[Vm-dev] The cooked and the raw [RE: Touch/MultiTouch Events]

ken.dickey at whidbey.com ken.dickey at whidbey.com
Mon Sep 21 14:02:08 UTC 2020


Greetings,

As I expected, there is someone here before me.

The devil is in the details of course, but the Qt framework allows for  
recognized events based on what widget takes the first touch event and 
recognized touch patterns (see below).  Custom event recognizers can be 
added (or bypass to take raw events).

? handlesTouch{,Down,Over} ?


=== from:
https://doc.qt.io/qt-5/gestures-overview.html
==============vvv=============
Overview

QGesture is the central class in Qt's gesture framework, providing a 
container for information about gestures performed by the user. QGesture 
exposes properties that give general information that is common to all 
gestures, and these can be extended to provide additional 
gesture-specific information. Common panning, pinching and swiping 
gestures are represented by specialized classes: QPanGesture, 
QPinchGesture and QSwipeGesture.

Developers can also implement new gestures by subclassing and extending 
the QGestureRecognizer class. Adding support for a new gesture involves 
implementing code to recognize the gesture from input events. This is 
described in the Creating Your Own Gesture Recognizer section.

==============^^^=============
https://doc.qt.io/qt-5/qgesturerecognizer.html
https://doc.qt.io/qt-5/qevent.html
https://doc.qt.io/qt-5/qtouchevent.html
==============vvv=============
Qt will group new touch points together using the following rules:

When the first touch point is detected, the destination widget is 
determined firstly by the location on screen and secondly by the 
propagation rules.
When additional touch points are detected, Qt first looks to see if 
there are any active touch points on any ancestor or descendant of the 
widget under the new touch point. If there are, the new touch point is 
grouped with the first, and the new touch point will be sent in a single 
QTouchEvent to the widget that handled the first touch point
==============^^^=============

FYI,
-KenD


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