Add date to document (#2371)

Cargo.lock

@@ -3471,9 +3471,9 @@ checksum = "ec7a2a501ed189703dba8b08142f057e887dfc4b2cc4db2d343ac6376ba3e0b9"
 
 [[package]]
 name = "xmp-writer"
-version = "0.1.0"
+version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9fd742bbbb930fc972b28bf66b7546dfbc7bb9a4c7924299df0ae6a5641fcadf"
+checksum = "4543ba138f64a94b19e1e9c66c165bca7e03d470e1c066cb76ea279d9d0e1989"
 
 [[package]]
 name = "xz2"

crates/typst-library/src/meta/document.rs

@@ -1,3 +1,5 @@
+use typst::eval::Datetime;
+
 use crate::layout::{LayoutRoot, PageElem};
 use crate::meta::ManualPageCounter;
 use crate::prelude::*;
@@ -30,6 +32,12 @@ pub struct DocumentElem {
     /// The document's keywords.
     pub keywords: Keywords,
 
+    /// The document's creation date.
+    ///
+    /// The year component must be at least zero in order to be embedded into
+    /// a PDF.
+    pub date: Option<Datetime>,
+
     /// The page runs.
     #[internal]
     #[variadic]
@@ -81,6 +89,7 @@ impl LayoutRoot for DocumentElem {
             title: self.title(styles),
             author: self.author(styles).0,
             keywords: self.keywords(styles).0,
+            date: self.date(styles),
         })
     }
 }

crates/typst/Cargo.toml

@@ -53,7 +53,7 @@ unicode-segmentation = "1"
 unscanny = "0.1"
 usvg = { version = "0.35", default-features = false, features = ["text"] }
 xmlwriter = "0.1.0"
-xmp-writer = "0.1"
+xmp-writer = "0.2"
 time = { version = "0.3.20", features = ["std", "formatting", "macros", "parsing"] }
 wasmi = "0.31.0"
 xmlparser = "0.13.5"

crates/typst/src/doc.rs

@@ -8,7 +8,7 @@ use std::sync::Arc;
 
 use ecow::{eco_format, EcoString};
 
-use crate::eval::{cast, dict, ty, Dict, Repr, Value};
+use crate::eval::{cast, dict, ty, Datetime, Dict, Repr, Value};
 use crate::export::PdfPageLabel;
 use crate::font::Font;
 use crate::geom::{
@@ -30,6 +30,8 @@ pub struct Document {
     pub author: Vec<EcoString>,
     /// The document's keywords.
     pub keywords: Vec<EcoString>,
+    /// The document's creation date.
+    pub date: Option<Datetime>,
 }
 
 /// A finished layout with items at fixed positions.

crates/typst/src/export/pdf/mod.rs

@@ -171,6 +171,24 @@ fn write_catalog(ctx: &mut PdfContext) {
         xmp.pdf_keywords(&joined);
     }
 
+    if let Some(date) = ctx.document.date {
+        if let Some(year) = date.year().filter(|&y| y >= 0) {
+            let mut pdf_date = pdf_writer::Date::new(year as u16);
+            if let Some(month) = date.month() {
+                pdf_date = pdf_date.month(month);
+            }
+            if let Some(day) = date.day() {
+                pdf_date = pdf_date.day(day);
+            }
+            info.creation_date(pdf_date);
+
+            let mut xmp_date = xmp_writer::DateTime::year(year as u16);
+            xmp_date.month = date.month();
+            xmp_date.day = date.day();
+            xmp.create_date(xmp_date);
+        }
+    }
+
     info.finish();
     xmp.num_pages(ctx.document.pages.len() as u32);
     xmp.format("application/pdf");

tests/typ/meta/document.typ

@@ -8,7 +8,11 @@ What's up?
 ---
 // This, too.
 // Ref: false
-#set document(author: ("A", "B"))
+#set document(author: ("A", "B"), date: datetime.today())
+
+---
+// Error: 21-28 expected datetime or none, found string
+#set document(date: "today")
 
 ---
 // This, too.