[RESOLVED] Transparency AND Alphablend

[Krzysztof#]

Hi, i imagine it would be nice and usefull effect if i make those two ways of image rendering possible at same time. So i have this code which makes picture transparency possible:

Option Explicit
Dim xMOVE
Private Declare Function TransparentBlt Lib "msimg32.dll" (ByVal hdc 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 nSrcWidth As Long, ByVal nSrcHeight As Long, ByVal crTransparent As Long) As Boolean
Private Sub Form_Load()
Picture1.AutoSize = True
    Picture1.ScaleMode = vbPixels
    Picture2.ScaleMode = vbPixels
    Picture1.AutoRedraw = True
    Picture2.AutoRedraw = True
    Picture3.ScaleMode = vbPixels
    Picture3.AutoRedraw = True
End Sub
Private Sub Timer1_Timer()
xMOVE = xMOVE + 1
'creating background from picture2 on picture3
Picture3.PaintPicture Picture2.Image, 0, 0, ScaleWidth, ScaleHeight, 0, 0, ScaleWidth, ScaleHeight
'putting picture1 with transparency on picture3
TransparentBlt Picture3.hdc, xMOVE, 0, Picture3.ScaleWidth, Picture3.ScaleHeight, Picture1.hdc, 0, 0, Picture1.ScaleWidth, Picture1.ScaleHeight, RGB(255, 0, 0)
'sending merged pictures from picture3 to form1
Form1.PaintPicture Picture3.Image, 0, 0, ScaleWidth, ScaleHeight, 0, 0, ScaleWidth, ScaleHeight
End Sub

or

Option Explicit
Private Declare Function BitBlt Lib "gdi32" (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 dwRop As Long) As Long
Dim a, x
Private Sub Form_Load()
x = 300
End Sub
Private Sub Form_Resize()
picBuffer.Move 0, 0, ScaleWidth, ScaleHeight
End Sub
Private Sub Timer1_Timer()
x = x - 1
End Sub
Private Sub Timer3_Timer()
'creating background
BitBlt picBuffer.hDC, 0, 0, ScaleWidth, ScaleHeight, frmBitBlt.Land.hDC, 0, 0, vbSrcCopy
'putting picture with transparency-using mask on backgroud
BitBlt picBuffer.hDC, x, 80, picture5.Width, picture5.Height, frmBitBlt.pictureMask.hDC, 0, 0, vbSrcAnd
BitBlt picBuffer.hDC, x, 80, picture5.Width, picture5.Height, frmBitBlt.picture5.hDC, 0, 0, vbSrcPaint
'sending all to form picture
BitBlt hDC, 0, 0, ScaleWidth, ScaleHeight, picBuffer.hDC, 0, 0, vbSrcCopy
End Sub

and code for alpha blending making picture semi-transparent:

Option Explicit
Const AC_SRC_OVER = &H0
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()
    Dim BF As BLENDFUNCTION, lBF As Long
    Picture1.AutoRedraw = True
    Picture2.AutoRedraw = True
    Picture1.ScaleMode = vbPixels
    Picture2.ScaleMode = vbPixels
    With BF
        .BlendOp = AC_SRC_OVER
        .BlendFlags = 0
        .SourceConstantAlpha = 128
        .AlphaFormat = 0
    End With
    RtlMoveMemory lBF, BF, 4
    AlphaBlend Picture2.hdc, 0, 0, Picture2.ScaleWidth, Picture2.ScaleHeight, Picture1.hdc, 0, 0, Picture1.ScaleWidth, Picture1.ScaleHeight, lBF
End Sub

Problem now is how i could display picture with transparent color (border of thing\sprite on picture) And semi-transparent of what is left visible (thing\sprite itself) at same time?
Any idea how make it possible?

[Schmidt]

Problem now is how i could display picture with transparent color (border of thing\sprite on picture) And semi-transparent of what is left visible (thing\sprite itself) at same time?

When the Source-Image does contain an Alpha-Channel already, then
the AlphaBlend-API is entirely sufficient to do both "at the same time".

Any extra-On/Off-Masking-Tricks are not necessary at all - a PNG which contains a proper Alpha-Channel
will "mask itself", when rendered with "full Opacity" using the AlphaBlend-API - and when you then
reduce the Opacity-Param in the AlphaBlend-call, it will respect this setting as well (in addition to the Masking).

Olaf

[Krzysztof#]

Thanks for suggestion but it seems is not so simple to load png files into vb6. Fortunately i have found solution on this forum i suppose here:
http://www.vbforums.com/showthread.p...round-a-sphere
I will test it and looks like answer to my problem.

[baka]

you can use gdi+ to load a raster png. theres a lot of examples on the forum, just search GDI PNG and you will find what you need.

[Krzysztof#]

Yes, i have found few examples here of what i need, but all of them too elaborated\complicated for my understanding to extract exact code for use:/ The simplest way to accomplish i have found here: http://www.freevbcode.com/ShowCode.asp?ID=4645 So for now im ok with it, much thanks for your time.