[英]WM_KEYDOWN, getting values from the lparam?
On MSDN, for the WM_KEYDOWN defition it says the bits of lparam contain: 在MSDN上,对于WM_KEYDOWN定义,它说lparam的位包含:
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 ) ( http://msdn.microsoft.com/en-us/library/ms646280%28VS.85%29.aspx )
So i created a union with a struct inside like this: 所以我创建了一个带有结构的联合,如下所示:
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: 然后,当我在编辑框中收到wm_keydown消息时,我将其打印出来:
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. 我在编辑框中输入时返回的值似乎不正确,有时nReserved甚至是1或0,nRepeatCount总是1,无论我按住键记录时间还是按下随机密钥。
Have i done something wrong? 我做错了什么吗? if so whats the ideal way to get these values from the LPARAM?
如果是这样,从LPARAM获得这些值的理想方法是什么?
嗯,一方面0-15是16位,而不是15位。
Yes it is easy to make mistakes (cf 500's answer). 是的,很容易出错(参见500的回答)。 I would simply use bit maps and bit shifts.
我只想使用位图和位移。
Eg. 例如。 NRepeat = lparam & 0xFFFF;
NRepeat = lparam&0xFFFF;
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