Creating iCalendar items in C#
Straightforward iCal creation code.
Oct 15 2010
For a while now whenever I've needed to generate a calendar item, I've used my trusty vCalendar code. The vCalendar format was simple, rather straightforward and up until recently, without too many faults. However I ran into a project where they wanted to embed html within the calendar item... You see one of the things about the vCalendar format is it can support Base64, 8bit, etc. in the description field but as far as I can tell there isn't any way to tell the client that the description is HTML. Even exporting an item from outlook seems to strip out any HTML that it finds (bullet points become *, etc.). So looking around I found out that you can embed it in an iCalendar item... Which is pretty much just vCalendar 2.0... So in other words it was simple to add to my existing code base:
/\*
Copyright (c) 2010 <a href="http://www.gutgames.com">James Craig</a>
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.\*/
#region Usings
using System;
using System.Text;
using System.Text.RegularExpressions;
#endregion
namespace Utilities.FileFormats
{
/// <summary>
/// Creates a VCalendar item
/// </summary>
public class VCalendar
{
#region Constructors
/// <summary>
/// Constructor
/// </summary>
public VCalendar()
{
}
#endregion
#region Properties
/// <summary>
/// The time zone adjustment for the calendar event
/// </summary>
public int TimeZoneAdjustment{get;set;}
/// <summary>
/// The start time
/// </summary>
public DateTime StartTime{get;set;}
/// <summary>
/// The end time
/// </summary>
public DateTime EndTime{get;set;}
/// <summary>
/// The location of the event
/// </summary>
public string Location{get;set;}
/// <summary>
/// The subject of the item to send
/// </summary>
public string Subject{get;set;}
/// <summary>
/// The description of the event
/// </summary>
public string Description{get;set;}
private static readonly Regex STRIP\_HTML\_REGEX = new Regex("<\[^>\]\*>", RegexOptions.Compiled);
#endregion
#region Private Functions
private string StripHTML(string HTML)
{
try
{
if (string.IsNullOrEmpty(HTML))
return string.Empty;
HTML = STRIP\_HTML\_REGEX.Replace(HTML, string.Empty);
HTML = HTML.Replace(" ", " ");
return HTML.Replace(" ", string.Empty);
}
catch { throw; }
}
private bool ContainsHTML(string Input)
{
try
{
if (string.IsNullOrEmpty(Input))
return false;
return STRIP\_HTML\_REGEX.IsMatch(Input);
}
catch { throw; }
}
#endregion
#region Public Functions
/// <summary>
/// Returns the VCalendar item
/// </summary>
/// <returns>a string output of the VCalendar item</returns>
public string GetVCalendar()
{
try
{
StringBuilder FileOutput = new StringBuilder();
FileOutput.AppendLine("BEGIN:VCALENDAR");
FileOutput.AppendLine("VERSION:1.0");
FileOutput.AppendLine("BEGIN:VEVENT");
StartTime = StartTime.AddHours(-TimeZoneAdjustment);
EndTime = EndTime.AddHours(-TimeZoneAdjustment);
string Start = StartTime.ToString("yyyyMMdd") + "T" + StartTime.ToString("HHmmss");
string End = EndTime.ToString("yyyyMMdd") + "T" + EndTime.ToString("HHmmss");
FileOutput.Append("DTStart:").AppendLine(Start);
FileOutput.Append("DTEnd:").AppendLine(End);
FileOutput.Append("Location;ENCODING=QUOTED-PRINTABLE:").AppendLine(Location);
FileOutput.Append("SUMMARY;ENCODING=QUOTED-PRINTABLE:").AppendLine(Subject);
FileOutput.Append("DESCRIPTION;ENCODING=QUOTED-PRINTABLE:").AppendLine(Description);
FileOutput.Append("UID:").Append(Start).Append(End).AppendLine(Subject);
FileOutput.AppendLine("PRIORITY:3");
FileOutput.AppendLine("End:VEVENT");
FileOutput.AppendLine("End:VCALENDAR");
return FileOutput.ToString();
}
catch { throw; }
}
/// <summary>
/// Returns the ICalendar item
/// </summary>
/// <returns>a string output of the ICalendar item</returns>
public string GetICalendar()
{
try
{
StringBuilder FileOutput = new StringBuilder();
FileOutput.AppendLine("BEGIN:VCALENDAR");
FileOutput.AppendLine("PRODID:-//Craigs Utility Library//EN");
FileOutput.AppendLine("VERSION:2.0");
FileOutput.AppendLine("METHOD:PUBLISH");
StartTime = StartTime.AddHours(-TimeZoneAdjustment);
EndTime = EndTime.AddHours(-TimeZoneAdjustment);
string Start = StartTime.ToString("yyyyMMdd") + "T" + StartTime.ToString("HHmmss");
string End = EndTime.ToString("yyyyMMdd") + "T" + EndTime.ToString("HHmmss");
FileOutput.AppendLine("BEGIN:VEVENT");
FileOutput.AppendLine("CLASS:PUBLIC");
FileOutput.Append("CREATED:").AppendLine(DateTime.Now.ToString("yyyyMMddTHHmmssZ"));
FileOutput.AppendLine(StripHTML(Description.Replace("<br />", "\\\\n")));
FileOutput.Append("DTEND:").AppendLine(Start);
FileOutput.Append("DTSTART:").AppendLine(End);
FileOutput.Append("LOCATION:").AppendLine(Location);
FileOutput.Append("SUMMARY;LANGUAGE=en-us:").AppendLine(Subject);
FileOutput.Append("UID:").Append(Start).Append(End).AppendLine(Subject);
if (ContainsHTML(Description))
{
FileOutput.Append("X-ALT-DESC;FMTTYPE=text/html:").AppendLine(Description.Replace("\\n", ""));
}
else
{
FileOutput.Append("DESCRIPTION:").AppendLine(Description);
}
FileOutput.AppendLine("BEGIN:VALARM");
FileOutput.AppendLine("TRIGGER:-PT15M");
FileOutput.AppendLine("ACTION:DISPLAY");
FileOutput.AppendLine("DESCRIPTION:Reminder");
FileOutput.AppendLine("END:VALARM");
FileOutput.AppendLine("END:VEVENT");
FileOutput.AppendLine("END:VCALENDAR");
return FileOutput.ToString();
}
catch { throw; }
}
/// <summary>
/// Returns the HCalendar item
/// </summary>
/// <returns>A string output of the HCalendar item</returns>
public string GetHCalendar()
{
try
{
StringBuilder Output = new StringBuilder();
Output.Append("<div class=\\"vevent\\">")
.Append("<div class=\\"summary\\">").Append(Subject).Append("</div>")
.Append("<div>Date: <abbr class=\\"dtstart\\" title=\\"")
.Append(StartTime.ToString("MM-dd-yyyy hh:mm tt")).Append("\\">")
.Append(StartTime.ToString("MMMM dd, yyyy hh:mm tt")).Append("</abbr> to ")
.Append("<abbr class=\\"dtend\\" title=\\"").Append(EndTime.ToString("MM-dd-yyyy hh:mm tt"))
.Append("\\">");
if (EndTime.Year != StartTime.Year)
{
Output.Append(EndTime.ToString("MMMM dd, yyyy hh:mm tt"));
}
else if (EndTime.Month != StartTime.Month)
{
Output.Append(EndTime.ToString("MMMM dd hh:mm tt"));
}
else if (EndTime.Day != StartTime.Day)
{
Output.Append(EndTime.ToString("dd hh:mm tt"));
}
else
{
Output.Append(EndTime.ToString("hh:mm tt"));
}
Output.Append("</abbr></div>");
Output.Append("<div>Location: <span class=\\"location\\">").Append(Location).Append("</span></div>");
Output.Append("<div class=\\"description\\">").Append(Description).Append("</div>");
Output.Append("</div>");
return Output.ToString();
}
catch { throw; }
}
#endregion
}
}The code above is actually the same as my previous vCalendar code with a couple of functions added. Not much needed to be changed (1 public function to generate an iCalendar item instead of a vCalendar item and 2 private functions to check if the description is HTML and strip it out in certain situations). But that's all there is to it. So take a look, try it out, leave feedback, and happy coding.
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