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use std::num::NonZeroUsize;
use pdf_writer::{Finish, Ref, TextStr};
use super::{AbsExt, PdfContext, RefExt};
use crate::geom::Abs;
use crate::model::Content;
use crate::util::NonZeroExt;
/// Construct the outline for the document.
#[tracing::instrument(skip_all)]
pub fn write_outline(ctx: &mut PdfContext) -> Option<Ref> {
let mut tree: Vec<HeadingNode> = vec![];
for heading in ctx.introspector.query(&item!(heading_func).select()) {
let leaf = HeadingNode::leaf(heading);
if let Some(last) = tree.last_mut() {
if last.try_insert(leaf.clone(), NonZeroUsize::ONE) {
continue;
}
}
tree.push(leaf);
}
if tree.is_empty() {
return None;
}
let root_id = ctx.alloc.bump();
let start_ref = ctx.alloc;
let len = tree.len();
let mut prev_ref = None;
for (i, node) in tree.iter().enumerate() {
prev_ref = Some(write_outline_item(ctx, node, root_id, prev_ref, i + 1 == len));
}
ctx.writer
.outline(root_id)
.first(start_ref)
.last(Ref::new(ctx.alloc.get() - 1))
.count(tree.len() as i32);
Some(root_id)
}
/// A heading in the outline panel.
#[derive(Debug, Clone)]
struct HeadingNode {
element: Content,
level: NonZeroUsize,
children: Vec<HeadingNode>,
}
impl HeadingNode {
fn leaf(element: Content) -> Self {
HeadingNode {
level: element.expect_field::<NonZeroUsize>("level"),
element,
children: Vec::new(),
}
}
fn len(&self) -> usize {
1 + self.children.iter().map(Self::len).sum::<usize>()
}
fn try_insert(&mut self, child: Self, level: NonZeroUsize) -> bool {
if level >= child.level {
return false;
}
if let Some(last) = self.children.last_mut() {
if last.try_insert(child.clone(), level.saturating_add(1)) {
return true;
}
}
self.children.push(child);
true
}
}
/// Write an outline item and all its children.
#[tracing::instrument(skip_all)]
fn write_outline_item(
ctx: &mut PdfContext,
node: &HeadingNode,
parent_ref: Ref,
prev_ref: Option<Ref>,
is_last: bool,
) -> Ref {
let id = ctx.alloc.bump();
let next_ref = Ref::new(id.get() + node.len() as i32);
let mut outline = ctx.writer.outline_item(id);
outline.parent(parent_ref);
if !is_last {
outline.next(next_ref);
}
if let Some(prev_rev) = prev_ref {
outline.prev(prev_rev);
}
if !node.children.is_empty() {
let current_child = Ref::new(id.get() + 1);
outline.first(current_child);
outline.last(Ref::new(next_ref.get() - 1));
outline.count(-(node.children.len() as i32));
}
outline.title(TextStr(node.element.plain_text().trim()));
let loc = node.element.location().unwrap();
let pos = ctx.introspector.position(loc);
let index = pos.page.get() - 1;
if let Some(&height) = ctx.page_heights.get(index) {
let y = (pos.point.y - Abs::pt(10.0)).max(Abs::zero());
outline.dest_direct().page(ctx.page_refs[index]).xyz(
pos.point.x.to_f32(),
height - y.to_f32(),
None,
);
}
outline.finish();
let mut prev_ref = None;
for (i, child) in node.children.iter().enumerate() {
prev_ref = Some(write_outline_item(
ctx,
child,
id,
prev_ref,
i + 1 == node.children.len(),
));
}
id
}
|
