William H. Bowers – Direct Manipulation and Pointing Devices Cooper 21

William H. Bowers – Agenda Direct manipulation Direct manipulation Visual feedback for direct manipulation Visual feedback for direct manipulation Pointing devices Pointing devices Using the mouse Using the mouse –Mouse buttons –Pointing and clicking

William H. Bowers – Agenda Using the mouse Using the mouse –Up and down mouse events Cursors Cursors Pliancy and hinting Pliancy and hinting Input focus Input focus Meta-keys Meta-keys

William H. Bowers – Direct Manipulation Coined by Shneiderman Coined by Shneiderman Consists of Consists of –Visual representation –Physical actions –Immediately visible feedback Requires rich visual interaction Requires rich visual interaction Must be visible Must be visible

William H. Bowers – Direct Manipulation Simple Simple Straightforward Straightforward Easy to use Easy to use Easy to remember Easy to remember Not intuitive Not intuitive Must be taught Must be taught May be difficult for fine control May be difficult for fine control

William H. Bowers – Direct Manipulation Five varieties Five varieties –Selection –Drag and drop –Control manipulation –Resizing, reshaping and repositioning –Connecting objects

William H. Bowers – Direct Manipulation Three phases Three phases –Free phase –Captive phase –Termination phase

William H. Bowers – Visual Feedback for Direct Manipulation Cursor hinting Cursor hinting –Free cursor hinting Cursor changes as it passes over an object Cursor changes as it passes over an object –Captive cursor hinting Changes to indicate the process is in progress Changes to indicate the process is in progress May show the object or an outline May show the object or an outline

William H. Bowers – Pointing Devices Light pens Light pens –Logical extension of fingers –Unusable with computers –Difficult to use on vertical surfaces –Requires anchor point for heel of hand –Relies on gross motor control

William H. Bowers – Pointing Devices Mice Mice –Not intuitive –No visual affordance –Motion is proportional, not one to one –Really indirect manipulation –Generally imprecise –Good for pointing

William H. Bowers – Pointing Devices Trackballs Trackballs –Used in games and early laptops –Button placement is an issue –More compact footprint than mouse Digitizing tablets Digitizing tablets –Artists, graphic designers –Absolute pointing devices –Relatively expensive

William H. Bowers – Pointing Devices Touchpads Touchpads –Combine mouse, trackball and digitizing –Relative pointing –Can be used to click or double click Trackpoint Trackpoint –“Eraser” in the middle of the keyboard –Can be difficult to control

William H. Bowers – Pointing Devices Touchscreens Touchscreens –Used in PDA –Uses stylus or finger –Can be used to write on the screen

William H. Bowers – Using the Mouse Near motions Near motions –Close to current cursor position –Fine motor skills –Finger motion Far motions Far motions –Moving across the screen –Requires lifting the hand –Uses gross motor skills

William H. Bowers – Using the Mouse Clicking uses fine motor skills Clicking uses fine motor skills Combining far motion and clicking is awkward Combining far motion and clicking is awkward

William H. Bowers – Using the Mouse

William H. Bowers – Mouse Buttons How many? How many? Left button Left button –Provides major function access Right button Right button –Secondary functions –Context sensitive Middle button Middle button –Optional, usually programmable

William H. Bowers – Pointing and Clicking Two atomic options Two atomic options –Point –Click Compound actions Compound actions –Click –Click and drag –Double click –Chord clicking

William H. Bowers – Up and Down Mouse Events A click uses both events A click uses both events Selection is based on the down event Selection is based on the down event Mouse up on the control means activate Mouse up on the control means activate Mouse up off the control means cancel Mouse up off the control means cancel

William H. Bowers – Cursors Visual representation of mouse position Visual representation of mouse position Shape independent Shape independent Must resolve point to single pixel Must resolve point to single pixel

William H. Bowers – Pliancy and Hinting Object or area reacts to mouse position Object or area reacts to mouse position Must be communicated to user Must be communicated to user –Static visual hinting –Cursor hinting

William H. Bowers – Static Visual Hinting Object changes appearance on mouse over Object changes appearance on mouse over Pushbuttons use visual hinting Pushbuttons use visual hinting Acts as training device Acts as training device Reminds user of object’s pliancy Reminds user of object’s pliancy Usually used with controls Usually used with controls

William H. Bowers – Cursor Hinting Changes cursor appearance Changes cursor appearance Resizing indicator Resizing indicator Frequently used with data Frequently used with data

William H. Bowers – Wait Cursor Hinting Program changes the cursor Program changes the cursor Indicates busyness Indicates busyness Really applies to program, not system Really applies to program, not system Depends on cursor being in the program’s active area Depends on cursor being in the program’s active area

William H. Bowers – Input Focus Only one program can be in contact with the user Only one program can be in contact with the user Usually indicated by title bar Usually indicated by title bar What happens if the user clicks on an inactive program area? What happens if the user clicks on an inactive program area? –Changes focus? –Discard click?

William H. Bowers – Meta-Keys Control Control Alt Alt Shift Shift Actual choice is less important than consistency Actual choice is less important than consistency

William H. Bowers – Questions & Discussion