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Let's write a PDF file

Ange Albertini
July 23, 2015
Technology
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Let's write a PDF file

A simple walk-through to learn the basics of the PDF format (at your rhythm)

2017/07/23 : first release
2015/07/28 : r2 - typos, improvements, stream filters

Ange Albertini

July 23, 2015
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Transcript

  1. Let’s write a PDF file A simple walk-through to learn

    the basics of the PDF format (at your rhythm) PDF = Portable Document Format r2

  2. Ange Albertini reverse engineering & visual documentation @angealbertini [email protected] http://www.corkami.com

  3. Goal: write a “Hello World” in PDF

  4. PDF is text-based, with some binary in specific cases. But

    not in this example, so just open a text editor.

  5. Statements are separated by white space. (any extra white space

    is ignored) Any of these: 0x00 Null 0x0C Form Feed 0x09 Tab 0x0D Carriage Return 0x0A Line feed 0x20 Space (yes, you can mix EOL style :( )

  6. Delimiters don’t require white space before. ( ) < >

    [ ] { } /

  7. _ Let’s start!

  8. %PDF-_ A PDF starts with a %PDF-? signature followed by

    a version number. 1.0 <= version number <= 1.7 (it doesn’t really matter here)

  9. %PDF-1.3 _ Ok, we have a valid signature ☺

  10. %PDF-1.3 %_ A comment starts with % until the end

    of the line.

  11. %PDF-1.3 %file body _ After the signature, comes the file

    body. (we’ll see about it later)

  12. %PDF-1.3 %file body xref _ After the file body, comes

    the cross reference table. It starts with the xref keyword, on a separated line.

  13. %PDF-1.3 %file body xref %xref table here _ After the

    xref keyword, comes the actual table. (we’ll see about it later)

  14. %PDF-1.3 %file body xref %xref table here trailer_ After the

    table, comes the trailer... It starts with a trailer keyword.

  15. %PDF-1.3 %file body xref %xref table here trailer %trailer contents

    _ (we’ll see that later too…) ...and its contents.

  16. %PDF-1.3 %file body xref %xref table here trailer %trailer contents

    startxref _ (with startxref) Then, a pointer to the xref table...

  17. %PDF-1.3 %file body xref %xref table here trailer %trailer contents

    startxref %xref pointer _ (later, too...)

  18. %PDF-1.3 %file body xref %xref table here trailer %trailer contents

    startxref %xref pointer %%EOF_ ...an %%EOF marker. Lastly, to mark the end of the file...

  19. %PDF-1.3 %file body xref %xref table here trailer %trailer contents

    startxref %xref pointer %%EOF Easy ;) That’s the overall layout of a PDF document!

  20. %PDF-1.3 %file body xref %xref table here trailer %trailer contents

    startxref %xref pointer %%EOF Now, we just need to fill in the rest :)

  21. Study time

  22. Def: name objects A.k.a. “strings starting with a slash”

  23. /Name A slash, then an alphanumeric string (no whitespace)

  24. Case sensitive /Name != /name Names with incorrect case are

    just ignored (no error is triggered)

  25. Def: dictionary object Sequence of keys and values (no delimiter

    in between) enclosed in << and >> sets each key to value

  26. Syntax << key value key value [key value]*… >>

  27. Keys are always name objects << /Index 1>> sets /Index

    to 1 << Index 1 >> is invalid (the key is not a name)

  28. Dictionaries can have any length << /Index 1 /Count /Whatever

    >> sets /Index to 1 and /Count to /Whatever

  29. Extra white space is ignored (as usual) << /Index 1

    /Count /Whatever >> is equivalent to << /Index 1 /Count /Whatever >>

  30. Dictionaries can be nested. << /MyDict << >> >> sets

    /MyDict to << >> (empty dictionary)

  31. White space before delimiters is not required. << /Index 1

    /MyDict << >> >> equivalent to <</Index 1/MyDict<<>>>>

  32. Def: indirect object an object number (>0), a generation number

    (0*) the obj keyword the object content the endobj keyword * 99% of the time

  33. Example 1 0 obj 3 endobj is object #1, generation

    0, containing “3”

  34. Def: object reference object number, object generation, R number number

    R ex: 1 0 R

  35. Object reference Refers to an indirect object as a value

    ex: << /Root 1 0 R >> refers to object number 1 generation 0 as the /Root

  36. Used only as values in a dictionary << /Root 1

    0 R >> is OK. << 1 0 R /Catalog>> isn’t.

  37. Be careful with the syntax! “1 0 3” is a

    sequence of 3 numbers 1 0 3 “1 0 R” is a single reference to an object number 1 generation 0

  38. Def: file body sequence of indirect objects object order doesn’t

    matter

  39. Example 1 0 obj 3 endobj 2 0 obj <<

    /Index 1 >> endobj defines 2 objects with different contents

  40. %PDF-1.3 %file body xref %xref table here trailer %trailer contents

    startxref %xref pointer %%EOF Remember this?

  41. A PDF document is defined by a tree of objects.

  42. %PDF-1.3 %file body xref %xref table here trailer %trailer contents

    startxref %xref pointer %%EOF Now, let’s start!

  43. %PDF-1.3 %file body xref %xref table here trailer << _

    >> startxref %xref pointer %%EOF The trailer is a dictionary.

  44. %PDF-1.3 %file body xref %xref table here trailer << /Root_

    >> startxref %xref pointer %%EOF It defines a /Root name...

  45. %PDF-1.3 %file body xref %xref table here trailer << /Root

    1 0 R_>> startxref %xref pointer %%EOF ...that refers to an object...

  46. %PDF-1.3 %file body xref %xref table here trailer << /Root

    1 0 R >> startxref %xref pointer %%EOF (like all the the other objects) ...that will be in the file body.

  47. Recap: the trailer is a dictionary that refers to a

    root object.

  48. %PDF-1.3 _ xref %xref table here trailer << /Root 1

    0 R >> startxref %xref pointer %%EOF Let’s create our first object...

  49. %PDF-1.3 1 0 obj _ endobj xref %xref table here

    trailer << /Root 1 0 R >> startxref %xref pointer %%EOF …(with the standard object declaration)...

  50. %PDF-1.3 1 0 obj << _ >> endobj xref %xref

    table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF (like most objects) ...that contains a dictionary.

  51. %PDF-1.3 1 0 obj << /Type_ >> endobj xref %xref

    table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...and its /Type is...

  52. %PDF-1.3 1 0 obj << /Type /Catalog_ >> endobj xref

    %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...defined as /Catalog...

  53. %PDF-1.3 1 0 obj << /Type /Catalog _ >> endobj

    xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF the /Root object also refers to the page tree...

  54. %PDF-1.3 1 0 obj << /Type /Catalog /Pages_ >> endobj

    xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...via a /Pages name...

  55. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0

    R_>> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...that refers to another object...

  56. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0

    R >> endobj _ xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...which we’ll create.

  57. Recap: object 1 is a catalog, and refers to a

    Pages object.

  58. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0

    R >> endobj _ xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Let’s create object 2.

  59. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0

    R >> endobj 2 0 obj _ endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF The usual declaration.

  60. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0

    R >> endobj 2 0 obj << _ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF It’s a dictionary too.

  61. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0

    R >> endobj 2 0 obj << /Type /Pages_ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF The pages’ object /Type has to be defined as … /Pages ☺

  62. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0

    R >> endobj 2 0 obj << /Type /Pages /Kids_ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF This object defines its children via /Kids...

  63. Def: array enclosed in [ ] values separated by whitespace

    ex: [1 2 3 4] is an array of 4 integers 1 2 3 4

  64. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0

    R >> endobj 2 0 obj << /Type /Pages /Kids [ _ ] >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...which is an array...

  65. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0

    R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R_] >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF … of references to each page object.

  66. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0

    R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] _ >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF One last step...

  67. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0

    R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1_>> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...the number of kids has to be set in /Count...

  68. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0

    R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...and now object 2 is complete!

  69. Recap: object 2 is /Pages; it defines Kids + Count

    (pages of the document).

  70. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj _ We can add our only Kid...

  71. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj _ endobj …(a single page)...

  72. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << _ >> endobj … a dictionary...

  73. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type_ >> endobj … defining a /Type...

  74. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page_ >> endobj … as /Page.

  75. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent_ >> endobj This grateful kid properly recognizes its own parent...

  76. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R_>> endobj … as you would expect ☺

  77. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R _ >> endobj Our page requires resources.

  78. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources_ >> endobj Let’s add them...

  79. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << _ >> >> endobj ...as a dictionary:

  80. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font_ >> >> endobj In this case, fonts...

  81. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << _ >> >> >> endobj ...as a dictionary.

  82. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << _ >> >> >> endobj We define one font...

  83. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1_ >> >> >> endobj ...by giving it a name...

  84. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << _ >> >> >> >> endobj ...and setting its parameters:

  85. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type_ >> >> >> >> endobj its type is ...

  86. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font_ >> >> >> >> endobj … font ☺

  87. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype_ >> >> >> >> endobj Its font type is...

  88. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1_ >> >> >> >> endobj …(Adobe) Type1...

  89. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont_>> >> >> >> endobj ...and its name is...

  90. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial_>> >> >> >> endobj .../Arial.

  91. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> _ >> endobj One thing is missing in our page...

  92. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents_ >> endobj The actual page contents...

  93. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R_ >> endobj … as a reference to another object.

  94. xref %xref table here trailer << /Root 1 0 R

    >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj That’s all for our page object.

  95. Recap: object 3 defines a /Page, its /Parent, /Resources (fonts)

    and its /Contents is in another object. (thank you Mario!)

  96. Study time

  97. Def: stream objects So far, everything is text. How do

    you store binary data (images,...) ?

  98. 1 0 obj … endobj Stream objects are objects. They

    start and they end like any other object: Ex: .

  99. Stream objects contain a stream. between stream and endstream keywords

    1 0 obj stream <stream content> endstream endobj

  100. Streams can contain anything Yes, really! Even binary, other file

    formats... (except the endstream keyword)

  101. Stream parameters are stored before the stream. a dictionary after

    obj, before stream required: stream length optional: compression algorithm, etc…

  102. 1 0 obj << /Length 10 >> stream 0123456789 endstream

    endobj Example

  103. _ %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2

    0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF

  104. 4 0 obj _ endobj %PDF-1.3 1 0 obj <<

    /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj We create a /Content object... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF

  105. 4 0 obj stream _ endstream endobj %PDF-1.3 1 0

    obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj ...that is a stream object... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF

  106. Study time

  107. Page contents syntax parameters sequence then operator ex: param1 param2

    operator

  108. 4 0 obj stream _ endstream endobj %PDF-1.3 1 0

    obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj Text objects are delimited by BT and ET... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF

  109. 4 0 obj stream BT _ ET endstream endobj %PDF-1.3

    1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj ...(BeginText & EndText). xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF

  110. 4 0 obj stream BT Tf_ ET endstream endobj %PDF-1.3

    1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj We need to set a font, with Tf. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF

  111. 4 0 obj stream BT _ Tf ET endstream endobj

    %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj It takes 2 parameters: a font name... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF

  112. 4 0 obj stream BT /F1_ Tf ET endstream endobj

    %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj ...(from the page’s resources)... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF

  113. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0

    R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj 4 0 obj stream BT /F1 100_Tf ET endstream endobj ...and a font size. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF

  114. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0

    R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj 4 0 obj stream BT /F1 100 Tf _ ET endstream endobj We move the cursor... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF

  115. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0

    R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj 4 0 obj stream BT /F1 100 Tf Td_ ET endstream endobj ...with the Td operator... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF

  116. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0

    R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj 4 0 obj stream BT /F1 100 Tf _ Td ET endstream endobj ...that takes 2 parameters... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF

  117. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0

    R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj 4 0 obj stream BT /F1 100 Tf 10 400_Td ET endstream endobj ...x and y coordinates. (default page size: 612x792) xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF

  118. Study time

  119. Def: literal strings enclosed in parentheses Ex: (Hi Mum)

  120. Can contain parentheses (Hello() World((()

  121. Can contain white space ( Hello World ! )

  122. Standard escaping is supported (Hello \ World \r\n)

  123. Escaping is in octal (Hell\157 World)

  124. 4 0 obj stream BT /F1 100 Tf 10 400

    Td _ ET endstream endobj Showing a text string... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj

  125. 4 0 obj stream BT /F1 100 Tf 10 400

    Td Tj_ ET endstream endobj ...is done with the Tj operator... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj

  126. 4 0 obj stream BT /F1 100 Tf 10 400

    Td _ Tj ET endstream endobj ...that takes a single parameter... xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj

  127. 4 0 obj stream BT /F1 100 Tf 10 400

    Td (_) Tj ET endstream endobj ...a literal string. xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj

  128. 4 0 obj stream BT /F1 100 Tf 10 400

    Td (Hello World_) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj

  129. 4 0 obj stream BT /F1 100 Tf 10 400

    Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Our contents stream is complete... %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj

  130. 4 0 obj stream BT /F1 100 Tf 10 400

    Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj

  131. 4 0 obj _ stream BT /F1 100 Tf 10

    400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF One last thing... %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj

  132. 4 0 obj << _ >> stream BT /F1 100

    Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...we need to set its parameters... %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj

  133. 4 0 obj << /Length_ >> stream BT /F1 100

    Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF … the stream length... %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj

  134. 4 0 obj << /Length 44_>> stream BT /F1 100

    Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF …including white space (new lines characters…). %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj

  135. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Our stream parameters are finished... %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj

  136. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...so our page contents object is finished. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj

  137. Recap: obj 4 is a stream object with a set

    length, defining the page’s contents: declare text, set a font and size, move cursor, display text.

  138. The whole document is defined. We need to polish the

    structure.

  139. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0

    R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Our PDF defines 4 objects, starting at index 1...

  140. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...but PDFs always have an object 0, that is null...

  141. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref %xref table here trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...so 5 objects, starting at 0.

  142. Warning: offsets & EOLs We have to define offsets, which

    are affected by the EOL conventions: 1 char under Linux/Mac, 2 under Windows. (I use 1 char newlines character here)

  143. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Let’s edit the XREF table!

  144. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF The next line defines the starting index...

  145. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...and the number of objects.

  146. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Then, one line per object...

  147. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...following the xxxxxxxxxx yyyyy a format (10 digits, 5 digits, 1 letter).

  148. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF The first parameter is the offset (in decimal) of the object...

  149. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...(for the null object, it’s 0).

  150. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Then, the generation number (that is almost always 0)...

  151. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...but for object 0, it’s 65535.

  152. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Then, a letter, to tell if this entry is free (f) or in use (n).

  153. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Lastly, each line should take 20 bytes, including EOL...

  154. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...so add a trailing space.

  155. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Next line (the first real object)...

  156. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF …object offset, in decimal...

  157. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF …generation number...

  158. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n_ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF …and declare the object index in use (n)...

  159. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF …and the trailing space

  160. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF Do the same with the other objects...

  161. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 00000 n 00000 n 00000 n _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF …knowing that all lines will end with “ 00000 n ”,...

  162. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n _ trailer << /Root 1 0 R >> startxref %xref pointer %%EOF ...set all offsets.

  163. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R >> startxref %xref pointer %%EOF The cross-reference table is finished.

  164. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R >> startxref %xref pointer %%EOF

  165. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R >> startxref %xref pointer %%EOF

  166. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R >> startxref _ %%EOF We set the startxref pointer...

  167. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R >> startxref 364_ %%EOF ...as xref’s offset, in decimal (no prepending 0s).

  168. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R >> startxref 364 %%EOF

  169. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R _ >> startxref 364 %%EOF We also need to update the trailer dictionary...

  170. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R /Size_ >> startxref 364 %%EOF ...with the number of objects...

  171. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R /Size 5_>> startxref 364 %%EOF … in the PDF (including object 0).

  172. 4 0 obj << /Length 44 >> stream BT /F1

    100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0 R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R /Size 5 >> startxref 364 %%EOF Our PDF is now complete.

  173. %PDF-1.3 1 0 obj << /Type /Catalog /Pages 2 0

    R >> endobj 2 0 obj << /Type /Pages /Kids [ 3 0 R ] /Count 1 >> endobj 3 0 obj << /Type /Page /Parent 2 0 R /Resources << /Font << /F1 << /Type /Font /Subtype /Type1 /BaseFont /Arial >> >> >> /Contents 4 0 R >> endobj 4 0 obj << /Length 44 >> stream BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET endstream endobj xref 0 5 0000000000 65535 f 0000000010 00000 n 0000000060 00000 n 0000000120 00000 n 0000000269 00000 n trailer << /Root 1 0 R /Size 5 >> startxref 364 %%EOF

  174. Disclaimer: this is a minimal PDF. Most PDF documents are

    much bigger, and contain many more elements. Our PDF: 528 bytes 4 objects text only A standard generated “Hello World”: 15 kiloBytes 20 objects text and binary (embedded fonts…)

  175. No need to type them yourself! Hint: use “mutool clean”

    to fix offsets and lengths. http://www.mupdf.com/

  176. ⇒ mutool version Slightly different content, but same rendering. %PDF-1.3

    %%μῦ 1 0 obj <</Type/Catalog/Pages 2 0 R>> endobj 2 0 obj <</Type/Pages/Kids[3 0 R]/Count 1>> endobj 3 0 obj <</Type/Page/Parent 2 0 R/Resources 5 0 R/Contents 4 0 R>> endobj 4 0 obj <</Length 49>> stream q BT /F1 100 Tf 10 400 Td (Hello World!) Tj ET Q endstream endobj 5 0 obj <</Font<</F1<</Type/Font/Subtype/Type1/BaseFont/Arial>>>>>> endobj xref 0 6 0000000000 65536 f 0000000018 00000 n 0000000064 00000 n 0000000116 00000 n 0000000191 00000 n 0000000288 00000 n trailer <</Size 6/Root 1 0 R>> startxref 364 %%EOF

  177. Hint: you can directly extract the PDF sources. use “pdftotext

    --layout” on the slide deck http://www.foolabs.com/xpdf/home.html

  178. One more thing... This one is important for self study.

  179. Def: stream filters streams can be encoded and/or compressed algorithms

    can be cascaded ex: compression, then ASCII encoding

  180. New stream parameter: /Filter ex: encode the stream in ASCII

    1 0 obj << /Length 12 >> stream Hello World! endstream endobj 1 0 obj << /Length 24 /Filter /ASCIIHexDecode>> stream 48656C6C6F20576F726C6421 endstream endobj ⇔

  181. Ex: compression (deflate = ZIP compression) 1 0 obj <<

    /Length 12 >> stream Hello World! endstream endobj 1 0 obj << /Length 20 /Filter /FlateDecode>> stream x£¾H═╔╔¤/╩IQ♦ ∟I♦> endstream endobj ⇔

  182. Filters can be cascaded. Ex: compressed, then encoded in ASCII

    1 0 obj << /Length 12 >> stream Hello World! endstream endobj 1 0 obj << /Length 40 /Filter [/ASCIIHexDecode /FlateDecode] >> stream 789CF348CDC9C95708CF2FCA495104001C49043E endstream endobj ⇔

  183. Hint: “mutool clean -d” to remove any stream filter. (if

    you want to explore PDFs by yourself) http://www.mupdf.com/

  184. Want more? pdf101.corkami.com

  185. Questions? (you can download this poster at http://pics.corkami.com)

  186. ACK @Doegox @ChrisJohnRiley @PDFKungFoo

  187. To be continued...? https://leanpub.com/binaryisbeautiful

  188. Let’s write a PDF file corkami.com @angealbertini Hail to the

    king, baby! r2