Could it be used to provide gait analysis for your pet mouse?
ivanjermakov · 1h ago
> TrackWeight utilizes the Open Multi-Touch Support library by Takuto Nakamura to gain private access to all mouse and trackpad events on macOS. This library provides detailed touch data including pressure readings that are normally inaccessible to standard applications.
How can something be available as a library but not as a native interface? Swift does not expose that API?
bri3d · 1h ago
Mac OS has "Private Frameworks" - shared libraries that are used by the system but don't ship with headers by default. It's trivial to produce these headers from the libraries, and then make wrappers for them like OpenMultitouchSupport which is a wrapper for MultitouchSupport.framework.
benoau · 4h ago
There used to be iPhone apps that did something similar -
The single most irritating killed feature from Apple. Redesign half of their UI to rely on 3D Touch to make sense, then get rid of 3D Touch without redesigning the UI. Previewing links, moving the cursor, interacting with items, they’re all “press and hold until haptic feedback” instead of “quickly press hard and get immediate feedback.” Easier to accidentally trigger, slower to trigger on purpose.
05 · 2h ago
Hardware cost+extra weight (need to make the glass thicker to be able to handle extra force and not push on the display). Turns out nobody was really using it because discoverability sucked..
jmb99 · 1h ago
Hardware cost & weight, fine. Glass doesn't need to be thicker than it currently is (I can press on my 13 Pro's screen about twice as hard as was needed for 3D Touch's max depth, and no issues with the screen), and the last time I replaced a battery on a 12, the screen was just as thick as the XS.
>Turns out nobody was really using it because discoverability sucked..
Sure, but then redesign the UI after removing 3D Touch to not be equally undiscoverable but less precise. Even on the latest iOS beta with its full redesign, there's still many, many actions that require a long press that are completely undiscoverable. (For example, if you don't have the Shazam app installed, go find the list of songs Siri has recognized when asked "What's this song?" Don't look up the answer.)
cluckindan · 1h ago
Nobody? Really? It’s definitely the UX feature I miss most on modern iPhones. Long press feels janky in comparison.
gxs · 1h ago
Really? For me it’s the “open image in new tab” option in safari
Have no idea why you’d go out of your way to do that other than placating image sharing services
wanderingstan · 2h ago
My memory was that the weight API was made private because they didn’t want people using iPhones for drug deals.
cryptoz · 1h ago
You can use any phone with a barometer to make a scale. All iPhones since the 6, and all the Pixels, and Samsung flagships have one. You get a zip loc bag, blow some air into it, put your phone in running an app that shows the pressure in a big font (so you can see it through the ziploc). Then you put an object of known weight on it like a quarter (balanced carefully on top of the air-filled ziploc) and note the pressure change on the display. With that, I think the weight / pressure change scales linearly, so you can now weigh anything small that you can balance on the ziploc.
I think this is neat, but only in a Rube Goldberg machine sort of way. The instructions are:
1. Open the scale
2. Rest your finger on the trackpad
3. While mainting finger contact, put your object on the trackpad
4. Try and put as little pressure on the trackpad while still maintaining contact. This is the weight of your object
That is, the pressure sensors only work if it detects capacitance, so you need to be touching the track pad (but not too much!!) while weighing something.
wanderingstan · 2h ago
This is a very clever hack, exactly the sort of thing that belongs on Hacker News.
namdnay · 3h ago
Could a small piece of conductive foam or some cleverly layered tin foil+paper work? So put the object on the shim (which has a known or even negligeable weight)
acct-litter-al · 12m ago
I once put some aluminum duct tape completely over the touch pad of an old laptop to see what would happen. Turns out it induced enough "eddy currents" to make the mouse move around the screen without me touching it--in a way, visualizing the currents! I connected the touchpad put a small strip of the tape to the ground metal of a USB port on the side and it disabled the touch pad.
svnt · 1h ago
No, you need roughly a small human's worth of ground mass for most capacitive touch sensors to register a touch.
83 · 2h ago
Could probably make a small stand with nubbins from touch screen pens as the feet.
jihadjihad · 2h ago
Could you accurately weigh a hot dog?
dtgriscom · 11m ago
No, only cool ones.
ashertrockman · 3h ago
On iPhones at least a hack was to rest a metal spoon on the screen and weigh something in the spoon...
whycome · 3h ago
Can’t you get capacitance with a wet sponge? Like your typical dish cellulose sponge. You could make a small platform?
asimovDev · 3h ago
I remember drawing on my old iPad back in the day by shoving a wet q-tip into a BIC pen and using it as a stylus. I am sure something similar could be rigged here
dotancohen · 3h ago
I've used carrots and cucumbers as a capacitive stylus while wearing gloves.
It's the reason why I love Note and S Ultra phones - the stylus. I'm using it now.
doubled112 · 2h ago
The recipe was on your phone/tablet and there was no way you were taking your gloves off?
dotancohen · 1h ago
Nice. No, I preemptively armed myself with a carrot before taking the dog for a walk in cold weather.
I only had a non-stylus smartphone for a year and a half before whimpering back to the Note series. It's what keeps me in the Samsung sphere of influence.
throwanem · 1h ago
Ever try putting gloves back on when your hands and the gloves are both wet? This is why I print recipes on the laser, and just take the paper version downstairs.
Y_Y · 1h ago
I use this to avoid touching the stupid self-checkout machines when buying groceries
linux2647 · 3h ago
Sometimes you can get capacitance to be detected if you hover your finger just millimeters over the trackpad
incanus77 · 3h ago
This reminds me of how, twenty years ago, I used the PowerBook’s hard drive vibration sensor to rig up a seismograph to measure construction noise:
I used an iPhone as an air pressure recorder. There's an app for that; many actually. Anyways, the trunk gate on my car wasn't sealing and when it went over pavement joints on the highway it would slightly open and then close in quick succession which was nauseating. I showed the data to Tesla service and they (grumbled and) readjusted the trunk gate. The problem disappeared.
stockresearcher · 3h ago
I heard that IBM decided to move out of this building [1] because vibration due to the construction of the tower across the street kept destroying hard drives in their computing center.
Gosh I hope there are some lucky 10K seeing this today.
bitwize · 3h ago
Reminds me of the people who used their ThinkPad's vibration sensor to detect smacks on the machine, and rigged their X window manager to switch virtual desktops when smacked from the appropriate side, panning right when smacked on the left, and left when smacked on the right.
1bpp · 3h ago
this update breaks my case smacking workflow, please revert
incanus77 · 3h ago
Oh, I vaguely remember someone hacking that for some sort of windowing back then on OS X!
Weed can be sticky depending on the strain/harvest/cure time
jahantech · 1h ago
This is exactly why normal people call us geeks "weird". Keep bringing on the cool stuff!
mig39 · 2h ago
Very cool, Krish! Hi from Fort McMurray! I'm going to use this project as an example for a Computer Science class.
pmxi · 4h ago
This is clever! and potentially useful too.
Have you done any testing to determine how precise and accurate this is? I suspect their must be a lot of variance between laptops, since this isn’t an intended use case.
cluckindan · 1h ago
I would assume Apple hardware comes precalibrated. Homogeneity is everything for their product lines, down to individual calibration of screens and audio hardware. It would be weird to get a new laptop and have its trackpad feel different.
mschuster91 · 3h ago
> I suspect their must be a lot of variance between laptops, since this isn’t an intended use case.
Yeah and so it is for ordinary strain gauges aka load cells. You can either use a 2 point calibration (aka no load followed by known load) or if you want more precision a 3 point calibration.
Apparantely on safari there's touch strength so this should be possible to make for the web too, cool
ashertrockman · 3h ago
Somebody could use this as a starting point. http://touchscale.co/ You'd have to collect new data on touch strength vs. weight to get the regression parameters.
(If you do this, let me know and I can add it to the site above, and then we can both delight in the surprisingly large amount of unmonetizable traffic it gets.)
fnord77 · 36m ago
What's the weight range it can handle? no mention of it and I don't want to dig through code
qwertytyyuu · 4h ago
Ah I remember being able to do this with the iPhone 6s
thrownawaysz · 3h ago
Can someone compile a binary? Don't want to download Xcode just for that...
tln · 4h ago
No download link?
ChrisMarshallNY · 4h ago
I think it's a DIY project.
addandsubtract · 2h ago
DIY projects can't be downloaded?
ChrisMarshallNY · 1h ago
By "downloaded," I expect that you mean "Built, tested, and deployed." It's not an App Store app. It's basically a technology demo. Get Xcode, and build it and run it.
theyknowitsxmas · 3h ago
Apple would've made an app a long time ago but would get sued after someone put a tire on it.
mrexroad · 2h ago
I can already picture the Reddit post of an inverted aeropress brew fail while using trackpad as scale.
DonHopkins · 3h ago
Just what I need to roll the quantitative doobie.
ynniv · 1h ago
Finally some hacker news
ChrisMarshallNY · 4h ago
Very cool, but I'd still probably just buy a cheap digital scale.
raldi · 2h ago
The best digital scale is the one you have with you ;)
How can something be available as a library but not as a native interface? Swift does not expose that API?
https://www.theverge.com/2015/10/28/9625340/iphone-6s-gravit...
>Turns out nobody was really using it because discoverability sucked..
Sure, but then redesign the UI after removing 3D Touch to not be equally undiscoverable but less precise. Even on the latest iOS beta with its full redesign, there's still many, many actions that require a long press that are completely undiscoverable. (For example, if you don't have the Shazam app installed, go find the list of songs Siri has recognized when asked "What's this song?" Don't look up the answer.)
Have no idea why you’d go out of your way to do that other than placating image sharing services
1. Open the scale
2. Rest your finger on the trackpad
3. While mainting finger contact, put your object on the trackpad
4. Try and put as little pressure on the trackpad while still maintaining contact. This is the weight of your object
That is, the pressure sensors only work if it detects capacitance, so you need to be touching the track pad (but not too much!!) while weighing something.
It's the reason why I love Note and S Ultra phones - the stylus. I'm using it now.
I only had a non-stylus smartphone for a year and a half before whimpering back to the Note series. It's what keeps me in the Samsung sphere of influence.
https://allthegooddomainsweretaken.justinmiller.io/2007/04/0...
[1] https://en.wikipedia.org/wiki/330_North_Wabash
Have you done any testing to determine how precise and accurate this is? I suspect their must be a lot of variance between laptops, since this isn’t an intended use case.
Yeah and so it is for ordinary strain gauges aka load cells. You can either use a 2 point calibration (aka no load followed by known load) or if you want more precision a 3 point calibration.
[1] https://en.wikipedia.org/wiki/Load_cell
(If you do this, let me know and I can add it to the site above, and then we can both delight in the surprisingly large amount of unmonetizable traffic it gets.)
[0] https://en.m.wikipedia.org/wiki/Macintosh_Portable