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.

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
NEW - Vertical
NEW - Carousel
NEW - Lazy Loading

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)
  - PageClick (Index As Int, Value As Object)
  - ReachEnd
  - ScrollChanged (Offset As Int)
  - TouchBegin
  - TouchEnd
- Fields:
  - Tag As Object
- Functions:
  - AddPage (xpnl_layout As B4XView, value As Object) As String
  - AddPageAt (index As Int, xpnl_layout As B4XView, value As Object) As String
    Adds an page at a special position
  - Base_Resize (Width As Double, Height As Double) As String
  - Class_Globals As String
  - Clear 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
  - getSize As Int
  - 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
  - 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) As String
  - setCurrentIndex2 (index As Int) As String
    sets the current index - jumps to the item
  - setIgnorePageChangedEvent (ignore As Boolean) As String
  - setIgnorePageChangeEvent (ignore As Boolean) 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]
  - IgnorePageChangedEvent
  - IgnorePageChangeEvent
  - isScrollEnabled As Boolean [read only]
    Checks if the swipe/scroll is enabled or disabled
  - 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

Have Fun

Alexander Stolte · Jan 26, 2022

Alexander Stolte said:
setCurrentIndex2 (index As Int) As String
sets the current index - jumps to the item

Lello1964 said:
a Property to scroll to page without effects ?, to move from a page to another without effects,

Lello1964 · Jan 26, 2022

there isn't SetCurrentIndex2 in ASViewPager,
also i have Pagine.AddPage(PanelServizi,"PaginaServizi")
is string not int

Lello1964 · Jan 26, 2022

i've found :CurrentIndex2 but it's int not String

Alexander Stolte · Jan 26, 2022

Update

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

Lello1964 · Jan 27, 2022

I replaced the B4A TabStripPager library with AsViewPager, because there is the possibility of blocking the side scroll. Unfortunately, I have encountered a problem that I cannot solve. If I move to a page and from code I modify an edittext that is on a page not visible at that moment; at the end of the operations, when I return to the main page, after a few seconds, for no reason, two pages in the middle are displayed, one half contains the edittext that was corrected by the code. I was unable to solve the problem. If I delete the editText editing, everything works fine. I can't change all the code to fix the problem. Has it already happened to anyone?

Alexander Stolte · Jan 27, 2022

For such a problem it is probably better to make a new thread and create an example project which shows the problem. Maybe the EditText get a focus and are triggered by Manifest keyboard settings?

Lello1964 · Jan 27, 2022

thanks for the reply, but i can't reproduce the problem with an example.

Alexander Stolte · Jan 30, 2022

Update

1.26
- 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

Lazy Loading
Lazy Loading can significantly improve the performance of pages with complex items.
Example: Calendar or Scheduler with 500 or more pages (Weeks, Months, Days)

Use:

Enable the "Lazy Loading" property in the designer
Add the "LazyLoadingAddContent" event to your form
Use the "Parent" parameter from the event to add your layout or views to this panel

wimpie3 · Jan 30, 2022

Good news about the lazy loading! Will you also modify your calendar to support this? Can be interesting if many, many months have to be shown.

Alexander Stolte · Jan 30, 2022

wimpie3 said:
Will you also modify your calendar to support this?

Yes, in the next weeks, currently I use the feature in a not yet released view. And in the calendar some things need to be adjusted to make lazy loading work, but I'm aware that there can be performance issues if there are many events on the calendar, which hopefully can be fixed with this.

Alexander Stolte · Feb 10, 2022

Update

1.27
- Add get and set LazyLoadingExtraSize

Alexander Stolte · Feb 13, 2022

Update

1.28
- Important LazyLoading improvments

Alexander Stolte · Mar 1, 2022

Update

1.29
- Add Commit - Triggers the LazyLoadingAddContent event
  - Call this after you have filled the list
- LazyLoading BugFixes

Commit

B4X:

For i = 0 To 500 -1   
    Dim xpnl As B4XView = xui.CreatePanel("")
    xpnl.SetLayoutAnimated(0,0,0,Root.Width,Root.Height)
    ASViewPager1.AddPage(xpnl,i +1)
Next
    
    Sleep(0)
    ASViewPager1.Commit

Alexander Stolte · Mar 8, 2022

Update

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

Example use case

B4X:

xASVP_Horizontal.AddPage(xpnl_background,"")
Sleep(0)
xASVP_Horizontal.ResetLazyloadingIndex
xASVP_Horizontal.Commit

In the example I am dynamically adding more panels after the PageChanged event, the problem is the lazy loading function has already been triggered and would not trigger again as the CurrentIndex has not changed after the add, so the newly added page would not be populated if it were on the next page. If we reset the internal LazyLoading index and then call commit, then it is guaranteed to find the empty newly added page and populate it via the event.

I needed it in the Version 3.0 of the ASCalendarAdvanced View.

Alexander Stolte · Mar 17, 2022

Update

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

Now you don't need to be afraid of resizing the window in B4J, it works much better now!
Why the Loading Panel?
Because otherwise you will see other pages, because when resizing the xclv not all panels are adjusted at the same time and this is a workaround to deliver a better user experience.

Version 1.30 is attached in the first post as backup.

Blueforcer · Mar 26, 2022

Is the Carousel function still beta?
when i check it it doesnt change anything in B4A, no infite scrolling

Alexander Stolte · Mar 26, 2022

Blueforcer said:
Is the Carousel function still beta?

Works great on B4A.

Blueforcer said:
when i check it it doesnt change anything in B4A, no infite scrolling

Blueforcer · Mar 26, 2022

Alexander Stolte said:
Works great on B4A.

View attachment 127051

I only have 2 pages at the moment, maybe this is the problem?

Alexander Stolte · Mar 26, 2022

Blueforcer said:
I only have 2 pages at the moment, maybe this is the problem?

be sure, you test it in release mode.

Blueforcer · Mar 26, 2022

Alexander Stolte said:
View attachment 127055
be sure, you test it in release mode.

Ah now i got it..
it does not work in vertical mode.
It works in horizontal mode, but between Last and First Page and vice versa its a instant screenjump instead of scrolling, is this correct?

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

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