问题描述
我有一个自定义类派生自CWnd,我想从工作线程发布消息。我使用PostMessage函数来实现这一点。 PostMessage的第一个参数是我的类的HWND类型句柄,下一个是我想处理的消息。对于第一个参数,我使用GetSafeHwnd()函数生成我的类的句柄,对于第二个参数,我使用WM_USER + 3。此外,我在类头文件中声明一个消息映射,并在BEGIN_MESSAGE_MAP和END_MESSAGE_MAP块中为消息处理程序添加一个条目。但是,我的处理程序没有得到调用。我也检查了PostMessage函数的返回值,它是1,这意味着成功。
I have a custom class derived from CWnd that I would like to post a message to from a worker thread. I am using the PostMessage function to achieve this. The first argument to PostMessage is the HWND type handle to my class, and the next is the message I would like handled. For the first parameter, I generate the handle to my class using GetSafeHwnd() function, and for the second parameter, I use WM_USER+3. Also, I declare a message map inside my class header file, and add an entry for the message handler inside the BEGIN_MESSAGE_MAP and END_MESSAGE_MAP block. However, my handler is not getting called. I have also checked the return value of PostMessage function, it is 1, that means success.
这是我的代码:
MyClass.h内部
Inside MyClass.h
class CMyClass : CWnd
{
....
....
public:
void InitHandle();
protected:
afx_msg LRESULT OnMessageReceived(WPARAM wParam, LPARAM lParam);
DECLARE_MESSAGE_MAP()
}
Inside MyClass.cpp
Inside MyClass.cpp
#define WM_MY_MESSAGE WM_USER+3
HWND handleToMyClassWindow;
BEGIN_MESSAGE_MAP(CMyClass, CWnd)
ON_MESSAGE(WM_MY_MESSAGE, OnMessageReceived)
END_MESSAGE_MAP()
LRESULT CMyClass::OnMessageReceived(WPARAM wParam, LPARAM lParam)
{ .... }
void CMyClass::InitHandle()
{
handleToMyClassWindow = GetSafeHwnd();
}
Inside Worker线程
Inside Worker thread
UINT WorkerThreadFunction(LPVOID pParam )
{
....
PostMessage(handleToMyClassWindow, WM_MY_MESSAGE, NULL, NULL);
....
}
我的问题是,原因为OnMessageReceived处理程序未被调用。
My question is, what are the possible reasons for the OnMessageReceived handler to not be called.
PS
我注意调用对象调用
我尝试了与我的程序的View类(从CView派生)相同的技术,它在那里工作,但在这里失败。
I tried the same technique with the View class (derived from CView) of my program, and it works there, but fails here.
推荐答案
如果尚未创建,您将无法发布到窗口。如果你没有使用你的类实际创建一个窗口,GetSafeHwnd()将返回NULL。
You cannot post to a window if it has not been created. GetSafeHwnd() will return NULL if you have not actually created a window using your class.
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