Merge pull request fschutt#141 from nubis/master

Adds escape hatch for pages to add annotations

Cargo.toml

@@ -101,6 +101,10 @@ required-features = []
 name = "svg"
 required-features = ["svg"]
 
+[[example]]
+name = "annotations"
+required-features = []
+
 [[example]]
 name = "hyperlink"
 required-features = ["annotations"]

examples/annotations.rs

@@ -0,0 +1,46 @@
+//! Uses the extend_with feature to add a link to the page.
+extern crate printpdf;
+
+use printpdf::*;
+use std::fs::File;
+use std::io::BufWriter;
+use lopdf::{
+  StringFormat::Literal,
+  Dictionary,
+  Object
+};
+
+fn main() {
+    let (doc, page1, layer1) =
+        PdfDocument::new("printpdf graphics test", Mm(210.0), Mm(297.0), "Layer 1");
+    let page = doc.get_page(page1);
+    let current_layer = page.get_layer(layer1);
+
+    let action = Dictionary::from_iter(vec![
+      ("Type", "Action".into()),
+      ("S", Object::Name(b"URI".to_vec())),
+      ("URI", Object::String(b"https://github.com/fschutt/printpdf".to_vec(), Literal)),
+    ]);
+
+    let annotation = Dictionary::from_iter(vec![
+        ("Type", "Annot".into()),
+        ("Subtype", Object::Name(b"Link".to_vec())),
+        ("Rect", vec![20.into(), 580.into(), 300.into(), 560.into()].into()),
+        ("C", vec![].into()),
+        ("Contents", Object::String("Hello World".into(), Literal)),
+        ("A", action.into()),
+    ]);
+
+    let annotations = Dictionary::from_iter(vec![
+        ("Annots", Object::Array(vec![annotation.into()]))
+    ]);
+
+    page.extend_with(annotations);
+
+    let text = "There's an invisible annotation with a link covering this text.";
+    let font = doc.add_builtin_font(BuiltinFont::Helvetica).unwrap();
+    current_layer.use_text(text, 10.0, Mm(10.0), Mm(200.0), &font);
+
+    doc.save(&mut BufWriter::new(File::create("test_annotations.pdf").unwrap()))
+        .unwrap();
+}

src/pdf_document.rs

@@ -664,6 +664,12 @@ impl PdfDocumentReference {
                 ("Parent", Reference(pages_id)),
             ]);
 
+            if let Some(extension) = &page.extend_with {
+              for (key, value) in extension.iter() {
+                p.set(key.to_vec(), value.clone())
+              }
+            }
+
             // this will collect the resources needed for rendering this page
             let layers_temp = ocg_list.iter().find(|e| e.0 == idx).unwrap();
             let (mut resources_page, layer_streams) =

src/pdf_page.rs

@@ -23,6 +23,10 @@ pub struct PdfPage {
     pub layers: Vec<PdfLayer>,
     /// Resources used in this page
     pub(crate) resources: PdfResources,
+    /// Extend the page with custom ad-hoc attributes, as an escape hatch to the low level lopdf library.
+    /// Can be used to add annotations to a page.
+    /// If your dictionary is wrong it will produce a broken PDF without warning or useful messages.
+    pub(crate) extend_with: Option<lopdf::Dictionary>,
 }
 
 /// A "reference" to the current page, allows for inner mutability
@@ -48,6 +52,7 @@ impl PdfPage {
             height: height.into(),
             layers: Vec::new(),
             resources: PdfResources::new(),
+            extend_with: None
         };
 
         let initial_layer = PdfLayer::new(layer_name);
@@ -189,4 +194,12 @@ impl PdfPageReference {
             layer,
         }
     }
+
+    #[inline]
+    pub fn extend_with(&self, dict: lopdf::Dictionary) {
+        let doc = self.document.upgrade().unwrap();
+        let mut doc = doc.borrow_mut();
+        let page = &mut doc.pages[self.page.0];
+        page.extend_with = Some(dict);
+    }
 }