In This Chapter
Creating a custom view
Drawing rectangles and ovals
Painting irregular shapes
From the beautiful fonts in a word processor to the shiny Finder interface, the Mac OS has always prided itself on fantastic looking graphics. Mac OS X is no different. With its sophisticated Quartz graphics engine, Mac OS X can produce stunning graphics. Cocoa gives you direct access to these powerful features of Mac OS X.
This chapter covers the basics of working with graphics in Cocoa. You create a custom view for displaying your graphics and draw on it with a variety of colors, shapes, and images. You even write code to change the opacity of your graphics, giving them the coveted see-through look.
Before jumping head first into graphics, you need to familiarize yourself with a few important Cocoa data types:
NSPoint, NSRect, NSSize, and
NSColor. You need them to do any type of graphics programming in Cocoa, so they make a good starting point.
Just like in geometry, Cocoa uses points to designate positions on a square grid. To work with points in Cocoa, you use an
NSPoint is a structure comprised of two floats (
y, respectively). Quartz, the graphics engine on the Mac OS, defines the bottom-left corner of a view as the origin (0,0). The
x value increases as you move to the right. The
y value increases as you advance up.
The bottom-left origin is different than what ...