Can you see this symbol? 🔊 Nice, this means you have a good set of fonts and a good browser. Mostly easy so view a good part of the Unicode Character Set. But when it comes to support these in your own programs it can be a hassle to render these.
The FreeType library supports rending basically every character but still, it can be quite complicated if you're not into the encoding of strings. First you'll want to set the charset FreeType should use if it isn't already specified in the font file by using FT_Select_Charmap(face, FT_ENCODING_UNICODE). You can also get some information about the charset tables in your font or set the one you want to use.
FreeType supports quite a bunch of charsets (I'm not sure why FreeType calls it's charsets encodings, as encodings are something very different):
FT_ENCODING_UNICODE is probably the one you want to use. Also, if you want won't be able to include the 🔊 character like this:
You'll have to do something like this to be sure that it works on every system:
Now let's find a font which supports the following characters: 🔊 (0x1F50A), ☁ (0x2601) and ⏰ (0x23F0)
The only font which supports all three characters I've found.
Awesome font by Google. Supported ☁ and ⏰. But didn't support 🔊. Probably because it's beyond 0xFFFF.
Should have been working, but didn't.