How to convert emoticons to its UTF-32/escaped unicode?

Question

I am working on a chatting application in WPF and I want to use emoticons in it. I am working on WPF app. I want to read emoticons which are coming from Android/iOS devices and show respective images.

On WPF, I am getting a black Emoticon looking like . I somehow got a library of emoji icons which are saved with respective hex/escaped unicode values. So, I want to convert these symbols of emoticons into UTF-32/escaped unicode so that I can directly replace related emoji icons with them.

I had tried to convert an emoticon to its unicode but end up getting a different string with couple of symbols, which are having different unicode.

string unicodeString = "\u1F642";  // represents 🙂 

Encoding unicode = Encoding.Unicode;
byte[] unicodeBytes = unicode.GetBytes(unicodeString);

char[] unicodeChars = new char[unicode.GetCharCount(unicodeBytes, 0, unicodeBytes.Length)];
unicode.GetChars(unicodeBytes, 0, unicodeBytes.Length, unicodeChars, 0);
string asciiString = new string(unicodeChars);

Any help is appreciated!!

Answer 1

Your escaped Unicode String is invalid in C#.

string unicodeString = "\u1F642";  // represents 🙂 

This piece of code doesnt represent the "slightly smiling face" since C# only respects the first 4 characters - representing an UTF-16 (with 2 Bytes).

So what you actually get is the letter representing 1F64 followed by a simple 2. http://www.fileformat.info/info/unicode/char/1f64/index.htm

So this: ὤ2

If you want to type hex with 4 Bytes and get the corresponding string you have to use:

var unicodeString = char.ConvertFromUtf32(0x1F642);

https://msdn.microsoft.com/en-us/library/system.char.convertfromutf32(v=vs.110).aspx

or you could write it like this:

\uD83D\uDE42

This string can than be parsed like this, to get your desired result which is again is the hex value that we started with:

var x = char.ConvertFromUtf32(0x1F642);

var enc = new UTF32Encoding(true, false);
var bytes = enc.GetBytes(x);
var hex = new StringBuilder();
for (int i = 0; i < bytes.Length; i++)
{
    hex.AppendFormat("{0:x2}", bytes[i]);
}
var o = hex.ToString();
//result is 0001F642

(The result has the leading Zeros, since an UTF-32 is always 4 Bytes)

Instead of the for Loop you can also use BitConverter.ToString(byte[]) https://msdn.microsoft.com/en-us/library/3a733s97(v=vs.110).aspx the result than will look like:

var x = char.ConvertFromUtf32(0x1F642);

var enc = new UTF32Encoding(true, false);
var bytes = enc.GetBytes(x);
var o = BitConverter.ToString(bytes);
//result is 00-01-F6-42

Answer 2

Since C# source files can contain UTF-32 string literals, there is no need to use any encodings for this task.

---

Example 1.

var rgch = "\U0001F642".ToCharArray();
var str = $"\\u{(ushort)rgch[0]:X4}\\u{(ushort)rgch[1]:X4}";

Result: "\uD83D\uDE42"         Length of string str is 12 UTF-16 code points (24 bytes)

---

Example 2.

var rgch = "\U0001F642".ToCharArray();
var str = rgch[0] + "" + rgch[1];

Result: "🙂"             Length of string str is 2 UTF-16 code points (4 bytes)

Answer 3

Please be aware that Encoding.Unicode is UTF-16 in C#. To read 32 bits Unicode, there is this Encoding.UTF32. Link on MSDN for Encoding.​UT​F32

Answer 4

You can simply use @using System.Web for encoding:

var columndata = "CSR story with emoji 😀"`
columndata   = HttpUtility.UrlEncode(columndata);

It will encode the text and emoji.

Here I have text with HTML tags so while decoding I have used Trim() for decoding:

string titleRaw = HttpUtility.UrlDecode(@Model.columnNamne.ToString().Trim());

If not storing in HTML tags then:

string titleRaw = HttpUtility.UrlDecode(@Model.columnNamne.ToString());