xzoom-alike written in Nim, simplified & extended to become xm

Installation

A simple nimble install xm should work, but if it does not, you can (in any scratch directory) do (either as root or amended with appropriate sudo/etc.):

git clone https://github.com/c-blake/cligen
git clone https://github.com/c-blake/xm
cd ./xm
nim c -p=../cligen -d:release xm &&
  install -cm755 xm /usr/local/bin &&
  install -cm444 xm.1 /usr/local/share/man/man1

Either way, you probably want to create a $HOME/.config/xm (cfg/xm in the repo is an example). Then all you need to do is run xm&. I've not yet tried building the binary on anything beyond Linux, but I'd expect most BSDs would work well. { X11 compatibility layers, e.g. XQuartz on OSX, require (at least) screen recording perms, but basically if xmag works then so should xm, but it could be some work to get going }.

Applications

I have UHD (aka 2160p aka 4K) displays. I occasionally use old programs like fontforge or xv with tiny UI fonts and no easy way to alter/upscale them. xm to the rescue! Looking at realized font rendering & glyphs is another idea. Temporary zoom for a guest with poorer eyesight or who is further away from the screen is another. More generally, it's not bad for any presentation to guide audience attention. There are web pages where firefox/chrome mess up page layouts quite a bit or literally will not zoom the page element you want. This bypasses layout complexity using dynamic redraws over an unrelated window. (This is the example in the animated GIF of this readme.md where a quick screenshot was unzoomable while the surrounding text was.¹) There are surely more since "I see" has come to broadly mean "I understand", perhaps culminating in "icic" chat-ese { or lately maybe some emoji(s)? }.

This tool is dynamic - it reads the input area over and over again and can keep up with high frame rates updates. (E.g., if in the example above, were chrome scrolling quickly, the zoomed view would also scroll quickly). Even so, it should be pretty fast &| use little CPU. For small, static 128x128 pixel areas, I clocked it at 36000+ FPS on a 2023-era i7-1370P Linux box running vanilla xorg. With CLI flags and keys you can turn on / off the bounding box or chasing the pointer or a re-spaceable/shiftable grid etc. The man page xm.1 more completely documents it.

Sources / History

While a manual re-write in Nim to a degree that copyright makes little sense, it would also be unfair to shoulders I stood upon to dub it "from scratch". Ideas, but not really code came from: https://github.com/mbarakatt/xzoom-follow-mouse ..basically a patch of a Debian-patched xzoom by Itai Nahshon nahshon@best.com with improvements by Markus F.X.J Oberhumer and Tony Mancill.

For those familiar with xzoom, here are some headliner deltas. All UI knobs are also CLI-accessible & there is a new print-config action to recreate them. Bbox drawing & pointer tracking are UI ideas (NOT compile-time options) and Shape-extension based bounding boxes not a stray pixel-prone xor GC. UI motion step sizes are UI-editable as is grid spacing and alignment. XSHM is tested for & ordinary X is used if not available (or forced) { not so bad on GigaBit LANs }. The CLI is cligen which gives ~/.config/xm for almost free. -i overrides -o (more robust than erroring out). Weakly helpful rotation & dynamic window titles complexity is all gone. (I don't even do title bars on my WM, and it seems ok to leave xm& printing stdout). Also added a watch feature to trigger p externally & toggle chase (since you may want to position w/the pointer & then freeze w/sloppy focus WM). I also added WM resize increments to track (mX, mY), better X11 error handling function to detail / filter err codes, preventing mouse clipping/panning areas from going off-screen, minimum window sizes (hard-coded to 6x6 for now) for key repeat oopses, on-screen help & its toggle for UI, input-data-hash-based skips of unchanged frames and wrote a new man page to reflect all the new realities. There are likely many things I've forgotten. At this point, it's only a vaguely similar program in philosophy in another PLang, but one users might enjoy more. Going forward, consult the version control log.

License

Original license is in http://webdiis.unizar.es/pub/unix/X11/xzoom-0.3.tgz . The main file in the mbarakatt github has the other. My license - standard MIT-ISC credit-where-it's-due style (as I do here even though it's all new code).

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1. In this specific case, there was a way to click on the image to give it its own browser tab and then zoom that. That option is not always available and or convenient. ↩︎