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Bug 4126 - Wrong touch input coords values
Summary: Wrong touch input coords values
Status: NEW
Alias: None
Product: SDL
Classification: Unclassified
Component: events (show other bugs)
Version: 2.0.8
Hardware: ARM Android (All)
: P2 critical
Assignee: Sam Lantinga
QA Contact: Sam Lantinga
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2018-04-06 09:57 UTC by 000whitedragon000
Modified: 2019-08-06 05:06 UTC (History)
1 user (show)

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Description 000whitedragon000 2018-04-06 09:57:46 UTC 
event (from PollEvent) SDL_FINGERDOWN/SDL_FINGERMOTION doesn't return right values..
Values are not normalized (the official guide shows values between 0 and 1) but negative values are also returned.

However, when the screen is in one place, the value returned is randomly wrong.

This bug occurs if the game / app texture is created with SDL_CreateTexture() and SDL_TEXTUREACCESS_STREAMING and if the texture is not fullscreen.
So in this case for example ev.tfinger.x*nativeWidth are randomly wrong.

reference project: https://github.com/DCurrent/openbor
files:
https://github.com/DCurrent/openbor/blob/master/engine/android/jni/openbor/video.c
https://github.com/DCurrent/openbor/blob/master/engine/sdl/control.c
Comment 1 000whitedragon000 2018-04-21 04:31:30 UTC 
I confirm the bug when use SDL_RenderSetLogicalSize()
Comment 2 Kostyarezkiy 2019-08-06 05:06:47 UTC 
This isn't a bug. You just need to multiply it by the screenwidth.

int Xclick = e.tfinger.x * SCREENWIDTH;//technically this is a float value, but we can make it int fine.
int Yclick = e.tfinger.y * SCREENWIDTH;
SDL_Log(" X %d  Y %d \n",Xclick , Yclick );