Struct ScrollPosition 

pub struct ScrollPosition {
    pub offset: (f32, f32),
    pub max: (f32, f32),
    pub viewport: Size,
}

Where a scroll region is, and how much room it has, at the moment it is reported.

Handed to Widget::on_scroll. Everything an application could want to know about a position is derivable from these three, and they are the three the layout already knows — no measurement is done to produce one.

Fields

offset: (f32, f32)

The offsets (x, y) the region is resting or moving at. Measured from the end its axis starts at, so a reversed list at 0 is at its newest end.

max: (f32, f32)

The largest offsets the content may rest at, per axis. 0 = that axis has nothing to scroll.

viewport: Size

The window the content is seen through.

Implementations

impl ScrollPosition

pub fn of(area: &Scrollable, offset: (f32, f32)) -> Self

The position of area, resting at offset.

pub fn x(&self) -> ScrollMetrics

The horizontal axis, as the physics states it.

pub fn y(&self) -> ScrollMetrics

The vertical axis, as the physics states it.

pub fn fraction_y(&self) -> f32

How far down the content is, 0.0..=1.0.

Zero when there is nothing to scroll, which is the only answer that is not a lie: a list shorter than its window is neither at its beginning nor at its end, and a progress rule over it should read empty rather than full.

pub fn fraction_x(&self) -> f32

How far across the content is, 0.0..=1.0. See ScrollPosition::fraction_y.

pub fn remaining_y(&self) -> f32

Pixels of content left below the window; 0 at the end, and 0 when there is nothing to scroll.

This is what a load-more asks: remaining_y() < 400.0 is “the end is coming”, said in the unit the reader is moving in rather than as a percentage, which means something quite different in a list of ten and a list of ten thousand.

pub fn remaining_x(&self) -> f32

Pixels of content left past the trailing edge. See ScrollPosition::remaining_y.

Trait Implementations

impl Clone for ScrollPosition

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for ScrollPosition

impl Debug for ScrollPosition

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

Formats the value using the given formatter.

impl PartialEq for ScrollPosition

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for ScrollPosition