ZPlay::SetCallbackFunc Method

Set callback function.

C++

bool SetCallbackFunc(TCallbackFunc ^ CallbackFunc, TCallbackMessage Messages, int UserData);

Parameters

Parameters	Description
TCallbackFunc ^ CallbackFunc	Address to callback function. Set this value to 0 to disable callback mechanism.
TCallbackMessage Messages	Specify messages you need to receive with callback function. This parameter can be combination of multiple callback messages.
int UserData	User data. This value will be passed to CallbackFunc as parameter.

Return Values

Return Values	Description
True	All OK.
False	Error. To get error message read here.

Remarks

All callback messages are sent from decoding thread.

There are 2 types of callback messages, blocking (sync) and not blocking (async).

Blocking message will block decoding thread until callback function returns. Non blocking mesage will not block decoding thread.

Warning: callback function must have __stdcall calling convention.

Note: You must protect CallbackFunc from garbage collector. Use global or static variable to keep alive callback function all the time. If you don't protect CallbackFunc, garbage collector will destroy or move this function and you will get memory access error when next callback event occurrs.

See Also

TCallbackFunc

Example

// global holder for our callback function, need this to prevent garbage collector to destroy our callback function
ZPlay::TCallbackFunc ^CallbackFunc;

// callback function
int MyCallbackFunc(System::UInt32 objptr, int user_data, TCallbackMessage msg, System::UInt32 param1, System::UInt32 param2)
{
  switch (msg)
  {
                
    case TCallbackMessage::MsgStreamBufferDoneAsync:
    {

      // read more data and push into stream
      array<System::Byte> ^stream_data = nullptr;
      int small_chunk = 100000;
      stream_data = br->ReadBytes(small_chunk);
      if (stream_data->Length > 0)
      {
         player->PushDataToStream(stream_data, System::Convert::ToUInt32(stream_data->Length));
      }
      else
      {
         array<System::Byte> ^tempMemNewData1 = nullptr;
         player->PushDataToStream(tempMemNewData1, 0);
      }
    }
    break;
  }

  return 0;
}

// ...

// global variable, prevent garbage collector to destroy this function
CallbackFunc = gcnew ZPlay::TCallbackFunc(this, &Form1::MyCallbackFunc);

// set callback function
player->SetCallbackFunc(CallbackFunc, safe_cast<TCallbackMessage>(TCallbackMessage::MsgStreamBufferDoneAsync), 0);

Group

ZPlay Methods

Web: http://libzplay.sourceforge.net/

Email: zcindori@inet.hr

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