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Thread: how do you store a window region in memory for later use?

  1. #1

    Thread Starter
    Junior Member
    Join Date
    Aug 2001
    Location
    London
    Posts
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    Unhappy how do you store a window region in memory for later use?

    Hi,
    I am using 2 functions to make forms of irregular shapes which I would like to animate(sort of MS Office Assistant). I got it working in two ways with code I found in vbforums. The problem is that they are too slow and the animation is not in "real time". I was wondering if there is a way to store "Window Regions" in memory so they all get made in advance behind a splash screen at the begining and then I can just display them when I need them.

    this function uses draw.dll 's BitmaptoRegion which many of you might be familiar with

    Private Sub Make_Transparent(frm As Form, pic As Picture)

    'BitmapToRegion
    'hBmp -> bitmap to convert to region
    'cTransparentColor -> Transparent color
    'cTolerance -> Tolerance
    'This function returns a region


    Dim mRGN As Long
    If bRegion = False Then
    mRGN = BitmapToRegion(frm.Picture, RGB(192, 192, 192), 0)
    'OffsetRgn mRGN, 0, 0 'used for the border
    Else
    mRGN = CreateRectRgn(0, 0, pic.Width, pic.Height)
    End If
    frm.Picture = pic
    SetWindowRgn frm.hwnd, mRGN, True

    DeleteObject mRGN
    bRegion = Not (bRegion)
    End Sub

    This is another different function that has the same effect and it uses a few api calls

    Public Declare Function GetPixel Lib "gdi32" (ByVal hdc As Long, ByVal X As Long, ByVal Y As Long) As Long
    Public Declare Function SetWindowRgn Lib "user32" (ByVal hwnd As Long, ByVal hRgn As Long, ByVal bRedraw As Boolean) As Long
    Public Declare Function CreateRectRgn Lib "gdi32" (ByVal X1 As Long, ByVal Y1 As Long, ByVal X2 As Long, ByVal Y2 As Long) As Long
    Public Declare Function CombineRgn Lib "gdi32" (ByVal hDestRgn As Long, ByVal hSrcRgn1 As Long, ByVal hSrcRgn2 As Long, ByVal nCombineMode As Long) As Long
    Declare Sub ReleaseCapture Lib "user32" ()
    Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long
    Public Declare Function DeleteObject Lib "gdi32" (ByVal hObject As Long) As Long

    Public Function AutoFormShape(bg As Form, transColor)
    Dim X, Y As Integer

    CurRgn = CreateRectRgn(0, 0, bg.ScaleWidth, bg.ScaleHeight) ' Create base region which is the current whole window

    While Y <= bg.ScaleHeight ' Go through each column of pixels on form
    While X <= bg.ScaleWidth ' Go through each line of pixels on form
    If GetPixel(bg.hdc, X, Y) = transColor Then ' If the pixels color is the transparency color (bright purple is a good one to use)
    TempRgn = CreateRectRgn(X, Y, X + 1, Y + 1) ' Create a temporary pixel region for this pixel
    success = CombineRgn(CurRgn, CurRgn, TempRgn, RGN_DIFF) ' Combine temp pixel region with base region using RGN_DIFF to extract the pixel and make it transparent
    DeleteObject (TempRgn) ' Delete the temporary pixel region and clear up very important resources
    End If
    X = X + 1
    Wend
    Y = Y + 1
    X = 0
    Wend
    success = SetWindowRgn(bg.hwnd, CurRgn, True) ' Finally set the windows region to the final product
    DeleteObject (CurRgn) ' Delete the now un-needed base region and free resources

    End Function


    I am sorry if this is an obvious question but I am new to VB and Windows programming.
    Thank you
    Why did I ever start learning VB?! I should have been happy with Java.

  2. #2

    Thread Starter
    Junior Member
    Join Date
    Aug 2001
    Location
    London
    Posts
    31
    I've got it!
    BitmapToRegion returns a pointer(?!) to the region as a long. I just use the long variable to then use the regions
    ie:
    SetWindowRgn Form1.hwnd, rgs(i), True
    where rgs(i) is an array of regions
    Why did I ever start learning VB?! I should have been happy with Java.

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