Using SendInput to send unicode characters beyond U+FFFF

Question

I'm writing an onscreen keyboard similar to the one in Windows 8. I have no problem sending most of the characters I need using Win32's SendInput.

The problem is when it comes to the new Windows 8 Emoji's. They start at U+1F600 using the Segoe UI Symbol font.

Using Spy++ on the Windows 8 onscreen keyboard I get the following output for all Emoji glyphs.

<00001> 000C064A P WM_KEYDOWN nVirtKey:VK_PACKET cRepeat:1 ScanCode:00 fExtended:0 fAltDown:0 fRepeat:0 fUp:0 <00002> 000C064A P WM_CHAR chCharCode:'63' (63) cRepeat:1 ScanCode:00 fExtended:0 fAltDown:0 fRepeat:0 fUp:0 <00003> 000C064A P WM_KEYUP nVirtKey:VK_PACKET cRepeat:1 ScanCode:00 fExtended:0 fAltDown:0 fRepeat:1 fUp:1 <00004> 000C064A P WM_KEYDOWN nVirtKey:VK_PACKET cRepeat:1 ScanCode:00 fExtended:0 fAltDown:0 fRepeat:0 fUp:0 <00005> 000C064A P WM_CHAR chCharCode:'63' (63) cRepeat:1 ScanCode:00 fExtended:0 fAltDown:0 fRepeat:0 fUp:0 <00006> 000C064A P WM_KEYUP nVirtKey:VK_PACKET cRepeat:1 ScanCode:00 fExtended:0 fAltDown:0 fRepeat:1 fUp:1

Since they all produce the same output I can't see what is sent that actually identifies the unique glyph.

I'm aware that SendInput has a KEYEVENTF_UNICODE parameter for sending unicode characters. But these characters seem to be in some sort of extended unicode page. Beyond the 16-bit unicode range (U+0000 to U+FFFF) a C# char or the short wScan value in the INPUT struct can represent.

Here is my SendCharUnicode method.

public static void SendCharUnicode(char ch) { Win32.INPUT[] input = new Win32.INPUT[2]; input[0] = new Win32.INPUT(); input[0].type = Win32.INPUT_KEYBOARD; input[0].ki.wVk = 0; input[0].ki.wScan = (short)ch; input[0].ki.time = 0; input[0].ki.dwFlags = Win32.KEYEVENTF_UNICODE; input[0].ki.dwExtraInfo = Win32.GetMessageExtraInfo(); input[1] = new Win32.INPUT(); input[1].type = Win32.INPUT_KEYBOARD; input[1].ki.wVk = 0; input[1].ki.wScan = (short)ch; input[1].ki.time = 0; input[1].ki.dwFlags = Win32.KEYEVENTF_UNICODE | Win32.KEYEVENTF_KEYUP; input[1].ki.dwExtraInfo = Win32.GetMessageExtraInfo(); Win32.SendInput(2, input, Marshal.SizeOf(typeof(Win32.INPUT))); }

How can I get this method modified to successfully send a Unicode character such as 😃 (U+1F600)?

I've already solved the problem; I just don't have enough points to post an answer. The solution is to break the UTF-32 character into its UTF-16 surrogate pair and send them using SendInput. — headkaze
– headkaze, Commented Mar 10, 2014 at 5:20

headkaze · Accepted Answer · 2023-02-08 15:55:11Z

I have used API Monitor on the Windows 8 onscreen keyboard and it does indeed use SendInput. After further investigation I have discovered you need to break the UTF-32 Unicode character down into its UTF-16 surrogate pair Eg. 😄 U+1F604 becomes [U+D83D U+DE04]. So if I send D83D then DE04 I can successfully send U+1F604.

Here is a working method:

public static void SendCharUnicode(int utf32) { string unicodeString = Char.ConvertFromUtf32(utf32); Win32.INPUT[] input = new Win32.INPUT[unicodeString.Length]; for (int i = 0; i < input.Length; i++) { input[i] = new Win32.INPUT(); input[i].type = Win32.INPUT_KEYBOARD; input[i].ki.wVk = 0; input[i].ki.wScan = (short)unicodeString[i]; input[i].ki.time = 0; input[i].ki.dwFlags = Win32.KEYEVENTF_UNICODE; input[i].ki.dwExtraInfo = IntPtr.Zero; } for (int i = 0; i < input.Length; i++) { input[i] = new Win32.INPUT(); input[i].type = Win32.INPUT_KEYBOARD; input[i].ki.wVk = 0; input[i].ki.wScan = (short)unicodeString[i]; input[i].ki.time = 0; input[i].ki.dwFlags = Win32.KEYEVENTF_UNICODE | Win32.KEYEVENTF_KEYUP; input[i].ki.dwExtraInfo = IntPtr.Zero; } Win32.SendInput((uint)input.Length, input, Marshal.SizeOf(typeof(Win32.INPUT))); }

No. There's no issue with 64 bit applications. What's wrong is that this code simply fails to send the KEYEVENTF_KEYUP input events.
I confirm it works with down and up input events. The right event sequence is [symb1_down, symb2_down, symb1_up, symb2_up]. Algorithm to calculate surrogate pair is here: unicodebook.readthedocs.io/…

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