Struct KeepVisible 

pub struct KeepVisible {
    pub key: u64,
    pub rect: Rect,
    pub centre: bool,
}

A box a scroll region has been asked to keep in view, and which box it is.

A tab bar wider than its window is what this is for. Declared by the content through Widget::keep_visible, carried on the region so it survives a repaint boundary like everything else about the region, and acted on by crate::Runtime::sync_visible.

Fields

key: u64

Which box this is. The region acts when this changes and not otherwise: the box moves as the region scrolls, so a region chasing the box itself would pin the content in place and no finger could move it.

rect: Rect

The box: in the declaring widget’s own coordinates when it comes back from Widget::keep_visible, and in the frame’s — as it would sit at offset zero — when it reaches the region.

At rest rather than where it is actually drawn, and that is the whole reason the answer can be trusted. A box recorded where it is drawn is a box whose position already contains the current offset, so the offset that would centre it can only be worked out relative to wherever the region happens to be — and on the first frame, before anything has been retained, there is no wherever to be relative to. Recorded at rest, the answer is absolute: the same number on the first frame and the hundredth.

centre: bool

Put it in the middle of the window rather than merely inside it. What a tab bar wants: a selected tab flush against the edge reads as the end of the row. Clamped either way, so the first tab still rests at the start.

Trait Implementations

impl Clone for KeepVisible

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 KeepVisible

impl Debug for KeepVisible

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

Formats the value using the given formatter.

impl PartialEq for KeepVisible

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for KeepVisible