Apple

But, I really wanted to learn how to communicate with the proc.

As suggested, I replaced the struct with a list of @properties and passed "self" to the midireadproc. Works great !

I've learned a few things today. Thanks to all of you for your help.

William (Al) Haynes

On Mar 6, 2013, at 11:31 AM, Christian Blomert wrote:

When creating your input port with:

The program closely follows the CABook - here's the callback part :
MIDIInputPortCreate(
midiInfo.client,
CFSTR("Input port"),
MIDIEchoReadProc,
&midiInfo,
&midiInfo.inPort),
and the read proc :
void MIDIEchoReadProc(const MIDIPacketList *pktlist,
   void *refCon,
   void *connRefCon) {
MIDIEchoStruct *midiInfo = (MIDIEchoStruct*) refCon;
--- do midi processing --- works
--- echo to destination --- works
--- printf to console --- works
[myTextField setIntValue:midiInfo->mVelIn];doesn't work
- or -
[self myWriteToTextfieldMethod];doesn't work - self is undefined
}

instead of &midiInfo, put a link to 'self' as (void*)inRefCon, and put your midiInfo in the interface & properties of your main class
In the read proc you can then create a pointer named self to refCon:

MIDIInputPortCreate(
midiInfo.client,
CFSTR("Input port"),
MIDIEchoReadProc,
self,
&midiInfo.inPort),
and the read proc :
void MIDIEchoReadProc(const MIDIPacketList *pktlist,
     void *refCon,
     void *connRefCon) {
MyMainClass * self = (MyMainClass*) refCon;
MIDIEchoStruct *midiInfo = self->midiInfo;
--- do midi processing --- works
--- echo to destination --- works
--- printf to console --- works
[self->myTextField setIntValue:midiInfo->mVelIn]
- or -
[self myWriteToTextfieldMethod];
}

But as this is a high priority audio thread, it would be better to 'read' a current value from the main thread (that you could store easily as an int in said pointer to self on the audio thread)

Cheers,
Chris

References:
	>MidiReadProc to Text Field (From: Haynes Electronics <email@hidden>)