Page selector and Split scheme
For some features, it is very important to have a flexible option to determine which pages to process and which pages not to process (e.g. all even pages, all odd pages, only the first two and the last pages or every 4th page, etc.). For this purpose, a flexible syntax is used to express the desired groups of pages or page ranges.
A page selector expression can be a list e.g. 1,2,3. It can also be a simple expression, e.g. 3--3 will find all pages except the first and last two (last page being -1). Or it uses more advanced syntax: e.g. *3 will select every third page. More information below.
"page_selector": "all|even|odd|<splitscheme_expression>"Split scheme is a TYPE of 'page selector'
Usage on CLI
The “Page selector” functionality can be used on CLI in the following way:
--pagerange=<expression>This is the same syntax as used for split schemes (--splitscheme=<expression>)
Usage in the SDK
The “Page selector” functionality can be used in the SDK where the following parameter is listed (with slightly different types in other languages).
const PTB_sys_char_t* pageselector /*!< Use page selector syntax, might be NULL for all pages */Split Scheme
A split scheme expression may be a number with an asterisk "*" or a more complex string. If it is a number with an asterisk "*", it creates groups of pages where each group has the defined number of pages. E.g. if the expression is "3*" it would group the PDF into groups of 3 pages.
Expressions
| Type | Syntax | Example | |
|---|---|---|---|
Simple expression |
number[-number] |
1-5 | Page 1 to 5: [1,2,3,4,5] |
| 5-1 | Page 5 to 1: [5,4,3,2,1] |
||
| 8 | Only page 8 | ||
| -1 | Last page | ||
| -3--1 |
Last 3 pages: [n, n-1, n-2] |
||
| -1--3 |
Last 3 pages in reverse order: [n-2, n-1, n] |
||
| -1-3 | Last n - 2 pages in reverse order: [n, n-1, ... ,3] |
| Type |
Syntax |
Example | |
|---|---|---|---|
Simple expression with Simple Range |
number[-number]_ number[-number][ "," joker$] |
1-2_-2--1 |
First 2 and last 2 pages: [1,2,n- 1,n] |
| 1-2_-2--1,$ |
First 2 and last 2 pages [1,2,n-1,n] and remaining inner pages [3, ... ,n-2] |
||
| 1_1_1_1 |
4 times page 1: [1,1,1,1] |
| Type | Syntax | Example | |
|---|---|---|---|
Multipage expression |
even_pages |
even |
All even pages(same as *2(2)) |
| uneven_pages |
odd | All odd pages (same as *2(1)) |
|
Package number* [(start_page)] |
5* | Packages of 5 pages |
|
| 5*(2) |
Packages of 5 pages, starting with page 2 |
||
*number [(start_page)] |
*5 |
Every 5th page |
|
| *5(2) |
Every 5th page, starting with page 2 |
||
| *5(-20) |
Every 5th page of the last 20 pages of a document (total 4 pages) |
||
| *number [(start_page,end_page)] |
*5(2,20) |
Every 5th page starting with the second page and up to the 20th page |
| Type | Syntax |
Example | |
|---|---|---|---|
Simple expression list |
simple_expression {"," simple_expression}[ "," joker$] |
1-5,8,-3--1 |
1 PDF with pages 1-5, page 8 and the last 3 pages of the input PDF |
| 1-5,8,-1--3 |
1 PDF with pages 1-5, page 8 and the last 3 pages of the input PDF, but the last 3 pages in reverse order |
||
| 1-5,8,$ |
1 PDF with pages 1-5, page 8 and all the remaining pages |
Joker
<expression>,$Can be combined with other expressions (has to be the last item in a list) in order to group all pages that are not part of any other expression into their own group.
Example
1-5,8,-3--1,$would create groups of pages with pages 1-5, page 8, the last 3 pages and the rest of the pages of the PDF.