Instance Method

layer:shouldInheritContentsScale:fromWindow:

Notifies you when a resolution changes occurs for the window that hosts the layer.

Declaration

- (BOOL)layer:(CALayer *)layer shouldInheritContentsScale:(CGFloat)newScale fromWindow:(NSWindow *)window;

Parameters

layer

The layer whose scale and content might need updating.

newScale

The new scale of the window.

window

The window that hosts the layer.

Return Value

A Boolean value that specifies whether to change the layer’s contentsScale property.

Discussion

When a resolution change occurs for a given window, the system traverses the layer trees in that window to decide what action, if any, to take for each layer. The system queries the layer’s delegate to determine whether to change the layer’s contentsScale property to the new scale (either 2.0 or 1.0).

Note that you don’t need to manage NSImage contents and that this method is not called on the delegate of a layer whose content is an NSImage object.

If the delegate returns YES, it should make any corresponding changes to the layer’s properties, as required by the resolution change. For example, a layer whose contents contain a CGImage object needs to determine whether an alternate CGImage object is available for the new scale factor. If the delegate finds a suitable CGImage object, then in addition to returning YES, it should set the appropriate CGImage object as the layer’s new contents.