What is BlendFlags and AlphaFormat used for?
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What is BlendFlags and AlphaFormat used for?
AlphaBlend is used to display bitmaps with transparency onto a device context - ie, kind of overwrite the original picture.
From www.allapi.net
BlendFlags is a part of a UDT, as you see in the code above.Code:'This project requires two picture boxes
'Both picture boxes should contain a picture
Private Type BLENDFUNCTION
BlendOp As Byte
BlendFlags As Byte
SourceConstantAlpha As Byte
AlphaFormat As Byte
End Type
Private Declare Function AlphaBlend Lib "msimg32.dll" (ByVal hdc As Long, ByVal lInt As Long, ByVal lInt As Long, ByVal lInt As Long, ByVal lInt As Long, ByVal hdc As Long, ByVal lInt As Long, ByVal lInt As Long, ByVal lInt As Long, ByVal lInt As Long, ByVal BLENDFUNCT As Long) As Long
Private Declare Sub RtlMoveMemory Lib "kernel32.dll" (Destination As Any, Source As Any, ByVal Length As Long)
Private Sub Form_Load()
'KPD-Team 2000
'URL: http://www.allapi.net/
'E-Mail: [email protected]
Dim BF As BLENDFUNCTION, lBF As Long
'Set the graphics mode to persistent
Picture1.AutoRedraw = True
Picture2.AutoRedraw = True
'API uses pixels
Picture1.ScaleMode = vbPixels
Picture2.ScaleMode = vbPixels
'set the parameters
With BF
.BlendOp = AC_SRC_OVER
.BlendFlags = 0
.SourceConstantAlpha = 128
.AlphaFormat = 0
End With
'copy the BLENDFUNCTION-structure to a Long
RtlMoveMemory lBF, BF, 4
'AlphaBlend the picture from Picture1 over the picture of Picture2
AlphaBlend Picture2.hdc, 0, 0, Picture2.ScaleWidth, Picture2.ScaleHeight, Picture1.hdc, 0, 0, Picture1.ScaleWidth, Picture1.ScaleHeight, lBF
End Sub
To get values for BlendFlags and the other members of BLENDFUNCTION, go to http://www.msdn.microsoft.com