Point and Draw Devices:
A variety of devices are available that move the graphics cursor to point and draw, each with its advantages. Some point and draw devices are as follow: 1. Mouse:
A mouse is an input device that actually looks a little bit like a mouse. The mouse, which has a ball on its underside, is rolled on a flat surface, usually desk on which the computer sits. Usually a mouse has two button and right button, which can perform the following functions: The rolling movement causes a corresponding movement on the screen. Moving the allows you to reposition the pointer, or cursor, an indicator on the screen that shows where the next interaction with the computer take place. The cursor can also be moved by pressing various keyboard keys. You can communicate commands to the computer by pressing a button on top of the mouse. In particular, a mouse button is often used to click on an icon, a command to the computer so clicking the icon invokes the commands.
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Term |
Definition |
Action |
| Point |
Move the pointer to the desire spot on the screen, such over a particular world or object. |
Move around the screen |
| click |
Press and quickly release the left mouse button. |
Select an icon, item, or object on the screen. |
| Double click |
Press and released the left button twice, as quickly as possible. |
To run or Execute a program |
| Drag |
Press and hold the left button while moving the pointer to an other location. |
Move the selected item with the pointer. |
| Drop |
Release the mouse button after dragging. |
The selected item is moved from one place to another. |
| Right click |
Press and quickly release the right mouse button. |
Bring the context popup menu relative to selected item. |
The relatively inexpensive mouse remain popular, but its disadvantages, namely its of precisions and desk space requirement, are encouraging users to seek alternative.
2. Trackball:
A variation on the mouse is the trackball. You may have used trackball to play a video game. The trackball is like an upside-down mouse, you roll the ball directly with your hand. The popularity of the trackball blast with the advent of laptop computers, when traveling users found themselves without a flat surface on which to role the traditional mouse. Trackballs are often built in on portable computers, but they can also be used as separate input devices with standard desktop computers. Many users prefer trackball because it requires less space when in operation.
3.
Joystick:
A joystick is another cursor controlling device. Joystick look like a car's stick shift and are often used for computer games and for screen drawing and design tasks. The joysticks move the cursor in the direction the stick is pushed.
4. Sensitive Screen Input:
The two common forms of sensitive screens are light sensitive screen and touch sensitive screen.
1. Light Sensitive screen:
A pen is used to input data via a light sensitive screen. The light pen is similar in shape to a ball point pen. When the pen is moved across the screen, its positioned is sensed because of the light it releases. It can be used to draw images on the screen. The images can then be printed, if desired. The light pen can also be used to make selection from a given list of menu items. The selection is made simply by pointing the pen at the selection required and pressing the button on the pen.
2. Touch Sensitive Screen:
A touch sensitive screen uses the human hand as the input medium. The effect is similar to that of light pen on a light sensitive screen, except that the pointing device is now finger. A common use is the selection of items or options from a given list. When a finger touches the screen, blocks out the light emitted from that portion of the screen. The screen then determines which part of the screen is being touched, an00d therefore which selection is required. Touch screens are useful for such applications as factory work; a laborer, who may be wearing gloves, can easily point to a selection on the screen instead of trying to press keys.
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Advantages |
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Disadvantages |
- Relatively Inexpensive
- Very little finger movement needed to reach buttons
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Mouse |
- When gripped too tightly can causes muscle strain
- uses more desk space then other pointing devices
- Must be cleaned regularly
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- Uses less desk space then mouse
- Requires less arm and hand movement then mouse
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Trackball |
- Wrist is bent during use
- More finger movement needed to reach button then with other pointing devices
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- Small footprint
- Least prone to dust
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Touchpad |
- Places more stress on index finger then other pointing devices do
- Small active area makes precise cursor control difficult.
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5. Graphics Tablet (Digitizer Tablet, Note pads):
This is used for entering drawings directly into the computer. A graphics tablet consists of a pad or tablet and a printing device, which is similar to a ballpoint pen. Paper is called on the pad and the use can trace lines or draw pictures using the "pen". The tablet senses the pressure on it when pen is used. It converts this "pressure" into x-y coordinates which describe what is being drawn. This data is then relayed to the computer, which can display the drawings on the screen or have them printed. This form of input is useful in engineering and art design; it is very easy for the uses to try out different designs.
Pen based technology are advanced handwriting recognition technologies they are also called notepad computers. Using a special stylus, users can print, draw or calculate directly on the screen. The CPU translate each pen stroke into digitalized characters.
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