public static extern int mixerGetLineControlsA(int hmxobj, ref VolumeStructures.LineControlStruct pmxlc, int fdwControls);
/// <summary>
/// method to retrieve a mixer control
/// </summary>
/// <param name="hmxObj"></param>
/// <param name="type"></param>
/// <param name="ctrlType"></param>
/// <param name="mixerCtrl"></param>
/// <param name="curVolume"></param>
/// <returns></returns>
private static bool GetSystemMixer(int hmxObj, int type, int ctrlType, out VolumeStructures.MixerStruct mixerCtrl, out int curVolume)
{
//create our method level variables
int details;
bool bReturn;
curVolume = -1;
//create our struct objects
VolumeStructures.LineControlStruct lineControls = new VolumeStructures.LineControlStruct();
VolumeStructures.MixerLineStruct line = new VolumeStructures.MixerLineStruct();
VolumeStructures.MixerDetailStruct mcDetails = new VolumeStructures.MixerDetailStruct();
VolumeStructures.UnsignedMixerDetailStruct detailsUnsigned = new VolumeStructures.UnsignedMixerDetailStruct();
//create a new mixer control
mixerCtrl = new VolumeStructures.MixerStruct();
//set the properties of out mixerline object
line.cbStruct = Marshal.SizeOf(line);
line.dwComponentType = type;
//get the line info and assign it to our details variable
details = WinXPSystem.mixerGetLineInfoA(hmxObj, ref line, VolumeConstants.MIXER_GETLINEINFOF_COMPONENTTYPE);
//make sure we didnt receive any errors
if (VolumeConstants.MMSYSERR_NOERROR == details)
{
int mcSize = 152;
//get the size of the unmanaged type
int control = Marshal.SizeOf(typeof(VolumeStructures.MixerStruct));
//allocate a block of memory
lineControls.pamxctrl = Marshal.AllocCoTaskMem(mcSize);
//get the size of the line controls
lineControls.cbStruct = Marshal.SizeOf(lineControls);
//set properties for our mixer control
lineControls.dwLineID = line.dwLineID;
lineControls.dwControl = ctrlType;
lineControls.cControls = 1;
lineControls.cbmxctrl = mcSize;
// Allocate a buffer for the control
mixerCtrl.cbStruct = mcSize;
// Get the control
details = WinXPSystem.mixerGetLineControlsA(hmxObj, ref lineControls, VolumeConstants.MIXER_GETLINECONTROLSF_ONEBYTYPE);
//once again check to see if we received any errors
if (VolumeConstants.MMSYSERR_NOERROR == details)
{
bReturn = true;
//Copy the control into the destination structure
mixerCtrl = (VolumeStructures.MixerStruct)Marshal.PtrToStructure(lineControls.pamxctrl, typeof(VolumeStructures.MixerStruct));
}
else
{
bReturn = false;
}
int mcDetailsSize = Marshal.SizeOf(typeof(VolumeStructures.MixerDetailStruct));
int mcDetailsUnsigned = Marshal.SizeOf(typeof(VolumeStructures.UnsignedMixerDetailStruct));
mcDetails.cbStruct = mcDetailsSize;
mcDetails.dwControlID = mixerCtrl.dwControlID;
mcDetails.paDetails = Marshal.AllocCoTaskMem(mcDetailsUnsigned);
mcDetails.cChannels = 1;
mcDetails.item = 0;
mcDetails.cbDetails = mcDetailsUnsigned;
details = WinXPSystem.mixerGetControlDetailsA(hmxObj, ref mcDetails, VolumeConstants.MIXER_GETCONTROLDETAILSF_VALUE);
detailsUnsigned = (VolumeStructures.UnsignedMixerDetailStruct)Marshal.PtrToStructure(mcDetails.paDetails, typeof(VolumeStructures.UnsignedMixerDetailStruct));
curVolume = detailsUnsigned.dwValue;
return(bReturn);
}
bReturn = false;
return(bReturn);
}
