Struct Viewport

pub struct Viewport<Msg: Clone> {
    pub child: Box<Element<Msg>>,
    pub width: Option<f32>,
    pub height: Option<f32>,
    pub fade_bottom: f32,
}

A non-scrollable clipped viewport for revealing only part of a child tree.

Unlike Scroll, this widget does not own any gesture state. It simply renders its child into an off-screen canvas and blits the result into the allocated rect, clipping anything outside.

Fields

child: Box<Element<Msg>>

The child element to render inside the viewport.

width: Option<f32>

Optional fixed width in logical pixels. When omitted the viewport reports max_width as its preferred width — i.e. it stretches to fill whatever horizontal slice the parent layout gives it. Set explicitly when the viewport has to coexist with flex siblings (the flex would otherwise lose every pixel to the viewport’s max_width claim) or whenever the inner content has its own intrinsic width and the viewport is just a vertical clip.

height: Option<f32>

Optional fixed height in logical pixels. When omitted the viewport reports the child’s natural height.

fade_bottom: f32

Logical pixels at the bottom edge that fade to transparent during the blit. Zero leaves the bottom hard-edged. Useful for slide-in panels so the leading edge of the animation does not knife-cut against the layer below it.

Implementations

impl<Msg: Clone> Viewport<Msg>

pub fn new(child: impl Into<Element<Msg>>) -> Self

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

Set a fixed viewport width in logical pixels. Mirrors Self::height: with an explicit value the viewport reports w as its preferred width and the child is laid out against w rather than the parent-supplied max_width.

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

Set a fixed viewport height in logical pixels.

pub fn fade_bottom(self, px: f32) -> Self

Feather the bottom px rows of the viewport so its lower edge dissolves to transparent. Drawn by the GLES blit shader as a linear alpha ramp over the bottom band; the software backend currently renders a hard edge regardless.

pub fn preferred_size(&self, max_width: f32, canvas: &Canvas) -> (f32, f32)

pub fn draw(&self)

No-op — rendering is handled by layout_and_draw in draw.rs.

Trait Implementations

impl<Msg: Clone + 'static> From<Viewport<Msg>> for Element<Msg>

fn from(v: Viewport<Msg>) -> Self

Converts to this type from the input type.