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关于vb.net实现抠图的信息

IT技术Long

怎样用VB把一张图片透明的放到Picture里,在线等Public Function TranBlt(DestHdc As Long, X As Long, Y As Long, W As Long, H As Long, srcHdcOrBmp As Long, Optional srcX As Integer, Optional srcY As Integer, Optional srcW As Long, Optional srcH As Long, Optional tc As Long = -1, Optional IsBmp As Boolean) As Long
'srcHdcOrBmp参数 传入的可以是hdc也可以是Bmp对象的Handle，
'IsBmp参数 为真时srcHdcOrBmp代表Bmp对象的Handle，为假时代表hdc
'返回值 成功时返回透明色，不成功时返回-1
Dim tHdc(3) As MemHdc
Dim J As Long, oc As Long, I As Long, Bm As BITMAP, cc As Long, NewDc As Long
Dim sw As Long, sh As Long, sBmp As Long, sHdc As Long, obm As Long, NewX As Long, NewY As Long
If DestHdc = 0 Or srcHdcOrBmp = 0 Or W = 1 And H = 1 Then GoTo fail
If IsBmp Then'若传入的是Bmp句柄，需为其创建一个临时DC
sBmp = srcHdcOrBmp
tHdc(3) = NewMyHdc(DestHdc, 0, 0, srcHdcOrBmp)
sHdc = tHdc(3).hdc
Else
sHdc = srcHdcOrBmp
If srcW = 0 Then sBmp = GetCurrentObject(sHdc, 7)
End If
If sHdc = 0 Or sBmp = 0 Then GoTo fail
If srcW = 0 Then'若没有提供源图大小，需取得整个源图大小
GetObj sBmp, Len(Bm), Bm
sw = Bm.bmWidth - srcX
sh = Bm.bmHeight - srcY
Else
sw = srcW
sh = srcH
End If
If sw1 Or sh1 Then GoTo fail
If tc = -1 Then
cc = GetPixel(sHdc, srcX, srcY)'将左上角第一个像素作为源图背景色，用于透明
Else
cc = tc
End If
If Wsw Or Hsh Then
tHdc(2) = NewMyHdc(DestHdc, W, H)
StretchBlt tHdc(2).hdc, 0, 0, W, H, sHdc, srcX, srcY, sw, sh, vbSrcCopy
'先将源图缩放，下面步骤就一样了 。
NewDc = tHdc(2).hdc
Else
NewDc = sHdc
NewX = srcX
NewY = srcY
End If
BitBlt DestHdc, X, Y, W, H, NewDc, NewX, NewY, vbSrcInvert
'将源图先反色（XOR）绘入目标图 ， 若源图背景为黑色，此步可省
'下面是制作Mask图的方法
I = CreateBitmap(W, H, 1, 1, ByVal 0)'建立单色位图
tHdc(0) = NewMyHdc(DestHdc, 0, 0, I)'为单色图建立新DC，并选入
tHdc(1) = NewMyHdc(DestHdc, W, H)'另建一个彩色图及DC ， 用于存放Mask图
oc = SetBkColor(NewDc, cc)'将源图背景色改为透明色
BitBlt tHdc(0).hdc, 0, 0, W, H, NewDc, NewX, NewY, vbSrcCopy
'先将源图绘入单色DC ， 由此产生只有正反的Mask图 ， 背景色（透明色）为黑，其它为白
SetBkColor NewDc, oc'恢复源图背景色，不是必须的，但这是个好习惯 。
BitBlt tHdc(1).hdc, 0, 0, W, H, tHdc(0).hdc, 0, 0, vbSrcCopy
'单色DC必须复制进彩色DC才能进行后面的的AND运算
'Mask图完成，并已放入彩色DC
BitBlt DestHdc, X, Y, W, H, tHdc(1).hdc, 0, 0, vbSrcAnd'标准透明绘图：选将Mask图用And运算绘入 ， 
BitBlt DestHdc, X, Y, W, H, NewDc, NewX, NewY, vbSrcInvert '再将源图以反色(XOR)绘入一次
DelMyHdc tHdc(0)
DelMyHdc tHdc(1)
If tHdc(2).hdc0 Then DelMyHdc tHdc(2)
If tHdc(3).hdc0 Then DelMyHdc tHdc(3)
TranBlt = cc
Exit Function
fail:
If tHdc(3).hdc0 Then DelMyHdc tHdc(3)
TranBlt = -1
End Function
Private Function NewMyHdc(dHdc As Long, W As Long, H As Long, Optional Bm As Long) As MemHdc
With NewMyHdc
.hdc = CreateCompatibleDC(dHdc)
If Bm = 0 Then
.Bmp = CreateCompatibleBitmap(dHdc, W, H)
Else
.Bmp = Bm
End If
.obm = SelectObject(.hdc, .Bmp)
End With
End Function
Private Function DelMyHdc(MyHdc As MemHdc, Optional nobmp As Boolean) As MemHdc
With MyHdc
If .hdc0 And .obm0 Then SelectObject .hdc, .obm
If nobmp = False And .Bmp0 Then DeleteObject .Bmp
If .hdc0 Then DeleteDC .hdc
End With
End Function

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