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// send core message that the thread finished SpecialEventAdd (CUSTOM_ID_RENDER_FINISH); this->DeleteDoc(); } const Char * GetThreadName () { return "RenderThread" ; } };

// the MessageData plugin class RenderThreadMessages : public MessageData { Bool CoreMessage ( Int32 id , const BaseContainer & bc) { if ( id == CUSTOM_ID_RENDER_FINISH) { if (g_displayBitmap) { ShowBitmap (g_displayBitmap); } } return true ; } };

// This example shows how to create and start a new custom thread instance.

// allocate thread if needed if (g_renderThread == nullptr ) { ifnoerr (g_renderThread = NewObj (RenderThread)) { if (g_renderThread == nullptr ) return false ; } }

// check if the thread is running if (g_renderThread->IsRunning()) { // stop the thread g_renderThread->End( true ); }

// thread takes ownership of the document clone but not of the bitmap! g_renderThread->SetData(documentClone, g_displayBitmap); const Bool started = g_renderThread->Start();

Creation

A custom thread class is created by implementing a class based on C4DThread :

Now an instance of this custom thread class can be created and used:

// create thread instance on demand if (g_exampleThread == nullptr ) { g_exampleThread = NewObj (ExampleThread) iferr_return ; } return maxon::OK ; }

// delete thread stored in the global variable MAXON_INITIALIZATION ( nullptr , []() { DeleteObj (g_exampleThread); });

Custom Threads

A custom thread class has to implement these virtual functions:

• C4DThread::Main() : The main function of the thread that is executed when the thread is started.
• C4DThread::GetThreadName() : Returns the thread name.
• C4DThread::TestDBreak() : The implementation of BaseThread::TestBreak() has to return false if the thread should stop.

// activity loop for ( Int32 i = 0; i < 60; ++i) { ApplicationOutput ( "perform background action " + String::IntToString (i));

// check if the thread should be stopped if (this->TestBreak()) return ; GeSleep (1000); } }

// This example just returns the thread name const Char * GetThreadName() { return "ExampleCustomThread" ; }

// This example checks how long the thread is running. // If the thread is running for longer than 20 seconds it should stop. Bool TestDBreak() { if (_startTime == -1) return true ; const Int32 time = GeGetTimer ();

// check if 20000 milliseconds have passed if ((time - _startTime) > 20000) return true ; return false ; }

注意

To send a message from a thread to the main thread use SpecialEventAdd() 。见 Core Messages Manual .

使用

The custom thread can be started and stopped with these functions:

• C4DThread::Start() : Starts the custom thread.
• C4DThread::End() : Stops the custom thread.

注意

The THREADPRIORITY should typically not be changed.

读取

Further thread properties are accessed with:

• C4DThread::Get() : Returns the corresponding BaseThread for the custom thread.
• C4DThread::IsRunning() : Returns true if the thread is running.
• C4DThread::TestBreak() : Returns true if the thread encountered a break condition.
• C4DThread::Wait() : Waits until the thread finished.

延伸阅读

• 线程
• Classic API Threading
• BaseThread Manual
• Thread Utility Manual
• Thread Synchronization Manual
• 线程手册