PDF/A docs (#35)

src/actions.rs

@@ -186,22 +186,32 @@ pub enum ActionType {
     /// Go to a destination in another document.
     RemoteGoTo,
     /// Launch an application.
+    ///
+    /// This action type is forbidden in PDF/A.
     Launch,
     /// Open a URI.
     Uri,
     /// Set an annotation's hidden flag. PDF 1.2+.
     SubmitForm,
     /// Set form fields to their default values. PDF 1.2+.
+    ///
+    /// This action type is forbidden in PDF/A.
     ResetForm,
     /// Import form field values from a file. PDF 1.2+.
+    ///
+    /// This action type is forbidden in PDF/A.
     ImportData,
     /// Execute a JavaScript action. PDF 1.2+.
     ///
     /// See Adobe's
     /// [JavaScript for Acrobat API Reference](https://opensource.adobe.com/dc-acrobat-sdk-docs/acrobatsdk/pdfs/acrobatsdk_jsapiref.pdf)
     /// and ISO 21757.
+    ///
+    /// This action type is forbidden in PDF/A.
     JavaScript,
     /// A rendition action to control the playing of multimedia content. PDF 1.5+.
+    ///
+    /// This action type is forbidden in PDF/A.
     Rendition,
 }
 

src/annotations.rs

@@ -58,6 +58,8 @@ impl<'a> Annotation<'a> {
     }
 
     /// Write the `/F` attribute.
+    ///
+    /// Required for all annotations in PDF/A except for `Popup`.
     pub fn flags(&mut self, flags: AnnotationFlags) -> &mut Self {
         self.pair(Name(b"F"), flags.bits() as i32);
         self
@@ -66,6 +68,8 @@ impl<'a> Annotation<'a> {
     /// Start writing the `/AP` dictionary to set how the annotation shall
     /// be presented visually. If this dictionary contains sub dictionaries,
     /// [`Self::appearance_state`] must be set. PDF 1.2+.
+    ///
+    /// Required for many annotations in PDF/A.
     pub fn appearance(&mut self) -> Appearance<'_> {
         self.insert(Name(b"AP")).start()
     }
@@ -147,12 +151,16 @@ impl<'a> Annotation<'a> {
 
     /// Start writing the `/A` dictionary. Only permissible for the subtypes
     /// `Link` and `Widget`.
+    ///
+    /// Note that this attribute is forbidden in PDF/A.
     pub fn action(&mut self) -> Action<'_> {
         self.insert(Name(b"A")).start()
     }
 
     /// Start writing the `/AA` dictionary. Only permissible for the subtype
     /// `Widget`. PDF 1.3+.
+    ///
+    /// Note that this attribute is forbidden in PDF/A.
     pub fn additional_actions(&mut self) -> AdditionalActions<'_> {
         self.insert(Name(b"AA")).start()
     }
@@ -246,10 +254,15 @@ pub enum AnnotationType {
     /// Strike out the text on the page. PDF 1.3+.
     StrikeOut,
     /// A reference to another file. PDF 1.3+.
+    ///
+    /// Note that this annotation type is forbidden in PDF/A-1 and restricted in
+    /// other PDF/A parts.
     FileAttachment,
     /// A widget annotation. PDF 1.2+.
     Widget,
     /// A screen annotation. PDF 1.5+.
+    ///
+    /// Note that this annotation type is forbidden in PDF/A.
     Screen,
 }
 
@@ -326,20 +339,32 @@ bitflags::bitflags! {
         /// This will hide the annotation if the viewer does not recognize its
         /// subtype. Otherwise, it will be rendered as specified in its appearance
         /// stream.
+        ///
+        /// Must not be set for PDF/A.
         const INVISIBLE = 1 << 0;
         /// This hides the annotation from view and disallows interaction. PDF 1.2+.
+        ///
+        /// Must not be set for PDF/A.
         const HIDDEN = 1 << 1;
         /// Print the annotation. If not set, it will be always hidden on print.
         /// PDF 1.2+.
+        ///
+        /// Must be set for PDF/A.
         const PRINT = 1 << 2;
         /// Do not zoom the annotation appearance if the document is zoomed in.
         /// PDF 1.3+.
+        ///
+        /// Must be set for text annotations in PDF/A.
         const NO_ZOOM = 1 << 3;
         /// Do not rotate the annotation appearance if the document is zoomed in.
         /// PDF 1.3+.
+        ///
+        /// Must be set for text annotations in PDF/A.
         const NO_ROTATE = 1 << 4;
         /// Do not view the annotation on screen. It may still show on print.
         /// PDF 1.3+.
+        ///
+        /// Must not be set for PDF/A.
         const NO_VIEW = 1 << 5;
         /// Do not allow interactions. PDF 1.3+.
         const READ_ONLY = 1 << 6;
@@ -348,6 +373,8 @@ bitflags::bitflags! {
         const LOCKED = 1 << 7;
         /// Invert the interpretation of the `no_view` flag for certain events.
         /// PDF 1.5+.
+        ///
+        /// Must not be set for PDF/A.
         const TOGGLE_NO_VIEW = 1 << 8;
         /// Do not allow content changes. PDF 1.7+.
         const LOCKED_CONTENTS = 1 << 9;

src/color.rs

@@ -353,6 +353,11 @@ impl ColorSpace<'_> {
 }
 
 /// Device color spaces.
+///
+/// Please note that the use of the device color spaces is restricted by several
+/// PDF standards such as PDF/A, PDF/X, et cetera. Their appearance will be
+/// governed by any applicable [output intent](crate::writers::OutputIntent) and
+/// default color spaces.
 impl ColorSpace<'_> {
     /// Write a `DeviceRGB` color space.
     pub fn device_rgb(self) {
@@ -647,7 +652,8 @@ impl DeviceNAttrs<'_> {
     /// Start writing the `/Colorants` dictionary. Its keys are the colorant
     /// names and its values are separation color space arrays.
     ///
-    /// Required if the `/Subtype` attribute is `NChannel`.
+    /// Required if the `/Subtype` attribute is `NChannel`. Required for spot
+    /// colors in PDF/A-2, PDF/A-3, and PDF/A-4.
     pub fn colorants(&mut self) -> TypedDict<'_, Dict> {
         self.dict.insert(Name(b"Colorants")).dict().typed()
     }
@@ -1234,7 +1240,7 @@ impl SeparationInfo<'_> {
 /// Writer for an _output intent dictionary_. PDF 1.4+.
 ///
 /// This describes the output conditions under which the document may be
-/// rendered.
+/// rendered. Encouraged by PDF/A.
 pub struct OutputIntent<'a> {
     dict: Dict<'a>,
 }
@@ -1289,6 +1295,8 @@ impl OutputIntent<'_> {
     /// Required if `/OutputConditionIdentifier` does not contain a well-known
     /// identifier for the output condition.
     /// Must reference an [ICC profile](IccProfile) stream.
+    ///
+    /// Required for PDF/A. The profile must have the `prtr` or `mntr` tag.
     pub fn dest_output_profile(&mut self, profile: Ref) -> &mut Self {
         self.dict.pair(Name(b"DestOutputProfile"), profile);
         self
@@ -1300,6 +1308,8 @@ pub enum OutputIntentSubtype<'a> {
     /// `GTS_PDFX`
     PDFX,
     /// `GTS_PDFA1`
+    ///
+    /// This is the right value for PDF/A-1 through PDF/A-4.
     PDFA,
     /// `ISO_PDFE1`
     PDFE,

src/content.rs

@@ -876,7 +876,7 @@ impl Content {
     }
 }
 
-// TODO: Inline images.
+// TODO: Inline images. Also check clause 6.1.10 of PDF/A-2 spec.
 
 /// XObjects.
 impl Content {
@@ -992,6 +992,8 @@ impl<'a> PropertyList<'a> {
 deref!('a, PropertyList<'a> => Dict<'a>, dict);
 
 /// Writer for an _actifact property list dictionary_. PDF 1.4+.
+///
+/// Required for marking up pagination artifacts in some PDF/A profiles.
 pub struct Artifact<'a> {
     dict: Dict<'a>,
 }
@@ -1342,6 +1344,8 @@ impl<'a> ExtGraphicsState<'a> {
 
     /// Write the `OPM` attribute to set the overprint mode for components that
     /// have been zeroed out. PDF 1.3+.
+    ///
+    /// Note that this attribute is restricted by PDF/A.
     pub fn overprint_mode(&mut self, mode: OverprintMode) -> &mut Self {
         self.pair(Name(b"OPM"), mode.to_int());
         self
@@ -1385,6 +1389,8 @@ impl<'a> ExtGraphicsState<'a> {
     }
 
     /// Write the `TR` attribute to set the transfer function.
+    ///
+    /// Note that this key is illegal in PDF/A.
     pub fn transfer(&mut self, func: Ref) -> &mut Self {
         self.pair(Name(b"TR"), func);
         self
@@ -1398,6 +1404,8 @@ impl<'a> ExtGraphicsState<'a> {
     }
 
     /// Write the `HT` attribute to set the halftone.
+    ///
+    /// Note that this value may be ignored in PDF/A.
     pub fn halftone(&mut self, ht: Ref) -> &mut Self {
         self.pair(Name(b"HT"), ht);
         self
@@ -1411,6 +1419,8 @@ impl<'a> ExtGraphicsState<'a> {
     }
 
     /// Write the `FL` attribute to set the flatness tolerance. PDF 1.3+.
+    ///
+    /// Note that this key may be ignored in PDF/A.
     pub fn flatness(&mut self, tolerance: f32) -> &mut Self {
         self.pair(Name(b"FL"), tolerance);
         self
@@ -1429,30 +1439,40 @@ impl<'a> ExtGraphicsState<'a> {
     }
 
     /// Write the `BM` attribute to set the blend mode. PDF 1.4+.
+    ///
+    /// Note that this key is restricted in PDF/A-1.
     pub fn blend_mode(&mut self, mode: BlendMode) -> &mut Self {
         self.pair(Name(b"BM"), mode.to_name());
         self
     }
 
     /// Start writing the `SMask` attribute. PDF 1.4+.
+    ///
+    /// Note that this key is forbidden in PDF/A-1.
     pub fn soft_mask(&mut self) -> SoftMask<'_> {
         self.insert(Name(b"SMask")).start()
     }
 
     /// Write the `SMask` attribute using a name. PDF 1.4+.
+    ///
+    /// Note that this key is forbidden in PDF/A-1.
     pub fn soft_mask_name(&mut self, mask: Name) -> &mut Self {
         self.pair(Name(b"SMask"), mask);
         self
     }
 
     /// Write the `CA` attribute to set the stroking alpha constant. PDF 1.4+.
+    ///
+    /// Note that this key is restricted in PDF/A-1.
     pub fn stroking_alpha(&mut self, alpha: f32) -> &mut Self {
         self.pair(Name(b"CA"), alpha);
         self
     }
 
     /// Write the `ca` attribute to set the non-stroking alpha constant. PDF
     /// 1.4+.
+    ///
+    /// Note that this key is restricted in PDF/A-1.
     pub fn non_stroking_alpha(&mut self, alpha: f32) -> &mut Self {
         self.pair(Name(b"ca"), alpha);
         self
@@ -1529,6 +1549,9 @@ pub enum OverprintMode {
     /// An overprint operation will only discard the underlying colorant
     /// component (e.g. cyan in CMYK) if the new corresponding colorant is
     /// non-zero.
+    ///
+    /// Note that this value is forbidden by PDF/A for ICCBased color spaces
+    /// when overprinting is enabled.
     IgnoreZeroChannel,
 }
 

src/files.rs

@@ -54,7 +54,10 @@ impl<'a> FileSpec<'a> {
     ///
     /// This only sets an embedded file for the `F` attribute corresponding to
     /// the [`path`](Self::path) method. You will need to write this dictionary
-    /// manually if you need to set `UF`.
+    /// manually if you need to set `UF` which is required in PDF/A-3.
+    ///
+    /// Note that this key is forbidden in PDF/A-1 and restricted in PDF/A-2 and
+    /// PDF/A-4.
     pub fn embedded_file(&mut self, id: Ref) -> &mut Self {
         self.insert(Name(b"EF")).dict().pair(Name(b"F"), id);
         self