Struct Modifier 

pub struct Modifier { /* private fields */ }

Re-export the UI crate so applications can depend on a single crate. 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 press_interaction_source( self, interaction_source: MutableInteractionSource, ) -> Modifier

impl Modifier

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

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

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

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

impl Modifier

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

Set the background color.

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

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

Add rounded corners with uniform radius.

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

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

Add rounded corners with a custom shape.

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

impl Modifier

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

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, ) -> Modifier

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, ) -> Modifier

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) -> Modifier

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, ) -> Modifier

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 content.

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

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

Draw content behind.

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

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

Draw with cache.

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

impl Modifier

pub fn fill_max_width(self) -> Modifier

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) -> Modifier

Fill a fraction of the maximum available width.

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

pub fn fill_max_height(self) -> Modifier

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) -> Modifier

Fill a fraction of the maximum available height.

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

pub fn fill_max_size(self) -> Modifier

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) -> Modifier

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, ) -> Modifier

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) -> Modifier

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>, ) -> Modifier

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, ) -> Modifier

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) -> Modifier

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, ) -> Modifier

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

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

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

pub fn backdrop_blur(self, radius: Dp) -> Modifier

Blur content behind this composable, clipped to the composable bounds.

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

pub fn glass_material(self, material: GlassMaterial) -> Modifier

Apply a frosted glass material: backdrop blur, clipped shape, and tint.

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

Convenience alias for applying a backdrop shader effect.

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

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

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

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

Convenience color filter that tints layer output.

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

Configures how the layer is composited into its parent.

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

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, ) -> Modifier

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, ) -> Modifier

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, ) -> Modifier

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) -> Modifier

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) -> Modifier

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) -> Modifier

Add uniform padding to all sides.

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

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

Add horizontal padding (left and right).

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

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

Add vertical padding (top and bottom).

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

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

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, ) -> Modifier

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) -> Modifier

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, ) -> Modifier

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, ) -> Modifier

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, ) -> Modifier

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, ) -> Modifier

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, ) -> Modifier

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, ) -> Modifier

Creates a horizontally scrollable modifier for lazy lists.

impl Modifier

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

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) -> Modifier

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

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

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) -> Modifier

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

impl Modifier

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

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) -> Modifier

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) -> Modifier

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) -> Modifier

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) -> Modifier

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

Matches Kotlin: Modifier.width(IntrinsicSize)

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

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

Matches Kotlin: Modifier.height(IntrinsicSize)

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

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) -> Modifier

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

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

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

impl Modifier

pub fn empty() -> Modifier

pub fn from_element<E>(element: E) -> Modifier

where E: ModifierNodeElement,

Creates a modifier from a custom modifier node element.

pub fn clip_to_bounds(self) -> Modifier

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, ) -> Modifier

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

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

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

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

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

pub fn focus_target(self) -> Modifier

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) -> Modifier

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) -> Modifier

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) -> Modifier

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.

Eagerly concatenates both element vectors into a single flat Single variant, avoiding recursive Rc tree overhead on drop and comparison.

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: &Modifier) -> 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<(), Error>

Formats the value using the given formatter.

impl Default for Modifier

fn default() -> Modifier

Returns the “default value” for a type.

impl Display for Modifier

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

Formats the value using the given formatter.

impl Eq for Modifier

impl PartialEq for Modifier

fn eq(&self, other: &Modifier) -> 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 WindowModifierExt for Modifier

fn window_drag_area(self) -> Modifier

Marks this component as a drag target for its containing OS window.

fn window_drag_area_with_callbacks( self, on_started: impl Fn() + 'static, on_finished: impl Fn() + 'static, ) -> Modifier

Marks this component as a drag target and reports the native drag lifecycle.

fn window_resize_area(self, direction: WindowResizeDirection) -> Modifier

Marks this component as a resize target for its containing OS window.