A Scaling Paginator - pagination

Question

<< 1 2 3 4 ... 15 16 17 ... 47 48 49 50 >>
<< 1 2 3 4 5 6 7 ... 47 48 49 50 >>
<< 1 2 3 4 ... 44 45 46 47 48 49 50 >>
(the bold is the selected page)
Is there any cleaver logic out there that creates scaling pagination like this? I have created one of these before but it ended up as a mess of logic statements.
The language i am doing this in now is PHP but if you have examples or tips for any language, it would be appreciated.
By scaling i mean when there are only a few pages. The pagination displays this.
<< 1 2 3 4 5 6 7 >>
As the number of pages grow to a certain point, the pagination stops showing all numbers and starts splitting them up.
<< 1 2 3 4 ... 47 48 49 50 >>
<< 1 2 3 4 5 6 ... 47 48 49 50 >>
<< 1 2 3 4 5 6 7 8 ... 47 48 49 50 >>
<< 1 2 3 4 .. 7 8 9 ... 47 48 49 50 >>
<< 1 2 3 4 .. 15 16 17 ... 47 48 49 50 >>
<< 1 2 3 4 ... 44 45 46 47 48 49 50 >>
<< 1 2 3 4 ... 47 48 49 50 >>
(note, the actual numbers and how many it shows before and after is not relevant)

Answer 1

Sorry for the blob of code but here goes. Hopefully the comments are enough to tell you how it works - if leave a comment and I might add some more.
/**
* Get a spread of pages, for when there are too many to list in a single <select>
* Adapted from phpMyAdmin common.lib.php PMA_pageselector function
*
* #param integer total number of items
* #param integer the current page
* #param integer the total number of pages
* #param integer the number of pages below which all pages should be listed
* #param integer the number of pages to show at the start
* #param integer the number of pages to show at the end
* #param integer how often to show pages, as a percentage
* #param integer the number to show around the current page
*/
protected function pages($rows, $pageNow = 1, $nbTotalPage = 1, $showAll = 200, $sliceStart = 5, $sliceEnd = 5, $percent = 20, $range = 10)
{
if ($nbTotalPage < $showAll)
return range(1, $nbTotalPage);
// Always show the first $sliceStart pages
$pages = range(1, $sliceStart);
// Always show last $sliceStart pages
for ($i = $nbTotalPage - $sliceEnd; $i <= $nbTotalPage; $i++)
$pages[] = $i;
$i = $sliceStart;
$x = $nbTotalPage - $sliceEnd;
$met_boundary = false;
while ($i <= $x)
{
if ($i >= ($pageNow - $range) && $i <= ($pageNow + $range))
{
// If our pageselector comes near the current page, we use 1
// counter increments
$i++;
$met_boundary = true;
}
else
{
// We add the percentate increment to our current page to
// hop to the next one in range
$i = $i + floor($nbTotalPage / $percent);
// Make sure that we do not cross our boundaries.
if ($i > ($pageNow - $range) && !$met_boundary)
$i = $pageNow - $range;
}
if ($i > 0 && $i <= $x)
$pages[] = $i;
}
// Since because of ellipsing of the current page some numbers may be double,
// we unify our array:
sort($pages);
return array_unique($pages);
}