7.7.3. Implement Page Tree

[victor-pogor]

Context

According to the ISO 32000-1:2008 specification, section 7.7.3, The pages of a document are accessed through a structure known as the page tree, which defines the ordering of pages in the document.

The tree contains nodes of two types — intermediate nodes, called page tree nodes (light blue), and leaf nodes, called page objects (purple).

graph TD;
    Root[Root Page Tree node]:::tree_node -->ChildNode1[Intermediate Node 1]:::tree_node;
    Root[Root Page Tree node]-->ChildNode2[Intermediate Node 2]:::tree_node;
    ChildNode1-->Page1[Page1]:::tree_leaf
    ChildNode1-->Page2[Page2]:::tree_leaf
    ChildNode2-->Page3[Page3]:::tree_leaf
    ChildNode2-->Page4[Page4]:::tree_leaf
    classDef tree_node fill:#03a9f4
    classDef tree_leaf fill:#673ab7

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Example of Page Tree:

2 0 obj
  << /Type /Pages
     /Kids [ 4 0 R
            10 0 R
            24 0 R
          ]
     /Count 3
  >>
endobj

4 0 obj
  << /Type /Page
    …Additional entries describing the attributes of this page…
  >>
endobj

10 0 obj
  << /Type /Page
    …Additional entries describing the attributes of this page…
  >>
endobj

24 0 obj
  << /Type /Page
    …Additional entries describing the attributes of this page…
  >>
endobj

Page Tree node dictionary

1. Page Tree dictionary keys

   Key	Type	Deps
   Type	name
   Parent	dictionary
   Kids	array
   Count	integer

2. Inheritable attributes 7.7.3.4 Implement inheritance of Attributes #65

   Key	Type	Deps
   Resources	dictionary	7.8.3. Implement Base Resource Dictionary #67
   MediaBox	rectangle	7.9.5. Implement Rectangle #68 14.11.2. Implement Page Boundaries #69
   CropBox	rectangle	14.11.2. Implement Page Boundaries #69
   Rotate	integer

Page Object dictionary

1. Page Object dictionary keys

   Key	Type	Deps
   Type	name
   Parent	dictionary
   LastModified	date	14.5. Implement Page-Piece Dictionary #57 7.9.4. Implement Date #66
   Resources	dictionary	7.8.3. Implement Base Resource Dictionary #67
   MediaBox	rectangle	7.9.5. Implement Rectangle #68 14.11.2. Implement Page Boundaries #69
   CropBox	rectangle	14.11.2. Implement Page Boundaries #69
   BleedBox	rectangle	14.11.2. Implement Page Boundaries #69
   TrimBox	rectangle	14.11.2. Implement Page Boundaries #69
   ArtBox	rectangle	14.11.2. Implement Page Boundaries #69
   BoxColorInfo	dictionary	14.11.2. Implement Page Boundaries #69
   Content	stream or array	7.8.2. Implement Content Streams #70 7.2. Implement Lexical Conventions #71
   Rotate	integer
   Group	dictionary	11.4.7. Implement Page Group #72
   Thumb	stream	12.3.4. Implement Thumbnail Images #74
   B	array	12.4.3. Implement Articles #46
   Dur	number	12.4.4. Implement Presentations #75
   Trans	dictionary	12.4.4. Implement Presentations #75
   Annots	array	12.5. Implement Annotations #76
   AA	dictionary	12.6.3. Implement Trigger Events | #48
   Metadata	stream	14.3.2. Implement Metadata Streams #51
   PieceInfo	dictionary	14.5. Implement Page-Piece Dictionary #57
   StructParents	integer	14.7.4. Implement Structure Content #77
   ID	byte string	14.10.6. Implement Object Attributes Related to Web Capture #78
   PZ	SeparationInfo	14.10.6. Implement Object Attributes Related to Web Capture #78
   SeparationInfo	dictionary	14.11.4. Implement Separation Dictionary #79
   Tabs	name
   TemplateInstantiated	name	12.7.6. Implement Named Pages #80
   PresSteps	dictionary	12.4.4. Implement Presentations #75
   UserUnit	number
   VP	dictionary