Chapter 7 - Interactive Input Methods and GUI
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Transcript of Chapter 7 - Interactive Input Methods and GUI
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Interactive Input Methods & GraphicalUser Input
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Explain the 6 logical classifications of input
devices
Differentiate the 7 interactive PictureConstruction Techniques
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Types of input data: coordinate positions,attribute values, character-string
specifications, geometric-transformationvalues, viewing conditions, illuminationparameters,
Input procedures require interaction withdisplay window managers & hardwaredevices.
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Logical input device refers to input devices classifiedaccording to data type.
LOCATOR specifies one coordinate position STROKE specifies a set of coordinate positions STRING specifies text input
VALUATOR specifies a scalar value
CHOICE specifies menu selection PICK specifies picture component selection
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Devices like mouse, joystick,trackball, are used for
screen-cursor position
General purpose keyboards may have 4 or 8 cursor-
control keys
Light pen used for interactive input of coordinateposition
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graphic tablet & continuous movement of mouse,
trackball, joystick are used to input a sequence of
coordinate positions
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primary physical device for string input is keyboard
other devices could generate character patterns
that is recognized using stored dictionary of
predefined patterns for specific application
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valuator input is used to set scalar values forgeometric transformations, viewing parameters& illumination parameters
panel of controls dials typically provides valuatorinput
display graphical representation of slider,buttons, rotating scales, menus
Joystick, trackball & keyboard could be adaptedfor valuator input by movement of the devicerelative to a scalar range
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menus are used to select processing options,
parameter values & object shapes
touch panel, keyboard & voice entry are also
common choice devices
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used to select part of a scene that is to be
transformed or edited
using mouse, joystick or keyboard, picking the
position of screen cursor to identify pixel
coordinates depending on type of object & complexity of scene,
several levels of search required to identify pickobject
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variety of interactive methods are incorporated into
graphic package as aids in construction of pictures:
1) Basic Positioning Methods
interactively choose a coordinate position with a pointingdevice that records the screen location
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2) Dragging
select an object & drag it to a new location, thus objectis then displayed in the new location.
3) Constraints
procedure for altering input coordinate values toobtain a particular orientation or alignment of an
object lines are constrained to have a particular slant
Input coordinates are constrained to lie alongpredefined paths
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4) Grids
rectangular grid displayed on screen area used to
round input coordinates to nearest grid intersection grids facilitate object construction when need to joins
new line to an existing line endpoint.
6) Rubber-Band Methods Line segments & other basic shapes constructed &
positioned using rubber-band methods to beinteractively stretched or contracted
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6) Gravity Field
to connect lines at positions between endpoints (thatare not in grid intersections) graphic packages includeprocedure to convert any input position near a line
segment into a position on the line using gravity fieldarea around the line
any selected position within the gravity field of a line ismoved to the nearest position on the line
7) Interactive Painting & Drawing Methods freehand drawing uses curves generated by following
the path of a stylus on a graphics tablet or path of thescreen cursor on a video monitor
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Applications include GUIs composed of displaywindows, icons, menus, etc to aid user inapplying the software to a particular problem
consideration for user interface area: User Dialogue
Windows & Icons
Accommodating Multiple Skills Levels
Consistency Minimizing Memorizing
Backup & Error Handling
Feedback