Get Picture Box hWnd.

[Chris]

Does antbody know how to get the PictureBox hWnd? Assume the PictureBox Object does not support the Picture1.hWnd properties.

Because I writing a program that run under WinCE OS where the PictureBox does not support the Picture1.hWnd properties.

Your feedback is very useful!

[kedaman]

Hehe, that was a pretty hard Q, i think, if WinCE does not support hWnds then why do you need it?

[Chris]

But I currently developing a program that run under WinCE. So I need to resolve it. I know it is a hard Q, but I know you're guy should be able to provide me some idea about this task.

In pricture box object, it does not have the Title, so can not use the FindWindow API function to locate the hWnd. Arhhhh Do help me!!!

[G.Kumaraguru]

Use Findwindow api but use the class name, it is

ThunderPictureBox

in VB.

[Chris]

Originally posted by G.Kumaraguru
Use Findwindow api but use the class name, it is

ThunderPictureBox

in VB.

I did try it, but how about the lpWindowName arguement? We can leave it blank or put "". But sis put it as "". The result is still 0. That mean the API also can not find the PictureBox.

But I used the Spy++ it does return me the PictureBox hWnd, Window, ClassName, Window Style, Window RECT value, Thread ID and Process ID. So I'm sure there must be a way to do it!

Can Some Guru help me!!!

[kedaman]

put a string variable instead of ""

[Chris]

Can not, still return zero to me. I think me can not simply pass a string to the lpWindowName arguement. Since it is one of the searching key for the FindWindow API function.

Some more hints... please...

[kedaman]

Then what about vbnull, if that doesn't work then i don't know

[gravyboy]

I was under the impression that the handle to a picture box could be obtained by just using

picture1.picture

Just to show what I mean try this

Private Sub Command1_Click()

MsgBox Picture1.Picture

End Sub

[kedaman]

Actuatlly that's the same as using picture1.picture1.handle not picture1.hwnd - you get the handle of the picture instead

[Chris]

gravyboy, yours does not work. Thanks Kedaman, it work with vbNull as the lpWindowName arguement.

Now, I've another problem... the vbNull work fine with one PictureBox control in the form. But, now I've 2 PictureBox (PictureBox1, PicureBox2) under the same Form call (frmMain.frm).

So, I still can not use the FindWindow API to get the 2 PictureBox1 and PictureBox2 hWnd value that I'll use it to set the PictureBox1 become the child Window of PictureBox2 by using the SetParent API function:

SetParent xHwnd, yHwnd

Assume the xHwnd is the handle value fot PictureBox1,
yHwnd is the handle value for PictureBox2.

So, how the single FindWindow API function can differentiate the handle for PictureBox1 and PictureBox2?

xHwnd = FindWindow("ThunderPictureBox",vbNull)
yHwnd = FindWindow("ThunderPictureBox",vbNull)

[Edited by Chris on 05-31-2000 at 06:28 AM]

[kedaman]

I'm not sure if there's any direct way then, but you could enumerate the parentwindow's childs, and get all the wnds

[Serge]

The second parameter (lpWindowName) is expected to be a string, therefore, you must pass a string data type value:

Dim lHwnd As Long

lHwnd = FindWindow("ThunderPictureBox",vbNullString)

Also, since the Picturebox belongs to the form then you better use FindWindowEx API:

Private Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" (ByVal hWnd1 As Long, ByVal hWnd2 As Long, ByVal lpsz1 As String, ByVal lpsz2 As String) As Long

Private Sub Command1_Click()
    Dim lHwnd As Long
    
    lHwnd = FindWindowEx(Me.hWnd, 0, "ThunderPictureBox", vbNullString)
End Sub

[grizzly]

Sorry for the off-topic post, but what version if VB do you have to have to develop Win CE programs? Is there an app wizard or tutorial?

Thanks,

Shawn

[Chris]

Originally posted by grizzly
Sorry for the off-topic post, but what version if VB do you have to have to develop Win CE programs? Is there an app wizard or tutorial?

Thanks,

Shawn

Just stay with you VB6 + SP3 + WinCE ToolKit for VB6 that enough already.

[kedaman]

Ok, i have this for you

Private Declare Function EnumChildWindows Lib "user32" (ByVal hWndParent As Long, ByVal lpEnumFunc As Long, ByVal lParam As Long) As Long
Private Declare Function GetParent Lib "user32" (ByVal hwnd As Long) As Long

Private returnval(), counter%, Parent&
Private Function EnumFunction(ByVal hwnd&, ByVal lParam&) As Long
    'If Parent = GetDesktopWindow Then
    'If GetParent(hwnd) <> Parent Then If GetParent(hwnd) > 0 Then EnumFunction = True: Exit Function  'Exits if it's a indirect child
    'Else
    If GetParent(hwnd) <> Parent Then EnumFunction = True: Exit Function 'Exits if it's a indirect child
    'End If
    counter = counter + 1
    ReDim Preserve returnval(counter - 1)
    returnval(counter - 1) = hwnd
    EnumFunction = True
End Function

Public Function Getchild(Parenthwnd&)
    Parent = Parenthwnd
    counter = 0
    EnumChildWindows Parenthwnd, AddressOf EnumFunction, 0
    If counter Then Getchild = returnval
End Function

[Chris]

Thanks Kedaman, your GetChild work great but it return all the available child hwnd to me, which I just interested in those have WindowClass "ThunderPictureBox"

Come on... more hints...

[kedaman]

Oh, i thought you would figure out, just make a loop checking the classnames of the wnd's and sort them out

[Chris]

Kedaman, I'll try & tell you later.

[Chris]

Hi Kedaman, I just add the GetClassName API function ontop of you code & it work. The only think is the GetClassNAme API return me the PictureBox Class Name = "ThunderPictureBoxDC" instead of "ThunderPictureBox" Anyway, I manage to differentiate between the PictureBox and others control.

Now, I have the handle for 2 different picture box, but how do I differentiate the handle is belong to which PictureBox.

Private Declare Function EnumChildWindows Lib "user32" (ByVal hWndParent As Long, ByVal lpEnumFunc As Long, ByVal lParam As Long) As Long
Private Declare Function GetParent Lib "user32" (ByVal hwnd As Long) As Long
Private Declare Function GetClassName Lib "user32" Alias "GetClassNameA" (ByVal hwnd As Long, ByVal lpClassName As String, ByVal nMaxCount As Long) As Long
Private Declare Function SetParent Lib "user32" (ByVal hWndChild As Long, ByVal hWndNewParent As Long) As Long

Private returnval(), counter%, Parent&
Private ReturnStr$, nReturn&, rethWnd$
Private PichWnd(), hWndCnt%
Private Function EnumFunction(ByVal hwnd&, ByVal lParam&) As Long
    'If Parent = GetDesktopWindow Then
    'If GetParent(hwnd) <> Parent Then If GetParent(hwnd) > 0 Then EnumFunction = True: Exit Function  'Exits if it's a indirect child
    'Else
    If GetParent(hwnd) <> Parent Then EnumFunction = True: Exit Function 'Exits if it's a indirect child
    'End If
    counter = counter + 1
    ReDim Preserve returnval(counter - 1)
    returnval(counter - 1) = hwnd
    
    ReturnStr = String(255, Chr(0))
    nReturn = GetClassName(hwnd, ReturnStr, 255)
    If nReturn <> 0 Then
        rethWnd = Left(ReturnStr, InStr(1, ReturnStr, Chr(0), vbBinaryCompare) - 1)
        If rethWnd = "ThunderPictureBoxDC" Then
            hWndCnt = hWndCnt + 1
            ReDim Preserve PichWnd(hWndCnt)
            PichWnd(hWndCnt) = hwnd
        End If
    End If
    EnumFunction = True
End Function

Public Function Getchild(Parenthwnd&)
    Parent = Parenthwnd
    counter = 0
    hWndCnt = 0
    EnumChildWindows Parenthwnd, AddressOf EnumFunction, 0
    If counter Then Getchild = returnval
    SetParent PichWnd(1), PichWnd(2)
End Function

[Serge]

Try something like this. Add a module to your project. Also, add a couple of pictureboxes a listbox and a button (for testing purposes). Copy this code to the module:

Private Declare Function GetClassName Lib "user32" Alias "GetClassNameA" (ByVal hwnd As Long, ByVal lpClassName As String, ByVal nMaxCount As Long) As Long
Public Declare Function EnumChildWindows Lib "user32" (ByVal hWndParent As Long, ByVal lpEnumFunc As Long, ByVal lParam As Long) As Long
Public m_arrHwndPicBoxes() As Long


Public Function EnumFunction(ByVal pHwnd As Long, ByVal lParam As Long) As Long
    Static intIndex As Long
    Dim lngRetVal As Long
    Dim strClassName As String
    
    'Get ClassName for pHwnd
    strClassName = Space(125)
    lngRetVal = GetClassName(pHwnd, strClassName, Len(strClassName))
    If lngRetVal Then
        strClassName = Left(strClassName, lngRetVal)
        'Check if the ClassName is ThunderPictureBox
        If strClassName = "ThunderPictureBoxDC" Then
            ReDim Preserve m_arrHwndPicBoxes(intIndex)
            m_arrHwndPicBoxes(intIndex) = pHwnd
            intIndex = intIndex + 1
        End If
    End If
    'Continue enumeration
    EnumFunction = 1
End Function

Copy this code to your form:

Private Sub Command1_Click()
    Dim i As Integer
    
    On Error Resume Next
    
    Call EnumChildWindows(Me.hwnd, AddressOf EnumFunction, 0)
    
    For i = LBound(m_arrHwndPicBoxes) To UBound(m_arrHwndPicBoxes)
        If Err.Number = 0 Then
            List1.AddItem m_arrHwndPicBoxes(i)
        End If
    Next
End Sub

[Chris]

Thanks both Kedaman & Serge, because you guys really look into my problem & I know this quite a hard question.

Although I manage to get the handle for both PictureBox with the sample code from both of you kedaman and Serge, I still can not differentiate the handle is belong to which picture box.

Thanks for your further Help.

[kedaman]

There must be other properties of the wnd's that differs those boxes, ie, you can't have them laying on each other do you? If not you can get their rect's

Declare Function GetWindowRect Lib "user32" Alias "GetWindowRect" (ByVal hwnd As Long, lpRect As RECT) As Long
Type RECT
        Left As Long
        Top As Long
        Right As Long
        Bottom As Long
End Type

[Chris]

Hi Kedaman, to get the Window Rect is not a problem, since your code can get the hWnd for both PictureBox. So, how do i differentiate the PictureBox just base on the window rect value? which should I set as a reference? because the PictureBox can be at any place when the program run.

Thansk for all those helpful feedback.

[kedaman]

Well you drived me almost nuts when you said that, then i realized, you can still get the location of the pictureboxes, do they have left, top,width and heigh? If so you can compare

[Chris]

no...Kedaman I did drive to nut, but just wander to find out how can achieve this task.

I know, but let said my intial PictureBox1 is at
Top = 0
Left = 0
Height = 100
Width = 100

and PictureBox2 at

Top = 200
Left = 200
Height = 100
Width = 100

later PictureBox1 and PictureBox2 also move by the user to somewhere else, then I may lost the refernce point. I may still can resolve it by keep thier respective value into the registry. Don't you see that there was some may procedure to do upon the user have move the picture box?

because I need to aware the Speed to the handheld device.

Thanks a lot.

[kedaman]

Compare the rect to the current picturebox position (you have their names and position)