B4X: ABMaterials B4JS – 07 The UI Connection (part 2)

b4jstut07

This is the second part of the UI (ABMaterial) Connection. I wanted to do this one before releasing ABM 4.25 because it contains some important concepts on defining the events for B4JS in an ABMPage.

I’ve created a B4JS Demo that includes the source code for all the tutorials (so far). It will be included in the download zip.

One of the major advantages of B4JS is that you can check a lot of the users input before heading to the server. And because we have some events (like KeyDown, KeyUp) that we do not have on the server side, we can even do some ‘masking’.

This example makes such a mask for a credit card (every 4 chars a space is inserted and a check is done). It is not finished (e.g. it does not take into account if the user puts its cursor in the middle), but it shows some major concepts of B4JS.

B4JSTut07image

Lets dive into the B4X code:

The B4JS class B4JSInputChecker:

<br>
'Class module
Sub Class_Globals
   Private Page As ABMPage 'ignore, just to be able to run ABMPage functions
   Private ToastID As Int
   Private ABM As ABMaterial 'ignore, just to be able to use ABM constants
End Sub

'Initializes the object. You can add parameters to this method if needed.
Public Sub InitializeB4JS

End Sub

public Sub InputDown(Key As String) As Boolean
   'Log("Down key: " &amp; Key)
   Dim cardInp As ABMInput 'ignore that it is not initialized, you can't initialize one in B4JS anyway
   cardInp.B4JSUniqueKey = "cardInp001"
   Dim CardNumber As String = cardInp.B4JSText
   If Key = "Backspace" Then
       If CardNumber.SubString2(0,CardNumber.Length-1).EndsWith(" ") Then
           CardNumber = CardNumber.SubString2(0,CardNumber.Length - 2)
           cardInp.B4JSText = CardNumber
           CheckCard(CardNumber.Replace(" ", ""))
           ' consume the event
           Return True
       End If
       ' let the Keydown do its thing
       Return False
   End If

   If CardNumber.Length = 19 Then
       CheckCard(CardNumber.Replace(" ", ""))
       Return True
   End If

   If Not(IsNumber(Key)) Then
       ToastID = ToastID + 1
       Page.B4JSShowToast("InputToast" &amp; ToastID, "red", "Please only enter numbers!", 3000, False)
       ' consume the event
       Return True
   End If

   ' let the Keydown do its thing
   Return False
End Sub

public Sub InputUp(KeyCode As Int) As Boolean
   'Log("Up keycode: " &amp; KeyCode)

   Dim cardInp As ABMInput 'ignore that it is not initialized, you can't initialize one in B4JS anyway
   cardInp.B4JSUniqueKey = "cardInp001"
   Dim CardNumber As String = cardInp.B4JSText

   ' we down't want to raise it for the combination keys
   ' AltGraph, Shift, Ctrl, Alt
   Select Case KeyCode
       Case 16, 17, 18
           ' consume the event
           Return True
       Case 8 ' and for the backspace, jump out too: we do not want to re-append the space
           ' consume the event
           CheckCard(CardNumber.Replace(" ", ""))
           Return True
   End Select

   Select Case CardNumber.Length
       Case 4,9,14
           cardInp.B4JSText = CardNumber &amp; " "
   End Select

   'a valid 4012 8888 8888 1881
   CheckCard(CardNumber.Replace(" ", ""))

   ' consume the event
   Return True
End Sub

public Sub CheckCard(CardNumber As String)
   'a valid 4012 8888 8888 1881
   Dim isValid As Boolean = Page.B4JSRunInlineJavascriptMethod("validateCCNum", Array As Object(CardNumber.Replace(" ", "")))
   Dim btnCheck As ABMButton 'ignore
   btnCheck.B4JSUniqueKey = "btnCheck"
   ' for our setButtonCSS method we do need the real ID of the button.  We can get this with the Page.B4JSGetComponentIDFromUniqueID() method!
   Dim ID As String = Page.B4JSGetComponentIDFromUniqueID("btnCheck")
   If isValid Then
       btnCheck.B4JSEnabled = True
       Page.B4JSRunInlineJavascriptMethod("setButtonCSS", Array As String(ID, "background-color: #4caf50 !important"))
   Else
       btnCheck.B4JSEnabled = False
       Page.B4JSRunInlineJavascriptMethod("setButtonCSS", Array As String(ID, "background-color: #F44336 !important"))
   End If
End Sub

' every method you want to call with a B4JSOn... call MUST return a boolean
public Sub InputGotFocus() As Boolean
   ToastID = ToastID + 1
   Page.B4JSShowToast("InputToast" &amp; ToastID, "red", "You are entering the Credit Card", 3000, False)
   ' consume the event
   Return True
End Sub

' every method you want to call with a B4JSOn... call MUST return a boolean
public Sub InputLostFocus() As Boolean
   ToastID = ToastID + 1
   Page.B4JSShowToast("InputToast" &amp; ToastID, "red", "Leaving the Credit Card field...", 3000, False)
   ' consume the event
   Return True
End Sub

' every method you want to call with a B4JSOn... call MUST return a boolean
public Sub CheckInput() As Boolean
   Dim switch1 As ABMSwitch  'ignore that it is not initialized, you can't initialize one in B4JS anyway
   switch1.B4JSUniqueKey = "switch001"

   Dim HasError As Boolean = False

   ToastID = ToastID + 1
   If Not(switch1.B4JSState) Then
       Page.B4JSShowToast("SwitchToast" &amp; ToastID, "green", "Please put the Switch to ON!", 3000, False)
       HasError = True
   End If

   ToastID = ToastID + 1
   Dim CheckBox1 As ABMCheckbox 'ignore that it is not initialized, you can't initialize one in B4JS anyway
   CheckBox1.B4JSUniqueKey = "CheckBox001"
   If Not(CheckBox1.B4JSState) Then
       Page.B4JSShowToast("CheckboxToast" &amp; ToastID, "green", "Please check the Checkbox!", 3000, False)
       HasError = True
   End If

   If HasError = False Then
       ToastID = ToastID + 1
       Page.B4JSShowToast("CheckboxInput" &amp; ToastID, "green", "All looks OK, well done!", 3000, False)
   End If
   ' consume the event
   Return True
End Sub

' every method you want to call with a B4JSOn... call MUST return a boolean
public Sub SwitchClick() As Boolean
   Dim switch1 As ABMSwitch  'ignore that it is not initialized, you can't initialize one in B4JS anyway
   switch1.B4JSUniqueKey = "switch001"

   ToastID = ToastID + 1
   If switch1.B4JSState Then
       Page.B4JSShowToast("SwitchToast" &amp; ToastID, "green", "Switch is ON", 3000, False)
   Else
       Page.B4JSShowToast("SwitchToast" &amp; ToastID, "green", "Switch is OFF", 3000, False)
   End If
   ' consume the event
   Return True
End Sub

' every method you want to call with a B4JSOn... call MUST return a boolean
public Sub CheckBoxClick() As Boolean
   Dim CheckBox1 As ABMCheckbox 'ignore that it is not initialized, you can't initialize one in B4JS anyway
   CheckBox1.B4JSUniqueKey = "CheckBox001"
   ToastID = ToastID + 1
   If CheckBox1.B4JSState Then
       Page.B4JSShowToast("CheckboxToast" &amp; ToastID, "green", "Checkbox ON", 3000, False)
   Else
       Page.B4JSShowToast("CheckboxToast" &amp; ToastID, "red", "Checkbox OFF", 3000, False)
   End If
   ' consume the event
   Return True
End Sub

' every method you want to call with a B4JSOn... call MUST return a boolean
public Sub RadioClick() As Boolean
   Dim Radio1 As ABMRadioGroup 'ignore that it is not initialized, you can't initialize one in B4JS anyway
   Radio1.B4JSUniqueKey = "Radio001"
   ToastID = ToastID + 1
   Page.B4JSShowToast("RadioToast" &amp; ToastID, "green", "Active Radio = " &amp;  Radio1.B4JSGetActive, 3000, False)
   ' example of setting the active radio
   'If Radio1.B4JSGetActive = 0 Then
   '   Radio1.B4JSSetActive(2)
   'End If
   Return True
End Sub

public Sub RangeOnChange(start As String, Stop As String, ConsumeEvent As Boolean) As Boolean
   Log("B4JS Start: " &amp; start)
   Log("B4JS Stop: " &amp; Stop)
   Return ConsumeEvent
End Sub

#if JAVASCRIPT
function setButtonCSS(id, val) {
   $('#' + id).attr('style', val);
}
#End If

And creating the components in ConnectPage():

public Sub ConnectPage()
   '   connecting the navigation bar
   ABMShared.ConnectNavigationBar(page)

   page.Cell(1,1).AddComponent(ABMShared.BuildParagraph(page,"par1","This demo is practical example of B4JS. It uses the B4JSInputChecker B4JS class.") )

   ' input
   Dim cardInp As ABMInput
   cardInp.Initialize(page, "inp1", ABM.INPUT_TEXT, "Credit Card", False, "")
   cardInp.B4JSUniqueKey = "cardInp001"
   ' special case, it has to pass at least the pressed key (ABM.B4JS_PARAM_INPUTKEY or ABM.B4JS_PARAM_INPUTKEYCODE) to it!
   cardInp.B4JSOnKeyDown("B4JSInputChecker", "InputDown", Array As Object(ABM.B4JS_PARAM_INPUTKEY))
   cardInp.B4JSOnKeyUp("B4JSInputChecker", "InputUp", Array As Object(ABM.B4JS_PARAM_INPUTKEYCODE))
   ' some focus stuff
   cardInp.B4JSOnGotFocus("B4JSInputChecker", "InputGotFocus", Null)
   cardInp.B4JSOnLostFocus("B4JSInputChecker", "InputLostFocus", Null)
   page.Cell(2,1).AddComponent(cardInp)

   ' switch
   Dim switch1 As ABMSwitch
   switch1.Initialize(page, "switch1", "ON", "OFF", False, "")
   switch1.B4JSUniqueKey = "switch001"
   switch1.B4JSOnClick("B4JSInputChecker", "SwitchClick", Null)
   page.Cell(3,1).AddComponent(switch1)

   ' checkbox
   Dim CheckBox1 As ABMCheckbox
   CheckBox1.Initialize(page, "CheckBox1", "B4JS Checkbox", False, "")
   CheckBox1.B4JSUniqueKey = "CheckBox001"
   CheckBox1.B4JSOnClick("B4JSInputChecker", "CheckBoxClick", Null)
   page.Cell(4,1).AddComponent(CheckBox1)

   ' radiogroup
   Dim Radio1 As ABMRadioGroup
   Radio1.Initialize(page, "Radio1", "")
   Radio1.B4JSUniqueKey = "Radio001"
   Radio1.AddRadioButton("radio 0", True)
   Radio1.AddRadioButton("radio 1", True)
   Radio1.AddRadioButton("radio 2", True)
   Radio1.SetActive(1)
   Radio1.B4JSOnClick("B4JSInputChecker", "RadioClick", Null)
   page.Cell(5,1).AddComponent(Radio1)

   ' range
   Dim range As ABMRange
   range.Initialize(page, "range", 10, 20, 0, 100, 1, "")
   range.B4JSUniqueKey = "range001"
   ' special case, it has to pass at least ABM.B4JS_PARAM_RANGESTART & ABM.B4JS_PARAM_RANGESTOP!

   range.B4JSOnChange("B4JSInputChecker", "RangeOnChange", Array As Object(ABM.B4JS_PARAM_RANGESTART, ABM.B4JS_PARAM_RANGESTOP, True))
   page.Cell(6,1).AddComponent(range)

   ' button
   Dim btnCheck As ABMButton
   btnCheck.InitializeFlat(page, "btnCheck", "", "", "Check", "red")
   btnCheck.Enabled = False
   btnCheck.B4JSUniqueKey = "btnCheck"
   btnCheck.B4JSOnClick("B4JSInputChecker", "CheckInput", Null)
   page.Cell(7,1).AddComponent(btnCheck) 

   ' refresh the page
   page.Refresh
   ' Tell the browser we finished loading
   page.FinishedLoading
   ' restoring the navigation bar position
   page.RestoreNavigationBarPosition
End Sub

As you see, for every component we want to use in a B4JS class, we have to set the B4JSUniqueKey property.

We also define some events (B4JSOn…). You notice some of them have special parameters, e.g. the ABMInputs B4JSOnKeyDown event. This event MUST have at least the parameter ABM.B4JS_PARAM_INPUTKEY or ABM.B4JS_PARAM_INPUTKEYCODE to be able to work.

For the B4JSOnKeyDown event for example, we pass the ABM.B4JS_PARAM_INPUTKEY param. The order of the params is very important!

In our B4JS class, this is our method definition:

public Sub InputDown(Key As String) As Boolean<span id="mce_SELREST_start" style="overflow:hidden;line-height:0;">&#65279;</span>

Here ABM.B4JS_PARAM_INPUTKEY’s value will be put into the Key param.

You can add additional params (if needed) as for example is done in the range.B4JSOnChange event declaration.

This concludes the tutorial. ABM 4.25 is now available for download for all donators in the feedback app!

Alwaysbusy

Click here to Donation and support ABMaterial

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