C H A P T E R 8

User Input

Like other graphical user interfaces, Mac OS X is optimized for use with a pointing device, such as a mouse. Many users, however, prefer or need to interact with the computer using the keyboard instead of the mouse. In Mac OS X, users have the option of enabling keyboard access for all functions available using a point-and-click device.

The Mouse and Other Pointing Devices

IntheMacintoshinterface,thestandardpointingdeviceisthemouse. Userscansubstituteotherdevices—such as trackballs and stylus pens—that maintain the behavior of direct manipulation of objects on screen.

Moving the mouse without pressing the mouse button moves the cursor, or pointer. The onscreen cursor can assume different shapes according to the context of the application and the cursor’s position. For example, in a word processor, the cursor takes the I-beam shape while it’s over the text and changes to an arrow when it’s over a tools palette. Change the cursor’s shape only to provide information to the user about changes in the cursor’s function. More information on using cursors correctly can be found in “Cursors” (page 157)

Just moving the mouse changes only the pointer’s location, and possibly its shape. Pressing the mouse button indicates the intention to do something, and releasing the mouse button completes the action.

These guidelines apply to single-button mice and to the primary button of multi-button mice. Note that users can select which button of a multi-button mouse to designate as the primary button in the Keyboard & Mouse System Preferences.

Clicking

Clicking has two components: pushing down on the mouse button and releasing it without moving the mouse. (If the mouse moves between button down and button up, it’s dragging, not clicking.)

The effect of a click should be immediate and obvious. If the function of the click is to cause an action (such as clicking a button), the selection is made when the button is pressed, and the action takes place when the button is released. For example, if a user presses down the mouse button while the pointer is over an onscreen button, thereby putting the button in a selected state, and then moves the pointer off the button before releasing the mouse button, the onscreen button is not clicked. If the user presses an onscreen button and rolls over another button before releasing the mouse, neither button is clicked.

Double-Clicking

Double-clicking involves a second click that follows immediately after the first click. If the two clicks are close enough to each other in terms of time (as set by the user in Keyboard & Mouse preferences) and location (usually within a couple of points), they constitute a double click.

The Mouse and Other Pointing Devices

95

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