Struct BoxDecoration 

pub struct BoxDecoration {
    pub color: Option<Color>,
    pub gradient: Option<Gradient>,
    pub border: Option<BoxBorder>,
    pub radius: BorderRadius,
    pub shadows: Vec<BoxShadow>,
    pub shape: BoxShape,
    pub image: Option<DecorationImage>,
    pub background_blend_mode: Option<BlendMode>,
}

The complete decoration of a box — the reference’s BoxDecoration (box_decoration.dart:81).

The paint order is fixed, the reference’s (box_decoration.dart:571): the shadows, in order, then the background, then the picture, then the border. The background is either flat (color) or a gradient, which replaces the colour. A border with no background paints an outline over transparency; a wholly empty decoration paints nothing at all.

Fields

color: Option<Color>

Background colour.

gradient: Option<Gradient>

A gradient filling the background, in place of color — linear, radial or sweep (milestone 644).

border: Option<BoxBorder>

The border, side by side.

radius: BorderRadius

Corner radii, per corner. A BoxShape::Circle has none.

shadows: Vec<BoxShadow>

The shadows, painted in order, behind the box (box_decoration.dart:448).

shape: BoxShape

A rectangle or a circle.

image: Option<DecorationImage>

A picture over the background, under the border, clipped to the shape (milestone 645).

background_blend_mode: Option<BlendMode>

How the background — the colour or the gradient — meets what is painted under the box (milestone 646): None paints it over. Nothing else of the decoration is blended, and with no colour or gradient it has nothing to do.

Implementations

impl BoxDecoration

pub fn lerp(self, other: BoxDecoration, t: f32) -> BoxDecoration

The decoration t of the way from self to other — what a decoration transition paints mid-flight. Each part has its own rule, and the rules are the point:

• Colours mix where both sides have one, in the space colours are stated in, as every animated colour in this framework does.
• A part on one side only arrives or leaves; it does not come from nowhere. A fill fades, keeping its hue. A border thickens from nought in its own colour. A shadow grows from under the box as it fades in. Each is the part scaled by how far along it is, which is also what the reference does with a part one side lacks.
• A flat fill is a gradient whose two ends agree, so flat to graded spreads the far end out of the fill rather than laying a gradient over it. Here a gradient starts at the fill colour, so the two always arrive and leave together.
• Corners travel one by one.

The absent colour here is not the absent colour of a text style, and the two rules differ for that reason. A text style that names no colour is asking the theme for one — a real, visible colour — so it holds still rather than fade. A decoration that names no fill paints nothing, so fading is exactly what reaching it means.

t is clamped to 0..=1, and a t that is not a number is no progress: past its ends a colour has nowhere to go, and a decoration whose colours stopped at the end while its corners kept going would be two clocks. At 0 and 1 the answer is the end itself, exactly.

impl BoxDecoration

pub fn filled(color: Color) -> Self

A decoration with a flat background.

pub fn radius(self, radius: impl Into<BorderRadius>) -> Self

Sets the corner radii — uniform through f32, per corner through BorderRadius.

pub fn border(self, border: impl Into<BoxBorder>) -> Self

Sets the border, side by side or by the line’s start and end.

pub fn shadow(self, shadow: BoxShadow) -> Self

Adds a shadow, after (so over) those already there.

pub fn shadows(self, shadows: impl IntoIterator<Item = BoxShadow>) -> Self

Sets the shadows, painted in order.

pub fn shape(self, shape: BoxShape) -> Self

Paints a rectangle or a circle.

pub fn gradient(self, gradient: impl Into<Gradient>) -> Self

Fills the background with a gradient — linear, radial or sweep — in place of the colour.

pub fn image(self, image: DecorationImage) -> Self

Paints a picture over the background, under the border.

pub fn background_blend_mode(self, mode: BlendMode) -> Self

Blends the background — the colour or the gradient — with what is under the box by mode, rather than painting it over.

pub fn content_padding(&self) -> Insets

The inner margin the border needs — add it to the padding so the content is not eaten by the line. This is what feeds taffy. A directional border is read left to right; see Self::content_padding_in.

pub fn content_padding_in(&self, direction: TextDirection) -> Insets

The inner margin the border needs, for a box in direction.

pub fn paint_into(&self, scene: &mut Scene, rect: Rect, opacity: f32)

Lowers the decoration into scene primitives, in the fixed order shadows → background → picture → border, for a box read left to right. See Self::paint_into_in.

pub fn paint_into_in( &self, scene: &mut Scene, rect: Rect, opacity: f32, direction: TextDirection, )

Lowers the decoration into scene primitives, in the fixed order shadows → background → picture → border. opacity (0..=1) modulates every colour, which is how a fade-in works. rect is the box in absolute coordinates; direction places a directional border’s start and end.

Trait Implementations

impl Clone for BoxDecoration

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for BoxDecoration

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

Formats the value using the given formatter.

impl Default for BoxDecoration

fn default() -> Self

Returns the “default value” for a type.

impl PartialEq for BoxDecoration

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for BoxDecoration