This article contains information about scales.

Overview

A scale is a highly customizable gauge element that displays a range of values that pointers can point to.

There are two types of scales: circular scales are used for circular gauges, and linear scales are used for linear gauges.

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Figure 1: Circular scale.

Figure 2: Linear scale.

Working with Scales in the UI

Scale properties can be set by:

Using the Scales Tab of either the Gauge or Sub-Gauge Designer dialog. Select the scale to be modified and then set its properties using this tab.
Using the Advanced Tab of either the Gauge or Sub-Gauge Designer dialog. Select a gauge object, and then open the Scale Collection Editor by clicking on the Scales property. Then select the scale in question and set its properties.

Common Layout Properties of Circular and Linear Scales

To modify the size of a scale bar set the Width property, which is measured as a percentage of the control's width.

If the Interval and IntervalOffset properties of major tick marks and labels are "Auto" (Double.NaN) then the Interval property determines the period between two successive major tick marks and labels, and IntervalOffset determines the offset of the first tick mark and label. All subsequent major tick marks and labels that appear on the scale will use the interval.

Major tick marks and labels have Interval and IntervalOffset properties, which can be used to override the Scale.Interval and Scale.IntervalOffset property values.

Minor tick marks and labels also have Interval and IntervalOffset properties. If they are "Auto" (Double.NaN) then they are automatically calculated using the major tick mark and label properties.

The Scale.MinimumPin and Scale.MaximumPin properties combine the attributes of a label and a tick mark. These properties set delimiters on the minimum and maximum values that a scale's pointer can point to (see figure 3 below). If the value of a scale's pointer is outside of these limits then the pointer will stop at the pins.

The minimum pin can also be used for an "Off" position (relevant if there is no data).

The behavior of these pin properties is best seen on the speedometer of a vehicle, when a value reaches above or below the scale range of the speedometer.

Figure 3: Minimum pin and maximum pins.

Layout Properties of Circular Scales

The SweepAngle property is a value between 0 and 360 that represents the number of degrees that the scale will sweep in a circle. A sweep angle of 360 degrees will produce a scale that is a complete circle.

The StartAngle property is a value between 0 and 360 that represents the angle of rotation where the scale will begin, relative to the Radius of the scale. A start angle of 90 degrees will start the scale at 90 degrees clockwise from the bottom of the scale.

Radius is measured as a percentage of the parent circular gauge's width.

All circular scale size and position-related properties are measured as a percentage of the radius of the circular gauge that the scale is associated with. For example, if a circular scale has a radius of 50 then its radius is 50% that of the circular scale radius.

Figure 4: Circular scale with start angle of 90 degrees, sweep angle of 270 degrees and a radius of 30.

Layout Properties of Linear Scales

The StartMargin and EndMargin properties are values that determine the width of the scale margins.

These margin properties are measured as a percentage of the parent linear gauge's height or width, depending on the orientation of the linear gauge.

Tick Marks

There are two types of tick marks: major and minor. Both sets of tick marks are enabled by default. Major tick marks are the major milestones on a gauge. In practice, major tick marks often contain labels to represent their individual values. Minor tick marks are the secondary marks that fall between the major tick marks on a gauge. Usually the minor tick marks do not have labels attached to represent their values.

To set tick mark properties for a scale select a scale in the Advanced Tab of the Gauge Designer dialog and then use the MajorTickmark and MinorTickMark properties.

The Placement property will place the value inside, outside or across the scale. To position tick marks, use the MajorTickMarks.Placement and MinorTickMarks.Placement properties. The tick marks can also be offset from the placement by using the MajorTickMarks.Offset and MinorTickMarks.Offset properties.

Fonts

Scale label font properties can be set using the designer via the LabelStyle property section in the Advanced Tab of the Gauge Designer dialog (note that a scale must be the selected gauge item).

By default scale labels will use a font with Scale.FontUnit set to "Percent". This means that the font is represented as a percentage of the parent gauge. For a linear scale it is a percentage of the linear gauge object's width/height. For a circular scale it is a percentage of the circular gauge object's radius.

If you want the font in its default font size, the Scale.FontUnit property must be set to Default. This will revert the font unit to the unit described by Font.Unit.

Behavior

To specify a logarithmic scale select a scale object in the Advanced Tab of the Gauge Designer dialog and then set its Scale.Logarithmic property.

If this property is set to True then the base of the logarithmic scale by default is 10. To modify the base of the scale set the Scale.LogarithmicBase property.

The minimum (i.e. start value) of a logarithmic scale must be greater than 0. If it is not it will be adjusted to 1.

Scales can be reversed by setting the boolean value Scale.Reversed to True (see figure below).

Scale values can also be multiplied by setting the Scale.Multiplier value. This multiplier will effectively multiply each value of the scale.

Figure 4: Circular gauge with Scale.Reversed = True, Scale.Logarithmic = True and Scale.LogarithmicBase = 2.

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