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Images

Images are an important part of any Mac OS X application. In Cocoa, images play a very important, but flexible, role in your user interface. You can use images to render preexisting content or act as a buffer for your application's drawing commands. At the heart of Cocoa's image manipulation code is the NSImage class. This class manages everything related to image data and is used for the following tasks:

• Loading existing images from disk.

• Drawing image data into your views.

• Creating new images.

• Scaling and resizing images.

• Converting images to any of several different formats.

You can use images in your program for a variety of tasks. You can load images from existing image files (such as JPEG, GIF, PDF, and EPS files) to draw elements of your user interface that might be too difficult (or too inefficient) to draw using primitive shapes. You can also use images as offscreen or temporary buffers and capture a sequence of drawing commands that you want to use at a later time.

Although bitmaps are one of the most common types of image, it is important not to think of the NSImage class as simply managing photographic or bitmap data. The NSImage class in Cocoa is capable of displaying a variety of image types and formats. It provides support for photograph and bitmap data in many standard formats. It also provides support for vector, or command-based data, such as PDF, EPS, and PICT. You can even use the NSImage class to represent an image created with the Core Image framework.

Contents:

Image Basics
Supported Image File Formats
Guidelines for Using Images
Creating NSImage Objects
Working with Images
Creating New Image Representation Classes

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