VB6 QR-Encoding+Decoding and IME-Window-Positioning

This Demo depends on vbRichClient5 (version 5.0.21 and higher), as well as the latest vbWidgets.dll.
One can download both new packages from the Download-page at: http://vbrichclient.com/#/en/Downloads.htm
(vbWidgets.dll needs to be extracted from the GitHub-Download-Zip and placed beside vbRichClient5.dll,
there's small "RegisterInPlace-Scripts" for both Dll-Binaries now).

After both dependencies were installed, one can load the below Demo-Project into the VB-IDE:
QRandIMEDemo.zip

According to the Title of this Thread, we try to show the:

Free positioning of an IME-Window:
delegating its IME_Char-Messages into free choosable Widget-controls (the Demo does
that against cwTextBox-Widgets exclusively - but could accomplish that also against cwLabels
or cwImages.

Here is the interesting part (the IME-API-Declarations and Wrapper-Functions are left out),
which is contained in the new cIME-Class (available in the Code-Download from the vbWidgets-GitHub-Repo):

Code:

'RC5-SubClasser-Handler

Private Sub SC_WindowProc(Result As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long)

Const WM_IME_SETCONTEXT = 641, WM_IME_STARTCOMPOSITION = 269, WM_IME_CHAR = 646

On Error GoTo 1



   Select Case Msg

      Case WM_IME_SETCONTEXT

        SwitchOpenStatus wParam

        

      Case WM_IME_STARTCOMPOSITION

        HandleIMEPos

      

      Case WM_IME_CHAR

        Dim WFoc As cWidgetBase, KeyCode As Integer

        Set WFoc = FocusedWidget: KeyCode = CInt("&H" & Hex(wParam And &HFFFF&))

        If Not WFoc Is Nothing Then 

           If WFoc.Key = tmrFoc.Tag Then RaiseEvent HandleIMEChar(WFoc, KeyCode, ChrW(KeyCode))

        End If

        Exit Sub 'handled ourselves - so we skip the default message-handler at the end of this function

   End Select

  

1: Result = SC.CallWindowProc(Msg, wParam, lParam)

End Sub

 

Private Sub tmrFoc_Timer()

  HandleIMEPos

End Sub



Private Function FocusedWidget() As cWidgetBase

  If Cairo.WidgetForms.Exists(hWnd) Then Set FocusedWidget = Cairo.WidgetForms(hWnd).WidgetRoot.ActiveWidget

End Function



Private Sub HandleIMEPos()

Dim WFoc As cWidgetBase, AllowIME As Boolean

On Error GoTo 1



   Set WFoc = FocusedWidget

   If WFoc Is Nothing Then

     tmrFoc.Tag = ""

   Else

     RaiseEvent HandleIMEPositioning(WFoc, AllowIME)

     If AllowIME Then tmrFoc.Tag = WFoc.Key

   End If

  

1: SwitchOpenStatus AllowIME

End Sub

As one can see, this Class is (currently) only raising two Events to the outside -
received by a hosting (RC5) cWidgetForm-Class.

The elsewhere mentioned problems with "forcibly ANSIed" IME-WChars do not happen in
this Demo, because of a "full queue of W-capable APIs" (including a W-capable MessageLoop,
which is available in the RC5 per Cairo.WidgetForms.EnterMessageLoop...

The Integration of an RC5-cWidgetForm into an existing VB6-Project is relative easy (no need
to rewrite everything you have) - this Demo shows how one can accomplish that, by showing
the RC5-Form modally - starting from a normal VB-Form-CommandButton:

Here's all the code in the normal VB6-Starter-Form, which accomplishes that:

Code:

Option Explicit



Private VBFormAlreadyUnloaded As Boolean



Private Sub cmdShowRC5IMEForm_Click()

  With New cfQRandIME ' instantiate the RC5-FormHosting-Class

  

    .Form.Show , Me 'this will create and show the RC5-Form with the VB-Form as the underlying Parent

    

    'now we enter the W-capable RC5-message-pump, which will loop "in  place" till the RC5-Form gets closed again

    Cairo.WidgetForms.EnterMessageLoop True, False

 

    'the RC5-Form was closed, so let's read-out the Public Vars of its hosting cf-Class

    If Not VBFormAlreadyUnloaded Then '<- ... read the comment in Form_Unload, on why we need to check this flag

      Set Picture1.Picture = .QR1.QRSrf.Picture

      Set Picture2.Picture = .QR2.QRSrf.Picture

    End If

  End With

End Sub



Private Sub Form_Unload(Cancel As Integer) 'this can happen whilst the RC5-ChildForm is showing, ...

  VBFormAlreadyUnloaded = True  'so we set a Flag, to not implicitely load this VB-ParentForm again, when filling the Result-PicBoxes

End Sub



Private Sub Form_Terminate() 'the usual RC5-cleanup call (when the last VB-Form was going out of scope)

  If Forms.Count = 0 Then New_c.CleanupRichClientDll

End Sub

The above Starter-Form (fMain.frm) will look this way

And pressing the CommandButton, it will produce the modal RC5-WidgetForm:

What one can see above is two (cwTextBox-based) Edit-Widgets - and the left one
is showing the free positioned IME-Window - the IME-Window (when visible), will
jump automatically, as soon as the user switches the Input-Focus to a different Widget.

To test this in a bit more extreme scenario even, I've made the two cwQRSimple-Widgets
(in the lower section of the Form) movable - and in case the IME-Window is shown
below one of them as in this ScreenShot:

... the IME-Window will follow the currently focused QR-Widget around, when it's dragged
with the Mouse...

Here's the complete code of the cfQRandIME.cls (which hosts the RC5-cWidgetForm-instance):

Code:

Option Explicit



Public WithEvents Form As cWidgetForm, WithEvents IME As cIME



Public QREnc As New cQREncode, QRDec As New cQRDecode 'the two (non-visible) QR-CodecClass-Vars

Public TB1 As cwTBoxWrap, TB2 As cwTBoxWrap 'the two TextBox-Wrapper-Classes

Public QR1 As cwQRSimple, QR2 As cwQRSimple 'the two QR-Widgets

 

Private Sub Class_Initialize()

  Set Form = Cairo.WidgetForms.Create(vbFixedDialog, "QR-Widgets and IME-Window-Positioning", , 800, 600)

      Form.IconImageKey = "QRico2"

      Form.WidgetRoot.ImageKey = "bgPatForm"

      Form.WidgetRoot.ImageKeyRenderBehaviour = ImgKeyRenderRepeat

      

  Set IME = New cIME 'create the vbWidgets.cIME-instance

      IME.BindToForm Form '...and bind our cWidgetForm-instance to it (IME will throw two Events at us then)

End Sub



Private Sub Form_Load() 'handle Widget-Creation and -Adding on this Form

  Form.Widgets.Add(New cwSeparatorLabel, "Sep1", 11, 8, Form.ScaleWidth - 22, 42).SetCaptionAndImageKey "EditBox-DemoArea", "Edit", &H11AA66

    Set TB1 = Form.Widgets.Add(New cwTBoxWrap, "TB1", 25, 60, 280, 38)

        TB1.TBox.CueBannerText = "Session-Login..."

        TB1.Widget.ImageKey = "session1"

    Set TB2 = Form.Widgets.Add(New cwTBoxWrap, "TB2", 325, 60, 280, 38)

        TB2.TBox.CueBannerText = "Place some Info here..."

        TB2.Widget.ImageKey = "info1"

      

  Form.Widgets.Add(New cwSeparatorLabel, "Sep2", 11, 155, Form.ScaleWidth - 22, 42).SetCaptionAndImageKey "QRCode-DemoArea", "Preview", &H1030EE

    Set QR1 = Form.Widgets.Add(New cwQRSimple, "QR1", 25, 240, 250, 220)

    Set QR2 = Form.Widgets.Add(New cwQRSimple, "QR2", 325, 280, 250, 220)

End Sub



Private Sub Form_BubblingEvent(Sender As Object, EventName As String, P1 As Variant, P2 As Variant, P3 As Variant, P4 As Variant, P5 As Variant, P6 As Variant, P7 As Variant)

  If EventName = "Change" And TypeOf Sender Is cwTextBox Then 'we handle the Change-Event of the QRWidget-Child-Textboxes here

    If Not (Sender Is QR1.TBox Or Sender Is QR2.TBox) Then Exit Sub

    

    'resolve to the (TextBox-Hosting) cwQRSimple-Widget in question

    Dim QR As cwQRSimple: Set QR = IIf(Sender Is QR1.TBox, QR1, QR2)

    

    'Encode the current Text of our QR-Widget - and place the returned Pixel-Surface in QR.QRSrf

    Set QR.QRSrf = QREnc.QREncode(New_c.Crypt.VBStringToUTF8(QR.Text))

 

    'to verify, we perform a true Decoding of the QR-Text from the Pixels of the just created QR-Widgets QR-Surface

    QRDec.DecodeFromSurface QR.QRSrf

    'and reflect this decoded Unicode-StringResult in the Caption of the QR-Widget (so, ideally QR.Caption should match QR.Text)

    If QRDec.QRDataLen(0) Then QR.Caption = New_c.Crypt.UTF8ToVBString(QRDec.QRData(0)) Else QR.Caption = ""

  End If

  

  'the QR-Widgets (cwQRSimple) are moveable - and in case they have an active IME-Window, we will move that too

  If EventName = "W_Moving" And TypeOf Sender Is cwQRSimple Then IME_HandleIMEPositioning Sender.TBox.Widget, True

End Sub



Private Sub IME_HandleIMEPositioning(FocusedWidget As cWidgetBase, AllowIME As Boolean)

  If TypeOf FocusedWidget.Object Is cwTextBox Then

    AllowIME = True '<- here we allow IME-Windows only for cwTextBox-Widgets (but we could also allow IME on other Widget-Types)

    IME.SetPosition FocusedWidget.AbsLeftPxl + 3, FocusedWidget.AbsTopPxl + FocusedWidget.ScaleHeightPxl + 4

  End If

End Sub



Private Sub IME_HandleIMEChar(FocusedWidget As cWidgetBase, ByVal IMEKeyCode As Integer, IMEWChar As String)

  FocusedWidget.KeyPress IMEKeyCode 'simply delegate the incoming IMEKeyCode into the Widget in question

  'the above is the more generic delegation-method into any Widget (which are all derived from cWidgetBase)

  

  '*alternatively* (for cwTextBoxes, which is the only Widget-Type we allow IME for in this Demo here)

  'we could also use:

'  Dim TB As cwTextBox

'  Set TB = FocusedWidget.Object

'      TB.SelText = IMEWChar

End Sub

Note the two blue marked EventHandlers at the bottom of the above code-section, which
make use of the two cIME-Events, which were mentioned at the top of this posting.

QR-Code Generation and Decoding:

The base QR-Encoding/Decoding-support is now included in vb_cairo_sqlite.dll (from two C-libs which are now statically contained).
And the vbWidgets.dll project contains the two Wrapper-Classes (cQREncode, cQRDecode) for these new exposed APIs.

cQREncode/cQRDecode is used in conjunction with thrown Change-Events of our cwQRSimple-Widgets
(which you saw in the ScreenShot above).

Here's the central Eventhandler which is contained in the RC5-WidgetForm-Hosting Class (cfQrandIME):

Code:

Private Sub Form_BubblingEvent(Sender As Object, EventName As String, P1, P2, P3, P4, P5, P6, P7)

  If EventName = "Change" And TypeOf Sender Is cwTextBox Then 'we handle the Change-Event of the QRWidget-Child-Textboxes here

    If Not (Sender Is QR1.TBox Or Sender Is QR2.TBox) Then Exit Sub

    

    'resolve to the (TextBox-Hosting) cwQRSimple-Widget in question

    Dim QR As cwQRSimple: Set QR = IIf(Sender Is QR1.TBox, QR1, QR2)

    

    'Encode the current Text of our QR-Widget - and place the returned Pixel-Surface in QR.QRSrf

    Set QR.QRSrf = QREnc.QREncode(New_c.Crypt.VBStringToUTF8(QR.Text))

 

    'to verify, we perform a true Decoding of the QR-Text from the Pixels of the just created QR-Widgets QR-Surface

    QRDec.DecodeFromSurface QR.QRSrf

    'and reflect this decoded Unicode-StringResult in the Caption of the QR-Widget (so, ideally QR.Caption should match QR.Text)

    If QRDec.QRDataLen(0) Then QR.Caption = New_c.Crypt.UTF8ToVBString(QRDec.QRData(0)) Else QR.Caption = ""

  End If

  

  'the QR-Widgets (cwQRSimple) are moveable - and in case they have an active IME-Window, we will move that too

  If EventName = "W_Moving" And TypeOf Sender Is cwQRSimple Then IME_HandleIMEPositioning Sender.TBox.Widget, True

End Sub

So that's quite simple as far as QR-codes are concerned (because of the Bubbling-Event-mechanism of the
RC5-WidgetEngine - but also due to the quite powerful Cairo-ImageSurface-Objects, which are used in the
cQREncode/Decode-classes to transport the encoded (or to be decoded) Pixel-Information.

From a cCairoSurface it is possible, to write to PNG-, or JPG-ByteArrays or -Files at any time,
so exporting of the QR-Code-Images is not covered by this Demo - but would require only
a line of Code or two, in concrete adaptions of the above example.

Have fun,

Olaf

Attached Files

QRandIMEDemo.zip (115.8 KB)

Latest Images

Trending Articles

Latest Images