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Bug 3348 - SDL_FINGERDOWN gives wrong cursor position on MultiTouch,OSX
Summary: SDL_FINGERDOWN gives wrong cursor position on MultiTouch,OSX
Status: RESOLVED INVALID
Alias: None
Product: SDL
Classification: Unclassified
Component: events (show other bugs)
Version: 2.0.4
Hardware: x86_64 Mac OS X 10.11
: P2 minor
Assignee: Sam Lantinga
QA Contact: Sam Lantinga
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2016-05-28 19:04 UTC by Denis
Modified: 2016-09-25 19:05 UTC (History)
2 users (show)

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Description Denis 2016-05-28 19:04:53 UTC 
I've described it here: https://forums.libsdl.org/viewtopic.php?t=11922
Duplicate:

Device: Macbook, OS X, multitouch, SDL2. 

My code:
float posX = event.tfinger.x; 
float posY = event.tfinger.y; 
if ( event.type == SDL_FINGERDOWN ) std::cout << "posX = " << posX << ", posY = " <<  posY << "\n"; 


It returns me coordinates of my multitouch device. If I tap my multitouch at the left-top corner it returns me coordinates something like 0.1x0.1. Ok, right. But how to get coordinates of the cursor position in OS X? 

I can get only coordinates of multitouch device but it doesn't mean that it's the coordinates of the cursor on the screen. I mean... I can tap my multitouch at the left-top corner but my cursor at this time will be at the right-bottom corner of the screen.
Comment 1 Alex Szpakowski 2016-05-29 12:16:33 UTC 
You can get the mouse cursor position via the SDL_MOUSEMOTION, SDL_MOUSEBUTTONDOWN, or SDL_MOUSEBUTTONUP events, or the SDL_GetMouseState function.
Comment 2 Denis 2016-05-29 15:00:45 UTC 
(In reply to Alex Szpakowski from comment #1)
> You can get the mouse cursor position via the SDL_MOUSEMOTION,
> SDL_MOUSEBUTTONDOWN, or SDL_MOUSEBUTTONUP events, or the SDL_GetMouseState
> function.

What if I need to use multiple finger gestures on my macbook?
Comment 3 Alex Szpakowski 2016-05-29 18:48:12 UTC 
Multi-finger trackpad gestures don't modify the mouse position, so you can just use the touch APIs.

The touch coordinates for trackpads and other non-touchscreen devices don't correspond to specific pixels on the screen, since they aren't touch screens.
Comment 4 Alex Szpakowski 2016-09-25 19:05:18 UTC 
It would be nice to be able to query whether a touch device is a touchscreen (direct touch input) or not (indirect touch input), but that's a somewhat separate issue.