Pointing device

A computer mouse helps you talk to a computer.

You slide it on a desk. This moves a little arrow on your screen. You can click buttons to pick things.

Some people use a flat pad instead. You can use your finger to move the arrow. You can also use a pen on a tablet.

Moving the device makes the arrow move too. This makes it easy to play or work!

A pointing device helps you talk to a computer.

You might use a mouse to move an arrow on your screen. This arrow is also called a cursor. Most mice are indirect devices. This means the mouse is not in the same spot as the cursor.

You move the mouse on a desk, and the cursor moves on the screen. Some devices are direct. A touch screen is a direct device. When you touch the screen, the pointer stays under your finger.

There are many ways to move a pointer. A mouse moves by sliding across a surface. This is called translational movement.

Some devices use a small stick to move the cursor. A joystick is another kind. It can change the speed of the pointer. This is called rate control.

Devices can also be in different states. A device might be tracking. This means it is moving the cursor. It might also be dragging. This happens when you hold a button while moving.

Using a pen on a tablet is a common way to work. These tools make it easy to use computers.

A pointing device is a tool that helps humans talk to computers.

It allows you to send spatial data to the machine. This data includes information about position and movement. Most people use these tools to control a graphical user interface. This is the visual part of the computer you see on the screen. By moving a device, you can control a pointer or cursor. This pointer makes visual changes on your monitor. You can use common gestures like point and click. You can also use drag and drop to move items.

These tools work in different ways. Some are called direct-input devices. A finger on a touch screen is a direct device. This means the pointer stays under your finger. Other tools are indirect-input devices. A computer mouse is an indirect device. You move the mouse on a desk, but the pointer is elsewhere. Some devices use absolute movement. This means a specific spot on the tool always matches a specific spot on the screen. Other tools use relative movement. This means the tool only tracks how far you move it from its start.

Scientists use rules to understand how we use these tools. One important rule is called Fitts's law. This law helps predict how fast a person can move to a target. It says that distance and width matter a lot. A large button that is close to your cursor is easy to hit. A small button that is far away takes more time to reach.

Designers use this law to make computer screens easier to use. They make important buttons larger so they are easier to select. They also know that cursors can get stuck on screen edges. This helps them place things in the best spots.

Different devices have different levels of freedom. A standard mouse has two degrees of freedom. It can move along the x-axis and the y-axis. A device like a Wiimote is much more complex. It has six degrees of freedom. This means it tracks movement on three axes and also tracks rotation.

Some tools use position control. These change the exact location of the pointer. Other tools use rate control. These change the speed and direction of the pointer. A joystick is a good example of rate control.

Pointing devices also exist in different states. Bill Buxton described a model with three common states. The first state is out of range. This means the device is not currently affecting the screen. The second state is tracking. This happens when you move the device without pressing a button. The third state is dragging. This occurs when you hold a button while moving the device.

A graphics tablet with a stylus can use all three states. When you lift the pen, it is out of range. When it touches the tablet, it is tracking. If you press harder, it enters the dragging state.

A pointing device is a human interface device used to input spatial data.

This data includes continuous and multi-dimensional information about position and movement. These devices allow users to interact with graphical user interfaces (GUI) or CAD systems. By using physical gestures, a person can control a computer. The movement of the device is echoed on the screen by a pointer or cursor. Common gestures include pointing, clicking, and the "drag and drop" action. While many devices exist, the term "mouse" is often used as a metaphor for any device that moves a cursor.

Scientists and engineers classify these devices using several specific features. One way to group them is by direct versus indirect input. A direct-input device, like a finger on a touch screen, places the pointer at the same physical position as the input.

An indirect-input device, such as a mouse or joystick, translates movement to the screen from a different location. Another classification is absolute versus relative movement. Absolute-movement devices, like a stylus, provide a consistent mapping between a point in the input space and a point on the screen. Relative-movement devices, like a mouse, map displacement to the cursor's position relative to its starting point.

Pointing devices also differ in how they handle force and movement. An isotonic device is movable and measures its displacement, such as a pen or a human arm. An isometric device is fixed and measures the force acting upon it, such as a trackpoint.

Some devices are elastic, meaning they increase force resistance as they are moved, like a joystick. We can also distinguish between position control and rate control. A position-control device, like a touch screen, directly changes the pointer's position. A rate-control device, like a trackpoint, changes the speed and direction of the pointer's movement.

Complexity can be measured by degrees of freedom (DOF). This term refers to the number of independent ways a device can move or rotate. A standard computer mouse has two degrees of freedom, moving along the x- and y-axes. In contrast, a Wiimote has six degrees of freedom. It tracks movement along the x, y, and z-axes, as well as rotation around those axes.

Other devices, like a 3D mouse, provide even more complex spatial input for specialized tasks.

Bill Buxton introduced a taxonomy to classify devices by their dimensions and sensed properties. This model is rooted in the human motor and sensory systems. It distinguishes between mechanical intermediary devices, like a stylus, and touch-sensitive devices.

Buxton also described a three-state model for how devices interact with systems. The three states are out of range, tracking, and dragging. A mouse is typically in a tracking state when moved without a button press. It enters a dragging state when a button is pressed during movement.

A stylus on a graphics tablet can use all three states: out of range when lifted, tracking when touching, and dragging when extra pressure is applied.

Fitts's law is a predictive model used to understand human-computer interaction. This law predicts the time required to move to a target area. It states that time is a function of the ratio between the distance to the target and the width of the target. In other words, a large button near the cursor is faster to click than a small button far away.

Designers use this law to improve user interfaces. They make interactive elements larger and place important buttons in accessible spots. They also consider that edges and corners of a screen can act as "pins" for the cursor, making them faster to reach.

Understanding these devices involves managing the Control-Display (CD) gain. The CD gain is the proportion between movements in the control space and the display space. For example, a physical mouse might move a different distance than the cursor on the screen. Users can often adjust these settings. High gains make it easier to reach distant targets, but they make selecting specific targets harder. Low gains make selection easier but take more time. Modern operating systems, like macOS and Windows, use mechanisms to adapt this gain to the user's movement velocity.