Split up PDF exporter

1 files changed, 98 insertions, 0 deletions

diff --git a/src/export/pdf/outline.rs b/src/export/pdf/outline.rs
new file mode 100644
index 00000000..f5530f86
--- /dev/null
+++ b/src/export/pdf/outline.rs
@@ -0,0 +1,98 @@
+use pdf_writer::{Finish, Ref, TextStr};
+
+use super::{LengthExt, PdfContext, RefExt};
+use crate::geom::{Length, Point};
+use crate::util::EcoString;
+
+/// A heading that can later be linked in the outline panel.
+#[derive(Debug, Clone)]
+pub struct Heading {
+    pub content: EcoString,
+    pub level: usize,
+    pub position: Point,
+    pub page: Ref,
+}
+
+/// A node in the outline tree.
+#[derive(Debug, Clone)]
+pub struct HeadingNode {
+    pub heading: Heading,
+    pub children: Vec<HeadingNode>,
+}
+
+impl HeadingNode {
+    pub fn leaf(heading: Heading) -> Self {
+        HeadingNode { heading, children: Vec::new() }
+    }
+
+    pub fn len(&self) -> usize {
+        1 + self.children.iter().map(Self::len).sum::<usize>()
+    }
+
+    pub fn insert(&mut self, other: Heading, level: usize) -> bool {
+        if level >= other.level {
+            return false;
+        }
+
+        if let Some(child) = self.children.last_mut() {
+            if child.insert(other.clone(), level + 1) {
+                return true;
+            }
+        }
+
+        self.children.push(Self::leaf(other));
+        true
+    }
+}
+
+/// Write an outline item and all its children.
+pub 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(-1 * node.children.len() as i32);
+    }
+
+    outline.title(TextStr(&node.heading.content));
+    outline.dest_direct().page(node.heading.page).xyz(
+        node.heading.position.x.to_f32(),
+        (node.heading.position.y + Length::pt(3.0)).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
+}