B4A Library [Lib] Gesture Detector

Informatix · Sep 20, 2012

This library adds the detection of standard gestures (press, single-tap, double-tap, long tap, drag, scroll, fling, pinch, rotation) to B4A. Instead of using the Touch events to figure out what the user really did, now you just set 15 different listeners with one line of code and you get the gestures as events with all the useful values (scrolling distance, fling velocity, pinch variation, rotation angle...).
With this library, you can also know easily the pressure or the size of a touch event.

It works with any view.

Note: you have to create an instance of GestureDetector (with Dim) for each view you want to bind to the detector with SetOnGestureListener.

v2.2:
- Freeware.

v2.3:
- I fixed an issue with the boolean value returned by the OnTouch event with some views (e.g. ListView or ScrollView);
- I added a new demo (GD_SwipeLV);
- The OnDown event is now raised before OnDoubleTap.

v2.4:
- I fixed an issue when a view is dragged after one of the pointer is up (delta values were computed according to the pointer 0, not to the remaining pointer).

Incompatible with Android versions < 2.

jazzzzzzz · Sep 20, 2016

How can I detect draging up,down,left,right ?

What i need is that, in onDrag example I need to drag the ball up,down,right,left only (like a joystick that goes like a + symbol only) .

How can i achieve it?

Informatix · Sep 20, 2016

jazzzzzzz said:
How can I detect draging up,down,left,right ?

What i need is that, in onDrag example I need to drag the ball up,down,right,left only (like a joystick that goes like a + symbol only) .

How can i achieve it?

By checking the direction of the move (the sign).

jazzzzzzz · Sep 20, 2016

Informatix said:
By checking the direction of the move (the sign).

How can i get direction?

B4X:

Sub Gesture_onDrag(deltaX As Float, deltaY As Float, MotionEvent As Object)
    likeBt.Top = Max(25%y+(actionBar.Height/2), Min(likeBt.Top + deltaY, 75%y+(actionBar.Height/2) - likeBt.Height))
End Sub

Sub Gesture_onTouch(Action As Int, X As Float, Y As Float, MotionEvent As Object) As Boolean
    Select Action
        Case Activity.ACTION_DOWN
            'Log("Action Down")
          
        Case Activity.ACTION_UP
            'Log("Action Up")
            If likeBt.Top <> 25%y+(actionBar.Height/2) Or likeBt.Top <> 75%y+(actionBar.Height/2)-likeBt.Height Then
                likeBt.Top = 50%y+(actionBar.Height/2)- 25dip
            End If
          
    End Select
  
    Return True
End Sub

this is my current snippet

this works for vertical direction only

Informatix · Sep 20, 2016

jazzzzzzz said:

How can i get direction?

B4X:

Sub Gesture_onDrag(deltaX As Float, deltaY As Float, MotionEvent As Object)
    likeBt.Top = Max(25%y+(actionBar.Height/2), Min(likeBt.Top + deltaY, 75%y+(actionBar.Height/2) - likeBt.Height))
End Sub

Sub Gesture_onTouch(Action As Int, X As Float, Y As Float, MotionEvent As Object) As Boolean
    Select Action
        Case Activity.ACTION_DOWN
            'Log("Action Down")
         
        Case Activity.ACTION_UP
            'Log("Action Up")
            If likeBt.Top <> 25%y+(actionBar.Height/2) Or likeBt.Top <> 75%y+(actionBar.Height/2)-likeBt.Height Then
                likeBt.Top = 50%y+(actionBar.Height/2)- 25dip
            End If
         
    End Select
 
    Return True
End Sub

this is my current snippet

this works for vertical direction only

Check the sign of DeltaX and DeltaY and the relative value of DeltaX (horizontal) to the value of DeltaY (vertical).

LucaMs · Feb 15, 2017

I tried the example Drag. Performing sequential rotation and dragging a couple of times, the rectangle flits wherever it wants .

Why?

Thank you.

Informatix · Feb 15, 2017

LucaMs said:
Why?

Because of the Animate function. You should try another way to rotate your view.

LucaMs · Feb 15, 2017

Informatix said:
Because of the Animate function. You should try another way to rotate your view.

All roads lead to RomA, but here there are few roads

Thank you.

Inman · Mar 23, 2017

I am testing OnDrag event and it works great. But at the end of the drag, how can I detect when the user lifts his finger off the screen so that I can "drop" the view back to its initial position? With OnTouch?

Informatix · Mar 23, 2017

Inman said:
I am testing OnDrag event and it works great. But at the end of the drag, how can I detect when the user lifts his finger off the screen so that I can "drop" the view back to its initial position? With OnTouch?

Yes, with OnTouch. Action = GD.ACTION_UP

Informatix · Apr 13, 2017

Syd Wright said:
Just to report that today I noticed a new behaviour (in an Android 5.1 smartwatch type S83) whereby an "Action=3" event occurs with the Gesture Detector. Normally Action=1 should occur (=Action_Up).
It only happens when swiping left to right. In all other directions the normal Action_Up event occurs. Is this an electronic (firmware) fault in this smart watch?

3 = Cancel. The touch event is cancelled by one of the activity views that catches this event.

ELCHARO · May 26, 2017

Hello.
The lib have a function to pass touch events like

B4X:

GD_Green.PassTouchEventTo(MotionEvent, pnlRed)

are a way to pass event like

B4X:

Gesture_onScroll(distanceX As Float, distanceY As Float, MotionEvent1 As Object, MotionEvent2 As Object)

The idea is intercept vertical swipes and pass de horizontal events.
A problem than i don't know how to resolve.

Regards.

ykucuk · Aug 24, 2017

Hello,

I added imageview into panel and trying resize and rotate image with pinch on runtime.

I have 2 problems

1- Too Slowly. Users wait 1 second after each pinch action.
2-Panel can rotate but Imageview in panel doesnt rotate with panel. How to rotate imageview as panel

Need help.

My code : www.amerikaileticaretyapin.com/pinch.zip

Alexander Stolte · Aug 24, 2017

ykucuk said:
1- Too Slowly. Users wait 1 second after each pinch action.

Test it on Release. On my Samsung S7 Edge i have no delay from 1 second.

ykucuk said:
2-Panel can rotate but Imageview in panel doesnt rotate with panel. How to rotate imageview as panel

set:

B4X:

pnlTwoFingers.AddView(img, 0, 0, 100%x, 100%x)

Alexander Stolte · Aug 24, 2017

ELCHARO said:
are a way to pass event like

Do you mean something like that?

B4X:

Sub Globals
      Private pnl_back As Panel
    Dim GD As GestureDetector    
End Sub

Sub Gesture_onDrag(deltaX As Float, deltaY As Float, MotionEvent As Object)   
    pnl_back.Top = Max(0, Min(pnl_back.Top + deltaY, 100%y - pnl_back.Height))
End Sub

if you press on your view and wish up or down, your view follow your finger.

Informatix · Aug 25, 2017

ykucuk said:
2-Panel can rotate but Imageview in panel doesnt rotate with panel. How to rotate imageview as panel

Your code does not rotate anything except a text drawn on a canvas, so the result is not surprising.
You have to use a library like NineOldAndroids that allows to rotate views.

Are you sure that your need is not already satisfied by an existing library (e.g. TouchImageView or PinchZoomAndMove)?

ykucuk · Aug 25, 2017

Informatix said:
Your code does not rotate anything except a text drawn on a canvas, so the result is not surprising.
You have to use a library like NineOldAndroids that allows to rotate views.

Are you sure that your need is not already satisfied by an existing library (e.g. TouchImageView or PinchZoomAndMove)?

Hello,

Im not sure. ı need drag few images on activity and pinch them on runtime. I thought this library best for this.

am i wrong ?

ykucuk · Aug 25, 2017

Alexander Stolte said:
Test it on Release. On my Samsung S7 Edge i have no delay from 1 second.

set:

B4X:

pnlTwoFingers.AddView(img, 0, 0, 100%x, 100%x)

1-It works great with release mode.
2- it doesnt help.

B4X:

pnlTwoFingers.AddView(img, 0, 0, 100%x, 100%x)

thank you

Informatix · Aug 26, 2017

ykucuk said:
Hello,

Im not sure. ı need drag few images on activity and pinch them on runtime. I thought this library best for this.

am i wrong ?

Don't know. It's you that know your need. If a library exists and fulfills the need, why do you want to spend time doing everything yourself?

ykucuk · Sep 14, 2017

Hi,
My panel is square. How can I resize proportionally?

mkh_fx · Nov 30, 2017

how to use this library for google map
i want to detect touch actions on the map by this library

B4A Library [Lib] Gesture Detector

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