How to use the command 'slop' (with examples)

The ‘slop’ command is a powerful tool that allows users to select a portion of their screen and output its geometry. This can be useful for a variety of purposes, such as capturing screenshots, creating screencasts, or implementing custom screen recording solutions. With its various options, ‘slop’ provides flexibility and control over the selection process.

Use case 1: Wait for the user to make a selection and output its geometry to stdout

Code:

slop

Motivation: This use case is the basic usage of the ‘slop’ command. By running ‘slop’ without any arguments, the command waits for the user to make a selection on the screen and then outputs the geometry (position and size) of the selected area to the standard output (stdout). This can be useful when you want to obtain the coordinates and size of a particular section of the screen for further use in a script or application.

Explanation: In this use case, the ‘slop’ command is invoked without any arguments. It simply waits for the user to make a selection on the screen. Once the selection is made, the command outputs the geometry of the selected area in a specific format, which includes the position (x and y coordinates) and size (width and height) of the selected area.

Example output:

503 294 538 215

Use case 2: Double click, rather than click and drag, to draw a selection

Code:

slop -D

Motivation: By default, ‘slop’ allows the user to draw a selection by clicking and dragging the cursor. However, in some cases, it might be more convenient to use a double-click instead. This can be useful when you need to quickly select an area without the need for precision or when your system configuration makes it difficult to click and drag accurately.

Explanation: In this use case, the ‘-D’ option is added to the ‘slop’ command. This option enables the use of double-clicks to draw a selection instead of the default click and drag method. When the user double-clicks on the screen, ‘slop’ captures the geometry of the selected area and outputs it to stdout.

Example output:

623 388 171 92

Use case 3: Highlight the selection rather than outlining it

Code:

slop -l

Motivation: When making a selection using ‘slop’, the default behavior is to outline the selected area with a rectangular box. However, in some cases, it might be more desirable to highlight the selected area instead. Highlighting the selection can make it more visually apparent and easier to identify for certain use cases, such as creating video tutorials or recording screencasts.

Explanation: In this use case, the ‘-l’ option is used with the ‘slop’ command. This option changes the default behavior of ‘slop’ to highlight the selected area instead of outlining it with a rectangular box. When the user makes a selection, the selected area will be visually emphasized with a highlight effect.

Example output:

[no output]

Use case 4: Specify the output format

Code:

slop -f "%g"

Motivation: The default output format of the ‘slop’ command includes the position and size of the selected area. However, in certain situations, you may only be interested in a specific part of the output, such as just the coordinates or just the size. By specifying a custom output format, you can retrieve exactly the information you need.

Explanation: In this use case, the ‘-f’ option is used to specify a custom format for the output of the ‘slop’ command. The format string “%g” is provided as the argument for the ‘-f’ option. This format string represents the entire geometry of the selected area. By using this format string, the output of ‘slop’ will only include the geometry of the selected area, without any additional information.

Example output:

503 294 538 215

Use case 5: Specify the selection rectangle’s color

Code:

slop -c 255,0,0,0.5

Motivation: By default, the selection rectangle created by ‘slop’ is outlined in white. However, in some cases, it might be desirable to customize the appearance of the selection rectangle, such as changing its color. This can be useful for various purposes, such as emphasizing the selection in a specific context or matching the visual style of an application.

Explanation: In this use case, the ‘-c’ option is used to specify the color of the selection rectangle created by ‘slop’. The color is specified in the RGBA format, where each component (red, green, blue, and alpha) is represented by a value between 0 and 255. In the example code, the selection rectangle is set to be red (255,0,0) with an alpha value of 0.5, creating a semi-transparent red rectangle.

Example output:

[no output]

Conclusion:

The ‘slop’ command is a versatile tool for selecting a portion of the screen and obtaining its geometry. By using the various options provided by ‘slop’, users can customize the selection process and output to suit their needs. Whether it’s capturing screenshots, creating screencasts, or implementing custom screen recording solutions, ‘slop’ offers flexibility and control for a variety of use cases.