Drag threshold default 10 now?!

Unity Engine
1

So the major issue with Drag Threshold on the event system is it is not DPI dependant as it should be.
But is that why is was changed from 5 to 10 (in 2018 I think)?

10 is probably right on 4k desktop and maybe on some mobile devices, it is kind of big on a 1080 desktop where the old 5 would make more sense.

Best would be best to set it in DPI not pixels

2

Here’s what I ended up doing in my game:

using UnityEngine;
using UnityEngine.EventSystems;

// Attach this to the object with your EventSystem and it will overwrite the Drag Threshold
// on Start to change it relative to the device's current DPI, allowing it to be specified
// in terms of physical distance instead of pixels
public class PhysicalDragThreshold : MonoBehaviour
{
    public float inchesDragThreshold = .05f;
    public float defaultDPI = 100;    // DPI to assume if we can't detect the device's

    // if touchThreshMultiplier > 1, then the threshold will be higher for touches than for
    // mouse input.  This works by checking the number of active touches every frame...
    public float touchThreshMultiplier = 4;

    private EventSystem evSys;


    void Start ()
    {
        evSys = GetComponent<EventSystem>();
        SetDragThreshold();
    }

    private void Update()
    {
        if (!Mathf.Approximately(touchThreshMultiplier, 1))
        {
            SetDragThreshold();
        }
    }

    public void SetDragThreshold()
    {
        if (evSys != null)
        {
            float dpi = Screen.dpi;
            if (dpi < 10) dpi = defaultDPI;

            if (Input.touchCount > 0) dpi *= touchThreshMultiplier;

            evSys.pixelDragThreshold = Mathf.RoundToInt(dpi * inchesDragThreshold);
        }
        else
        {
            Debug.LogWarning("PhysicalDragThreshold component should be on an object with EventSystem", gameObject);
        }
    }
}

You could remove the touch-related stuff to avoid having code that runs every frame, but I couldn’t find any threshold that “felt right” for mouse and touch input simultaneously.

3 Likes