[Q] App that mirrors the screen to use it as a HUD

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Phexi

Member
Sep 17, 2007
15
7
Hi there. I need an app that mirrors the screen of my android phone to use it as a HUD in my car. I've already found an app that shows the current speed mirrored, but i would like to have it for other apps, too. So that i can use apps like Google Maps Navigation with my front window.

I googled a lot, but i sadly didn't find anything...
 

owenfernaldi

Member
Jan 18, 2018
17
1
I have been working on an optics/mount solution that will achieve this. I attach a photo that I took at night:



For this photo I was using Google Maps, but this would work with any app such as Waze, Uber, Lyft, Android Auto etc. A few other things that might not be evident:

1. The virtual image (reflection) appears to be floating 1m or more in front of the windshield. In the photo the virtual image is focused closer to the white wall. With the current mode of reflecting the phone directly on the windshield the reflection is at the windshield, so the driver's has to refocus close.
2. The double reflection is "virtually" eliminated. It is never actually eliminated but the second reflection becomes more aligned with the first reflection. This will depend on the car, as each car has slightly different windshield.
3. No special wedge windshield or reflective film is required.

So this solution does more than what a software fix would do. Also during the day the "gadget" could be used as a regular mount.

I can't give away the secret but I wanted to gauge if there is any interest in such a gadget.
Hey really interested int this solution , I did think the same solution too , I'm no good with these but is it possibly you're using a magnifying glass ?? Or is there some kind of "reverse glass film"
 
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slku

New member
Mar 30, 2020
1
2
I know im late. But thanks to this thread. After reading all these posts, i was convinced that there are no existing mods, or any other ready made solution available.
So thought of doing it myself. Changed the source and built a custom ROM on top of lineageOS. Added a new option (HUD Mode :cool:)
Here is a working video of my HUD display. cheers. :D
youtube.com /watch?v=kXynuJO0584
Since im a new member, im not allowed to post links. Use the above without space.

You are not late. But can you teach us how to do the same? Maybe without the checker box. It will be enough if you explain what we should change in settings/ files. Please, show us how you do that, so we can repeat your result.
 

nikosbocho

Member
Jan 3, 2013
21
2
I know im late. But thanks to this thread. After reading all these posts, i was convinced that there are no existing mods, or any other ready made solution available.
So thought of doing it myself. Changed the source and built a custom ROM on top of lineageOS. Added a new option (HUD Mode :cool:)
Here is a working video of my HUD display. cheers. :D
youtube.com /watch?v=kXynuJO0584
Since im a new member, im not allowed to post links. Use the above without space.

Well done, this is exactly what people where looking for when this thread was started 10 years ago!!! Can you please share how you can implement the HUD mode on lineageOS?
 

wen2ri4

New member
Aug 18, 2016
2
0
Can you share how to do it in detail?

I know im late. But thanks to this thread. After reading all these posts, i was convinced that there are no existing mods, or any other ready made solution available.
So thought of doing it myself. Changed the source and built a custom ROM on top of lineageOS. Added a new option (HUD Mode :cool:)
Here is a working video of my HUD display. cheers. :D
youtube.com /watch?v=kXynuJO0584
Since im a new member, im not allowed to post links. Use the above without space.

Thank you so much for sharing this. I can't imgine many people has the same ideal with me, flip mirror the phone screen. But I do this for other purpose, I haven't had a car yet. hahaha
 

nikosbocho

Member
Jan 3, 2013
21
2
I am not a programmer but I think there might be a way to do the HUD without rooting or hacking ones phone. Split the screen on Android in landscape mode, on the left part of the screen load Google Maps or Waze, on the right part of the screen load the HUD mirroring app. The HUD mirroring app takes a screenshot of the phone every 0.1, 0.2 or 0.5 secs, flips the image vertically, crops out the right half and then shows the image in the app on the right half. When placing the phone on the dashboard the left half is covered with a piece of black cloth or paper card. Only the right half is reflected. There will be a small lag, but if it can be refreshed every 0.1secs then it will probably not be a real problem when driving. If it can be done continuously then the lag can be eliminated.

The disadvantage is that the image will be a little smaller and have more square proportions. However the advantage is that this could work with any app that is displayed on the left side of the split screen, Waze, Android Auto etc. Also, since the image is smaller a smaller reflective film can be used on the windshield to make this visible during the day.

Is this possible with an app? If so, is it easy to write such an app?
 
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ciobi

Member
Sep 8, 2012
17
5
I've been thinking about doing this for more than 10 years now, and last week I finally spent a few days to work on it and ended up with https://play.google.com/store/apps/details?id=tech.ciobi.mirrorscreen

It's in beta, and all sorts of things could be improved (like battery life or color processing), but let's see first if there's still any interest in this.

Here's an actual picture of my windshield, with the HUD mirror and the phone running Google Maps:

Featured.02.jpg
 
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ashish_jha

Member
Feb 6, 2019
18
1
Hi guys, any updates on this?

I've been thinking about doing this for more than 10 years now, and last week I finally spent a few days to work on it and ended up with https://play.google.com/store/apps/details?id=tech.ciobi.mirrorscreen

It's in beta, and all sorts of things could be improved (like battery life or color processing), but let's see first if there's still any interest in this.

Here's an actual picture of my windshield, with the HUD mirror and the phone running Google Maps:

View attachment 5327663
Good app but need to adjust too much. Need to automate the adjustments to make it user friendly.
 
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ciobi

Member
Sep 8, 2012
17
5
Good app but need to adjust too much. Need to automate the adjustments to make it user friendly.
I totally agree that the setup is a bit of a pain, and I have an idea on how to improve things, but it's also not particularly nice, and might not work all the time. (It involves creating a new, simple app to run it in the other half, to calibrate the main app. Then I could see exactly which part of the screen is taken by Half HUD and which part is used by the app you want to project.)

Also, I don't expect improving this would dramatically change the adoption, which is at a grand total of 21 users after it peaked at 23 a few days ago. My question is: After taking the time to set it up, is this something people actually want to use? How many?

Anyway, when I find some time I guess I could try the approach I described above, to see how well it works. Or, does anybody have a better idea?
 
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ciobi

Member
Sep 8, 2012
17
5
Anyway, when I find some time I guess I could try the approach I described above, to see how well it works. Or, does anybody have a better idea?
I think a better idea would be a full screen mirror flip with a small floating widget on top to bring to normal as and when needed.

Sure, but I don't think it is possible to do this in a reasonable way. I'm pretty sure you'd need to root your phone, and interfere with the screen drivers to make them flip the image and the touch input. These would quite likely involve significant effort and be model specific, at least to some extent.
 

ashish_jha

Member
Feb 6, 2019
18
1
Anyway, when I find some time I guess I could try the approach I described above, to see how well it works. Or, does anybody have a better idea?


Sure, but I don't think it is possible to do this in a reasonable way. I'm pretty sure you'd need to root your phone, and interfere with the screen drivers to make them flip the image and the touch input. These would quite likely involve significant effort and be model specific, at least to some extenfor
The first thing I do after unboxing a phone is to root it. There is no life without root ! 😀
 

mladen074

New member
Nov 27, 2018
3
0
Google will never implement this feature willingly, considering it directly competes with their Android Auto, which they want to push as a default navigation app for everyone. They like collecting private information, and driving habits are so attractive to Google, they would be idiots to implement this feature and ruin the advantage their app has over other apps. It's not gonna happen, at least not up until they decide they have the absolute dominance with their Android Auto app, and don't feel other apps will be able to endanger that dominance anymore.

That being said, the only thing we can do is to modify the source code and change the display driver to invert the coordinates. It's a fairly easy task, but for someone who knows how to write such code. Here on xda I've seen a lot of smart people, capable of doing such stuff, so it puzzles me noone has took the opportunity to write it. I can only imagine there is something more to this feature than meets the eye. Until then, 2 mirrors in the car, under the windshield, can do the job.
 

Parmeet.sethi

New member
Dec 28, 2018
1
0
I totally agree that the setup is a bit of a pain, and I have an idea on how to improve things, but it's also not particularly nice, and might not work all the time. (It involves creating a new, simple app to run it in the other half, to calibrate the main app. Then I could see exactly which part of the screen is taken by Half HUD and which part is used by the app you want to project.)

Also, I don't expect improving this would dramatically change the adoption, which is at a grand total of 21 users after it peaked at 23 a few days ago. My question is: After taking the time to set it up, is this something people actually want to use? How many?

Anyway, when I find some time I guess I could try the approach I described above, to see how well it works. Or, does anybody have a better idea?

This is great! Thank you for developing this application.

I guess a part of the issue with adoption is that folks looking for something like this might not know where to look or how to find it.

Case in point, I stumbled on this thread after not finding anything on the Play Store or YouTube. Maybe a bit of SEO and backlinks from YouTube could help get the word out.

Consider this video that appears on top when searching for "Google Maps HUD". If the comments (and like counts) indicate anything, at least a hundred people may have entered that exact query in search. Note that the video has has around 50k views, which is much higher than the channel's average.

A similar video covering this app would certainly encourage adoption. I'd be happy to help out and take this up as a holiday project.
 
Anyway, when I find some time I guess I could try the approach I described above, to see how well it works. Or, does anybody have a better idea?


Sure, but I don't think it is possible to do this in a reasonable way. I'm pretty sure you'd need to root your phone, and interfere with the screen drivers to make them flip the image and the touch input. These would quite likely involve significant effort and be model specific, at least to some extent.
If I may be so bold as to make a suggestion, how about this:

First get a phone with support for USB Type-C (DisplayPort Alt mode) transmission (like a Galaxy, Pixel, certain Mac and IPads and windows devices; if you don't already have one).

Next get a USB Type C to HDMI Hi-Res Cable with USB Power Supply Charger Cable.

Then, get a small teleprompter monitor that supports both vertical and horizontal image flip. Most are designed for high ambient light level use and have a adjustments for brightness and contrast (and everything else).

You will also want some type of light gel or film to help reflect the image.

If you already have a device with USB C DisplayPort Alt mode, then you can get out at anywhere from $200-350 total. Compare that with the cost of your time to develop the app and how much time you want to spend in development and testing.

Of course you can still connect your device to the car audio via bluetooth. Then you can use your device as normal without any hassle. Just a thought...
 
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You may also wish to checkout Open Broadcaster Software. It is a free and open source software program for live streaming and video recording. Features of the software include device/source capture, recording, encoding and broadcasting.

Short version is that you can use it on Windows, Mac, and Linux devices to flip an image via software, so any HDMI monitor will work for your HUD. A small tablet and a bit of velcro might be nice for this project... ;)

Good luck!
 
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PhotonIce

Senior Member
Jan 23, 2022
387
96
Redmi 9
I don't know why a thread from 2012 has been bumped, niether have I read any messages after the first page, but my simple question to everyone here is:

Why didnt anyone use an ACTUAL mirror to mirror their phone screen?

Invert the phone screen once with a real mirror so that its backwards, then when it reflects onto the windshield it'll invert itself again; simple as heck!
 
I don't know why a thread from 2012 has been bumped, niether have I read any messages after the first page, but my simple question to everyone here is:

Why didnt anyone use an ACTUAL mirror to mirror their phone screen?

Invert the phone screen once with a real mirror so that its backwards, then when it reflects onto the windshield it'll invert itself again; simple as heck!
Just off the top of my head, brightness will diminish by distance squared, so it would get very dim very quickly. Not so good in even dim lighting much less in daylight. Second, in most cars there isn't a lot of room to squeeze in your device, a mirror and room to reflect off the windshield. Have you drawn this and diagramed how this idea would work? Finally, I believe the image would be flipped vertically, not horizontally. So, maybe not so simple.
 

PhotonIce

Senior Member
Jan 23, 2022
387
96
Redmi 9
Just off the top of my head, brightness will diminish by distance squared, so it would get very dim very quickly. Not so good in even dim lighting much less in daylight. Second, in most cars there isn't a lot of room to squeeze in your device, a mirror and room to reflect off the windshield. Have you drawn this and diagramed how this idea would work? Finally, I believe the image would be flipped vertically, not horizontally. So, maybe not so simple.
1. Of course it'll be dim, but to be fair, your phone screen isnt too bright to begin with, so unless your using a modded lcd panel, its gonna be dim either way.
2. I've done this myself using a mirror (phone reflecting vertically on the right side of my windshield, it takes up a little space, but you dont use the space of the right of your speedo anyways..)
3. Hold your phone infront of a mirror, it will reflect it horizontally. then upon reflecting again off of the windshield, it will flip horizontally again and become normal. You can even try this at home by taking two hand mirrors, and reflecting your phone onto one mirror, while reflecting the image from the 1st mirror onto the second mirror, then look at the image on the second mirror, it is normal again.
It would only be flipped vertically if your were using a lens, which we aren't using here.
 

PhotonIce

Senior Member
Jan 23, 2022
387
96
Redmi 9
Either way, because its bright during the day, you'd need a hud glass/mirror panel, which makes the whole project quite janky (i didnt use one as I only used my HUD at night). My suggestion for the future of this project is to use bendable oled panels. We're in the future now, all we need is a hdmi bendable oled, which can be stuck onto the windshield. It'd be bright, and would look much better than the janky setups which have all been suggested here. I'm sure these panels will be available to the public soon (they might already be on sites like aliexpress, not sure though). There are already oled panels which can be used as one way mirrors, its only a matter of time before both technologies combine and we'll have the perfect hud.
 

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  • 5
    Hi there. I need an app that mirrors the screen of my android phone to use it as a HUD in my car. I've already found an app that shows the current speed mirrored, but i would like to have it for other apps, too. So that i can use apps like Google Maps Navigation with my front window.

    I googled a lot, but i sadly didn't find anything...
    5
    i have been working with custom apps development for work, and I think (I HAVE VERY LIMITED KNOWLEDGE DONT QUOTE ME AS AN EXPERT OR CODER) you are right, this should be a one-button widget/one-option setting under 'settings' of a ROM, not an APP, that simply reverses display on the Y - axis (hell, option for x-axis too, don't know if vertical or landscape display wanted/needed, especially with tablets), reverses control functions, and control locations. (ESPECIALLY ICS controls)

    My understanding of coding for this, you can't have an app that would effect the output of another app, the only 'system wide' apps, like 'Screen Filter' for example, can control a system-wide "overlay" but not change the actual output of display options.

    I am only posting this because we had the same issue come up with something hella specific we were working on, an education in-house app, needed a left-hand and right-hand version, and at first were thinking some kind of library call to either mirror or flip just a specific layer of display within the app, but it turned out it was much much much much easier to just recode a 2nd location for the controls and set it under options within the app to choose which one to use, the 'mirroring' i think proved to be impossible without a custom rom, which most of us would've been ok with but can't add new people or expect to have enterprise control of the app if it was a rom change. See, if you mirror the display, the touch controls work opposite their button location. If you mirror the control buttons as well, the functionality of Left Right becomes reversed too, essentially breaking the app. (think of the old helicopter game controls, only left right instead of up down)

    but, not only for HUD, but for left-hand/right hand, disability access, and other various uses, a ROM-wide setting to control reversing the display of both controls layer and app-display layer would be most excellent for custom roms and eventually the Android core code as well (Here is the problem everyone in this thread is ignoring, if the display output is simply reversed, your touch controls, especially for ICS system buttons, functionality would be broken, controls in the dead center would work backwards and controls on the left or right side of axis would still work on the opposite side of where the display shows the button to be, and this would, for the common user, essentially break functionality of the phone itself) --- Am I making sense? someone who is a better developer should be able to rephrase what i'm saying in a better way.

    But the app controls would also need to be reversed, and I don't think that can be done via an app, at least not to control the behavior of other apps. An overlay wouldn't work, even if it was a mirrored output of display over a blank overlay of the original display output, because control options can't be manipulated by an additional app for the app you are actively using.

    But i agree, this should be easy enough to do for CM10 and other custom roms.

    I would just suggest you separate the two within settings, so there is an option to reverse controls only (for left handed, disabled, special situations, etc -- which should really be included in Android core itself) for accessibility, let apps call on the control layout option so can just code once and have it reverse A) location, for handedness, B)functionality, for special use, options, and HUD, and then C) also reverse display, for either HUD or Mirrored projection/video output/special uses. So, if I understand the android programming correctly, you just need to include 3 separate reverse-output libraries for app programmers to call, which could also just be set system-wide within options, they are 1)reverse touchscreen control location based on a flip of y-axis or x-axis in landscape, 2)reverse touchscreen control functionality based on the gyroscope-detected axis, and 3) reverse the display rendering output along the axis, also gyroscope-detected.

    I guess I would suggest begging CM folks to incorporate this, and once its in use with enough people out there, maybe by the time Android is at Sweetbread or Truffles it will be incorporated into the main libraries. Either that or a group of disabled and left-handed folks (NOT IMPLYING THE SAME THING BETWEEN THE TWO GROUPS PEOPLE, I HAPPEN TO BE LEFT HANDED MYSELF) sue google class action to include these in the programming libraries under the disabilities act violations for accessibility.

    ----

    of course, if someone else knows a much, much easier way to do this with just a standalone app, please speak up!!!!!!!
    4
    not that I've found. you'd think mirroring the display on the y axis would be simple. I'll make it of I ever learn java/linux/android programming
    3
    I think 5 is enough. Any of these float your boat? (those all *should* have mirrored "HUD" settings so when laid on your dash under your windshield you get the effect of the BMW HUD above. I haven't tried any of them personally, though.)

    He isn't looking for a speedometer, he wants to mirror his screen for all apps, so that way he can use the maps app or the navigation app or any other app of his choosing and see it on his windshield. Before you go off on your next pissy fit, read carefully.
    3
    Do it physically. Make a holder that will let your phone sit upright with a mirror in front of it angled 45 degrees. Now the windshield will show the mirror image of the mirror; ie. not backward / upside down...

    Of course it would be tough to actually USE the phone... maybe voice commands? :)

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