如何用SendMessage发送组合键信息？(alt+"向下箭头")

[Michaelyfj]

我想通过Alt+"向下箭头"下拉TComboBox，用消息发送该如何实现？
注：不能用CB_DROPDOWNSHOW这个消息，而是用WM_KEYDOWN消息？
如：sendmessage(ComboBox1.Handle, WK_KEYDOWN, ________, _______);

[Michaelyfj]

?

[王集鹄]

procedure SendKey(const mKey: Word; mShiftState: TShiftState; mCount: Integer = 1); overload;
const
cExtended: set of Byte = [VK_UP, VK_DOWN, VK_LEFT, VK_RIGHT, VK_HOME,
VK_END, VK_PRIOR, VK_NEXT, VK_INSERT, VK_DELETE];

procedure pKeyboardEvent(mKey, mScanCode: Byte; mFlags: Longint);
var
vKeyboardMsg: TMsg;
begin
keybd_event(mKey, mScanCode, mFlags, 0);
while PeekMessage(vKeyboardMsg, 0, WM_KEYFIRST, WM_KEYLAST, PM_REMOVE) do begin
TranslateMessage(vKeyboardMsg);
DispatchMessage(vKeyboardMsg);
end;
end; { pKeyboardEvent }

procedure pSendKeyDown(mKey: Word; mGenUpMsg: Boolean);
var
vScanCode: Byte;
vNumState: Boolean;
vKeyBoardState: TKeyboardState;
begin
if (mKey = VK_NUMLOCK) then begin
vNumState := ByteBool(GetKeyState(VK_NUMLOCK) and 1);
GetKeyBoardState(vKeyBoardState);
if vNumState then
vKeyBoardState[VK_NUMLOCK] := (vKeyBoardState[VK_NUMLOCK] and not 1)
else vKeyBoardState[VK_NUMLOCK] := (vKeyBoardState[VK_NUMLOCK] or 1);
SetKeyBoardState(vKeyBoardState);
Exit;
end;

vScanCode := Lo(MapVirtualKey(mKey, 0));
if (mKey in cExtended) then begin
pKeyboardEvent(mKey, vScanCode, KEYEVENTF_EXTENDEDKEY);
if mGenUpMsg then
pKeyboardEvent(mKey, vScanCode, KEYEVENTF_EXTENDEDKEY or KEYEVENTF_KEYUP)
end else begin
pKeyboardEvent(mKey, vScanCode, 0);
if mGenUpMsg then pKeyboardEvent(mKey, vScanCode, KEYEVENTF_KEYUP);
end;
end; { pSendKeyDown }

procedure pSendKeyUp(mKey: Word);
var
vScanCode: Byte;
begin
vScanCode := Lo(MapVirtualKey(mKey, 0));
if mKey in cExtended then
pKeyboardEvent(mKey, vScanCode, KEYEVENTF_EXTENDEDKEY and KEYEVENTF_KEYUP)
else pKeyboardEvent(mKey, vScanCode, KEYEVENTF_KEYUP);
end; { pSendKeyUp }

var
I: Integer;
begin
for I := 1 to mCount do begin
if ssShift in mShiftState then pSendKeyDown(VK_SHIFT, False);
if ssCtrl in mShiftState then pSendKeyDown(VK_CONTROL, False);
if ssAlt in mShiftState then pSendKeyDown(VK_MENU, False);
pSendKeyDown(mKey, True);
if ssShift in mShiftState then pSendKeyUp(VK_SHIFT);
if ssCtrl in mShiftState then pSendKeyUp(VK_CONTROL);
if ssAlt in mShiftState then pSendKeyUp(VK_MENU);
end;
end; { SendKey }

//demo
SendKey(VK_DOWN, [ssAlt]);

[Michaelyfj]

如何向菜单项发送单击消息？
sendmessage(N1.Handle, _____, ____, ____);

[王集鹄]

N1.Click;

[Michaelyfj]

用SendMessage发送消息啊，老兄！