change the number of results per page in drupal views

I need to have an option on my search page which will allow the users to select the number of results that they want to display in the view i.e 25 results, 50 , 100 results per page. My theme_pager code is

function theme_pager($tags = array(), $limit = 10, $element = 0, $parameters = array(), $quantity = 9) {
  global $pager_page_array, $pager_total;
  $tags = array("", "< prev", "", "next >", "");

    // Calculate various markers within this pager piece:
    // Middle is used to "center" pages around the current page.
    $ pager_middle = ceil($quantity / 2);
    // current is the page we are currently paged to
    $pager_current = $pager_page_array[$element] + 1;
    // first is the first page listed by this pager piece (re quantity)
    $pager_first = $pager_current - $pager_middle + 1;
    // last is the last page listed by this pager piece (re quantity)
    $pager_last = $pager_current + $quantity - $pager_middle;
    // max is the maximum page number
    $pager_max = $pager_total[$element];
    // End of marker calculations.

    // Prepare for generation loop.
    $i = $pager_first;
    if ($pager_last > $pager_max) {
      // Adjust "center" if at end of query.
    $i = $i + ($pager_max - $pager_last);
    $pager_last = $pager_max;
    }
    if ($i <= 0) {
      // Adjust "center" if at start of query.
    $pager_last = $pager_last + (1 - $i);
    $i = 1;
    }
    // End of generation loop preparation.
    $view = views_get_current_view();

    // ensure view exists
    if (!$view) return;

    // set object property to return total rows  
    $view->get_total_rows = true;



    // set display_id
    $view->set_display($display_id);

    // execute view
    $view->execute();

    // acquire data from views object and $_REQUEST    
    $itemsPerPage = $view->pager['items_per_page'];
    $currentPage = $_REQUEST['page']+1;
    $total = $view->total_rows;

    // start calculation    
    $start = ($itemsPerPage * $currentPage) - ($itemsPerPage-1);
    $end = $itemsPerPage * $currentPage;

    if ($end>$total) $end = $total;

    // return html
    $x =  "<b>Displaying $start - $end of $total</b>";
    $li_previous = theme('pager_previous', (isset($tags[1]) ? $tags[1] : t('‹ previous')), $limit,    $element, 1, $parameters);
    $li_next = theme('pager_next', (isset($tags[3]) ? $tags[3] : t('next ›')), $limit, $element, 1, $parameters);

     if ($pager_total[$element] > 1) {
     $items[] = array(
                                 'class' => 'pager',
                                 'data' => $x,
                                );
      if ($li_previous) {


      $items[] = array(
        'class' => 'pager-previous',
        'data' => $li_previous,
      );
    }

    // When there is more than one page, create the pager list.
    if ($i != $pager_max) {
      // Now generate the actual pager piece.
      for (; $i <= $pager_last && $i <= $pager_max; $i++) {
        if ($i < $pager_current) {
                     if ($pager_first > 1 && $i == $pager_first) {
                                               $output = '...'.$i;
                                               $stopPreEllipsis = true;
                                } else {
                                               $output = $i;
                                }
          $items[] = array(
            'class' => 'pager-item',
            'data' => theme('pager_previous', $output, $limit, $element, ($pager_current - $i), $parameters),
          );
        }
        if ($i == $pager_current) {

          $items[] = array(
            'class' => 'pager-current',
            'data' => $i,
          );
        }
        if ($i > $pager_current) {

                     if ($pager_last < $pager_max && $i == $pager_last) {
                                               $output = $i.'...';
                                } else {
                                               $outpu开发者_JAVA技巧t = $i;
                                }

          $items[] = array(
            'class' => 'pager-item',
            'data' => theme('pager_next', $output, $limit, $element, ($i - $pager_current), $parameters),
          );

        }
      }
    }
    // End generation.
    if ($li_next) {
      $items[] = array(
        'class' => 'pager-next',
        'data' => $li_next,
      );
    }
     return theme('item_list', $items, NULL, 'ul', array('class' => 'pager'));
   }
 }

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As you might have noticed, theme_pager does not call the database, it merely presents the items from the database. It does not even render the items in the list that is paged.

You will therefore need to override the amount before it gets passed into pager_query(). With views, I have no idea. In a custom module it would be really simple: read out an url parameter or POSTed variable and pass that along as second parameter into pager_query(). I suspect views has some hook to override the amount-per-page in runtime, just before it gets passed to the query-builder. But due to the poor documentation of views, it is not easily found.