Using PostMessage to send Unicode characters

Question

I am using PostMessage to send input to a flash object in another application. It works fine until I try to send a unicode character. In this example:

Michael’s Book

The apostrophe is not really that, it is not an ASCII 39, but rather a unicode U+2019. By the time it is sent across 1 character at a time, it is lost as a unicode value and lands as the raw characters making up the unicode

Michaelâ€™s Book

If I copy and paste into that window it moves fine, and if I load a text file into that window it loads fine. So the receiving window is able to receive unicode, but the way I am sending it must not be correct. Any help would be greatly appreciated.

  private void SendKeysToForm(string Message)
    {
        for (int i = 0; i < Message.Length; i++)
        {
            PostMessage(hwnd, WM_CHAR, (IntPtr)Message[i], IntPtr.Zero);
        }
    }

Maybe WM_UNICHAR will work better. Depends, Adobe software is, erm, special. — Hans Passant, Jul 06 '16 at 12:29
Why are you sending the character as `IntPtr` instead of int ? — Panagiotis Kanavos, Jul 06 '16 at 12:30
@HansPassant [WM_CHAR](https://msdn.microsoft.com/en-us/library/windows/desktop/ms646276(v=vs.85).aspx) uses UTF-16-bit, `WM_UNICHAR` is for UTF-32 — Panagiotis Kanavos, Jul 06 '16 at 12:31
That's not the point. The key is whether the window was created with CreateWindowExA() or CreateWindowsExW(). Visible in Spy++ btw. If you want an Ansi window to still eat a Unicode character then WM_UNICHAR might work. But sure, @Mike might well have correctly guessed that PostMessage wasn't declared correctly. — Hans Passant, Jul 06 '16 at 12:48

score 6 · Accepted Answer · edited Jul 06 '16 at 12:45

6

Per the MSDN documentation, to send Unicode, you need to use PostMessageW.

It's the same method signature, just import the name PostMessageW and execute that.

UPDATE

As Hans very well stated, an even better approach would be to set the CharSet of the DllImport:

[DllImport("user32.dll", CharSet=CharSet.Unicode, SetLastError=true)]
private static extern bool PostMessage(IntPtr hWnd, int msg, IntPtr wp, IntPtr lp);

This should cause the framework to ultimately import PostMessageW.

Thanks a lot Hans!

edited Jul 06 '16 at 12:45

Hans Passant

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answered Jul 06 '16 at 12:35

Mike Perrenoud

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Could be it, best to recommend using the CharSet property correctly. – Hans Passant Jul 06 '16 at 12:38
@HansPassant, if there is a way to do that, absolutely! I just don't see anything in the documentation verifying how to set that in the `wParam`. Did I miss it? – Mike Perrenoud Jul 06 '16 at 12:40
1

The CharSet property of the [DllImport] attribute. The default is wrong in 99.99% of the cases where you'd pinvoke a winapi function. – Hans Passant Jul 06 '16 at 12:41
Oh great, thanks @HansPassant! I've updated the answer. – Mike Perrenoud Jul 06 '16 at 12:43
Adding the CharSet property to the declaration solved it. TY everyone – Vincent James Jul 06 '16 at 13:18

Using PostMessage to send Unicode characters

1 Answers1

UPDATE