Set callback function.
Public Function SetCallbackFunc(ByVal CallbackFunc As TCallbackFunc, ByVal Messages As TCallbackMessage, ByVal UserData As Integer) As Boolean
Parameters |
Description |
ByVal CallbackFunc As TCallbackFunc |
Address to callback function. Set this value to 0 to disable callback mechanism. |
ByVal Messages As TCallbackMessage |
Specify messages you need to receive with callback function. This parameter can be combination of multiple callback messages. |
ByVal UserData As Integer |
User data. This value will be passed to CallbackFunc as parameter. |
Return Values |
Description |
True |
All OK. |
False |
Error. To get error message read here. |
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.
// global holder for our callback function, need this to prevent garbage collector to destroy our callback function Private CallbackFunc As TCallbackFunc // callback function Public Function MyCallbackFunc(ByVal objptr As UInteger, ByVal user_data As Integer, ByVal msg As TCallbackMessage, ByVal param1 As UInteger, ByVal param2 As UInteger) As Integer Select Case msg Case TCallbackMessage.MsgStreamBufferDoneAsync ' read more data and push into stream Dim stream_data() As Byte = Nothing Dim small_chunk As Integer = 100000 stream_data = br.ReadBytes(small_chunk) If stream_data.Length > 0 Then player.PushDataToStream(stream_data, CUInt(stream_data.Length)) Else Dim tempMemNewData1() As Byte = Nothing player.PushDataToStream(tempMemNewData1, 0) End If End Select Return 0 End Function // ... // global variable, prevent garbage collector to destroy this function CallbackFunc = AddressOf MyCallbackFunc // set callback function player.SetCallbackFunc(CallbackFunc, CType(TCallbackMessage.MsgStreamBufferDoneAsync, TCallbackMessage), 0)
Copyright (c) 2010. Zoran Cindori - All rights reserved.
Web: http://libzplay.sourceforge.net/ Email: zcindori@inet.hr |