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NSCachedImageRep Class Reference

Overview

An NSCachedImageRep object store image data in a form that can be readily transferred to the screen. An NSCachedImageRep object differs from other image representation objects in that it simply stores the already rendered image, whereas other image representation objects generally have knowledge about how to render the image from source data.

You typically do not use this class directly. Instead, NSImage and its other image representation objects create instances of NSCachedImageRep as needed to cache versions of the rendered image. This caching speeds up screen-based drawing for existing images during subsequent rendering operations. Cached image representations are also used to capture drawing commands for images created programmatically by locking focus on an image.

Tasks

Initializing an NSCachedImageRep

• – initWithSize:depth:separate:alpha:
• – initWithWindow:rect:

Getting the Representation

• – rect
• – window

Instance Methods

initWithSize:depth:separate:alpha:

Returns an NSCachedImageRep object initialized with the specified image characteristics.

- (id)initWithSize:(NSSize)size depth:(NSWindowDepth)depth separate:(BOOL)flag alpha:(BOOL)alpha

Parameters

size

The size of the image, measured in points.

depth

The bit depth of the image. Specify 0 if you want the image to be the same depth as the deepest screen on the current system.

flag

YES if the receiver should use a separate offscreen window to store the image; otherwise, NO if the receiver should use a shared window.

alpha

YES if the image includes transparency information; otherwise, NO.

Return Value

The initialized NSCachedImageRep object or nil if the object could not be initialized.

Availability

• Available in Mac OS X v10.0 and later.

See Also

• – setAlpha: (NSImageRep)
• – setBitsPerSample: (NSImageRep)
• – setCacheDepthMatchesImageDepth: (NSImage)
• – setCachedSeparately: (NSImage)

Declared In

NSCachedImageRep.h

initWithWindow:rect:

Returns an NSCachedImageRep object initialized for drawing in the specified window.

- (id)initWithWindow:(NSWindow *)aWindow rect:(NSRect)aRect

Parameters

aWindow

The window (typically offscreen) in which the image is to be rendered. The window is retained by the receiver.

aRect

The position and size of the image in the specified window. This rectangle should be specified in the base coordinate system of the window.

Discussion

You must draw the image yourself in the designated part of the window. There are no NSCachedImageRep methods for this purpose.

Availability

• Available in Mac OS X v10.0 and later.

See Also

• – size (NSImageRep)

Declared In

NSCachedImageRep.h

rect

Returns the rectangle where the receiver is cached.

- (NSRect)rect

Return Value

The rectangle in the associated offscreen window where the receiver's image is located.

Availability

• Available in Mac OS X v10.0 and later.

See Also

• – size (NSImageRep)

Declared In

NSCachedImageRep.h

window

Returns the window where the receiver is cached.

- (NSWindow *)window

Return Value

The window (typically offscreen) used to store the image.

Availability

• Available in Mac OS X v10.0 and later.

Declared In

NSCachedImageRep.h

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