraphicsLayer value.

pub fn graphics_layer_params( self, scale_x: f32, scale_y: f32, alpha: f32, translation_x: f32, translation_y: f32, shadow_elevation: f32, rotation_x: f32, rotation_y: f32, rotation_z: f32, camera_distance: f32, transform_origin: TransformOrigin, shape: LayerShape, clip: bool, render_effect: Option<RenderEffect>, ambient_shadow_color: Color, spot_shadow_color: Color, compositing_strategy: CompositingStrategy, blend_mode: BlendMode, color_filter: Option<ColorFilter>, ) -> Self

Compose-compatible parameter-style graphics layer entry point.

This mirrors Modifier.graphicsLayer(...) style APIs and maps directly to GraphicsLayer fields currently implemented by the renderer stack.

pub fn graphics_layer_block( self, configure: impl Fn(&mut GraphicsLayer) + 'static, ) -> Self

Compose-compatible block-style graphics layer entry point.

Example: Modifier::empty().graphics_layer_block(|layer| { layer.alpha = 0.5; layer.scale_x = 1.2; })

pub fn shadow(self, elevation: f32) -> Self

Compose-style elevation shadow convenience.

This mirrors Modifier.shadow(elevation) defaults: rectangle shape, black ambient/spot colors, and clipping enabled when elevation is positive.

pub fn shadow_with( self, elevation: f32, shape: LayerShape, clip: bool, ambient_color: Color, spot_color: Color, ) -> Self

Compose-style shadow API with explicit shape/clip/colors.

pub fn backdrop_effect(self, effect: RenderEffect) -> Self

Apply a backdrop effect to content behind this composable’s bounds.

pub fn shader_background(self, shader: RuntimeShader) -> Self

Convenience alias for applying a backdrop shader effect.

pub fn color_filter(self, filter: ColorFilter) -> Self

Apply a color filter to this composable’s graphics layer output.

This mirrors Compose’s graphicsLayer(colorFilter = ...) capability.

pub fn tint(self, tint: Color) -> Self

Convenience color filter that tints layer output.

pub fn compositing_strategy(self, strategy: CompositingStrategy) -> Self

Configures how the layer is composited into its parent.

pub fn layer_blend_mode(self, blend_mode: BlendMode) -> Self

Configures blend mode for this layer output.

Runtime support is backend-dependent. Current renderers fully support SrcOver and DstOut; unsupported modes fall back to SrcOver.

pub fn gradient_cut_mask( self, area_width: f32, area_height: f32, spec: GradientCutMaskSpec, ) -> Self

Apply a directional gradient cut mask to this composable output.

This masks the rendered layer with rounded corners and a feathered edge.

pub fn rounded_alpha_mask( self, area_width: f32, area_height: f32, corner_radius: f32, edge_feather: f32, ) -> Self

Apply a rounded alpha mask to this composable output.

Useful to constrain a preceding render effect (for example blur) to a rounded shape while preserving a soft edge transition.

pub fn gradient_fade_dst_out( self, area_width: f32, area_height: f32, spec: GradientFadeMaskSpec, ) -> Self

Apply a directional gradient fade mask with destination-out semantics.

This mirrors Compose’s drawWithContent + drawRect(..., BlendMode.DstOut) pattern for fading content to transparent along one axis.

impl Modifier

pub fn offset(self, x: f32, y: f32) -> Self

Offset the content by (x, y). The offsets can be positive or negative.

This modifier is RTL-aware: positive x offsets move content right in LTR and left in RTL layouts.

Matches Kotlin: Modifier.offset(x: Dp, y: Dp)

Example: Modifier::empty().offset(10.0, 20.0)

pub fn absolute_offset(self, x: f32, y: f32) -> Self

Offset the content by (x, y) without considering layout direction.

Positive x always moves content to the right regardless of RTL.

Matches Kotlin: Modifier.absoluteOffset(x: Dp, y: Dp)

Example: Modifier::empty().absolute_offset(10.0, 20.0)

impl Modifier

pub fn padding(self, p: f32) -> Self

Add uniform padding to all sides.

Example: Modifier::empty().padding(16.0)

pub fn padding_horizontal(self, horizontal: f32) -> Self

Add horizontal padding (left and right).

Example: Modifier::empty().padding_horizontal(16.0)

pub fn padding_vertical(self, vertical: f32) -> Self

Add vertical padding (top and bottom).

Example: Modifier::empty().padding_vertical(8.0)

pub fn padding_symmetric(self, horizontal: f32, vertical: f32) -> Self

Add symmetric padding (horizontal and vertical).

Example: Modifier::empty().padding_symmetric(16.0, 8.0)

pub fn padding_each(self, left: f32, top: f32, right: f32, bottom: f32) -> Self

Add padding to each side individually.

Example: Modifier::empty().padding_each(8.0, 4.0, 8.0, 4.0)

impl Modifier

pub fn pointer_input<K, F, Fut>(self, key: K, handler: F) -> Self

where K: Hash + 'static, F: Fn(PointerInputScope) -> Fut + 'static, Fut: Future<Output = ()> + 'static,

impl Modifier

pub fn horizontal_scroll( self, state: ScrollState, reverse_scrolling: bool, ) -> Self

Creates a horizontally scrollable modifier.

Arguments

• state - The ScrollState to control scroll position
• reverse_scrolling - If true, reverses the scroll direction in layout. Note: This affects how scroll offset is applied to content (via ScrollNode), NOT the drag direction. Drag gestures always follow natural touch semantics: drag right = scroll left (content moves right under finger).

Example

let scroll_state = ScrollState::new(0.0);
Row(
    Modifier::empty().horizontal_scroll(scroll_state, false),
    // ... content
);

pub fn vertical_scroll( self, state: ScrollState, reverse_scrolling: bool, ) -> Self

Creates a vertically scrollable modifier.

Arguments

• state - The ScrollState to control scroll position
• reverse_scrolling - If true, reverses the scroll direction in layout. Note: This affects how scroll offset is applied to content (via ScrollNode), NOT the drag direction. Drag gestures always follow natural touch semantics: drag down = scroll up (content moves down under finger).

pub fn horizontal_scroll_guarded( self, state: ScrollState, reverse_scrolling: bool, guard: impl Fn() -> bool + 'static, ) -> Self

Creates a horizontally scrollable modifier with a guard that can disable scrolling.

pub fn vertical_scroll_guarded( self, state: ScrollState, reverse_scrolling: bool, guard: impl Fn() -> bool + 'static, ) -> Self

Creates a vertically scrollable modifier with a guard that can disable scrolling.

impl Modifier

pub fn lazy_vertical_scroll( self, state: LazyListState, reverse_scrolling: bool, ) -> Self

Creates a vertically scrollable modifier for lazy lists.

This connects pointer gestures to LazyListState for scroll handling. Unlike regular vertical_scroll, no layout offset is applied here since LazyListState manages item positioning internally. Creates a vertically scrollable modifier for lazy lists.

This connects pointer gestures to LazyListState for scroll handling. Unlike regular vertical_scroll, no layout offset is applied here since LazyListState manages item positioning internally.

pub fn lazy_horizontal_scroll( self, state: LazyListState, reverse_scrolling: bool, ) -> Self

Creates a horizontally scrollable modifier for lazy lists.

impl Modifier

pub fn drop_shadow( self, shape: LayerShape, block: impl Fn(&mut ShadowScope) + 'static, ) -> Self

Draws a drop shadow behind the current content.

This mirrors Compose 1.9’s dropShadow(shape) { ... }.

Backend note: the pixels renderer currently draws the shadow geometry without Gaussian blur; wgpu applies the requested blur radius.

pub fn drop_shadow_value(self, shape: LayerShape, shadow: Shadow) -> Self

Static shadow configuration variant mirroring Compose’s dropShadow(shape, shadow).

pub fn inner_shadow( self, shape: LayerShape, block: impl Fn(&mut ShadowScope) + 'static, ) -> Self

Draws an inner shadow on top of current content.

This mirrors Compose 1.9’s innerShadow(shape) { ... }.

Backend note: the pixels renderer currently draws the shadow geometry without Gaussian blur; wgpu applies the requested blur radius.

pub fn inner_shadow_value(self, shape: LayerShape, shadow: Shadow) -> Self

Static shadow configuration variant mirroring Compose’s innerShadow(shape, shadow).

impl Modifier

pub fn size(self, size: Size) -> Self

Declare the preferred size of the content to be exactly [size].

The incoming measurement constraints may override this value, forcing the content to be either smaller or larger.

Matches Kotlin: Modifier.size(size: Dp)

Example: Modifier::empty().size(Size { width: 100.0, height: 200.0 })

pub fn size_points(self, width: f32, height: f32) -> Self

Declare the preferred size of the content to be exactly [width]dp by [height]dp.

Convenience method for size(Size { width, height }).

Example: Modifier::empty().size_points(100.0, 200.0)

pub fn width(self, width: f32) -> Self

Declare the preferred width of the content to be exactly [width]dp.

The incoming measurement constraints may override this value, forcing the content to be either smaller or larger.

Matches Kotlin: Modifier.width(width: Dp)

Example: Modifier::empty().width(100.0).height(200.0)

pub fn height(self, height: f32) -> Self

Declare the preferred height of the content to be exactly [height]dp.

The incoming measurement constraints may override this value, forcing the content to be either smaller or larger.

Matches Kotlin: Modifier.height(height: Dp)

Example: Modifier::empty().width(100.0).height(200.0)

pub fn width_intrinsic(self, intrinsic: IntrinsicSize) -> Self

Declare the width of the content based on its intrinsic size.

Matches Kotlin: Modifier.width(IntrinsicSize)

pub fn height_intrinsic(self, intrinsic: IntrinsicSize) -> Self

Declare the height of the content based on its intrinsic size.

Matches Kotlin: Modifier.height(IntrinsicSize)

pub fn required_size(self, size: Size) -> Self

Declare the size of the content to be exactly [size], ignoring incoming constraints.

The incoming measurement constraints will not override this value. If the content chooses a size that does not satisfy the incoming constraints, the parent layout will be reported a size coerced in the constraints.

Matches Kotlin: Modifier.requiredSize(size: Dp)

impl Modifier

pub fn weight(self, weight: f32) -> Self

pub fn weight_with_fill(self, weight: f32, fill: bool) -> Self

pub fn columnWeight(self, weight: f32, fill: bool) -> Self

pub fn rowWeight(self, weight: f32, fill: bool) -> Self

impl Modifier

pub fn empty() -> Self

pub fn clip_to_bounds(self) -> Self

Clip the content to the bounds of this modifier.

Example: Modifier::empty().clip_to_bounds()

pub fn modifier_local_provider<T, F>( self, key: ModifierLocalKey<T>, value: F, ) -> Self

where T: 'static, F: Fn() -> T + 'static,

pub fn modifier_local_consumer<F>(self, consumer: F) -> Self

where F: for<'scope> Fn(&mut ModifierLocalReadScope<'scope>) + 'static,

pub fn semantics<F>(self, recorder: F) -> Self

where F: Fn(&mut SemanticsConfiguration) + 'static,

pub fn focus_target(self) -> Self

Makes this component focusable.

This adds a focus target node that can receive focus and participate in focus traversal. The component will be included in tab order and can be focused programmatically.

pub fn on_focus_changed<F>(self, callback: F) -> Self

where F: Fn(FocusState) + 'static,

Makes this component focusable with a callback for focus changes.

The callback is invoked whenever the focus state changes, allowing components to react to gaining or losing focus.

pub fn focus_requester(self, requester: &FocusRequester) -> Self

Attaches a focus requester to this component.

The requester can be used to programmatically request focus for this component from application code.

pub fn debug_chain(self, tag: &'static str) -> Self

Enables debug logging for this modifier chain.

When enabled, logs the entire modifier chain structure including:

• Element types and their properties
• Inspector metadata
• Capability flags

This is useful for debugging modifier composition issues and understanding how the modifier chain is structured at runtime.

Example:

Modifier::empty()
    .padding(8.0)
    .background(Color(1.0, 0.0, 0.0, 1.0))
    .debug_chain("MyWidget")

pub fn then(&self, next: Modifier) -> Modifier

Concatenates this modifier with another.

This creates a persistent tree structure (CombinedModifier pattern) rather than eagerly flattening into a vector, enabling O(1) composition and structural sharing.

Mirrors Jetpack Compose: infix fun then(other: Modifier): Modifier = if (other === Modifier) this else CombinedModifier(this, other)

pub fn total_padding(&self) -> f32

pub fn explicit_size(&self) -> Option<Size>

pub fn padding_values(&self) -> EdgeInsets

pub fn box_alignment(&self) -> Option<Alignment>

pub fn column_alignment(&self) -> Option<HorizontalAlignment>

pub fn row_alignment(&self) -> Option<VerticalAlignment>

pub fn draw_commands(&self) -> Vec<DrawCommand>

pub fn clips_to_bounds(&self) -> bool

pub fn collect_inspector_records(&self) -> Vec<ModifierInspectorRecord>

Returns structured inspector records for each modifier element.

pub fn resolved_modifiers(&self) -> ResolvedModifiers

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

Checks whether two modifiers are structurally equivalent for layout decisions.

This ignores identity-sensitive modifier elements (e.g., draw closures) so draw-only updates do not force measure/layout invalidation.

Trait Implementations

impl Clone for Modifier

fn clone(&self) -> Modifier

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Modifier

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

Formats the value using the given formatter.

impl Default for Modifier

fn default() -> Self

Returns the “default value” for a type.

impl Display for Modifier

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

Formats the value using the given formatter.

impl PartialEq for Modifier

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

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for Modifier