From da351cda8f0bef0265da4bedf7d4144cb8020cc3 Mon Sep 17 00:00:00 2001 From: mtlcl410 <2368091+mtlcl410@users.noreply.github.com> Date: Mon, 19 Oct 2026 22:26:31 +0800 Subject: [PATCH] fix(forms): cache field appearances drawn for display, redraw only what changed (#3470) Review follow-up (CodeRabbit on #3475). A form edit refreshes the display copy on every keystroke, and with /NeedAppearances that redrew every field of the form: 68 ms per edit on a 1000-field form against 7 ms on main. FieldAppearanceCache keeps each widget's drawing with the objects it was drawn from: the widget and its field ancestors, the form dictionary and the fonts of its /DR, each with the objects its entries refer to. An entry is used only while each of them is still the same object (Arc::ptr_eq); the document replaces an object it edits, so a changed input is a miss, never a stale hit. The engine keeps one per editor. A field edit on that form now takes 13 ms. The repair note on a failed display write now names field appearances too. Co-Authored-By: Claude Opus 5.5 Claude-Session: https://claude.ai/code/session_01Gv2WwdgjmBz33GWkwgNn3Q --- crates/engine/src/lib.rs | 10 ++- crates/engine/src/tests.rs | 5 ++ crates/forms/README.md | 4 +- crates/forms/src/lib.rs | 127 ++++++++++++++++++++++++++++++++++- crates/forms/src/tests.rs | 107 +++++++++++++++++++++++++++++ parity/acrobat-features.toml | 4 +- 6 files changed, 251 insertions(+), 6 deletions(-) diff --git a/crates/engine/src/lib.rs b/crates/engine/src/lib.rs index 3caa0c828..af80271b9 100644 --- a/crates/engine/src/lib.rs +++ b/crates/engine/src/lib.rs @@ -316,6 +316,10 @@ struct Editor { /// runs (content edits leave every annotation dictionary alone). Cleared on any refresh /// that may change annotations; see [`AppearanceCache`]. appearances: AppearanceCache, + /// Display appearances drawn for form fields the file leaves to the viewer (#3470), reused + /// for each widget while the objects it was drawn from are unchanged; see + /// [`pdfcraft_forms::FieldAppearanceCache`]. + field_appearances: pdfcraft_forms::FieldAppearanceCache, /// The text blocks last computed for one page, reused while the document is unchanged. text_blocks: TextBlocksCache, } @@ -882,13 +886,14 @@ fn is_placeholder_title(title: &str) -> bool { fn display_bytes(editor: Option<&mut Editor>, bytes: &Arc>) -> Arc> { let Some(e) = editor else { return bytes.clone() }; let comments = pdfcraft_annot::with_missing_appearances_cached(&e.cos, &mut e.appearances); - let Some(display) = with_field_appearances(comments, &e.cos) else { + let fields = pdfcraft_forms::with_field_appearances_cached(comments.as_ref().unwrap_or(&e.cos), &mut e.field_appearances); + let Some(display) = fields.or(comments) else { return bytes.clone(); }; match write_incremental(&display, &SaveOptions::default()) { Ok(written) => Arc::new(written), Err(err) => { - e.cos.note_repair(format!("missing comment appearances could not be drawn ({err})")); + e.cos.note_repair(format!("missing comment or field appearances could not be drawn ({err})")); bytes.clone() } } @@ -3576,6 +3581,7 @@ impl Session { redo: Vec::new(), keys, appearances: AppearanceCache::default(), + field_appearances: pdfcraft_forms::FieldAppearanceCache::default(), text_blocks: TextBlocksCache::default(), }), None, diff --git a/crates/engine/src/tests.rs b/crates/engine/src/tests.rs index d199eeb70..46dbe4ce3 100644 --- a/crates/engine/src/tests.rs +++ b/crates/engine/src/tests.rs @@ -6160,6 +6160,11 @@ fn fields_left_to_the_viewer_are_displayed_from_their_values() { let n = widget("a").as_dict().and_then(|d| d.get(b"AP").and_then(|ap| saved.resolve(ap).as_dict().and_then(|ap| ap.reference(b"N")))).unwrap(); let pdfcraft_cos::Object::Stream(n) = &*saved.get(n) else { panic!("A's appearance is a stream") }; assert_eq!(n.decoded().unwrap().trim_ascii_end(), b"q\nQ", "A keeps its empty appearance"); + // Typing in one field redraws that field only, not the whole form, on each keystroke. + let builds = |s: &Session| s.get(id).unwrap().editor.as_ref().unwrap().field_appearances.builds(); + let before = builds(&s); + s.apply(id, Edit::SetFieldValue { name: "a".into(), value: pdfcraft_forms::FieldValue::Text("Typed".into()) }).unwrap(); + assert_eq!(builds(&s), before + 1); // Without the flag, the empty appearance is the file's own, and only B is drawn. let id = s.open("form.pdf", None, Arc::new(pdf(false)), None).unwrap(); diff --git a/crates/forms/README.md b/crates/forms/README.md index a05b69b94..96f1f01f9 100644 --- a/crates/forms/README.md +++ b/crates/forms/README.md @@ -45,7 +45,9 @@ delete_field(&mut doc, "email")?; - Displaying a form that leaves its appearances to the viewer (`/NeedAppearances`, or a text or choice widget with no `/AP /N`): `with_field_appearances` returns a copy with those widgets drawn from their values, as typing them would draw them; the engine shows and prints that copy - and saves the file as it was (#3470). + and saves the file as it was (#3470). `with_field_appearances_cached` keeps each widget's + drawing while the objects it was drawn from are the same (`FieldAppearanceCache`), so typing in + one field redraws that field, not the form. - Check boxes and radio buttons switch `/V` and each widget's `/AS`. Widgets with no appearances get PdfCraft's own (a drawn check mark or dot; no symbol font needed). - Values are validated (options, `MaxLen`, single vs multi-select, NoToggleToOff, read-only) and a diff --git a/crates/forms/src/lib.rs b/crates/forms/src/lib.rs index 8d78fb899..8a27d3ebd 100644 --- a/crates/forms/src/lib.rs +++ b/crates/forms/src/lib.rs @@ -1238,6 +1238,12 @@ pub fn need_appearances(doc: &Document) -> bool { /// and otherwise each widget without a normal appearance (`/AP /N`). Drawn as typing the value /// would draw it (#3470). `doc` is not changed: saving writes the file as it was. pub fn with_field_appearances(doc: &Document) -> Option { + with_field_appearances_cached(doc, &mut FieldAppearanceCache::default()) +} + +/// [`with_field_appearances`], reusing the appearances `cache` drew for widgets whose inputs are +/// the same objects as then (see [`FieldAppearanceCache`]). +pub fn with_field_appearances_cached(doc: &Document, cache: &mut FieldAppearanceCache) -> Option { let all = need_appearances(doc); let mut copy: Option = None; for f in fields(doc).iter().filter(|f| matches!(f.kind, FieldKind::Text | FieldKind::Combo | FieldKind::List)) { @@ -1247,7 +1253,15 @@ pub fn with_field_appearances(doc: &Document) -> Option { if drawn && !all { continue; } - let (stream, _) = appearance::field_appearance_drawn(doc, f, w, &f.value, true); + let inputs = appearance_inputs(doc, w); + let stream = match cache.get(w.obj, &inputs) { + Some(stream) => stream, + None => { + let (stream, _) = appearance::field_appearance_drawn(doc, f, w, &f.value, true); + cache.insert(w.obj, inputs, &stream); + stream + } + }; let target = copy.get_or_insert_with(|| doc.clone()); let ap = target.add(Object::Stream(stream)); let mut fresh = Dict::new(); @@ -1260,6 +1274,117 @@ pub fn with_field_appearances(doc: &Document) -> Option { copy } +/// The objects a widget's drawn appearance is built from, as the document holds them: the widget +/// and the fields above it (value, `/DA`, `/Q`, flags, options, `/MK`, formatting actions), the +/// form dictionary (`/DA`) and the fonts of its `/DR`, each with the objects its entries refer to +/// (an indirect `/MK` or `/V`). Not the page: a field's rotation is its own `/MK /R`. +fn appearance_inputs(doc: &Document, w: &Widget) -> Vec> { + // The objects a dictionary's entries refer to. The tree links and the drawn appearance itself + // are not inputs, and `/Kids` and `/Fields` can be long. + let referred = |d: &Dict, inputs: &mut Vec>| { + for (k, v) in d.iter() { + if !matches!(&k[..], b"Kids" | b"Fields" | b"P" | b"Parent" | b"AP") + && let Some(r) = v.as_ref() + { + inputs.push(doc.get(r)); + } + } + }; + let mut inputs = Vec::new(); + let mut seen = std::collections::HashSet::new(); + let mut node = Some(w.obj); + // The /Parent chain; the seen-set and the cap end a cycle or an absurd depth. + while let Some(r) = node.filter(|r| seen.insert(*r) && seen.len() <= 64) { + let obj = doc.get(r); + if let Some(d) = obj.as_dict() { + node = d.reference(b"Parent"); + referred(d, &mut inputs); + } else { + node = None; + } + inputs.push(obj); + } + let Some(root) = doc.root() else { return inputs }; + let catalog = doc.get(root); + let form = match catalog.as_dict().and_then(|c| c.reference(b"AcroForm")) { + Some(r) => doc.get(r), + None => catalog, + }; + if let Some(f) = form.as_dict() { + referred(f, &mut inputs); + // The fonts of /DR. An indirect /DR or /Font is listed through the entries that refer to + // it; a direct one is part of the object that holds it. `held` only finds them: a copy + // of a direct object is a new one each time, never an input. + let held = |o: &Object| o.as_ref().map_or_else(|| std::sync::Arc::new(o.clone()), |r| doc.get(r)); + if let Some(dr) = f.get(b"DR").map(held) + && let Some(dr) = dr.as_dict() + { + referred(dr, &mut inputs); + if let Some(font) = dr.get(b"Font").map(held) + && let Some(fonts) = font.as_dict() + { + referred(fonts, &mut inputs); + } + } + } + inputs.push(form); + inputs +} + +/// Field appearances drawn for the display copy ([`with_field_appearances_cached`]), so a refresh +/// redraws only the widgets whose inputs changed: a form that leaves every appearance to the +/// viewer otherwise redrew all of its fields on each keystroke in any one of them (#3470). An +/// entry holds the input objects it was drawn from and is used only while each is still the same +/// object (`Arc::ptr_eq`); the document replaces an object it edits, so a changed input is a +/// miss, never a stale hit. +#[derive(Clone, Debug, Default)] +pub struct FieldAppearanceCache { + entries: std::collections::HashMap>, pdfcraft_cos::Stream)>, + bytes: usize, + hits: u64, + builds: u64, +} + +impl FieldAppearanceCache { + /// Cached appearance data restarts past this instead of growing without bound. + const MAX_BYTES: usize = 64 << 20; + + /// Forget every entry. + pub fn clear(&mut self) { + *self = Self::default(); + } + + fn get(&mut self, w: ObjRef, inputs: &[std::sync::Arc]) -> Option { + let (from, stream) = self.entries.get(&w)?; + if from.len() != inputs.len() || !from.iter().zip(inputs).all(|(a, b)| std::sync::Arc::ptr_eq(a, b)) { + return None; + } + self.hits += 1; + Some(stream.clone()) + } + + fn insert(&mut self, w: ObjRef, inputs: Vec>, stream: &pdfcraft_cos::Stream) { + self.builds += 1; + if self.bytes.saturating_add(stream.raw.len()) > Self::MAX_BYTES { + self.clear(); + } + self.bytes = self.bytes.saturating_add(stream.raw.len()); + if let Some((_, old)) = self.entries.insert(w, (inputs, stream.clone())) { + self.bytes = self.bytes.saturating_sub(old.raw.len()); + } + } + + /// Cache hits so far (reused appearances); for tests. + pub fn hits(&self) -> u64 { + self.hits + } + + /// Appearances drawn so far; for tests. + pub fn builds(&self) -> u64 { + self.builds + } +} + /// Whether the document's XMP metadata declares PDF/A conformance (`pdfaid:part`). pub fn declares_pdfa(doc: &Document) -> bool { let Some(root) = doc.root() else { return false }; diff --git a/crates/forms/src/tests.rs b/crates/forms/src/tests.rs index 987a74f2c..7a4bd8695 100644 --- a/crates/forms/src/tests.rs +++ b/crates/forms/src/tests.rs @@ -2338,3 +2338,110 @@ fn without_need_appearances_only_missing_appearances_are_drawn() { assert!(ap(©, &field(&all, "g").widgets[0]).contains("(Value G) Tj"), "a down appearance alone is no normal one"); assert!(with_field_appearances(©).is_none(), "every widget has one now"); } + +/// #3470: refreshing the display copy redraws only the widgets whose inputs changed. Typing in +/// one field of a form that leaves every appearance to the viewer otherwise redrew all of them. +#[test] +fn the_field_appearance_cache_redraws_only_what_changed() { + let mut doc = left_to_the_viewer(true); + let mut cache = FieldAppearanceCache::default(); + with_field_appearances_cached(&doc, &mut cache).expect("fields to draw"); + let drawn = cache.builds(); + assert_eq!(drawn, 6, "a, b, c, d, f and g"); + with_field_appearances_cached(&doc, &mut cache).expect("fields to draw"); + assert_eq!((cache.builds(), cache.hits()), (drawn, drawn), "nothing changed, nothing redrawn"); + + set_value(&mut doc, "b", &FieldValue::Text("Typed".into())).unwrap(); + let copy = with_field_appearances_cached(&doc, &mut cache).expect("fields to draw"); + assert_eq!(cache.builds(), drawn + 1, "only b is redrawn"); + assert!(ap(©, &field(&fields(©), "b").widgets[0]).contains("(Typed) Tj"), "and shows its new value"); + assert!(ap(©, &field(&fields(©), "a").widgets[0]).contains("(Value A) Tj"), "a reuses its drawing"); +} + +/// #3470: each kind of input a field's drawing depends on invalidates its cached appearance when +/// it changes, wherever it lives: the parent field's value, the form's `/DA`, an indirect `/MK` +/// and a `/DR` font. Field H is a parent with one kid widget; I is a plain field. +#[test] +fn the_field_appearance_cache_sees_every_input() { + let mut doc = document(&[ + "<< /Type /Catalog /Pages 2 0 R /AcroForm 4 0 R >>".into(), + "<< /Type /Pages /Kids [3 0 R] /Count 1 /MediaBox [0 0 600 800] >>".into(), + "<< /Type /Page /Parent 2 0 R /Annots [6 0 R 7 0 R] >>".into(), + "<< /Fields [5 0 R 7 0 R] /NeedAppearances true /DA (/Helv 12 Tf 0 g) /DR << /Font << /Helv 8 0 R >> >> >>".into(), + "<< /FT /Tx /T (h) /V (Kid value) /Kids [6 0 R] >>".into(), + "<< /Type /Annot /Subtype /Widget /Parent 5 0 R /Rect [50 700 350 720] /P 3 0 R /MK 9 0 R >>".into(), + "<< /Type /Annot /Subtype /Widget /FT /Tx /T (i) /V (Plain) /Rect [50 650 350 670] /P 3 0 R >>".into(), + "<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica /Encoding /WinAnsiEncoding >>".into(), + "<< /BG [1 1 1] >>".into(), + ]); + let r = |n: u32| pdfcraft_cos::ObjRef::new(n, 0); + let mut cache = FieldAppearanceCache::default(); + let mut redraw = |doc: &Document| { + let before = cache.builds(); + let copy = with_field_appearances_cached(doc, &mut cache).expect("fields to draw"); + (cache.builds() - before, copy) + }; + assert_eq!(redraw(&doc).0, 2); + assert_eq!(redraw(&doc).0, 0, "unchanged"); + + doc.update_dict(r(5), |d| d.set(b"V".to_vec(), Object::String(PdfString::text("New value")))).unwrap(); + let (n, copy) = redraw(&doc); + assert_eq!(n, 1, "the parent's value: only its kid"); + assert!(ap(©, &field(&fields(©), "h").widgets[0]).contains("(New value) Tj")); + + doc.update_dict(r(9), |d| d.set(b"BG".to_vec(), Object::Array(vec![Object::Int(1), Object::Int(0), Object::Int(0)]))).unwrap(); + let (n, copy) = redraw(&doc); + assert_eq!(n, 1, "the kid's indirect /MK"); + assert!(ap(©, &field(&fields(©), "h").widgets[0]).contains("1 0 0 rg"), "the new background"); + + doc.update_dict(r(4), |d| d.set(b"DA".to_vec(), Object::String(PdfString::text("/Helv 9 Tf 0 g")))).unwrap(); + let (n, copy) = redraw(&doc); + assert_eq!(n, 2, "the form's /DA: both fields"); + assert!(ap(©, &field(&fields(©), "i").widgets[0]).contains("/Helv 9 Tf")); + + doc.update_dict(r(8), |d| d.set(b"BaseFont".to_vec(), Object::Name(b"Courier".to_vec()))).unwrap(); + assert_eq!(redraw(&doc).0, 2, "a /DR font: both fields"); +} + +/// #3470: an indirect `/DR` and an indirect `/Font` inside it are inputs too, with a font written +/// directly into the `/Font` dictionary, and so is the form's `/DA` when it is an indirect string. +#[test] +fn the_field_appearance_cache_sees_indirect_resources() { + let mut doc = document(&[ + "<< /Type /Catalog /Pages 2 0 R /AcroForm 4 0 R >>".into(), + "<< /Type /Pages /Kids [3 0 R] /Count 1 /MediaBox [0 0 600 800] >>".into(), + "<< /Type /Page /Parent 2 0 R /Annots [5 0 R] >>".into(), + "<< /Fields [5 0 R] /NeedAppearances true /DA 8 0 R /DR 6 0 R >>".into(), + "<< /Type /Annot /Subtype /Widget /FT /Tx /T (i) /V (Plain) /Rect [50 650 350 670] /P 3 0 R >>".into(), + "<< /Font 7 0 R >>".into(), + "<< /Helv << /Type /Font /Subtype /Type1 /BaseFont /Helvetica /Encoding /WinAnsiEncoding >> >>".into(), + "(/Helv 12 Tf 0 g)".into(), + ]); + let r = |n: u32| pdfcraft_cos::ObjRef::new(n, 0); + let mut cache = FieldAppearanceCache::default(); + let mut redraw = |doc: &Document| { + let before = cache.builds(); + with_field_appearances_cached(doc, &mut cache).expect("a field to draw"); + cache.builds() - before + }; + assert_eq!(redraw(&doc), 1); + assert_eq!(redraw(&doc), 0); + let courier = || { + let mut f = Dict::new(); + f.set(b"Type".to_vec(), Object::Name(b"Font".to_vec())); + f.set(b"Subtype".to_vec(), Object::Name(b"Type1".to_vec())); + f.set(b"BaseFont".to_vec(), Object::Name(b"Courier".to_vec())); + Object::Dict(f) + }; + doc.update_dict(r(7), |d| d.set(b"Helv".to_vec(), courier())).unwrap(); + assert_eq!(redraw(&doc), 1, "the indirect /Font dictionary"); + doc.update_dict(r(6), |d| { + let mut fonts = Dict::new(); + fonts.set(b"Helv".to_vec(), courier()); + d.set(b"Font".to_vec(), Object::Dict(fonts)); + }) + .unwrap(); + assert_eq!(redraw(&doc), 1, "the indirect /DR"); + doc.set(r(8), Object::String(PdfString::text("/Helv 9 Tf 0 g"))); + assert_eq!(redraw(&doc), 1, "the form's indirect /DA"); +} diff --git a/parity/acrobat-features.toml b/parity/acrobat-features.toml index 35812170b..872018003 100644 --- a/parity/acrobat-features.toml +++ b/parity/acrobat-features.toml @@ -806,8 +806,8 @@ milestone = "M2" status = "shipped" commands = [] tools = [] -evidence = ["crates/render/src/raster.rs::widget_appearance_states", "crates/render/src/raster.rs::highlights_without_an_appearance_are_drawn", "crates/engine/src/tests.rs::comments_without_appearances_are_drawn_but_not_saved", "crates/engine/src/tests.rs::cli_display_adds_missing_appearances_without_changing_the_source", "crates/engine/src/tests.rs::fields_left_to_the_viewer_are_displayed_from_their_values", "crates/forms/src/tests.rs::need_appearances_draws_every_text_and_choice_field_in_the_display_copy"] -notes = "comments without /AP (FreeText, Ink, notes, stamps, shapes, markup) are drawn from their dictionaries in the page view, page_render and page images, including the CLI render command, never saved; text and choice fields are drawn from their values when the form sets /NeedAppearances (every one) or a widget has no /N (#3470), also display-only. Not cached: a form with 1000 such fields adds about 80 ms to each refresh (a read-only document still gets the renderer's Highlight fallback only); Link borders without /AP and printing are not covered yet" +evidence = ["crates/render/src/raster.rs::widget_appearance_states", "crates/render/src/raster.rs::highlights_without_an_appearance_are_drawn", "crates/engine/src/tests.rs::comments_without_appearances_are_drawn_but_not_saved", "crates/engine/src/tests.rs::cli_display_adds_missing_appearances_without_changing_the_source", "crates/engine/src/tests.rs::fields_left_to_the_viewer_are_displayed_from_their_values", "crates/forms/src/tests.rs::need_appearances_draws_every_text_and_choice_field_in_the_display_copy", "crates/forms/src/tests.rs::the_field_appearance_cache_sees_every_input"] +notes = "comments without /AP (FreeText, Ink, notes, stamps, shapes, markup) are drawn from their dictionaries in the page view, page_render and page images, including the CLI render command, never saved; text and choice fields are drawn from their values when the form sets /NeedAppearances (every one) or a widget has no /N (#3470), also display-only and cached per widget (a field edit on a 1000-field /NeedAppearances form takes ~13 ms against ~7 ms on a form that needs none) (a read-only document still gets the renderer's Highlight fallback only); Link borders without /AP and printing are not covered yet" [[feature]] id = "view.render-error-isolation"