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wired
wired
Senior II
November 10, 2021
Solved

Why is TouchGFX Swipe Threshold inconsistent?

  • November 10, 2021
  • 4 replies
  • 1277 views

I'm using the STM32F469I-DISCO board with TouchGFX. In portrait mode, I set the swipe threshold to 400 because I want the user to swipe almost all the way across the screen to switch pages. When I swipe slowly, it seems to work. However, a fast swipe changes pages with a swipe distance of only 1/2" or so. Is there a way to not make this speed-dependent? Right now, it is very easy to accidentally change pages. I want the page change to be very intentional.

This topic has been closed for replies.
Best answer by wired

So I filed a support request from ST, and they told me that the fast swipe feature is the default implementation. If you wish to make the swipeThreshold behave as it is documented in the API documentation, you must override the gesture handler in the screen that has the Swipe Container. See below for the added declaration. This is all that needs to be done - no function needs to be written. I suggested that they provide additional detail in the API for the swipeThreshold member so that people know it is only applicable for a slow swipe, and provide instructions an how to disable the fast swipe feature as shown below.

class Screen1View : public Screen1ViewBase
{
public:
 Screen1View();
 virtual ~Screen1View() {}
 virtual void setupScreen();
 virtual void tearDownScreen();
	
 virtual void handleGestureEvent(const GestureEvent& event) {}
 //event from Presenter
protected:
};

4 replies

wired
wiredAuthor
Senior II
November 16, 2021

Is there nobody at ST who can explain this? What good is a threshold if it will not produce the desired result?

wired
wiredAuthor
Senior II
November 23, 2021

This is critical to my application, as I am unintentionally activating a swipe on many occasions on a 480 pixel wide display, using a swipe threshold of 400 pixels, just by trying to press a button. This occurs both in the simulator and in the target. Why is this happening??? I tried setting the threshold to 1200, almost three times wider than the display, and set the elastic width to zero, and those changes made no difference whatsoever. It's bad enough that just a minor brush of a tiny portion of the screen causes a swipe, but when I'm trying to press a button? Surely someone at ST is monitoring this and can provide an explanation. I need to know if I need to abandon swipe containers in my application, which has serious design implications.

wired
wiredAuthorBest answer
Senior II
December 9, 2021

So I filed a support request from ST, and they told me that the fast swipe feature is the default implementation. If you wish to make the swipeThreshold behave as it is documented in the API documentation, you must override the gesture handler in the screen that has the Swipe Container. See below for the added declaration. This is all that needs to be done - no function needs to be written. I suggested that they provide additional detail in the API for the swipeThreshold member so that people know it is only applicable for a slow swipe, and provide instructions an how to disable the fast swipe feature as shown below.

class Screen1View : public Screen1ViewBase
{
public:
 Screen1View();
 virtual ~Screen1View() {}
 virtual void setupScreen();
 virtual void tearDownScreen();
	
 virtual void handleGestureEvent(const GestureEvent& event) {}
 //event from Presenter
protected:
};

Michael K
Michael K
Senior III
December 9, 2021

Strange and unintuitive... Glad it worked out.

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