B4A Library [B4X] [XUI] AS ViewPager based on xCustomListView

Alexander Stolte · Apr 22, 2020

Hey,
thanks to @KZero for his good zPager class, i was able to extract a few things from it to make this cross platform view.

I spend a lot of time in creating views, some views i need by my self, but some views not and to create a high quality view cost a lot of time. If you want to support me, then you can do it here by Paypal or with a coffee.

This library is compatible and tested with B4A,B4I and B4J!
If you have bugs or a wish then tell me it in the comments.

Don't use autoscale in the layouts that are added to the viewpager.

On B4J use the LEFT and RIGHT keys on your keyboard to change the page.
~~On B4I you need the GestureRecognizer class. Download it down below.~~

B4j: jXUI,JavaObject,jPager,jReflection
B4a: XUi,Reflection,xCustomListView
B4i: iXUI,xCustomListView

Features

cross-platform compatible
based on a cross-platform ListView
add and remove pages
scroll to pages
a good swipe feeling
Vertical
Carousel
Lazy Loading
NEW - AllowNext and AllowBack

Horizontal and Vertical

B4A Carousel and B4I Carousel

ASViewPager
Author: Alexander Stolte
Version: 2.00

ASViewPager
- Events:
  - LazyLoadingAddContent (Parent As B4XView, Value As Object)
  - PageChange (Index As Int)
  - PageChanged (Index As Int)
  - PageChanged2 (NewIndex As Int, OldIndex As Int)
  - PageClick (Index As Int, Value As Object)
  - ReachEnd
  - ScrollChanged (Offset As Int)
  - TouchBegin
  - TouchEnd
- Fields:
  - Tag As Object
- Functions:
  - AddPage (LayoutPanel As B4XView, Value As Object) As String
  - AddPageAt (index As Int, LayoutPanel As B4XView, Value As Object) As String
    Adds an page at a special position
  - AllowBack (Allow As Boolean) As String
    If False: Prevents the user from moving to the previous page
    -The PreviousPage function will not work
    -The CurrentIndex property can be used without restrictions
  - AllowNext (Allow As Boolean) As String
    If False: Prevents the user from moving to the next page
    -The NextPage function will not work
    -The CurrentIndex property can be used without restrictions
  - Base_Resize (Width As Double, Height As Double)
  - Class_Globals As String
  - Clear As String
  - Commit As String
  - DesignerCreateView (Base As Object, Lbl As Label, Props As Map) As String
    Base type must be Object
  - getBase As B4XView
  - getCurrentIndex As Int
  - getCustomListView As b4a.example3.customlistview
  - getisScrollEnabled As Boolean
    Checks if the swipe/scroll is enabled or disabled
  - getLazyLoading As Boolean
  - getLazyLoadingExtraSize As Int
  - getLoadingPanelColor As Int
  - GetPanel (Index As Int) As B4XView
  - getSize As Int
  - GetValue (Index As Int) As Object
  - Initialize (Callback As Object, EventName As String) As String
  - IsInitialized As Boolean
    Tests whether the object has been initialized.
  - NextPage As String
  - NextPage2 As String
    Jump to next page
  - PreviousPage As String
  - PreviousPage2 As String
    jump to previous page
  - RemovePage (index As Int) As String
  - ResetLazyloadingIndex As String
  - ResetLazyLoadingPanels As String
    Removes all child views from all visible pages
    Usage:
    <code>
    xASVP_Horizontal.ResetLazyLoadingPanels
    Sleep(0)
    xASVP_Horizontal.ResetLazyloadingIndex
    xASVP_Horizontal.Commit</code>
  - Scroll2Value (Value As String) As String
    sets the current index by the value - smooth scrolls to the item
  - Scroll2Value2 (Value As String) As String
    sets the current index by the value - jumps to the item
  - setCurrentIndex (index As Int)
  - setCurrentIndex2 (index As Int)
    sets the current index - jumps to the item
  - setIgnoreLazyLoading (Ignore As Boolean) As String
    If True, the Lazy Loading event is not triggered
  - setIgnorePageChangedEvent (ignore As Boolean) As String
  - setIgnorePageChangeEvent (ignore As Boolean) As String
  - setLazyLoading (Enabled As Boolean) As String
  - setLazyLoadingExtraSize (ExtraSize As Int) As String
  - setLoadingPanelColor (Color As Int) As String
    The color of the Loading panel if Base_Resize is executed
  - setLoadingPanelHideDuration (Duration As Int) As String
  - setScroll (enabled As Boolean) As String
    B4I and B4A only
    enabled - False the scroll is deactivated
- Properties:
  - Base As B4XView [read only]
  - CurrentIndex As Int
  - CurrentIndex2
    sets the current index - jumps to the item
  - CustomListView As b4a.example3.customlistview [read only]
  - IgnoreLazyLoading
    If True, the Lazy Loading event is not triggered
  - IgnorePageChangedEvent
  - IgnorePageChangeEvent
  - isScrollEnabled As Boolean [read only]
    Checks if the swipe/scroll is enabled or disabled
  - LazyLoading As Boolean
  - LazyLoadingExtraSize As Int
  - LoadingPanelColor As Int
    The color of the Loading panel if Base_Resize is executed
  - LoadingPanelHideDuration
  - Scroll
    B4I and B4A only
    enabled - False the scroll is deactivated
  - Size As Int [read only]

Changelog

1.00
- Release
1.01
- Base_Resize is now public
- NextPage and PreviousPage Bug Fix
- setCurrentIndex Bug Fix
- PageChangeEvent Bug Fix
1.02
- B4I Bug Fixes
- NextPage and PreviousPage Bug Fix
1.03
- Resize BugFix
1.04
- B4I Page-Height BugFix
- B4I Page-Swipe BugFix
1.05
- BugFix
1.06
- Add Designer Property "Orientation" - Vertical is now supported
1.07
- BugFix getCurrentIndex
- BugFix PageChanged event is now only firing if the index is changed
- Add setIgnorePageChangedEvent Property
- Add TouchBegin Event
- Add TouchEnd Event
- BugFix PageChanged is now firing if you press on a emulator, for example the arrow up or down keys on yor keyboard
1.08
- Add Tag Property
  - https://www.b4x.com/android/forum/t...om-clv-or-any-other-container.117992/#content
- Add Clear - clears the list and sets the index to 0
- BugFix xCustomListview Top was always 0
1.09
- B4I BugFixes for Release Mode - swiping is now better
1.10
- Add AddPageAt (experimental it works for my need, if you have issuses, then tell me) - Adds an page at a special position
- Add set CurrentIndex2 - sets the current index - jumps to the item
- Better resize handling
1.11
- RemovePage Bugfixes
- B4J ScrollPane under the hood is now Transparent
- Add NextPage2 -Jump to next page
- Add PrevoiusPage2 - Jump to previous page
1.12
- [BETA] Add DesignerProperty Carousel - infinite swipe
  - On B4I Bounce Effect is disabled
- B4I ScrollView Paging is now activated, this can improve the handling
1.13
- Add PageClick Event
1.14 - read more about this update here
- [B4I only] Add Scroll - enable or disable scroll with finger
  - ASViewPager1.Scroll(False)'disable scroll with finger
1.15
- Intern Function IIF renamed to iif2
1.16
- set Scroll is now B4X - disable the swipe/scroll
  - In B4J the arrow keys (Left/Right/Up/Down) are disabled if you deactivate the swipe/scroll
- New property isScrollEnabled - checks if the swipe/scroll is enabled or disabled
- Intern Function iif2 removed and the core iif is now used
  - B4A V11+ - B4J V9.10+ - B4I V7.50+
1.18
- PageChanged Event is now firing in some cases with a delay, because of a scroll animation
- BugFix B4A setScroll - Events from other views are now no longer blocked
1.19
- BugFix on NextPage and PreviousPage
1.20 (read more about this update)
- Add Event PageChange - This event is triggered immediately after the page is changed, no delay because of animations
- Add setIgnorePageChangeEvent - prevents the PageChange event from being triggered
1.21
- BugFixes
1.22
- B4I Scroll = False BugFix
1.24
- BugFix AddPageAt is now working better on B4A
1.25
- Add Scroll2Value - sets the current index by the value - smooth scrolls to the item
  - from the AddPage and AddPageAt function the "Value" property
  - must be a string to be found
- Add Scroll2Value2 - sets the current index by the value - jump to the item
1.26 (read more about this update)
- Add Designer Property LazyLoading - activates lazy loading
  - Default: False
- Add Designer Property LazyLoadingExtraSize - How many pages to load in advance
  - Default: 5
- Add Event LazyLoadingAddContent - Add here your layout or views
1.27
- Add get and set LazyLoadingExtraSize
1.28
- Important LazyLoading improvments
1.29
- Add Commit - Triggers the LazyLoadingAddContent event
  - Call this after you have filled the list
- LazyLoading BugFixes
1.30
- Add ResetLazyloadingIndex - when you call "commit" afterwards, it is guaranteed to check if there are empty panels in the lazy loading range, if so, the LazyLoading event is triggered
1.31
- important resize improvments
- Add Loading Panel if Base_Resize is calling
- Add Designer Property LoadingPanelColor
- Add set IgnoreLazyLoading - If True, the Lazy Loading event is not triggered
- Add ResetLazyLoadingPanels - Removes all child views from all visible pages
- LazyLoading Improvments
1.32
- Carousel works now in Vertical mode
1.33
- B4I Native paging is now used
  - The paging feels smoother now
  - In debug mode, the swiping should now also run better
1.34
- B4I The GestureRecognizer is no longer needed
1.35 (read more)
- Add Designer Property BackGestureGap - Only for B4I. If you use the ViewPager on a 2nd page and still want to close the page with the swipe gesture then set the checkbox to true
  - Default: False
2.00 (read more)
- New dependency in B4J: jPager
- Removed dependency in B4J: xCustomListView
- Add GetPanel
- Add GetValue
- In B4J, the jPager is now used instead of the xCustomListView
  - Better performance
  - No more unwanted scrolling with the mouse
2.01
- BugFixes and Improvements
- Add Event PageChanged2
2.02
- Add set LoadingPanelHideDuration - The duration of how quickly the loading panel is hidden
  - Default: 500
2.03
- B4I BugFix - Prevents vertical scrolling when in horizontal mode and vice versa
2.04
- B4I BugFix - The safe area is no longer observed
  - Fixes unwanted behavior when the viewpager is in the safe area
2.05
- BugFix - by setting the set CurrentIndex or set CurrentIndex2, the PageChange and PageChanged event have been triggered multiple times
2.06
- B4A BugFix
2.07
- B4I BugFix

2.08
- B4I - PageChange event is now triggered as soon as you lift your finger when changing pages, just like in B4A
- B4J - You need jPager V1.03
- Add AllowNext
  - Default: True
  - If False: Prevents the user from moving to the next page
    - The NextPage function will not work
    - The CurrentIndex property can be used without restrictions
- Add AllowBack
  - Default: True
  - If False: Prevents the user from moving to the previous page
    - The PreviousPage function will not work
    - The CurrentIndex property can be used without restrictions

Have Fun

Alexander Stolte · Apr 21, 2021

I will always change it in the future. I did not know that people look at this. Thanks

Alexander Stolte · Jun 8, 2021

Update
1.14

[B4I only] Add Scroll - enable or disable scroll with finger

In some cases it is useful to prevent scrolling. Especially if you work with several xCustomLsitView at the same time.
In B4I you can disable native, in B4A native is not possible. There you have to add a dummy item, which then blocks the touch event.
An example from a real project of mine:

B4X:

Private Sub ASCalendarAdvanced1_TouchDown
    #If B4I
    ASViewPager1.Scroll(False)
    #End If
End Sub

Why do I have to deactivate the ViewPager to expand the calendar with my finger?
Answer: as soon as I drag the calendar downwards, I also address the ViewPager at the same time and it scrolls along and that is not a nice behavior.

When do I enable the ViewPager?
The calendar has an event called "_TouchUp" so I can be sure that the user has his fingers off the ViewPager and can activate it again.

Alexander Stolte · Jul 7, 2021

Update

1.15
- Intern Function IIF renamed to iif2

AnandGupta · Jul 7, 2021

Alexander Stolte said:
ntern Function IIF renamed to iif2

Ouch !

Alessandro71 · Jul 11, 2021

any reports of crashing in GestureRecognizer on B4i?
I've just upgraded to 1.15 and my previously working app crashes as soon as touch the screen with the following message

B4X:

Error occurred on line: 174 (GestureRecognizer)
Expected: NSInputStream, object type: __NSCFNumber
Stack Trace: (
  CoreFoundation       F3021642-E3C0-33F8-9911-DD303A6056D0 + 1157612
  libobjc.A.dylib      objc_exception_throw + 56
  CoreFoundation       F3021642-E3C0-33F8-9911-DD303A6056D0 + 120016
  Power checK Control  -[B4IObjectWrapper setObject:] + 276
  Power checK Control  +[B4IObjectWrapper createWrapper:object:] + 108
  Power checK Control  -[b4i_gesturerecognizer _uigesture_longpress:::::::] + 1116
  CoreFoundation       F3021642-E3C0-33F8-9911-DD303A6056D0 + 1175856
  CoreFoundation       F3021642-E3C0-33F8-9911-DD303A6056D0 + 8656
  Power checK Control  +[B4I runDynamicMethod:method:throwErrorIfMissing:args:] + 1608
  Power checK Control  -[B4IShell runMethod:] + 448
 Power checK Control  -[B4IShell raiseEventImpl:method:args::] + 2172
 Power checK Control  -[B4IShellBI raiseEvent:event:params:] + 1580
 Power checK Control  -[b4i_gesturerecognizer handleLongPress:] + 848
 UIKitCore            CC6E5AC7-8248-35F6-8B42-2E25C93DCF0A + 7029756
 UIKitCore            CC6E5AC7-8248-35F6-8B42-2E25C93DCF0A + 7068016
 UIKitCore            CC6E5AC7-8248-35F6-8B42-2E25C93DCF0A + 7054840
 UIKitCore            CC6E5AC7-8248-35F6-8B42-2E25C93DCF0A + 7052224
 UIKitCore            CC6E5AC7-8248-35F6-8B42-2E25C93DCF0A + 7004496
 UIKitCore            CC6E5AC7-8248-35F6-8B42-2E25C93DCF0A + 7001312
 UIKitCore            CC6E5AC7-8248-35F6-8B42-2E25C93DCF0A + 11998412
 UIKitCore            CC6E5AC7-8248-35F6-8B42-2E25C93DCF0A + 11848460
 UIKitCore            CC6E5AC7-8248-35F6-8B42-2E25C93DCF0A + 12382328
 UIKitCore            CC6E5AC7-8248-35F6-8B42-2E25C93DCF0A + 12400664
 UIKitCore            CC6E5AC7-8248-35F6-8B42-2E25C93DCF0A + 12364540
 CoreFoundation       F3021642-E3C0-33F8-9911-DD303A6056D0 + 633840
 CoreFoundation       F3021642-E3C0-33F8-9911-DD303A6056D0 + 633584
 CoreFoundation       F3021642-E3C0-33F8-9911-DD303A6056D0 + 630328
 CoreFoundation       F3021642-E3C0-33F8-9911-DD303A6056D0 + 607200
 CoreFoundation       CFRunLoopRunSpecific + 572
 GraphicsServices     GSEventRunModal + 160
 UIKitCore            CC6E5AC7-8248-35F6-8B42-2E25C93DCF0A + 11723508
 UIKitCore            UIApplicationMain + 164
 Power checK Control  main + 128
 libdyld.dylib        0B475C78-3C12-3121-B7F8-2B95B83DAF44 + 5480
)

line 174 is the last one in this block from GestureRecognizer class

B4X:

Private Sub uigesture_longpress(state As Int,numtouch As Int, Numtaps As Int, x As Float, y As Float, obj As Object)
Dim att As  LongPress_Attributes
att.NumberOfTaps=Numtaps            'ignore

Alexander Stolte · Jul 11, 2021

Alessandro71 said:
any reports of crashing in GestureRecognizer on B4i?
I've just upgraded to 1.15 and my previously working app crashes as soon as touch the screen with the following message

I have no errors, in the simulator and on a real device.
It is better to open a new thread.

Alessandro71 · Jul 11, 2021

I was able to reproduce the issue with your B4A Example package also, so I'm still using this thread because it looks like a library issue.
Here are the steps I followed (environment is B4i 7.20 with hosted builder: please note that this is a B4i, not a B4A issue)
- Download the B4A Example zip from the first page
- Extract
- Download GestureRecognizer.bas from the link in the first page also, and put it in the B4i project directory
- Flag ASPageViewer in the Libraries Manager tab (it's missing in the example project)
- Change the provisioning file and the package name to match my original project (along with a blessing to Apple for turning even a simple step into a waste of time)
- Compile in Debug mode and send to B4i Bridge on a real device
The app starts fine, but as soon as you touch the screen, it crashes with

B4X:

Error occurred on line: 174 (GestureRecognizer)

Line 174 is

B4X:

att.NumberOfTaps=Numtaps

Where a warning #22 is also present since NumberOfTaps is an InputStream while Numtaps is an Int

Alexander Stolte · Jul 11, 2021

Alessandro71 said:
Download GestureRecognizer.bas from the link in the first page also, and put it in the B4i project directory

then download the .bas file againn, I have now added the class to the 1st post. Months ago I had already adapted the class for the ASCalendarAdvanced there I had said error.

wimpie3 · Jul 21, 2021

Alexander Stolte said:
Update
1.14

[B4I only] Add Scroll - enable or disable scroll with finger

In some cases it is useful to prevent scrolling. Especially if you work with several xCustomLsitView at the same time.
In B4I you can disable native, in B4A native is not possible. There you have to add a dummy item, which then blocks the touch event.
An example from a real project of mine:

B4X:

Private Sub ASCalendarAdvanced1_TouchDown #If B4I ASViewPager1.Scroll(False) #End If End Sub

Why do I have to deactivate the ViewPager to expand the calendar with my finger?
Answer: as soon as I drag the calendar downwards, I also address the ViewPager at the same time and it scrolls along and that is not a nice behavior.

When do I enable the ViewPager?
The calendar has an event called "_TouchUp" so I can be sure that the user has his fingers off the ViewPager and can activate it again.

Sorry but this is not very clear to me. What do I have to do to disable finger scrolling completely? I guess for IOS it's:

B4X:

    #If B4I
    ASViewPager1.Scroll(False)
    #End If

But how do you do it on Android?

Alexander Stolte · Jul 22, 2021

wimpie3 said:
Sorry but this is not very clear to me. What do I have to do to disable finger scrolling completely? I guess for IOS it's:

yes, in B4I the scrollview has an internal function to disable swiping. The B4A listview unfortunately does not have this.

wimpie3 said:
But how do you do it on Android?

In B4A you have to place a panel with the full width and length and catch the touch event from it.
An example is attached.
And if you want to enable it again, simply call panel1.visible = False

wimpie3 · Jul 22, 2021

A bit cumbersome, but thanks.

Alexander Stolte · Jul 22, 2021

wimpie3 said:
A bit cumbersome, but thanks.

It is not possible otherwise!
I could still make it build in...

wimpie3 · Jul 22, 2021

Alexander Stolte said:
It is not possible otherwise!
I could still make it build in...

Yes why not, I think other people could find this interesting as well. As long as the panel supports click-throughs (we still need to be able to fill in form fields for instance on the page below the panel) I think I'd prefer this solution.

Alexander Stolte · Jul 23, 2021

Update

1.16
- set Scroll is now B4X - disable the swipe/scroll
  - In B4J the arrow keys (Left/Right/Up/Down) are disabled if you deactivate the swipe/scroll
- New property isScrollEnabled - checks if the swipe/scroll is enabled or disabled
- Intern Function iif2 removed and the core iif is now used
  - B4A V11+ - B4J V9.10+ - B4I V7.50+

wimpie3 · Jul 25, 2021

Alexander Stolte said:
Update

1.16

set Scroll is now B4X - disable the swipe/scroll

In B4J the arrow keys (Left/Right/Up/Down) are disabled if you deactivate the swipe/scroll

New property isScrollEnabled - checks if the swipe/scroll is enabled or disabled

Intern Function iif2 removed and the core iif is now used

B4A V9.10+ - B4J V9.10+ - B4I V7.50+

Thanks, great work!

When isScrollEnabled is false, are events still passed onto the underlying views? In other words, can you still scroll through a list view on a view page for instance?

Alexander Stolte · Jul 25, 2021

wimpie3 said:
can you still scroll through a list view on a view page for instance?

Anything above the viewpager, yes.

wimpie3 · Jul 25, 2021

But not to the contents of the current visible page inside the page viewer?

Alexander Stolte · Jul 25, 2021

Update

1.18
- PageChanged Event is now firing in some cases with a delay, because of a scroll animation
- BugFix B4A setScroll - Events from other views are now no longer blocked

Alexander Stolte · Jul 26, 2021

Update

1.19
- BugFix on NextPage and PreviousPage

angel_ · Jul 28, 2021

Alexander Stolte said:
Update

1.18

PageChanged Event is now firing in some cases with a delay, because of a scroll animation

BugFix B4A setScroll - Events from other views are now no longer blocked

When sliding to the sides the tab line has a little delay, I liked it better before.

~~By the way, the problem I had with the intermediate position of the tab seems to be solved~~

B4A Library [B4X] [XUI] AS ViewPager based on xCustomListView

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