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Bug 4884

Summary: [Patch] Add support for multitouch on iOS
Product: SDL Reporter: Aaron Barany <akb825>
Component: eventsAssignee: Sam Lantinga <slouken>
Status: RESOLVED INVALID QA Contact: Sam Lantinga <slouken>
Severity: normal    
Priority: P2    
Version: 2.0.10   
Hardware: iPhone/iPod touch   
OS: iOS (All)   
Attachments: Add support for multitouch on iOS.

Description Aaron Barany 2019-11-30 23:39:15 UTC 
Created attachment 4080 [details]
Add support for multitouch on iOS.

Rather than using hard-coded touch IDs for a single touch, use the UITouch pointer as the touch ID. Since SDL_TouchID is a 64-bit integer, this should be a lossless
conversion, and according to the documentation for UITouch (https://developer.apple.com/documentation/uikit/uitouch) it is guaranteed to persist between events.
Comment 1 Sam Lantinga 2019-12-04 06:27:42 UTC 
The SDL touch ID is an input device, not a finger ID.
For example, if a system had 3 trackpads they would each get their own touch ID, and then any multi-touch input on each device would come through with it's own finger ID.
Comment 2 Aaron Barany 2019-12-04 07:06:12 UTC 
Thanks, I misunderstood the meaning of the IDs. I originally had problems with 2.0.9, and while the code had changed with 2.0.10, the management for touchId 1 should be more or less the same. (the patch I submitted was an updated version for the one I was using locally for 2.0.9 to fix it)

When I have a chance, I will verify whether or not I can still reproduce the lack of multitouch with the normal 2.0.10 code. If not, I may re-open this ticket with an updated patch that takes the proper IDs into account.
Comment 3 Sam Lantinga 2019-12-04 13:53:56 UTC 
Sure, that would be great, thanks!
Comment 4 Aaron Barany 2019-12-07 21:52:15 UTC 
I double checked and it looks like it is working as expected. I probably had other problems preventing multitouch from working when I first implemented the patch and didn't realize that it was a separate change that fixed it.
Comment 5 Sam Lantinga 2019-12-08 19:29:53 UTC 
Great, I'm glad you fixed it.