style: rustfmt

crates/pdf/src/export.rs

@@ -77,6 +77,7 @@ fn write_attempt(doc: &Document, lay: &DocLayout, opts: &PdfOptions, pages: &[us
         cmaps: HashMap::new(),
         images: HashMap::new(),
         vectors: HashMap::new(),
+        vector_bytes_left: crate::exporter::MAX_CACHED_VECTOR_BYTES,
         tags: Vec::new(),
         tag_index: HashMap::new(),
         links: Vec::new(),

crates/pdf/src/exporter.rs

@@ -15,6 +15,9 @@ mod draw;
 mod nav;
 mod text;
 
+/// Most bytes of parsed metafiles (geometry, text and pixels) one export keeps between pages.
+pub(crate) const MAX_CACHED_VECTOR_BYTES: usize = 256 << 20;
+
 pub(crate) struct Exporter<'a> {
     pub(crate) doc: &'a Document,
     pub(crate) lay: &'a DocLayout,
@@ -30,6 +33,8 @@ pub(crate) struct Exporter<'a> {
     pub(crate) images: HashMap<String, Option<Image>>,
     /// Parsed metafiles by media key (`None`: not readable).
     pub(crate) vectors: HashMap<String, Option<Arc<Vector>>>,
+    /// Bytes of parsed metafiles `vectors` may still keep ([`MAX_CACHED_VECTOR_BYTES`]).
+    pub(crate) vector_bytes_left: usize,
     pub(crate) tags: Vec<TagEntry>,
     pub(crate) tag_index: HashMap<(StoryRef, DocPath), usize>,
     /// Link rectangles on the current page: (x0, y0, x1, y1, target).
@@ -84,7 +89,7 @@ impl Exporter<'_> {
 
     /// The metafile picture for a media key, parsed once. None when the bytes are not a metafile
     /// (the raster path takes them) or do not parse (the raster path then draws the grey box).
-    fn vector(&mut self, key: &str) -> Option<Arc<Vector>> {
+    pub(crate) fn vector(&mut self, key: &str) -> Option<Arc<Vector>> {
         let doc = self.doc;
         let bytes = doc.media.get(key)?;
         if !wordcraft_metafile::is_metafile(bytes) {
@@ -97,7 +102,16 @@ impl Exporter<'_> {
         if v.is_none() {
             log::warn!("PDF: metafile `{key}` could not be read");
         }
-        self.vectors.insert(key.to_string(), v.clone());
+        // Kept for the pages that draw it again while the cache has room; past that it is parsed
+        // again when it is next drawn, rather than every metafile's geometry piling up.
+        let size = v.as_ref().map_or(0, |v| v.heap_bytes());
+        match self.vector_bytes_left.checked_sub(size) {
+            Some(left) => {
+                self.vector_bytes_left = left;
+                self.vectors.insert(key.to_string(), v.clone());
+            }
+            None => log::debug!("PDF: metafile `{key}` ({size} bytes parsed) is not kept between pages"),
+        }
         v
     }
 

crates/pdf/src/picture.rs

@@ -14,6 +14,23 @@ pub(crate) struct Vector {
     images: Vec<Option<Image>>,
 }
 
+impl Vector {
+    /// Bytes the parsed picture holds: its paths' segments, its text and its bitmaps' pixels.
+    pub(crate) fn heap_bytes(&self) -> usize {
+        let item = |it: &wordcraft_metafile::Item| match it {
+            wordcraft_metafile::Item::Path { segs, .. } => segs.len().saturating_mul(std::mem::size_of::<wordcraft_metafile::Seg>()),
+            wordcraft_metafile::Item::Bitmap { width, height, .. } => (*width as usize).saturating_mul(*height as usize).saturating_mul(4),
+            wordcraft_metafile::Item::Text(t) => t.text.len().saturating_add(t.font.len()),
+        };
+        let items = self
+            .pic
+            .items
+            .iter()
+            .fold(self.pic.items.len().saturating_mul(std::mem::size_of::<wordcraft_metafile::Item>()), |n, it| n.saturating_add(item(it)));
+        items.saturating_add(self.images.len().saturating_mul(std::mem::size_of::<Option<Image>>()))
+    }
+}
+
 /// Parses a metafile and embeds its bitmaps. None when the picture has no usable size.
 pub(crate) fn build_vector(bytes: &[u8]) -> Option<Vector> {
     let mut pic = wordcraft_metafile::parse(bytes).ok()?;

crates/pdf/src/tests.rs

@@ -1367,6 +1367,7 @@ fn bookmark_destination_is_the_page_of_its_start() {
         cmaps: HashMap::new(),
         images: HashMap::new(),
         vectors: HashMap::new(),
+        vector_bytes_left: crate::exporter::MAX_CACHED_VECTOR_BYTES,
         tags: Vec::new(),
         tag_index: HashMap::new(),
         links: Vec::new(),
@@ -2488,3 +2489,37 @@ fn baseline_is_the_most_shared_y() {
     assert_eq!(baseline(&[(1, 0.0, 9.0), (2, 3.0, 4.0)]), Some(4.0));
     assert_eq!(baseline(&[(1, 0.0, -0.0), (2, 3.0, 0.0)]), Some(0.0));
 }
+
+#[test]
+fn parsed_metafiles_are_kept_only_within_the_cache_budget() {
+    let mut d = Document::new();
+    let media = d.add_media(red_right_half_emf(), "emf");
+    let lay = layout(&d, &mut LayoutCache::new(), &LayoutOptions::default());
+    let outlined = HashSet::new();
+    let mut ex = Exporter {
+        doc: &d,
+        lay: &lay,
+        opts: &PdfOptions::default(),
+        out_index: HashMap::new(),
+        fonts: HashMap::new(),
+        font_error: None,
+        outlined: &outlined,
+        cmaps: HashMap::new(),
+        images: HashMap::new(),
+        vectors: HashMap::new(),
+        vector_bytes_left: crate::exporter::MAX_CACHED_VECTOR_BYTES,
+        tags: Vec::new(),
+        tag_index: HashMap::new(),
+        links: Vec::new(),
+        bookmarks: std::cell::OnceCell::new(),
+    };
+    let v = ex.vector(&media).expect("parses");
+    assert!(v.heap_bytes() > 0);
+    assert_eq!(ex.vectors.len(), 1, "kept while the budget has room");
+    assert_eq!(ex.vector_bytes_left, crate::exporter::MAX_CACHED_VECTOR_BYTES - v.heap_bytes());
+    // With the budget spent, a metafile is still drawn, just not kept.
+    ex.vectors.clear();
+    ex.vector_bytes_left = 0;
+    assert!(ex.vector(&media).is_some());
+    assert!(ex.vectors.is_empty());
+}