Linux touchscreen not detecting touch release

Development Platform & Builds
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1

We’ve been testing the multi-touch capabilities of UE 4.15 on Linux and it looks like it’s finally working, the only problem we have at the moment is that we are not capable of detecting when a touch is released, we are getting these errors:

[2017.02.21-22.48.17:560][166]LogLinuxWindow:Warning: Ignoring touch event SDL_FINGERMOTION (finger: 5, x=546.518738, y=1137.303833) that doesn't have a window associated with it

[2017.02.21-22.48.20:922][373]LogLinuxWindow:Warning: Ignoring touch event SDL_FINGERUP (finger: 5, x=546.518738, y=1137.303833) that doesn't have a window associated with it

It might be the case that Linux is using a slightly different method to assign touches/release touches than Android or Windows. The same code works perfectly on Windows and Android but not in Linux.

2

It looks like the issue is caused by the window check with the following changes I was able to make it work, its probably not the way it should be done however…

It seems that on linux the check “if (LIKELY(!bWindowlessEvent))” is invalid so it always returns false for SDL_FINGERUP and SDL_FINGERMOTION

Change is to the file Engine/Source/Runtime/Core/Private/Linux/LinuxApplication.cpp

Diff

3

Hi, any news about this? Is there a way you can implement this fix into an official release or provide an alternative solution? This is tested in our end and it works fine for us.

Thanks.

4

Hey! necroposting only to ley you know that as unreal 4.25 this has not been fixed yet. trying Botanicvelious solution right now to see if it still applies.