https://github.com/sigalor/x-physical-screen-size

Getting the physical screen size in millimeters from the X window system using C++
https://github.com/sigalor/x-physical-screen-size

physical-units screen-size x-window-manager

Last synced: 3 months ago
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Getting the physical screen size in millimeters from the X window system using C++

• Host: GitHub
• URL: https://github.com/sigalor/x-physical-screen-size
• Owner: sigalor
• License: mit
• Created: 2018-10-06T20:52:52.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2018-10-06T20:57:35.000Z (over 6 years ago)
• Last Synced: 2025-01-15T07:36:27.475Z (5 months ago)
• Topics: physical-units, screen-size, x-window-manager
• Language: C++
• Size: 8.79 KB
• Stars: 2
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        

# Physical screen size for the X window system

## Introduction

It's not particularly easy to get the physical screen size in millimeters (or centimeters, inches, however you want to convert it) in the X window system. Using the command line, it's possible to use `xrandr | grep ' connected'`, which might produce output like

    eDP-1-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 309mm x 173mm

    HDMI-1-1 disconnected (normal left inverted right x axis y axis)

    DP-1-1 disconnected (normal left inverted right x axis y axis)

    HDMI-1-2 disconnected (normal left inverted right x axis y axis)

for my FullHD laptop with 309mm × 173mm resulting in a diagonal measurement of about 14 inches.

But: this only works on the command line. If you'd like to get this information from a native C++ Linux application, you're in trouble. I ran into the same problem, and of course calling shell commands is evil, thus I created this library.

It is based on GitHub user raboof's [xrandr](https://github.com/raboof/xrandr) project. You can find the license for it [here](/LICENSE.xrandr). I extracted the parts responsible for fetching the screen sizes and put them into C++ classes to make using them easier and more intuitive.

## Requirements

- a Linux OS using the X window system

- g++ supporting at least C++11

- installed development files for X11 and Xrandr

## Usage

The only file for you to include is [`XScreenSize.hpp`](/src/XScreenSize.hpp). It defines the `XScreenSize` namespace. Looking at the short piece of demo code in [`main.cpp`](/src/main.cpp), you can see that it's enough to produce output like this:

    screen 0: 1920px x 1080px

        eDP-1-1 [connected] at 60.0079Hz: 1920x1080+0+0, 309mm x 173mm

        HDMI-1-1 [disconnected]

        DP-1-1 [disconnected]

        HDMI-1-2 [disconnected]

- `XScreenSize::XrandrOutput`  contains the members `name`, `connection`, `has_details`, `refresh`, `x`, `y`, `width`, `height`, `mmWidth` and `mmHeight` which should be self-explanatory when looking at the sample output above; only when `has_details` is true, the members following it are well-defined

- note that the internal code for getting all of this information is kept in the constructor of `XScreenSize::Getter`, so right after creating an instance, you can refer to its outputs

- the constructor will throw an `std::runtime_error` in case of an error, so make sure to catch it if needed

- if you'd like to use a different X display or a different screen, pass them to the constructor in that order

To build and run the demo file, run `make`, followed by `bin/x-physical-screen-size`.