Struct Visibility 

pub struct Visibility { /* private fields */ }

Which of a page’s objects optional content hides, shaped like the page.

Why a tree and not a set of ids

A page object has no id. The graph is Vec<PageObject> with a form’s children nested inside it, so the only thing that names an object is its position — and that is exactly what this mirrors: hidden[i] answers for objects[i], and a form’s children answer for that form’s own list. Walking the two together costs one index per object and needs no identity the page graph does not have.

An empty tree means nothing is hidden, which is what a document with no /OCProperties produces and what Visibility::shows_everything reports, so a renderer can skip the descent entirely.

Implementations

impl Visibility

pub fn all_visible() -> Self

Nothing hidden, for a document with no optional content.

pub fn shows_everything(&self) -> bool

Whether this tree hides nothing anywhere beneath it.

A renderer can take this as licence to stop descending: an empty tree is the answer for a page with no optional content at all, and Self::visible already reports an absent entry as visible.

pub fn visible(&self, index: usize) -> bool

Whether the object at index is drawn.

An index this tree does not cover is visible. That is not permissiveness for its own sake: it is what makes all_visible() an empty tree rather than a vector of true, and it means a caller whose object list has grown since the pre-pass ran draws the new objects rather than silently dropping them.

pub fn children(&self, index: usize) -> Self

The tree describing the form at index’s own objects.

Trait Implementations

impl Clone for Visibility

fn clone(&self) -> Visibility

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Visibility

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

Formats the value using the given formatter.

impl Default for Visibility

fn default() -> Visibility

Returns the “default value” for a type.

impl Eq for Visibility

impl PartialEq for Visibility

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for Visibility