Mechanism of clipboard of xwindow

Introduction

X Window System, commonly known as X11 or simply X, is a windowing system for bitmap displays. It was initially designed in mid-1980s to run on Unix-like operating systems. X Window System has a fundamental concept of a clipboard, which is used to transfer data between applications. In this article, we will explore mechanism of clipboard in X Window System.

What is a Clipboard?

A clipboard is a temporary storage area in memory that allows you to copy and paste text, images, or other data between applications. X Window System uses a clipboard to transfer data between applications. It allows you to copy data from one application, store it in clipboard, and then paste it into another application.

Types of Clipboard in X Window System

In X Window System, there are two types of clipboard: PRIMARY clipboard and SECONDARY clipboard.

PRIMARY Clipboard

The PRIMARY clipboard is used for selecting text in X11. When you select text, selected text is automatically copied to PRIMARY clipboard. You can then paste text into another application by clicking middle mouse button. For example, if you select text in a web browser, you can paste it into a text editor by clicking middle mouse button in text editor.

SECONDARY Clipboard

The SECONDARY clipboard is used for more general copying and pasting. You can use it to copy and paste text, images, and other data between applications. To copy data to SECONDARY clipboard, you need to highlight data and then use copy command in application’s menu. To paste data, you need to use paste command in application’s menu.

How does Clipboard work in X Window System?

The clipboard mechanism in X Window System works through use of two selection buffers: PRIMARY selection and SECONDARY selection. These two selection buffers are implemented by X server and are shared between all applications running on system.

When you select text in an X application, application places selected text in PRIMARY selection buffer. When you want to paste selected text, you can simply click middle mouse button in destination application, and X server will retrieve text from PRIMARY selection buffer and paste it into destination application.

Similarly, when you copy text from an application, application places copied text in SECONDARY selection buffer. When you want to paste copied text, you can use paste command in destination application, and X server will retrieve text from SECONDARY selection buffer and paste it into destination application.

Example of Clipboard Mechanism in X Window System

To understand clipboard mechanism in X Window System, let’s take an example. Suppose you have a web browser and a text editor open on your desktop. You want to copy some text from web browser and paste it into text editor.

To copy text, you first need to select text in web browser by dragging mouse over it. selected text will be automatically copied to PRIMARY selection buffer.

To paste text into text editor, you need to click middle mouse button in text editor. X server will retrieve text from PRIMARY selection buffer and paste it into text editor.

If you want to copy an image from web browser and paste it into text editor, you need to first highlight image in web browser and then use copy command in web browser’s menu to copy image to SECONDARY selection buffer.

To paste image into text editor, you need to use paste command in text editor’s menu. X server will retrieve image from SECONDARY selection buffer and paste it into text editor.

One of main advantages of clipboard mechanism in X Window System is that it is shared between all applications running on system. This means that you can copy data from one application and paste it into another without having to save data to a file first. This can save a lot of time and make it easier to work with multiple applications at same time.

Another advantage of clipboard mechanism in X Window System is that it is very easy to use. There are no complicated commands or settings to worry about. To copy data to clipboard, you simply select data and use copy command in application’s menu. To paste data, you use paste command in destination application’s menu. This makes it very intuitive and user-friendly.

The clipboard mechanism in X Window System can also be customized to suit your needs. For example, you can use a clipboard manager to store multiple items in clipboard and retrieve them later. This can be very useful if you need to copy and paste multiple items between applications. There are many clipboard managers available for X11, and they can be easily installed and configured.

In addition to text and images, clipboard mechanism in X Window System can also be used to transfer other types of data, such as URLs, file paths, and even commands. This can be very useful for automating tasks or for quickly accessing frequently used data.

However, there are also some limitations to clipboard mechanism in X Window System. For example, clipboard can only store one item at a time, which means that you need to copy and paste each item separately. This can be time-consuming if you need to transfer multiple items between applications. Also, clipboard mechanism in X11 is not secure and can be accessed by other applications. This means that sensitive data should not be stored in clipboard.

Conclusion

The clipboard mechanism in X Window System is a useful feature that allows users to transfer data between applications easily. X server implements two selection buffers: PRIMARY selection and SECONDARY selection. PRIMARY selection is used for selecting text in X11, while SECONDARY selection is used for general copying and pasting.