[VB6] GDI+ Usage & Samples

[Jonney]

Jonney, nope. Notice that clrMatrix(4, 4) is set to non-null when grayscale matrix was created. The lightness matrix section is only filling in those matrix items if clrMatrix(4, 4) is null. That should be the case for all the matrix sections. Only fill in the required items if they haven't already been filled in.

My alpha image control rewrote that logic, but fundamentally, it uses the same checks & balances.

I miss the check.

I am troubleshooting why the alpha doesn't work： hGraphics bind to hImage.

GdipGetImageGraphicsContext hImage, hGraphics 
imgAttributesHandle = pvModifyAttributes(Alpha,Lightness, TransColor,GrayScale)
GdipDrawImageRectRectI hGraphics, hImage, 0, 0, imgWidth, imgHeight, 0, 0, imgWidth, imgHeight, UnitPixel, imgAttributesHandle
If imgAttributesHandle Then GdipDisposeImageAttributes imgAttributesHandle
GdipDeleteGraphics hGraphics

Edited:
But this one is OK: hGraphics created by hdc.

Public Sub gdipStretchPicture(ByVal hdc As Long, ByVal x As Long, ByVal y As Long, ByVal Width As Long, ByVal Height As Long, hImage As Long, ByVal srcX As Long, ByVal srcY As Long, ByVal srcWidth As Long, ByVal srcHeight As Long, Optional ByVal srcUnit As GpUnit = UnitPixel)
   
   If hImage <> 0 Then
      Dim hGraphics As Long
      GdipCreateFromHDC hdc, hGraphics
      Dim Attributes As Long                              'Testing Code
      Attributes = pvModifyAttributes(70, 0, 0, 1)  'Testing Code
      GdipDrawImageRectRectI hGraphics, hImage, x, y, Width, Height, srcX, srcY, srcWidth, srcHeight, srcUnit, Attributes
      If Attributes <> 0 Then GdipDisposeImageAttributes Attributes
      GdipReleaseDC hGraphics, hdc
      GdipDeleteGraphics hGraphics
   End If
   
End Sub