VST 3 Interfaces: IInfoListener Class Reference
Author: Steinberg

VST 3 Interfaces VST 3.7 SDK for developing VST plug-in

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IInfoListener Class Referenceabstract

Channel context interface: Vst::IInfoListener. More...

`#include <ivstchannelcontextinfo.h>`

Inheritance diagram for IInfoListener:

## Public Member Functions
virtual tresult | setChannelContextInfos (IAttributeList *list)=0
| Receive the channel context infos from host.
Public Member Functions inherited from FUnknown
virtual tresult | queryInterface (const TUID _iid, void **obj)=0
virtual uint32 | addRef ()=0
virtual uint32 | release ()=0

## Static Public Attributes
static const FUID | iid
Static Public Attributes inherited from FUnknown
static const FUID | iid

## Detailed Description

Channel context interface: Vst::IInfoListener.

- [plug imp]
- [extends IEditController]
- [released: 3.6.5]
- [optional]

Allows the host to inform the plug-in about the context in which the plug-in is instantiated, mainly channel based info (color, name, index,...). Index can be defined inside a namespace (for example, index start from 1 to N for Type Input/Output Channel (Index namespace) and index start from 1 to M for Type Audio Channel).
As soon as the plug-in provides this IInfoListener interface, the host will call setChannelContextInfos for each change occurring to this channel (new name, new color, new indexation,...)

# Example

//------------------------------------------------------------------------
tresult PLUGIN_API MyPlugin::setChannelContextInfos (IAttributeList* list)
{
if (list)
{
// optional we can ask for the Channel Name Length
int64 length;
if (list->getInt (ChannelContext::kChannelNameLengthKey, length) == kResultTrue)
{
...
}
// get the Channel Name where we, as plug-in, are instantiated
String128 name;
if (list->getString (ChannelContext::kChannelNameKey, name, sizeof (name)) == kResultTrue)
{
...
}
// get the Channel UID
if (list->getString (ChannelContext::kChannelUIDKey, name, sizeof (name)) == kResultTrue)
{
...
}
// get Channel Index
int64 index;
if (list->getInt (ChannelContext::kChannelIndexKey, index) == kResultTrue)
{
...
}
// get the Channel Color
int64 color;
if (list->getInt (ChannelContext::kChannelColorKey, color) == kResultTrue)
{
uint32 channelColor = (uint32)color;
String str;
str.printf ("%x%x%x%x", ChannelContext::GetAlpha (channelColor),
ChannelContext::GetRed (channelColor),
ChannelContext::GetGreen (channelColor),
ChannelContext::GetBlue (channelColor));
String128 string128;
Steinberg::UString (string128, 128).fromAscii (str);
...
}
// get Channel Index Namespace Order of the current used index namespace
if (list->getInt (ChannelContext::kChannelIndexNamespaceOrderKey, index) == kResultTrue)
{
...
}
// get the channel Index Namespace Length
if (list->getInt (ChannelContext::kChannelIndexNamespaceLengthKey, length) == kResultTrue)
{
...
}
// get the channel Index Namespace
String128 namespaceName;
if (list->getString (ChannelContext::kChannelIndexNamespaceKey, namespaceName, sizeof (namespaceName)) == kResultTrue)
{
...
}
// get plug-in Channel Location
int64 location;
if (list->getInt (ChannelContext::kChannelPluginLocationKey, location) == kResultTrue)
{
String128 string128;
switch (location)
{
case ChannelContext::kPreVolumeFader:
Steinberg::UString (string128, 128).fromAscii ("PreVolFader");
break;
case ChannelContext::kPostVolumeFader:
Steinberg::UString (string128, 128).fromAscii ("PostVolFader");
break;
case ChannelContext::kUsedAsPanner:
Steinberg::UString (string128, 128).fromAscii ("UsedAsPanner");
break;
default: Steinberg::UString (string128, 128).fromAscii ("unknown!");
break;
}
}
// do not forget to call addRef () if you want to keep this list
}
}

## Member Function Documentation

virtual tresult setChannelContextInfos | ( | IAttributeList * | list | ) |
| pure virtual

Receive the channel context infos from host.

## Member Data Documentation

const FUID iid
| static

Empty

Copyright ©2022 Steinberg Media Technologies GmbH. All Rights Reserved. This documentation is under this license.