Drawing onto c32bppDIB causes transparent areas when saved (but not when rendered)

Hello!

I would like to load an image into a c32bppDIB class and then draw onto its dc.

I do it like this:

Code:

---

    Dim c As c32bppDIB
    Set c = New c32bppDIB

    c.LoadPicture_File "D:\someimage.png"

    Dim lDC&
    lDC = c.LoadDIBinDC(True)
    APIFillRect lDC, r, vbRed

    c.SaveToFile_PNG "c:\users\myuser\desktop\test1.png", False

---

If I render it onto a dc, a do see the red area.
However, if I save it to a file, the red area is transparent.

If I save it using c.SaveToFile_JPG "c:\users\myuser\desktop\test1.jpg", False, vbBlue, the red area is blue. So it's obvious that drawing the area causes the area to become transparent.

How do I avoid this?

Thanks for any help!

ps:
This drawing function works fine, I have used it since several years.
I'm just stating it here for completeness:

Code:

---

Public Function APIRectangle(ByVal hDC As Long, _
                              ByVal X As Long, _
                              ByVal Y As Long, _
                              ByVal w As Long, _
                              ByVal h As Long, _
                              Optional lColor As OLE_COLOR = -1) As Long
  On Error GoTo APIRectangle_Error

  Dim hPen As Long, hPenOld As Long
  Dim pt As POINTAPI
  hPen = CreatePen(0, 1, lColor)
  hPenOld = SelectObject(hDC, hPen)
  MoveToEx hDC, X, Y, pt
  LineTo hDC, X + w, Y
  LineTo hDC, X + w, Y + h
  LineTo hDC, X, Y + h
  LineTo hDC, X, Y
  SelectObject hDC, hPenOld
  DeleteObject hPen
  Exit Function

APIRectangle_Error:
End Function

---

Edit:

I have resolved it by calling this sub when I'm done drawing:

Code:

---

Public Sub MakeOpaque()

    Dim tSA As SafeArray
    Dim dibBytes() As Byte

    ' here we will force every alpha byte to be fully opaque
    iparseOverlayHost_Byte dibBytes, VarPtr(tSA), 2, m_Height, m_Width * 4&, m_Pointer ' overlay DMA array
   
    Dim x&
    Dim y&
    For y = 0& To m_Height - 1&
        For x = 3& To m_Width * 4& - 1& Step 4&
            dibBytes(x, y) = 255
        Next
    Next
    iparseOverlayHost_Byte dibBytes, 0, 0, 0, 0, 0  ' remove DMA overlay

    m_AlphaImage = AlphaNone        ' we are not using transparency
    m_Format = imgCheckerBoard      ' special flag for user

End Sub

---

I have stolen it from the sub CreateWhiteCanvas.
It works now, but I wonder why I have to make the pixels opaque again after drawing onto them.

Thanks for any insights.