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Controls

Checkboxes

A checkbox describes a state, action, or value that can be either on or off. In a group of checkboxes, each checkbox should be independent of all the others, unless interdependency is clearly indicated (for example, by displaying a subordinate checkbox indented below a superior checkbox).

For example, in Sound preferences (shown in Figure 15-23), checkboxes allow users to make choices about sound effects and choose whether to display the volume setting in the menu bar. Notice that users can select or deselect any of the three sound effects checkboxes, because these controls are independent of each other.

Figure 15-23 Checkboxes provide on-off choices to the user

Checkboxes

Checkbox Usage

Use a checkbox when you want to allow users to choose between two opposite states, actions, or values. If you want to provide a set of choices from which users can choose only one, use a set of radio buttons instead (see “Radio Buttons” (page 272) for more on this control).

If there are several independent values or states you want users to control, you can provide a group of checkboxes (see Figure 15-23 for an example of a group of independent checkboxes). If, on the other hand, you need to allow users to make an on-off type of choice that can lead to additional, related on-off choices, you can display checkboxes in a hierarchy that indicates the relationship.

For example, the Trackpad pane of the Keyboard & Mouse preferences allows users to decide which trackpad gestures to use (this window is shown in Figure 15-24). Notice that the “Allow horizontal scrolling” checkbox is dependent on the “Use two fingers to scroll” checkbox, because if users choose not to use two fingers to scroll, they don’t care about horizontal scrolling. Similarly, the Dragging and Drag Lock checkboxes are

Selection Controls

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2008-06-09 | © 1992, 2001-2003, 2008 Apple Inc. All Rights Reserved.

C H A P T E R 1 5

Controls

unavailable unless the Clicking checkbox is selected, because the dragging gestures are dependent on the clicking gesture. The Trackpad pane uses indentation to tell users that some of these settings are dependent on others.

Figure 15-24 Checkboxes can be indented to show a dependent relationship

The indented checkboxes are available when the unindented ones are checked

Checkbox Contents and Labeling

Each checkbox label should clearly imply two opposite states so it’s clear what happens when the option is selected or deselected. If you can’t find an unambiguous label, consider using a pair of radio buttons so you can clarify the states with two different labels.

Checkbox labels should have sentence-style capitalization (see “Capitalization of Interface Element Labels and Text” (page 131) for more on this style), unless the state or value is the title of some other element in the interface that is capitalized.

When a user selection comprises more than one state, use a dash in the appropriate checkboxes. This symbol is consistent with the mixed-state indicator in menus, as described in “Using Symbols in Menus” (page 166).

Checkbox Specifications

Control sizes: The dimensions of the checkbox itself are fixed for each size, but you determine the length of the introductory label and checkbox label.

Label spacing and fonts: Checkbox text (both the introductory label and control label) should be in a font that is proportional to the size of the control. The following fonts are supplied automatically by Interface Builder:

■Regular size: System font.

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2008-06-09 | © 1992, 2001-2003, 2008 Apple Inc. All Rights Reserved.