Formatting Pointers on a Gauge
A gauge pointer indicates the current value of the gauge. By default, when a field is added, the values contained in the field are aggregated into one value that is shown by the pointer on the gauge. You can add multiple pointers to the gauge to point at multiple values on the same scale or add multiple scales and a pointer for every scale you have added. After you add a field to a gauge, you must set the maximum and minimum values on the corresponding scale in order to give context to the pointer value. You also have the option of setting the minimum and maximum values on a range, which shows a critical area on the scale.
You can set appearance properties on the pointer by right-clicking on the pointer and selecting Radial Pointer Properties or Linear Pointer Properties. Each gauge pointer contains the same set of properties. There are also corresponding appearance properties unique to each gauge type:
On a radial gauge, you can specify a needle pointer and a needle cap.
On a linear gauge, you can specify a thermometer pointer, which is a variation of the bar pointer. The thermometer pointer allows you to specify the shape of the bulb.
By default, when a gauge is added, it contains one pointer with no associated field. This is known as an empty pointer. It will display zero until a field is added to the data field drop-zone. When you add a field to the data field drop-zone, the pointer is connected to that field. If you delete a field from the data field drop-zone, the pointer associated with that field is also deleted.
After data is added, when you right-click on the pointer, you will get Clear Pointer Value and Delete Pointer options. The Clear Pointer Value option will remove the field attached to the gauge, but the pointer will still appear on the gauge. The Delete Pointer option will remove the field from the gauge and delete the pointer from view. If you re-add a field to the gauge, the default pointer will reappear. When you set the pointer's Hidden property to True, the pointer is not hidden on the design surface, but it is hidden at run time.
You can add multiple pointers to the gauge to point at multiple values on the same scale. This can be useful for showing a low and a high value at the same time. To specify more than one pointer on the gauge for the same scale, right-click anywhere inside the gauge and click Add Pointer on the shortcut menu. Alternatively, you can add a scale by right-clicking anywhere in the gauge and clicking Add Scale. Then you can add a new pointer, and it will automatically be associated to the last scale.
When pointers overlap, the drawing order of the pointers is determined by the order in which they are added to the gauge. You cannot reorder the drawing order of the pointers by changing the order of the fields in the data field drop-zone. To change the order of drawing for multiple pointers, open the Properties pane and click on Pointers (…). Then change the order of the pointers in the Pointer collection.
A snapping interval defines the multiple to which values are rounded. By default, the gauge will point to the exact value of the field you have specified in the data field drop-zone. However, you may want to round the exact value up or down so that the pointer will snap to a pre-set interval. For example, if the value on your gauge is 34.2 and you specify a snapping interval of 5, the gauge pointer will point to 35. If the value on your gauge is 31.2 and you specify a snapping interval of 5, the gauge pointer will point to 30. For more information, see How to: Set a Snapping Interval on a Gauge.
In addition to the built-in list of pointer styles, you can specify an image as a pointer. This is most effective when you use an image to replace an existing needle pointer style. The image is superimposed over the pointer, but all pointer functionality is applicable. Color and gradient options are not applicable when an image is used for the pointer.
If the pointer image is an irregular shape, you should define the color as transparent to hide the areas of your image that should not appear on the gauge. When you define a transparent color, the gauge transposes the image on top of your existing pointer and trims the image so that only the shape of the pointer appears. The gauge rescales the image to fit the size of your pointer. When you specify an image for a pointer, any subsequent pointer that is added on top of the gauge will be drawn underneath the image. For this reason, it is better not to specify an image for the pointer if there are multiple pointers on the gauge. For more information, see How to: Specify an Image as a Pointer on a Gauge.