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Raspberry PI 4 Touchscreen Touch Points Transformed

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  • S Offline
    S Offline
    starman2049
    wrote on 19 May 2023, 20:57 last edited by
    #1

    I have QT cross compile working for Raspberry PI 4 and everything is working fine. I can build and run Qt Widget apps just file, using mouse is just fine. When I use touch however the touch points are mapped into mouse events and the x,y are "transformed". I have tried rotating the screen using the mfg drivers which works but the touch coordinates are always rotated 90 degrees from what they should be. This is a custom LCD I bought off of the internet.
    when I run the PI built-in desktop windows GUI the touchscreen works fine and I can use my finger to interact and the points are not transformed.
    I have been trying a number of things from this forum and others but nothing works.
    This TFT LCD I bought (MHS35) "appears" to be pretty universal. I have seen various ones from different vendors but they all look identical and they fit in a PI case just the size of PI4, and come with fan and heat sinks.
    I have tried different version versions of PI OS (Buster and Bullseye). I am using Qt 5.15.
    I know this is not a lot to go on, but I have tried so many different things and nothing is working and the fact that it works on PI Desktop GUI and not QT Widget apps makes me think it is a Qt-based issue, and since it looks like there are only one 3.5" TFT LCD out there it makes me wonder if anyone on the planet has got Qt and a 3.5 TFT LCD MHS35 working ever?
    I just don't know what to do. I really don't want to use the bigger screen that comes with the PI because it is to big for my purposes, but I have been working on this for close to 100 hrs over the past year and have gotten nowhere.
    If there is anybody that has gotten a 3.5" LCD working for PI and Qt 5 I would love to hear. May be I just need to dump this LCD and by another one, but they all look the same so I wonder if it will make any difference.
    Any response is appreciated. I have a bunch of ideas I want to flesh out and I can't even begin.

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