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This tip shows you how create a VB Picture object from a GDI bitmap handle. This
is useful if you are dealing with real GDI bitmaps.
Start a new project and add a module. Then add the following code to the module:
Option Explicit
Private Type PictDesc
cbSizeofStruct As Long
picType As Long
hImage As Long
xExt As Long
yExt As Long
End Type
Private Type Guid
Data1 As Long
Data2 As Integer
Data3 As Integer
Data4(0 To 7) As Byte
End Type
Private Declare Function OleCreatePictureIndirect Lib "olepro32.dll" (lpPictDesc As PictDesc, riid As Guid, ByVal fPictureOwnsHandle As Long, ipic As IPicture) As Long
Public Function BitmapToPicture(ByVal hBmp As Long) As IPicture
If (hBmp = 0) Then Exit Function
Dim oNewPic As Picture, tPicConv As PictDesc, IGuid As Guid
' Fill PictDesc structure with necessary parts:
With tPicConv
.cbSizeofStruct = Len(tPicConv)
.picType = vbPicTypeBitmap
.hImage = hBmp
End With
' Fill in IDispatch Interface ID
With IGuid
.Data1 = &H20400
.Data4(0) = &HC0
.Data4(7) = &H46
End With
' Create a picture object:
OleCreatePictureIndirect tPicConv, IGuid, True, oNewPic
' Return it:
Set BitmapToPicture = oNewPic
End Function
To try out a the function, add a Command Button and a Picture Box to
your project's form. Set the Picture Box's AutoSize property to True, then
copy a bitmap to the project's directory, and
rename it TEST.BMP.
Then add this code to the form:
Option Explicit
Private Declare Function LoadImage Lib "user32" Alias "LoadImageA" _
(ByVal hInst As Long, ByVal lpsz As String, _
ByVal iType As Long, _
ByVal cx As Long, ByVal cy As Long, _
ByVal fOptions As Long) As Long
' iType options:
Private Const IMAGE_BITMAP = 0
Private Const IMAGE_ICON = 1
Private Const IMAGE_CURSOR = 2
' fOptions flags:
Private Const LR_LOADMAP3DCOLORS = &H1000
Private Const LR_LOADFROMFILE = &H10
Private Const LR_LOADTRANSPARENT = &H20
Private Sub Command1_Click()
Dim hBmp As Long
' Load an icon called Test.Ico from the directory:
' If the icon contains more than one size of image,
' set cx and cy to the width and height to load
' the appropriate image in:
hBmp = LoadImage(App.hInstance, App.Path & "\TEST.BMP", IMAGE_BITMAP, 0, 0, LR_LOADFROMFILE Or LR_LOADMAP3DCOLORS)
' Set the picture to this icon:
Set Picture1.Picture = BitmapToPicture(hBmp)
End Sub
Start the project. When you click the button, the bitmap will be loaded as a GDI
bitmap handle, converted to a picture and then shown in the PictureBox. Whilst this
simple example could be achieved more quickly using the VB LoadPicture method, the
method shown has several advantages:
- You can specify that Gray (RGB 192,192,192) and Dark Gray (128,128,128) are mapped
to the appropriate system colours (vbButtonFace and vbButtonShadow respectively).
(LR_LOADMAP3DCOLORS flag)
- You can specify that all occurrences of the colour in the top left pixel are mapped
to the vbButtonFace colour (LR_LOADTRANSPARENT flag).
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