Mac OS X Leopard - ARCAism

460
CHAPTER 25 MAC OS X DEVELOPMENT: THE TOOLS
The Inspector
Like any inspector panel, Interface Builder’s Inspector allows you to see and change the attributes
of your interface items. The Inspector is open by default, but you can always call it forth by
selecting Inspector from the Tools menu, or by typing Shift+Cmd+I. To inspect an item, simply
click it, and the Inspector’s contents will change as appropriate. The Inspector’s attributes are
divided into several tabs.
Attributes
As interface objects are reusable, they have several configuration options. Although interface
objects can be instantiated and configured in code, it’s easier to set up as many attributes as possible
in Interface Builder itself. This keeps the attributes with the objects they affect, and presents
them in a visual way that often makes their effects easier to understand.
The Attributes tab is divided into subsections based on the object’s inheritance. Our text
field has several attributes, chief among them is its title, which is the text it displays. Editing the
title will change the text just as you did by double-clicking and editing it in place. You can also
set text attributes such as alignment, color, and whether to use rich text, which allows things like
bold or italic formatting.
You can also set attributes on the text field itself, such as its border, whether it should draw
a background, and if so, what color it should be.
Since your text field, as an instance of the class NSTextField, is a subclass of NSControl, the
next subsection allows you to edit the attributes of a control. These include the text’s direction,
how it handles line breaks, and whether it is enabled or grayed out.
As NSControl is in turn a subclass of NSView, you can then edit view attributes like how it
draws a focus ring to indicate it’s the currently selected item, or whether it’s visible at all.
Effects
As discussed in Chapter 24, many Core Animation effects are available from within Interface
Builder. These are settable from the myriad subsections of the Effects tab. Since your text field is
a view subclass, you can take advantage of Core Animation.
When a view uses Core Animation, we say it is layer-backed. Once a view is layer-backed,
all of its subviews are also layer-backed. You can see the view hierarchy and decide at which level
to activate layer-backing from the Rendering Tree subsection.
NOTE Core Animation was originally called Layer Kit, because it uses a lightweight layerbased
model. For whatever reason, Leopard’s architects decided to emphasize the framework’s
easy animation over its nifty rendering model. Regardless of this change, we still refer to
layers and call views that can use Core Animation “layer-backed.”
Once your view is layer-backed, you can change its transparency and set a custom shadow
from the Appearance tab. You can add Core Image filters from the Content Filters, Background
Filters, and Compositing Filters subsections. Finally, you can affect the style of animation by setting
custom transitions in the Transitions subsection.
Feel free to play with the various Core Animation and Core Image effects later if you like,
but since none of this affects resizing (the task at hand), let’s move on.
Size
The Size tab would be more properly called Geometry, as it affects more than just size. Nevertheless,
this is where you need to go to set the resizing attributes of your text field. Much like the
Attributes tab, you’ll notice subsections based on inheritance. There are no special text field size
attributes, so the first subsection comes from being a control subclass.