Public Type rBlendProps
tBlendOp As Byte
tBlendOptions As Byte
tBlendAmount As Byte
tAlphaType As Byte
End Type
Public Declare Function AlphaBlend Lib "msimg32" (ByVal hDestDC As Long, _
ByVal x As Long, ByVal y As Long, ByVal nWidth As Long, _
ByVal nHeight As Long, ByVal hSrcDC As Long, _
ByVal xSrc As Long, ByVal ySrc As Long, ByVal widthSrc As Long, _
ByVal heightSrc As Long, ByVal blendFunct As Long) As Boolean
Public Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" _
(Destination As Any, Source As Any, ByVal Length As Long)
Sub ShowTransparency(cSrc As PictureBox, cDest As PictureBox, _
ByVal nLevel As Byte)
Dim LrProps As rBlendProps
Dim LnBlendPtr As Long
cDest.Cls
LrProps.tBlendAmount = nLevel
CopyMemory LnBlendPtr, LrProps, 4
With cSrc
AlphaBlend cDest.hDC, 0, 0, .ScaleWidth, .ScaleHeight, _
.hDC, 0, 0, .ScaleWidth, .ScaleHeight, LnBlendPtr
End With
cDest.Refresh
End Sub
Private Sub Command1_Click()
lTime = 0
Timer1.Interval = 100
Timer1.Enabled = True
End Sub
Private Sub Timer1_Timer()
lTime = lTime + 1
ShowTransparency Picture2, Picture1, lTime
If lTime >= 255 Then
Timer1.Enabled = False
End If
Me.Caption = Str(Int(lTime / 2.55)) + "%"
End Sub
AlphaBlend(
HDC hdcDest,
int nXOriginDest,
int nYOriginDest,
int nWidthDest,
int hHeightDest,
HDC hdcSrc,
int nXOriginSrc,
int nYOriginSrc,
int nWidthSrc,
int nHeightSrc,
BLENDFUNCTION blendFunction
);
Parameter
hdcDest
Handle to the destination device context.
nXOriginDest
Specifies the x-coordinate, in logical units, of the upper-left corner of the destination rectangle.
nYOriginDest
Specifies the y-coordinate, in logical units, of the upper-left corner of the destination rectangle.
nWidthDest
Specifies the width, in logical units, of the destination rectangle.
hHeightDset
Handle to the height, in logical units, of the destination rectangle.
hdcSrc
Handle to the source device context.
nXOriginSrc
Specifies the x-coordinate, in logical units, of the upper-left corner of the source rectangle.
nYOriginSrc
Specifies the y-coordinate, in logical units, of the upper-left corner of the source rectangle.
nWidthSrc
Specifies the width, in logical units, of the source rectangle.
nHeightSrc
Specifies the height, in logical units, of the source rectangle.
blendFunction
Specifies the alpha blending function for source and destination bitmaps, a global alpha value to be applied to the entire source bitmap, and format information for the source bitmap. The source and destination blend functions are currently limited to AC_SRC_OVER. See the BLENDFUNCTION and EMRALPHABLEND structures.
Return Values
If the function succeeds, the return value is TRUE.