NSClipView

NSClipView is a subclass of NSView in the AppKit framework that provides clipping of its content to a specified rectangle. In macOS applications that use scrolling, an NSScrollView uses an NSClipView as its content view to display a portion of a larger document. The clip view draws only within its bounds, so drawing outside the visible area is not rendered.

The clip view maintains a reference to its documentView—the view that contains the full content to be displayed. The documentView is a subview of the clip view, and the clip view clips its rendering to its own bounds. When scrolling, the scroll view adjusts the origin of the clip view’s bounds, which in turn moves the document view to reveal the correct portion of content.

Typical usage involves setting the document view with setDocumentView: and obtaining it with documentView. The clip view participates in coordinate conversions between the scroll view and the document view via NSView methods, enabling layout and hit-testing to respect the visible region.

Customization and notes: NSClipView is usually not subclassed, but it can be overridden to customize clipping behavior or coordinate handling. It integrates with layer-backed rendering and participates in the standard AppKit drawing cycle.