使用 CB_SETCURSEL 消息时，不会发送 CBN_SELCHANGE 消息。
如何通知控件选择已更改？
附言
我在Sexchange 网站上发现了一个非常丑的黑客：
SendMessage( hwnd, 0x014F/*CB_SHOWDROPDOWN*/, 1, 0 );
SendMessage( hwnd, 0x014E/*CB_SETCURSEL*/, ItemIndex, 0 );
SendMessage( hwnd, 0x0201/*WM_LBUTTONDOWN*/, 0, -1 );
SendMessage( hwnd, 0x0202/*WM_LBUTTONUP*/, 0, -1 );
暂时可以...不是真的。
附言2
为了解决我的问题，我会在 cmets 中遵循 Ken 的建议。
【问题讨论】：
标签： c++ winapi controls combobox message
这可能会帮助下一个人：
[DllImport("User32.dll", EntryPoint = "SendMessage")]
private static extern int SendMessage(IntPtr hwnd, int msg, int wParam, int lParam);
[DllImport("user32.dll", EntryPoint = "GetWindowLong")]
private static extern IntPtr GetWindowLongPtr32(IntPtr hWnd, int nIndex);
[DllImport("user32.dll", EntryPoint = "GetWindowLongPtr")]
private static extern IntPtr GetWindowLongPtr64(IntPtr hWnd, int nIndex);
public static IntPtr GetWindowLongPtr(IntPtr hWnd, int nIndex)
{
if (IntPtr.Size == 8)
return GetWindowLongPtr64(hWnd, nIndex);
else
return GetWindowLongPtr32(hWnd, nIndex);
}
static int MakeWParam(int loWord, int hiWord)
{
return (loWord & 0xFFFF) + ((hiWord & 0xFFFF) << 16);
}
public const int CB_SETCURSEL = 0x014E;
public const int CBN_SELCHANGE = 0x0001;
public enum GWL
{
GWL_WNDPROC = (-4),
GWL_HINSTANCE = (-6),
GWL_HWNDPARENT = (-8),
GWL_STYLE = (-16),
GWL_EXSTYLE = (-20),
GWL_USERDATA = (-21),
GWL_ID = (-12)
}
public static IntPtr Hwnd_select_control_parent = IntPtr.Zero;
public static IntPtr Hwnd_select_control = IntPtr.Zero;
static void changeit()
{
// Google WinSpy for tips on how to figure out how to get window handles from known ctrl_id
Hwnd_select_control = 14298; // or whatever the handle of the combo box is
// Get the parent of the selectbox control
Hwnd_select_control_parent = GetWindowLongPtr(service_window_control, (int)GWL.GWL_HWNDPARENT);
// Get the control id of the selectbox if you don't already have it
IntPtr nID = GetWindowLongPtr(Hwnd_select_control, (int)GWL.GWL_ID);
int ctrl_id = nID.ToInt32();
// Change the combo box to the value "My Value"
SendMessage(Hwnd_select_control, CB_SETCURSEL, "My Value", null);
// low ID is the ctrl_id of the combo box, high id is CBN_SELCHANGE
int send_cbn_selchange = MakeWParam(ctrl_id, CBN_SELCHANGE);
// Send the WM_COMMAND to the parent, not the control itself
SendMessage(Hwnd_serviceselect_control_parent, 0x111 /* WM_COMMAND */, send_cbn_selchange, Hwnd_serviceselect_control.ToInt32());
}
【讨论】：
除非用户更改了选择，否则不应使用 CBN_SELCHANGE。
您没有指明您使用的是什么语言；如果您这样做，它将更容易为您提供解决方法。
在 Delphi 中，OnChange() 将与组合框相关联，您只需直接调用事件方法：
// Send the CB_SETCURSEL message to the combobox
PostMessage(ComboBox1.Handle, CB_SETCURSEL, Whatever, WhateverElse);
// Directly call the OnChange() handler, which is the equivalent to CBN_SELCHANGE
ComboBox1Change(nil);
【讨论】：
我刚刚发现将这些 SendMessages 调用到 Combobox 两次有效...我知道这并不完美，但它对我有用。 （用VB6编写）
For looper = 1 To 2
bVal = SendMessage(inHandle, COMBO.CB_SHOWDROPDOWN, True, 0)
count = SendMessage(inHandle, COMBO.CB_SETCURSEL, 1, 0)
count = SendMessage(inHandle, WIND.WM_LBUTTONDOWN, 0, -1)
Next
【讨论】：