MaskColor

Salu2!

Option Explicit
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Copyright ©1996-2002 VBnet, Randy Birch, All Rights Reserved.
' Some pages may also contain other copyrights by the author.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
' Distribution: You can freely use this code in your own
' applications, but you may not reproduce
' or publish this code on any web site,
' online service, or distribute as source
' on any media without express permission.
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Public Type RECT
Left As Long
Top As Long
Right As Long
Bottom As Long
End Type

Public Declare Function BitBlt Lib "gdi32" _
(ByVal hDCDest As Long, ByVal XDest As Long, _
ByVal YDest As Long, ByVal nWidth As Long, _
ByVal nHeight As Long, ByVal hDCSrc As Long, _
ByVal XSrc As Long, ByVal YSrc As Long, _
ByVal dwRop As Long) As Long

Public Declare Function CreateBitmap Lib "gdi32" _
(ByVal nWidth As Long, _
ByVal nHeight As Long, _
ByVal nPlanes As Long, _
ByVal nBitCount As Long, _
lpBits As Any) As Long

Public Declare Function SetBkColor Lib "gdi32" _
(ByVal hdc As Long, _
ByVal crColor As Long) As Long

Public Declare Function SelectObject Lib "gdi32" _
(ByVal hdc As Long, _
ByVal hObject As Long) As Long

Public Declare Function CreateCompatibleBitmap Lib "gdi32" _
(ByVal hdc As Long, _
ByVal nWidth As Long, _
ByVal nHeight As Long) As Long

Public Declare Function CreateCompatibleDC Lib "gdi32" _
(ByVal hdc As Long)As Long

Public Declare Function DeleteDC Lib "gdi32" _
(ByVal hdc As Long) As Long

Public Declare Function DeleteObject Lib "gdi32" _
(ByVal hObject As Long) As Long
'--end block--'

*************


Option Explicit
Private Sub Command1_Click()

Dim rc As RECT

With rc
.Left = 0
.Top = 0
.Right = Picture1.ScaleWidth
.Bottom = Picture1.ScaleHeight
End With

TransparentBlt Form1.hdc, Form1.hdc, Picture1.hdc, rc, 20, 20, vbWhite

End Sub


Private Sub TransparentBlt(OutDstDC As Long, _
DstDC As Long, _
SrcDC As Long, _
SrcRect As RECT, _
DstX As Integer, _
DstY As Integer, _
TransColor As Long)

'DstDC- Device context into which image must be
'drawn transparently

'OutDstDC- Device context into image is actually drawn,
'even though it is made transparent in terms of DstDC

'Src- Device context of source to be made transparent
'in color TransColor

'SrcRect- Rectangular region within SrcDC to be made
'transparent in terms of DstDC, and drawn to OutDstDC

'DstX, DstY - Coordinates in OutDstDC (and DstDC)
'where the transparent bitmap must go. In most
'cases, OutDstDC and DstDC will be the same
Dim nRet As Long, W As Integer, H As Integer
Dim MonoMaskDC As Long, hMonoMask As Long
Dim MonoInvDC As Long, hMonoInv As Long
Dim ResultDstDC As Long, hResultDst As Long
Dim ResultSrcDC As Long, hResultSrc As Long
Dim hPrevMask As Long, hPrevInv As Long
Dim hPrevSrc As Long, hPrevDst As Long

W = SrcRect.Right - SrcRect.Left + 1
H = SrcRect.Bottom - SrcRect.Top + 1

'create monochrome mask and inverse masks
MonoMaskDC = CreateCompatibleDC(DstDC)
MonoInvDC = CreateCompatibleDC(DstDC)
hMonoMask = CreateBitmap(W, H, 1, 1, ByVal 0&)
hMonoInv = CreateBitmap(W, H, 1, 1, ByVal 0&)
hPrevMask = SelectObject(MonoMaskDC, hMonoMask)
hPrevInv = SelectObject(MonoInvDC, hMonoInv)

'create keeper DCs and bitmaps
ResultDstDC = CreateCompatibleDC(DstDC)
ResultSrcDC = CreateCompatibleDC(DstDC)
hResultDst = CreateCompatibleBitmap(DstDC, W, H)
hResultSrc = CreateCompatibleBitmap(DstDC, W, H)
hPrevDst = SelectObject(ResultDstDC, hResultDst)
hPrevSrc = SelectObject(ResultSrcDC, hResultSrc)

'copy src to monochrome mask
Dim OldBC As Long
OldBC = SetBkColor(SrcDC, TransColor)
nRet = BitBlt(MonoMaskDC, 0, 0, W, H, SrcDC, _
SrcRect.Left, SrcRect.Top, vbSrcCopy)
TransColor = SetBkColor(SrcDC, OldBC)

'create inverse of mask
nRet = BitBlt(MonoInvDC, 0, 0, W, H, _
MonoMaskDC, 0, 0, vbNotSrcCopy)

'get background
nRet = BitBlt(ResultDstDC, 0, 0, W, H, _
DstDC, DstX, DstY, vbSrcCopy)

'AND with Monochrome mask
nRet = BitBlt(ResultDstDC, 0, 0, W, H, _
MonoMaskDC, 0, 0, vbSrcAnd)

'get overlapper
nRet = BitBlt(ResultSrcDC, 0, 0, W, H, SrcDC, _
SrcRect.Left, SrcRect.Top, vbSrcCopy)

'AND with inverse monochrome mask
nRet = BitBlt(ResultSrcDC, 0, 0, W, H, _
MonoInvDC, 0, 0, vbSrcAnd)

'XOR these two
nRet = BitBlt(ResultDstDC, 0, 0, W, H, _
ResultSrcDC, 0, 0, vbSrcInvert)

'output results
nRet = BitBlt(OutDstDC, DstX, DstY, W, H, _
ResultDstDC, 0, 0, vbSrcCopy)

'clean up
hMonoMask = SelectObject(MonoMaskDC, hPrevMask)
DeleteObject hMonoMask

hMonoInv = SelectObject(MonoInvDC, hPrevInv)
DeleteObject hMonoInv

hResultDst = SelectObject(ResultDstDC, hPrevDst)
DeleteObject hResultDst

hResultSrc = SelectObject(ResultSrcDC, hPrevSrc)
DeleteObject hResultSrc

DeleteDC MonoMaskDC
DeleteDC MonoInvDC
DeleteDC ResultDstDC
DeleteDC ResultSrcDC

End Sub
'--end block--'


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Att.
El Tiko
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