Computing notes 2022 part one

This document contains only my personal opinions and calls of judgement, and where any comment is made as to the quality of anybody's work, the comment is an opinion, in my judgement.

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2022 January

20220107 Fri: Trends in computing in the past 20 years

Twenty years ago the first dot.com crash ended, and many things have changed since. There have been some major trends:

• Most client-facing computers today are battery-powered and have a built-in display, which makes power consumption even more important than speed and capacity as to performance.
• The old question as to whether cellphones that are also PDAs or PDAs that are also cellphones has been settled: PDAs won, and cellphone functionality is currently a small and often little used part of misnamed PDAs like the iPhone and similar products.
• The tendency of both physical and logical computer infrastructures to become concentrated because of network effects has become even stronger, with most networks and most computer infrastructures owned by a few giant corporations that are both strongly allied with and strongly influenced by governments.
• Powerful computers have become affordable even to poor countries and to their inhabitants, much widening the opportunities to offshore programming and other IT work from richer to poorer countries.

Also some minor trends:

• High-DPI computer screens are common making font and graphics anti-aliasing less necessary.
• Because of the wide diffusion of fast ADSL and firbre connections to homes, movie streaming and video conferencing have become routine.
• because of the increase in speed of even embedded CPUs, video and audio compression and thus their streaming has become pervasive, and so has communication and storage encryption.

2022 February

2022 March

20220305 Sun: Changing DPI in X-Windows, 2022 edition

Over time there have been many different ways to change DPI in X-Windows, whether it means to change the reported DPI of a screen, or the rendering DPI of a GUI library. Originally there were just:

• The reported DPI of a screen, a function of the screen's reported physical size and pixel size, but there was no clear way to change it other than switching the screen configuration to a different pixel size.
• The explicit rendering DPI for a font's XLFD (1, 2).

But other ways have been added: the RANDR extension added very clumsily (as I think is often done by Keith Packard) a way to change the display's reported DPI, and various ways to set the rendering DPI for various GUI libraries.

Therefore I have written a simple script that I call xdpinow that attempts to set the reported and rendering DPIs for the most common relatively new ways of setting it:

• Server-side RANDR
• Server-side X-resource for the FreeType/FontConfig library.
• Client-side settings for the XFCE4/Gtk3 framework.
• Client-side settings for the GNOME/Gtk3 framework.
• Client-side settings for the KDE5/QT5 framework.

These usually work relatively well, but with some limitations:

• As a rule native X11 applications do not dynamically change rendering when the DPI changes and have to be restarted.
• The EMACS GUI windows do not dynamically change rendering, but simply cloning them with C-x 5 2 works.
• While most GUI framework window do change rendering dynamically when the DPI setting is changed, they do not resize the relevant windows.

Note: as to the latter point their code is arguably poorly designed, because changes font or icon logical size should not result in changes in window size, but changes in DPI should result in proportional changes in physical font or icon size and physical window size: a change in logical font or icon size is a decision to alter the appearance of windows (with smaller or larger fonts or icons) but a change in DPI is decision to adapt to a different physical setting (for example switching from a 1920x1080 24in display to 3840x2160 27in one) while maintaining the same appearance.