CWinThread Class

Article
04/28/2015

Represents a thread of execution within an application.

class CWinThread : public CCmdTarget

Members

Public Constructors

Name	Description
CWinThread::CWinThread	Constructs a CWinThread object.

Public Methods

Name	Description
CWinThread::CreateThread	Starts execution of a CWinThread object.
CWinThread::ExitInstance	Override to clean up when your thread terminates.
CWinThread::GetMainWnd	Retrieves a pointer to the main window for the thread.
CWinThread::GetThreadPriority	Gets the priority of the current thread.
CWinThread::InitInstance	Override to perform thread instance initialization.
CWinThread::IsIdleMessage	Checks for special messages.
CWinThread::OnIdle	Override to perform thread-specific idle-time processing.
CWinThread::PostThreadMessage	Posts a message to another CWinThread object.
CWinThread::PreTranslateMessage	Filters messages before they are dispatched to the Windows functions TranslateMessage and DispatchMessage.
CWinThread::ProcessMessageFilter	Intercepts certain messages before they reach the application.
CWinThread::ProcessWndProcException	Intercepts all unhandled exceptions thrown by the thread's message and command handlers.
CWinThread::PumpMessage	Contains the thread's message loop.
CWinThread::ResumeThread	Decrements a thread's suspend count.
CWinThread::Run	Controlling function for threads with a message pump. Override to customize the default message loop.
CWinThread::SetThreadPriority	Sets the priority of the current thread.
CWinThread::SuspendThread	Increments a thread's suspend count.

Public Operators

Name	Description
CWinThread::operator HANDLE	Retrieves the handle of the CWinThread object.

Public Data Members

Name	Description
CWinThread::m_bAutoDelete	Specifies whether to destroy the object at thread termination.
CWinThread::m_hThread	Handle to the current thread.
CWinThread::m_nThreadID	ID of the current thread.
CWinThread::m_pActiveWnd	Pointer to the main window of the container application when an OLE server is in-place active.
CWinThread::m_pMainWnd	Holds a pointer to the application's main window.

Remarks

The main thread of execution is usually provided by an object derived from CWinApp; CWinApp is derived from CWinThread. Additional CWinThread objects allow multiple threads within a given application.

There are two general types of threads that CWinThread supports: worker threads and user-interface threads. Worker threads have no message pump: for example, a thread that performs background calculations in a spreadsheet application. User-interface threads have a message pump and process messages received from the system. CWinApp and classes derived from it are examples of user-interface threads. Other user-interface threads can also be derived directly from CWinThread.

Objects of class CWinThread typically exist for the duration of the thread. If you wish to modify this behavior, set m_bAutoDelete to FALSE.

The CWinThread class is necessary to make your code and MFC fully thread-safe. Thread-local data used by the framework to maintain thread-specific information is managed by CWinThread objects. Because of this dependence on CWinThread to handle thread-local data, any thread that uses MFC must be created by MFC. For example, a thread created by the run-time function _beginthread, _beginthreadex cannot use any MFC APIs.

To create a thread, call AfxBeginThread. There are two forms, depending on whether you want a worker or user-interface thread. If you want a user-interface thread, pass to AfxBeginThread a pointer to the CRuntimeClass of your CWinThread-derived class. If you want to create a worker thread, pass to AfxBeginThread a pointer to the controlling function and the parameter to the controlling function. For both worker threads and user-interface threads, you can specify optional parameters that modify priority, stack size, creation flags, and security attributes. AfxBeginThread will return a pointer to your new CWinThread object.

Instead of calling AfxBeginThread, you can construct a CWinThread-derived object and then call CreateThread. This two-stage construction method is useful if you want to reuse the CWinThread object between successive creation and terminations of thread executions.

For more information on CWinThread, see the articles Multithreading with C++ and MFC, Multithreading: Creating User-Interface Threads, Multithreading: Creating Worker Threads, and Multithreading: How to Use the Synchronization Classes.

Inheritance Hierarchy

CObject

CCmdTarget

CWinThread

Requirements

Header: afxwin.h