PageCalc

It calculates the page number and cursor (first item number on the current page) vice versa.

It also calculates

next cursor (first item number on the next page if applicable)
previous cursor (first item number on the previous page if applicable)
last cursor (first item number on the last page)
next page number if applicable
previous page number if applicable
last page number
total number of pages

Installation

Install with composer:

composer require "ck/pagecalc:@dev"

Usage example

require '../vendor/autoload.php';

use CK\PageCalc;

$pc = new PageCalc(20) ; // Initiate with a default number of items on one page (limit)

// Someone makes a request on page 3 and a limit of 20 items on the page
$pc->gotoPage($_GET['page'], $_GET['limit']);

// Now do your query using the cursor (offset)
doYourQuery($query = $_GET['q'], $offset = $pc->getCursor(), $limit = $_GET['limit']);

/*
*  With the results you have a total number of results (e.g. $total = 100)
*/

echo 'There are '. $pc->getTotalPages($total) .' pages'; # There are 5 pages

echo 'Page '. $pc->getPage() . ' starts at ' .$pc->getCursor(); # Page 3 starts at 41

// make sure there is a next page
if($pc->getNextPage($total)) {
    echo 'Next page is '. $pc->getNextPage($total) . ' and starts at ' . $pc->getNextCursor($total); # Next page is 4 and starts at 61
}

// make sure there is a previous page
if($pc->getPreviousPage()) {
    echo 'Previous page was '. $pc->getPreviousPage() . ' and started at ' . $pc->getPreviousCursor(); # Previous page was 2 and started at 21
}

// there is always a last page (same as total number of pages)
echo $pc->getLastPage($total) .' is the last page and starts at '. $pc->getLastCursor($total); # 5 is the last page and starts at 81

Methods

__construct($limit)

Sets the default limit. If limit is lower than one, default limit will be 1.

moveCursor($cursor, $limit = false)

Moves cursor, calcultes page number and optionally sets a new limit

Since cursor is always the first item number on the current page, cursor must be a multitude of the limit plus 1. If cursor number is not correct method moveCursor will correct this. E.g.:

$pc = new PageCalc(3); // limit 3
$pc->moveCursor(5); // cursor can't be 5
echo $pc->getCursor(); // current cursor is now 4.
//4 is the first item number on page 2, wich contains item number 5

gotoPage($page, $limit = false)

Sets the current page number, calculates cursor number and optionally sets a new limit