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IOAudioLevelControl

Inherits from:	IOAudioControl
Declared In:	IOAudioLevelControl.h

Overview

Functions

create: Allocates a new level control with the given attributes
init: Initializes a newly allocated IOAudioLevelControl with the given attributes
setLinearScale: This function tells CoreAudio if it should apply a curve to the scaler representation of the volume.
setMaxDB: Sets the maximum value in db that the control may have
setMaxValue: Sets the maximum value the control may have
setMinDB: Sets the minimum value in db that the control may have
setMinValue: Sets the minimum value the control may have

create

Allocates a new level control with the given attributes

public

static IOAudioLevelControl *create(
    SInt32 initialValue, 
    SInt32 minValue, 
    SInt32 maxValue, 
    IOFixed minDB, 
    IOFixed maxDB, 
    UInt32 channelID, 
    const char *channelName = 0, 
    UInt32 cntrlID = 0, 
    UInt32 subType = 0, 
    UInt32 usage = 0);

Parameters

initialValue: The initial value of the control
minValue: The lowest possible value the control may have
maxValue: The highest possible value the control may have
minDB: A fixed point representation of the db value matching minValue
maxDB: A fixed point representation of the db value matching maxValue
channelID: The ID of the channel(s) that the control acts on. Common IDs are located in IOAudioTypes.h.
channelName: An optional name for the channel. Common names are located in IOAudioTypes.h.
cntrlID: An optional ID for the control that can be used to uniquely identify controls.

Return Value

Returns a newly allocted and initialized level IOAudioControl

init

Initializes a newly allocated IOAudioLevelControl with the given attributes

public

virtual bool init(
    SInt32 initialValue, 
    SInt32 minValue, 
    SInt32 maxValue, 
    IOFixed minDB, 
    IOFixed maxDB, 
    UInt32 channelID, 
    const char *channelName = 0, 
    UInt32 cntrlID = 0, 
    UInt32 subType = 0, 
    UInt32 usage = 0, 
    OSDictionary *properties = 0);

Parameters

initialValue: The initial value of the control
minValue: The lowest possible value the control may have
maxValue: The highest possible value the control may have
minDB: A fixed point representation of the db value matching minValue
maxDB: A fixed point representation of the db value matching maxValue
channelID: The ID of the channel(s) that the control acts on. Common IDs are located in IOAudioTypes.h.
channelName: An optional name for the channel. Common names are located in IOAudioTypes.h.
cntrlID: An optional ID for the control that can be used to uniquely identify controls.
properties: Standard property list passed to the init() function of any new IOService. This dictionary gets stored in the registry entry for this service.

Return Value

Returns true on success

setLinearScale

This function tells CoreAudio if it should apply a curve to the scaler representation of the volume.

public

virtual void setLinearScale(
    bool useLinearScale);

Parameters

useLinearScale: TRUE instructs CoreAudio to not apply a curve to the scaler representation of the volume, FALSE instructs CoreAudio to apply a curve, which is CoreAudio's default behavior.

setMaxDB

Sets the maximum value in db that the control may have

public

virtual void setMaxDB(
    IOFixed maxDB);

Parameters

maxDB: The maximum value in db for the control

Discussion

This value is represented as an IOFixed value which is a fixed point number. The IOFixed type is a 16.16 fixed point value.

setMaxValue

Sets the maximum value the control may have

public

virtual void setMaxValue(
    SInt32 maxValue);

Parameters

maxValue: The maximum value for the control

setMinDB

Sets the minimum value in db that the control may have

public

virtual void setMinDB(
    IOFixed minDB);

Parameters

minDB: The minimum value in db for the control

Discussion

This value is represented as an IOFixed value which is a fixed point number. The IOFixed type is a 16.16 fixed point value.

setMinValue

Sets the minimum value the control may have

public

virtual void setMinValue(
    SInt32 minValue);

Parameters

minValue: The minimum value for the control

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Last Updated: 2008-12-19