Chapter 7 - Interactive Input Methods and GUI

7/27/2019 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

Chapter 7 - Interactive Input Methods and GUI

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