CODEWITHSUNDEEP
pdf
James Yeomans
James Yeomans

Reputation: 31

pdf decoding, what do the bracket and numbers do?

my PDF file has deflate encoding, when inflating the string, it outputs something like this:

[(Lorem)-21( ipsum)-55( dolor)-14( sit)-55( amet,)-56( consectetur)-8( adipiscing)-14( elit.)-34( Donec)-15( faucibus)-49( lorem)-42( varius2)-56( mauris)-28( porttitor,)-34( et)-28( pellentesque)-1( )]TJ

what do the numbers and brackets mean?

it does not seems to be character count, or spacing,

does anyone know?

Upvotes: 0

Views: 863

Answers (1)

Jesse Good
Jesse Good

Reputation: 52365

That is an array for showing text (Stuff in brackets denote array objects []), it should be followed by the TJ operator. The number is used to translate the text matrix (adjust the positioning of the text). Assuming horizontal text, a negative number moves the next glyph to the right.

From 9.4.3 Text-Showing Operators (Please see the spec for more details)

Show one or more text strings, allowing individual glyph positioning. Each element of array shall be either a string or a number. If the element is a string, this operator shall show the string. If it is a number, the operator shall adjust the text position by that amount; that is, it shall translate the text matrix, Tm. The number shall be expressed in thousandths of a unit of text space (see 9.4.4, "Text Space Details"). This amount shall be subtracted from the current horizontal or vertical coordinate, depending on the writing mode. In the default coordinate system, a positive adjustment has the effect of moving the next glyph painted either to the left or down by the given amount.

The parentheses denote string objects:

String objects shall be written in one of the following two ways:

As a sequence of literal characters enclosed in parentheses ( ) (using LEFT PARENTHESIS (28h) and RIGHT PARENThESIS (29h)); see 7.3.4.2, "Literal Strings."

...

A literal string shall be written as an arbitrary number of characters enclosed in parentheses. Any characters may appear in a string except unbalanced parentheses (LEFT PARENHESIS (28h) and RIGHT PARENTHESIS (29h)) and the backslash (REVERSE SOLIDUS (5Ch)), which shall be treated specially as described in this sub-clause. Balanced pairs of parentheses within a string require no special treatment.

I suggest getting the PDF Spec and reading it to find out more info.

Upvotes: 2

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