Class

NSScroller

An NSScroller object controls scrolling of a document view within the clip view of an NSScrollView instance (or potentially of another kind of container view). A scroller displays a slot containing a knob that the user can drag directly to the desired location. The knob indicates both the position within the document view and—by varying in size within the slot—the amount visible relative to the size of the document view.

Overview

Prior to OS X v10.7, an NSScroller object can also optionally display scroll buttons. The scroll buttons are a pair of buttons that the user can click to scroll by a small amount (called a line increment or decrement) and Alt-click to scroll by a large amount (called a page increment or decrement).

You normally don’t need to program with scrollers; instead, you typically configure them with an NSScrollView object in a Nib file.

Don’t use an scroller when a slider would be more appropriate. An NSSlider object represents a range of values for something in the application and lets the user choose a setting. A scroller represents the relative position of the visible portion of a view and lets the user choose which portion to view.

Nested Types

NSScrollerArrow

These constants describe the two scroller buttons and are used by drawArrow(_:highlight:).

NSScrollerPart

These constants specify the different parts of the scroller:

NSScrollerStyle

Constants to specify the scroller style.

NSUsableScrollerParts

These constants specify which parts of the scroller are visible.

NSScrollerKnobStyle

Specify different knob styles.

NSScrollArrowPosition

These constants specify where the scroller’s buttons appear and are used by the arrowsPosition property.

Symbols

Managing Overlay Style Compatibility

class func isCompatibleWithOverlayScrollers()

Returns a Boolean value that indicates whether the class is compatible with overlay scroller style and behavior.

Determining Scroller Size

class func scrollerWidth(for: NSControlSize, scrollerStyle: NSScrollerStyle)

Returns the width for scrollers of the receiving class for a given control size and scroller style.

var controlSize: NSControlSize

The size of the scroller.

Laying out a Scroller

var arrowsPosition: NSScrollArrowPosition

The location of the scroll buttons within the scroller, as described in NSScrollArrowPosition.

Calculating Layout

func rect(for: NSScrollerPart)

Returns the rectangle occupied by aPart, which for this method is interpreted literally rather than as an indicator of scrolling direction.

func testPart(NSPoint)

Returns the part that would be hit by a mouse-down event at aPoint (expressed in the window’s coordinate system).

func checkSpaceForParts()

Checks to see if there is enough room in the receiver to display the knob and buttons.

var usableParts: NSUsableScrollerParts

A value that indicates which parts of the receiver are displayed and usable.

Drawing Scroller Parts

func drawArrow(NSScrollerArrow, highlight: Bool)

Draws the scroll button indicated by arrow, which is either NSScrollerIncrementArrow (the down or right scroll button) or NSScrollerDecrementArrow (up or left).