On MSDN, for the WM_KEYDOWN defition it says the bits of lparam contain:
Bits Meaning
0-15 The repeat count for the current message. The value is the number of times the keystroke is autorepeated as a result of the user holding down the key. If the keystroke is held long enough, multiple messages are sent. However, the repeat count is not cumulative.
16-23 The scan code. The value depends on the OEM.
24 Indicates whether the key is an extended key, such as the right-hand ALT and CTRL keys that appear on an enhanced 101- or 102-key keyboard. The value is 1 if it is an extended key; otherwise, it is 0.
25-28 Reserved; do not use.
29 The context code. The value is always 0 for a WM_KEYDOWN message.
30 The previous key state. The value is 1 if the key is down before the message is sent, or it is zero if the key is up.
31 The transition state. The value is always 0 for a WM_KEYDOWN message.
(http://msdn.microsoft.com/en-us/library/ms646280%28VS.85%29.aspx)
So i created a union with a struct inside like this:
union KeyState
{
LPARAM lparam;
struct
{
unsigned nRepeatCount : 15;
unsigned nScanCode : 8;
unsigned nExtended : 1;
unsigned nReserved : 4;
unsigned nContext : 1;
unsigned nPrev : 1;
unsigned nTrans : 1;
};
};
Then when i recieve a wm_keydown message on my edit box, i print it like this:
if (msg == WM_KEYDOWN)
{
std::tstringstream ss;
KeyState ks;
ks.lparam = lparam;
ss << "Key: " << (TCHAR)wparam << ", Val: " << (UINT)wparam << ", nRepeatCount: " << ks.nRepeatCount <<
", nScanCode: " << ks.nScanCode << ", nExtended: " << ks.nExtended << ", nReserved: " << ks.nReserved <<
", nContext: " << ks.nContext << ", nPrev: " << ks.nPrev << ", nTrans: " << ks.nTrans;
SetWindowText(hOut, ss.str().c_str());
}
The values that i get back when i'm typing in my edit box don't seem correct, sometimes the nReserved is even 1 or 0, and nRepeatCount is ALWAYS 1 no matter if i hold down the key for a logn time or just press random keys.
Have i done something wrong? if so whats the ideal way to get these values from the LPARAM?
Well, for one thing 0-15 is 16 bits, not 15.
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