[Accepted] SDL 0049 - Gesture cancellation on video streaming

[theresalech]

Hello SDL community,

The review of "Gesture cancellation on video streaming" begins now and runs through April 11, 2017. The proposal is available here:

https://github.com/smartdevicelink/sdl_evolution/blob/master/proposals/0049-touch-cancellation.md

Reviews are an important part of the SDL evolution process. All reviews should be sent to the associated Github issue at:

#144

What goes into a review?

The goal of the review process is to improve the proposal under review through constructive criticism and, eventually, determine the direction of SDL. When writing your review, here are some questions you might want to answer in your review:

• Is the problem being addressed significant enough to warrant a change to SDL?
• Does this proposal fit well with the feel and direction of SDL?
• If you have used competitors with a similar feature, how do you feel that this proposal compares to those?
• How much effort did you put into your review? A glance, a quick reading, or an in-depth study?
  Please state explicitly whether you believe that the proposal should be accepted into SDL.

More information about the SDL evolution process is available at

https://github.com/smartdevicelink/sdl_evolution/blob/master/process.md

Thank you,
Theresa Lech

Program Manager - Livio
theresa@livio.io

[tpulatha]

What is the difference between END and the new proposed CANCEL touchevent type?
Wouldn't the HMI just send END if a current gesture gets interrupted?
Because effectively, if the user is dragging.. we don't want to "cancel" the drag (which would mean to move back to the start of the drag) but just "end" the dragging, right?

[masatoogawa]

@tpulatha Thank you for your prompt review. END is the end of input by a user. CANCEL is an interruption of the input by system.

if the user is dragging..

For example, in the case of tap gestures, END may be a decision behavior.

1. A user taps on the screen. BEGIN is sent to an application.
2. A user keeps on tapping. A native dialog interrupts.
3. A user keeps on tapping. END is sent to an application.

An application may decide END which system send is a decision action even a user does not release his finger.

"cancel" the drag (which would mean to move back to the start of the drag)

CANCEL expects not to rewind touch position but to cancel gesture recognition.

[joeljfischer]

@tpulatha I think what they're trying to say, for example: the user is in the middle of a pinch gesture, a popup appears. If END is sent, the pinch will register, which is not intended. If CANCEL is sent, the pinch should be discarded.

The problem I see with this is that I'm not sure it's necessary. A pinch or drag generally occurs in real time, and simply using END seems appropriate. I'm not sure of what touch event use case would occur where a popup appearing would require a CANCEL and not simply an END. A long-press is the only one I can think of that might be relevant? It may be possible to get a short-press when a long was intended?

[masatoogawa]

For example, we have drag and drop in the user case.

Although they are edge cases, there are possibilities where END causes a decision action. We believe that introducing CANCEL is reasonable.

[theresalech]

The Steering Committee has agreed to accept this proposal, citing the drag and drop example as a valid use case.

[theresalech]

Issues entered:
Core
Android
iOS
RPC