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Bug 4183

Summary: [patch] Incorrect touch normalization using X11 XInput2
Product: SDL Reporter: Zack Middleton (zturtleman) <zack>
Component: eventsAssignee: Ryan C. Gordon <icculus>
Status: ASSIGNED --- QA Contact: Sam Lantinga <slouken>
Severity: normal    
Priority: P2 CC: icculus, sezeroz
Version: HG 2.0   
Hardware: ARM   
OS: Linux   
Attachments: Normalize x11xinput2 touch x to be 1.0 at width

Description Zack Middleton (zturtleman) 2018-05-31 20:55:10 UTC 
Created attachment 3253 [details]
Normalize x11xinput2 touch x to be 1.0 at width

Applications (such as SDL's testgesture) do "event.tfinger.x * window_width" to find window coord. Currently the X11 XInput2 backend expects application to do "event.tfinger.x * (window_width-1)" instead.

X11 XInput2 touch events are normalized so x is 1.0 at "width - 1" but other SDL backends appear to have x be 1.0 at "width". Same issue for touch event y with regards to height.

Related to bug #3871.
Comment 1 Ryan C. Gordon 2018-06-25 05:49:35 UTC 
This patch is now https://hg.libsdl.org/SDL/rev/dfebed374d73, thanks!

--ryan.
Comment 2 Sam Lantinga 2018-06-26 22:50:53 UTC 
This is wrong, the other backends should be fixed. Mouse coordinates are 0 based, so at (width,height) they are outside the window.
Comment 3 Ryan C. Gordon 2018-07-02 17:21:06 UTC 
I'll back this out for now, then. Sorry!

--ryan.
Comment 4 Ryan C. Gordon 2018-08-03 21:23:10 UTC 
This was backed out in https://hg.libsdl.org/SDL/rev/317db3d3712c ; leaving this assigned to me for now.

--ryan.