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NSLevelIndicator Class Reference

Overview

NSLevelIndicator is a subclass of NSControl that displays a value on a linear scale. Level indicators provide a visual representation of a level or amount of something, using discrete values. While similar to NSSlider, it provides a more customized visual feedback to the user. Level indicators do not have a “knob” indicating the current setting or allowing the user to adjust settings. The supported indicator styles include:

• A capacity style level indicator. The continuous mode for this style is often used to indicate conditions such as how much data is on hard disk. The discrete mode is similar to audio level indicators in audio playback applications. You can specify both a warning value and a critical value that provides additional visual feedback to the user.

• A ranking style level indicator. This is similar to the star ranking displays provided in iTunes and iPhoto. You can also specify your own ranking image.

• A relevancy style level indicator. This style is used to display the relevancy of a search result, for example in Mail.

NSLevelIndicator uses an NSLevelIndicatorCell to implement much of the control’s functionality. NSLevelIndicator provides cover methods for most of NSLevelIndicatorCell’s methods, which invoke the corresponding cell method.

Tasks

Configuring the Range of Values

• – setMinValue:
• – minValue
• – setMaxValue:
• – maxValue
• – setWarningValue:
• – warningValue
• – setCriticalValue:
• – criticalValue

Managing Tick Marks

• – setTickMarkPosition:
• – tickMarkPosition
• – setNumberOfTickMarks:
• – numberOfTickMarks
• – setNumberOfMajorTickMarks:
• – numberOfMajorTickMarks
• – tickMarkValueAtIndex:
• – rectOfTickMarkAtIndex:

Instance Methods

criticalValue

Returns the receiver’s critical value.

- (double)criticalValue

Availability

• Available in Mac OS X v10.4 and later.

See Also

• – setCriticalValue:

Declared In

NSLevelIndicator.h

maxValue

Returns the receiver’s maximum value.

- (double)maxValue

Availability

• Available in Mac OS X v10.4 and later.

See Also

• – setMaxValue:

Declared In

NSLevelIndicator.h

minValue

Returns the receiver’s minimum value.

- (double)minValue

Availability

• Available in Mac OS X v10.4 and later.

See Also

• – setMinValue:

Declared In

NSLevelIndicator.h

numberOfMajorTickMarks

Returns the number of major tick marks associated with the receiver.

- (NSInteger)numberOfMajorTickMarks

Availability

• Available in Mac OS X v10.4 and later.

See Also

• – setNumberOfMajorTickMarks:

Declared In

NSLevelIndicator.h

numberOfTickMarks

Returns the number of tick marks associated with the receiver.

- (NSInteger)numberOfTickMarks

Discussion

The tick marks assigned to the minimum and maximum values are included.

Availability

• Available in Mac OS X v10.4 and later.

See Also

• – setNumberOfTickMarks:

Declared In

NSLevelIndicator.h

rectOfTickMarkAtIndex:

Returns the bounding rectangle of the tick mark identified by index (the minimum-value tick mark is at index 0).

- (NSRect)rectOfTickMarkAtIndex:(NSInteger)index

Discussion

If no tick mark is associated with index, the method raises a NSRangeException.

Availability

• Available in Mac OS X v10.4 and later.

Declared In

NSLevelIndicator.h

setCriticalValue:

Sets the receiver’s critical value to criticalValue.

- (void)setCriticalValue:(double)criticalValue

Availability

• Available in Mac OS X v10.4 and later.

See Also

• – criticalValue

Declared In

NSLevelIndicator.h

setMaxValue:

Sets the maximum value the receiver can represent to maxValue.

- (void)setMaxValue:(double)maxValue

Availability

• Available in Mac OS X v10.4 and later.

See Also

• – maxValue

Declared In

NSLevelIndicator.h

setMinValue:

Sets the minimum value the receiver can represent to minValue.

- (void)setMinValue:(double)minValue

Availability

• Available in Mac OS X v10.4 and later.

See Also

• – minValue

Declared In

NSLevelIndicator.h

setNumberOfMajorTickMarks:

Sets the number of major tick marks displayed by the receiver.

- (void)setNumberOfMajorTickMarks:(NSInteger)count

Discussion

The count must be less than or equal to the number of tick marks returned by numberOfTickMarks. For example, if the number of tick marks is 11 and you specify 3 major tick marks, the resulting level indicator will display 3 major tickmarks alternating with 8 minor tick marks, as in the example shown in Figure 1.

Availability

• Available in Mac OS X v10.4 and later.

See Also

• – numberOfMajorTickMarks

Declared In

NSLevelIndicator.h

setNumberOfTickMarks:

Sets the number of tick marks displayed by the receiver (which include those assigned to the minimum and maximum values) to count.

- (void)setNumberOfTickMarks:(NSInteger)count

Discussion

By default, this value is 0, and no tick marks appear. The number of tick marks assigned to a slider, along with the slider’s minimum and maximum values, determines the values associated with the tick marks.

Availability

• Available in Mac OS X v10.4 and later.

See Also

• – numberOfTickMarks

Declared In

NSLevelIndicator.h

setTickMarkPosition:

Sets where tick marks appear relative to the receiver.

- (void)setTickMarkPosition:(NSTickMarkPosition)position

Discussion

This method has no effect if no tick marks have been assigned (that is, numberOfTickMarks returns 0).

Availability

• Available in Mac OS X v10.4 and later.

See Also

• – tickMarkPosition

Declared In

NSLevelIndicator.h

setWarningValue:

Sets the receiver’s warning value to warningValue.

- (void)setWarningValue:(double)warningValue

Availability

• Available in Mac OS X v10.4 and later.

See Also

• – warningValue

Declared In

NSLevelIndicator.h

tickMarkPosition

Returns how the receiver’s tick marks are aligned with it.

- (NSTickMarkPosition)tickMarkPosition

Discussion

The default alignments are NSTickMarkBelow and NSTickMarkLeft.

Availability

• Available in Mac OS X v10.4 and later.

See Also

• – setTickMarkPosition:

Declared In

NSLevelIndicator.h

tickMarkValueAtIndex:

Returns the receiver’s value represented by the tick mark at index (the minimum-value tick mark has an index of 0).

- (double)tickMarkValueAtIndex:(NSInteger)index

Availability

• Available in Mac OS X v10.4 and later.

Declared In

NSLevelIndicator.h

warningValue

Returns the receiver’s warning value.

- (double)warningValue

Availability

• Available in Mac OS X v10.4 and later.

See Also

• – setWarningValue:

Declared In

NSLevelIndicator.h

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