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# CGScrollEventUnit

Constants that specify the unit of measurement for a scrolling event.

```
enum CGScrollEventUnit
```

## Overview

You may pass one of these constants to the function [`CGEventCreateScrollWheelEvent`](/documentation/CoreGraphics/CGEventCreateScrollWheelEvent) to specify the unit of measurement for the event. The constant `kCGScrollEventUnitPixel` produces an event that most applications interpret as a smooth scrolling event. By default, the scale is about ten pixels per line. You can alter the scale with the function [`CGEventSourceSetPixelsPerLine`](/documentation/CoreGraphics/CGEventSourceSetPixelsPerLine).

## Topics

### Constants

[`CGScrollEventUnit.pixel`](/documentation/CoreGraphics/CGScrollEventUnit/pixel)

Specifies that the unit of measurement is pixels.

[`CGScrollEventUnit.line`](/documentation/CoreGraphics/CGScrollEventUnit/line)

Specifies that the unit of measurement is lines.


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