PHP: a function for building an HTML calendar

The below function is a modified version of the one from David Walsh Blog. You can get the original one from this very good post.

This PHP function will return an HTML calendar (built using the table tag), for the given year and month and (optionally) will add an event entry on some days if you provide an array of events:

/**
 * Returns the calendar's html for the given year and month.
 *
 * @param $year (Integer) The year, e.g. 2015.
 * @param $month (Integer) The month, e.g. 7.
 * @param $events (Array) An array of events where the key is the day's date
 * in the format "Y-m-d", the value is an array with 'text' and 'link'.
 * @return (String) The calendar's html.
 */
function build_html_calendar($year, $month, $events = null) {

  // CSS classes
  $css_cal = 'calendar';
  $css_cal_row = 'calendar-row';
  $css_cal_day_head = 'calendar-day-head';
  $css_cal_day = 'calendar-day';
  $css_cal_day_number = 'day-number';
  $css_cal_day_blank = 'calendar-day-np';
  $css_cal_day_event = 'calendar-day-event';
  $css_cal_event = 'calendar-event';

  // Table headings
  $headings = ['M', 'T', 'W', 'T', 'F', 'S', 'S'];

  // Start: draw table
  $calendar =
    "<table cellpadding='0' cellspacing='0' class='{$css_cal}'>" .
    "<tr class='{$css_cal_row}'>" .
    "<td class='{$css_cal_day_head}'>" .
    implode("</td><td class='{$css_cal_day_head}'>", $headings) .
    "</td>" .
    "</tr>";

  // Days and weeks
  $running_day = date('N', mktime(0, 0, 0, $month, 1, $year));
  $days_in_month = date('t', mktime(0, 0, 0, $month, 1, $year));

  // Row for week one
  $calendar .= "<tr class='{$css_cal_row}'>";

  // Print "blank" days until the first of the current week
  for ($x = 1; $x < $running_day; $x++) {
    $calendar .= "<td class='{$css_cal_day_blank}'> </td>";
  }

  // Keep going with days...
  for ($day = 1; $day <= $days_in_month; $day++) {

    // Check if there is an event today
    $cur_date = date('Y-m-d', mktime(0, 0, 0, $month, $day, $year));
    $draw_event = false;
    if (isset($events) && isset($events[$cur_date])) {
      $draw_event = true;
    }

    // Day cell
    $calendar .= $draw_event ?
      "<td class='{$css_cal_day} {$css_cal_day_event}'>" :
      "<td class='{$css_cal_day}'>";

    // Add the day number
    $calendar .= "<div class='{$css_cal_day_number}'>" . $day . "</div>";

    // Insert an event for this day
    if ($draw_event) {
      $calendar .=
        "<div class='{$css_cal_event}'>" .
        "<a href='{$events[$cur_date]['href']}'>" .
        $events[$cur_date]['text'] .
        "</a>" .
        "</div>";
    }

    // Close day cell
    $calendar .= "</td>";

    // New row
    if ($running_day == 7) {
      $calendar .= "</tr>";
      if (($day + 1) <= $days_in_month) {
        $calendar .= "<tr class='{$css_cal_row}'>";
      }
      $running_day = 1;
    }

    // Increment the running day
    else {
      $running_day++;
    }

  } // for $day

  // Finish the rest of the days in the week
  if ($running_day != 1) {
    for ($x = $running_day; $x <= 7; $x++) {
      $calendar .= "<td class='{$css_cal_day_blank}'> </td>";
    }
  }

  // Final row
  $calendar .= "</tr>";

  // End the table
  $calendar .= '</table>';

  // All done, return result
  return $calendar;
}

Example usage

Draw a calendar for the month of July 2015:

echo "<h2>July 2015</h2>";
echo build_html_calendar(2015, 7);

With events:

$events = [
  '2015-07-05' => [
    'text' => "An event for the 5 july 2015",
    'href' => "http://example.com/link/to/event"
  ],
  '2015-07-23' => [
    'text' => "An event for the 23 july 2015",
    'href' => "/path/to/event"
  ],
];

echo "<h2>July 2015</h2>";
echo build_html_calendar(2015, 7, $events);

Styles (CSS)

You should add some styles on the calendar, otherwise it is not very usable.

These are from the David Walsh’s original post and they works with the classes used above:

/* calendar */
table.calendar		{ border-left:1px solid #999; }
tr.calendar-row	{  }
td.calendar-day	{ min-height:80px; font-size:11px; position:relative; } * html div.calendar-day { height:80px; }
td.calendar-day:hover	{ background:#eceff5; }
td.calendar-day-np	{ background:#eee; min-height:80px; } * html div.calendar-day-np { height:80px; }
td.calendar-day-head { background:#ccc; font-weight:bold; text-align:center; width:120px; padding:5px; border-bottom:1px solid #999; border-top:1px solid #999; border-right:1px solid #999; }
div.day-number		{ background:#999; padding:5px; color:#fff; font-weight:bold; float:right; margin:-5px -5px 0 0; width:20px; text-align:center; }
/* shared */
td.calendar-day, td.calendar-day-np { width:120px; padding:5px; border-bottom:1px solid #999; border-right:1px solid #999; }