Developer Documentation

QuickTime 4 API Documentation
QuickTime Music Architecture

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Knob Flags

Knob flags specify characteristics of a knob. They are used in the flags field of a knob description structure. Some flags describe the type of values a knob takes and others describe the user interface. Knob flags are mutually exclusive, so only one should be set (all knob flag constants begin " kKnobType ").

enum {
    kKnobReadOnly               = 16,
    kKnobInterruptUnsafe        = 32,
    kKnobKeyrangeOverride       = 64,
    kKnobGroupStart             = 128,
    kKnobFixedPoint8            = 1024,
    kKnobFixedPoint16           = 2048,
    kKnobTypeNumber             = 0 << 12,
    kKnobTypeGroupName          = 1 << 12,
    kKnobTypeBoolean            = 2 << 12,
    kKnobTypeNote               = 3 << 12,
    kKnobTypePan                = 4 << 12,
    kKnobTypeInstrument         = 5 << 12,
    kKnobTypeSetting            = 6 << 12,
    kKnobTypeMilliseconds       = 7 << 12,
    kKnobTypePercentage         = 8 << 12,
    kKnobTypeHertz              = 9 << 12,
    kKnobTypeButton             = 10 << 12
};

Constant descriptions

kKnobReadOnly
The knob value cannot be changed by the user or with a set knob call.

kKnobInterruptUnsafe
Alter this knob only from foreground task time.

kKnobKeyrangeOverride
The knob can be overridden within a single key range (software synthesizer only).

kKnobGroupStart
The knob is first in some logical group of knobs.

kKnobFixedPoint8
Interpret knob numbers as fixed-point 8-bit.

kKnobFixedPoint16
Interpret knob numbers as fixed-point 16-bit.

kKnobTypeNumber
The knob value is a numerical value.

kKnobTypeGroupName
The name of the knob is really a group name for display purposes.

kKnobTypeBoolean
The knob is an on/off knob. If the range of the knob (as specified by the low value and high value in the knob description structure) is greater than one, the knob is a multi-checkbox field.

kKnobTypeNote
The knob value range is equivalent to MIDI keys.

kKnobTypePan
The knob value is the pan setting and is within a range (as specified by the low value and high value in the knob description structure) that goes from left to right.

kKnobTypeInstrument
The knob value is a reference to another instrument number.

kKnobTypeSetting
The knob value is one of n different discrete settings--for example, items on a pop-up menu.

kKnobTypeMilliseconds
The knob value is in milliseconds.

kKnobTypePercentage
The knob value is a percentage of the range.

kKnobTypeHertz
The knob value represents frequency.

kKnobTypeButton
The knob is a momentary trigger push button.

 

© 1999 Apple Computer, Inc.

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