vbAccelerator - Contents of code file: cAlphaDibSection.cls

VERSION 1.0 CLASS
BEGIN
  MultiUse = -1  'True
  Persistable = 0  'NotPersistable
  DataBindingBehavior = 0  'vbNone
  DataSourceBehavior  = 0  'vbNone
  MTSTransactionMode  = 0  'NotAnMTSObject
END
Attribute VB_Name = "cAlphaDibSection"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = True
Attribute VB_PredeclaredId = False
Attribute VB_Exposed = False
Option Explicit

'
 ===============================================================================
===
' cAlphaDIBSection.cls
' Copyright  1998-2003 Steve McMahon (steve@vbaccelerator.com)
' Visit vbAccelerator at www.vbaccelerator.com
'
' Creates and manages an ARGB (32bit) GDI DibSection.
' This is DIB in which the bitmap bits are stored in windows
' memory so can be modified.
' See the RandomiseBits and Resample methods for how to do it.
'
' For example, fading in an out a 256x256 true colour DIB by
' directly modifying the bytes runs at 38fps on my machine
' (PII 266Mhz, 32Mb RAM, 8Mb ATI Xpert@Work AGP card)
'
' Note: for best performance, when compiling an executable check
' all the boxes on the Properties-Compile tab Advanced Optimisations
' button.  This really makes a difference! (e.g. the fading example
' ran at 22fps before I did this so > 50%!).
'
 ===============================================================================
===
Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" ( _
    lpvDest As Any, lpvSource As Any, ByVal cbCopy As Long)

Private Type SAFEARRAYBOUND
    cElements As Long
    lLbound As Long
End Type
Private Type SAFEARRAY2D
    cDims As Integer
    fFeatures As Integer
    cbElements As Long
    cLocks As Long
    pvData As Long
    Bounds(0 To 1) As SAFEARRAYBOUND
End Type
Private Declare Function VarPtrArray Lib "msvbvm60.dll" Alias "VarPtr" (Ptr()
 As Any) As Long

Private Type RGBQUAD
    rgbBlue As Byte
    rgbGreen As Byte
    rgbRed As Byte
    rgbReserved As Byte
End Type
Private Type BITMAPINFOHEADER '40 bytes
    biSize As Long
    biWidth As Long
    biHeight As Long
    biPlanes As Integer
    biBitCount As Integer
    biCompression As Long
    biSizeImage As Long
    biXPelsPerMeter As Long
    biYPelsPerMeter As Long
    biClrUsed As Long
    biClrImportant As Long
End Type
Private Type BITMAPINFO
    bmiHeader As BITMAPINFOHEADER
    bmiColors As RGBQUAD
End Type
Private Declare Function CreateCompatibleDC Lib "gdi32" (ByVal hDC As Long) As
 Long
Private Declare Function CreateCompatibleBitmap Lib "gdi32" (ByVal hDC As Long,
 ByVal nWidth As Long, ByVal nHeight As Long) As Long
Private Declare Function GetDC Lib "user32" (ByVal hwnd As Long) As Long
Private Declare Function ReleaseDC Lib "user32" (ByVal hwnd As Long, ByVal hDC
 As Long) As Long
Private Declare Function GetDesktopWindow Lib "user32" () As Long
' Note - this is not the declare in the API viewer - modify lplpVoid to be
' Byref so we get the pointer back:
Private Declare Function CreateDIBSection Lib "gdi32" _
    (ByVal hDC As Long, _
    pBitmapInfo As BITMAPINFO, _
    ByVal un As Long, _
    lplpVoid As Long, _
    ByVal handle As Long, _
    ByVal dw As Long) As Long
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
Private Type BLENDFUNCTION
  BlendOp As Byte
  BlendFlags As Byte
  SourceConstantAlpha As Byte
  AlphaFormat As Byte
End Type
' BlendOp:
Private Const AC_SRC_OVER = &H0
' AlphaFormat:
Private Const AC_SRC_ALPHA = &H1

Private Declare Function AlphaBlend Lib "MSIMG32.DLL" ( _
  ByVal hdcDest As Long, _
  ByVal nXOriginDest As Long, _
  ByVal nYOriginDest As Long, _
  ByVal nWidthDest As Long, _
  ByVal nHeightDest As Long, _
  ByVal hdcSrc As Long, _
  ByVal nXOriginSrc As Long, _
  ByVal nYOriginSrc As Long, _
  ByVal nWidthSrc As Long, _
  ByVal nHeightSrc As Long, _
  ByVal lBlendFunction As Long _
) As Long

Private Declare Function SelectObject Lib "gdi32" ( _
   ByVal hDC As Long, ByVal hObject As Long) As Long
Private Declare Function DeleteObject Lib "gdi32" ( _
   ByVal hObject As Long) As Long
Private Declare Function DeleteDC Lib "gdi32" (ByVal hDC As Long) As Long
Private Declare Function LoadImage Lib "user32" Alias "LoadImageA" ( _
   ByVal hInst As Long, ByVal lpsz As String, ByVal un1 As Long, _
   ByVal n1 As Long, ByVal n2 As Long, ByVal un2 As Long) As Long
Private Const BI_RGB = 0&
Private Const BI_RLE4 = 2&
Private Const BI_RLE8 = 1&
Private Const DIB_RGB_COLORS = 0 '  color table in RGBs

Private Type BITMAP
    bmType As Long
    bmWidth As Long
    bmHeight As Long
    bmWidthBytes As Long
    bmPlanes As Integer
    bmBitsPixel As Integer
    bmBits As Long
End Type
Private Declare Function GetObjectAPI Lib "gdi32" Alias "GetObjectA" ( _
   ByVal hObject As Long, ByVal nCount As Long, lpObject As Any) As Long

' Start of structure:
Private Const BITMAPTYPE As Integer = &H4D42
Private Type BITMAPFILEHEADER
   bfType As Integer '- type  ="BM" i.e &H4D42 - 2
   bfSize As Long ' - size in bytes of file - 6
   bfReserved1 As Integer ' - reserved, must be 0 - 8
   bfReserved2 As Integer ' - reserved, must be 0 - 10
   bfOffBits As Long ' offset from this structure to the bitmap bits - 14
End Type
Private Declare Function CreateFile Lib "kernel32" Alias "CreateFileA" ( _
   ByVal lpFileName As String, ByVal dwDesiredAccess As Long, _
   ByVal dwShareMode As Long, lpSecurityAttributes As Any, _
   ByVal dwCreationDisposition As Long, _
   ByVal dwFlagsAndAttributes As Long, ByVal hTemplateFile As Long) As Long
Private Declare Function ReadFile Lib "kernel32" ( _
   ByVal hFile As Long, lpBuffer As Any, _
   ByVal nNumberOfBytesToRead As Long, lpNumberOfBytesRead As Long, _
   lpOverlapped As Any) As Long
Private Declare Function WriteFile Lib "kernel32" ( _
   ByVal hFile As Long, _
   lpBuffer As Any, ByVal nNumberOfBytesToWrite As Long, _
   lpNumberOfBytesWritten As Long, lpOverlapped As Any) As Long
Private Declare Function SetFilePointer Lib "kernel32" ( _
   ByVal hFile As Long, _
   ByVal lDistanceToMove As Long, lpDistanceToMoveHigh As Long, _
   ByVal dwMoveMethod As Long) As Long
Private Declare Function CloseHandle Lib "kernel32" ( _
   ByVal hObject As Long) As Long
Private Const INVALID_HANDLE_VALUE = -1
Private Const CREATE_ALWAYS = 2
Private Const GENERIC_READ = &H80000000
Private Const GENERIC_WRITE = &H40000000
Private Const FILE_ATTRIBUTE_ARCHIVE = &H20
Private Const FILE_ATTRIBUTE_COMPRESSED = &H800
Private Const FILE_ATTRIBUTE_DIRECTORY = &H10
Private Const FILE_ATTRIBUTE_HIDDEN = &H2
Private Const FILE_ATTRIBUTE_NORMAL = &H80
Private Const FILE_ATTRIBUTE_READONLY = &H1
Private Const FILE_ATTRIBUTE_SYSTEM = &H4
Private Const FILE_ATTRIBUTE_TEMPORARY = &H100
Private Const FILE_BEGIN = 0
Private Declare Function GlobalLock Lib "kernel32" (ByVal hMem As Long) As Long
Private Declare Function GlobalAlloc Lib "kernel32" ( _
   ByVal wFlags As Long, _
   ByVal dwBytes As Long) As Long
Private Declare Function GlobalFree Lib "kernel32" (ByVal hMem As Long) As Long
Private Declare Function GlobalUnlock Lib "kernel32" ( _
   ByVal hMem As Long) As Long
Private Const GMEM_FIXED = &H0
Private Const GMEM_ZEROINIT = &H40
Private Const GPTR = (GMEM_FIXED Or GMEM_ZEROINIT)

Private Const FORMAT_MESSAGE_ALLOCATE_BUFFER = &H100
Private Const FORMAT_MESSAGE_ARGUMENT_ARRAY = &H2000
Private Const FORMAT_MESSAGE_FROM_HMODULE = &H800
Private Const FORMAT_MESSAGE_FROM_STRING = &H400
Private Const FORMAT_MESSAGE_FROM_SYSTEM = &H1000
Private Const FORMAT_MESSAGE_IGNORE_INSERTS = &H200
Private Const FORMAT_MESSAGE_MAX_WIDTH_MASK = &HFF
Private Declare Function FormatMessage Lib "kernel32" Alias "FormatMessageA" ( _
 ByVal dwFlags As Long, lpSource As Any, _
 ByVal dwMessageId As Long, ByVal dwLanguageId As Long, _
 ByVal lpBuffer As String, ByVal nSize As Long, _
 Arguments As Long) As Long

Private Declare Function GetDIBits Lib "gdi32" (ByVal aHDC As Long, _
   ByVal hBitmap As Long, ByVal nStartScan As Long, _
   ByVal nNumScans As Long, _
   lpBits As Long, _
   lpBI As BITMAPINFO, ByVal wUsage As Long) As Long
Private Declare Function CreateDIBitmap Lib "gdi32" ( _
   ByVal hDC As Long, _
   lpInfoHeader As BITMAPINFOHEADER, _
   ByVal dwUsage As Long, lpInitBits As Any, _
   lpInitInfo As BITMAPINFO, ByVal wUsage As Long) As Long

' DrawDIB functions:
Private Declare Function DrawDibOpen Lib "msvfw32.dll" () As Long
Private Declare Function DrawDibClose Lib "msvfw32.dll" ( _
   ByVal hDD As Long) As Long
Private Declare Function DrawDibDraw Lib "msvfw32.dll" ( _
   ByVal hDD As Long, _
   ByVal hDC As Long, _
   ByVal xDst As Long, ByVal yDst As Long, _
   ByVal dxDst As Long, ByVal dyDst As Long, _
   lpBI As Any, lpBits As Any, _
   ByVal xSrc As Long, ByVal ySrc As Long, _
   ByVal dxSrc As Long, ByVal dySrc As Long, _
   ByVal wFlags As Long) As Long

Private Declare Function OleTranslateColor Lib "OLEPRO32.DLL" (ByVal OLE_COLOR
 As Long, ByVal HPALETTE As Long, pccolorref As Long) As Long
Private Const CLR_INVALID = -1


Private m_hDIb As Long
Private m_hBmpOld As Long
Private m_hDC As Long
Private m_hDD As Long
Private m_lPtr As Long
Private m_tBI As BITMAPINFO

Public Function ExtractHBmp() As Long
Dim lhWndDesktop As Long
Dim lhDCDesktop As Long
Dim lhDCC As Long
Dim lhBmpC As Long
Dim lhBmpOld As Long

   ' Clone the DIB:
   lhWndDesktop = GetDesktopWindow()
   lhDCDesktop = GetDC(lhWndDesktop)
   lhDCC = CreateCompatibleDC(lhDCDesktop)
   lhBmpC = CreateCompatibleBitmap(lhDCDesktop, Width, Height)
   ReleaseDC lhWndDesktop, lhDCDesktop
   lhBmpOld = SelectObject(lhDCC, lhBmpC)
   PaintPicture lhDCC
   SelectObject lhDCC, lhBmpOld
   DeleteDC lhDCC
   ExtractHBmp = lhBmpC
   
End Function

Public Property Get UseDrawDib() As Boolean
   UseDrawDib = Not (m_hDD = 0)
End Property
Public Property Let UseDrawDib(ByVal bState As Boolean)
   If bState Then
      If m_hDD = 0 Then
         m_hDD = DrawDibOpen()
      End If
   Else
      If Not (m_hDD = 0) Then
         DrawDibClose m_hDD
      End If
   End If
End Property


Public Function CreateDIB( _
        ByVal lhDC As Long, _
        ByVal lWidth As Long, _
        ByVal lHeight As Long, _
        ByRef hDib As Long _
    ) As Boolean
    With m_tBI.bmiHeader
        .biSize = Len(m_tBI.bmiHeader)
        .biWidth = lWidth
        .biHeight = lHeight
        .biPlanes = 1
        .biBitCount = 32
        .biCompression = BI_RGB
        .biSizeImage = BytesPerScanLine * .biHeight
    End With
    hDib = CreateDIBSection( _
            lhDC, _
            m_tBI, _
            DIB_RGB_COLORS, _
            m_lPtr, _
            0, 0)
    CreateDIB = (hDib <> 0)
End Function
Public Function CreateFromPicture( _
        ByRef picThis As StdPicture _
    )
    CreateFromHBitmap picThis.handle
End Function
Public Function CreateFromHBitmap( _
      ByVal hBmp As Long _
   )
Dim lhDC As Long
Dim lhWndDesktop As Long
Dim lhDCDesktop As Long
Dim lhBmpOld As Long
Dim tBMP As BITMAP
   GetObjectAPI hBmp, Len(tBMP), tBMP
   If (Create(tBMP.bmWidth, tBMP.bmHeight)) Then
      lhWndDesktop = GetDesktopWindow()
      lhDCDesktop = GetDC(lhWndDesktop)
      If (lhDCDesktop <> 0) Then
          lhDC = CreateCompatibleDC(lhDCDesktop)
          ReleaseDC lhWndDesktop, lhDCDesktop
          If (lhDC <> 0) Then
              lhBmpOld = SelectObject(lhDC, hBmp)
              LoadPictureBlt lhDC
              SelectObject lhDC, lhBmpOld
              DeleteObject lhDC
          End If
      End If
   End If
   
End Function
Public Function Create( _
        ByVal lWidth As Long, _
        ByVal lHeight As Long _
    ) As Boolean
Dim bDrawDib As Boolean
   bDrawDib = UseDrawDib()
    ClearUp
    m_hDC = CreateCompatibleDC(0)
    If (m_hDC <> 0) Then
        If (CreateDIB(m_hDC, lWidth, lHeight, m_hDIb)) Then
            m_hBmpOld = SelectObject(m_hDC, m_hDIb)
            UseDrawDib = bDrawDib
            Create = True
        Else
            DeleteObject m_hDC
            m_hDC = 0
        End If
    End If
End Function
Public Property Get BytesPerScanLine() As Long
    ' Scans must align on dword boundaries; easy with an alpha bitmap!
    BytesPerScanLine = m_tBI.bmiHeader.biWidth * 4
End Property

Public Property Get Width() As Long
    Width = m_tBI.bmiHeader.biWidth
End Property
Public Property Get Height() As Long
    Height = m_tBI.bmiHeader.biHeight
End Property

Public Sub LoadPictureBlt( _
        ByVal lhDC As Long, _
        Optional ByVal lSrcLeft As Long = 0, _
        Optional ByVal lSrcTop As Long = 0, _
        Optional ByVal lSrcWidth As Long = -1, _
        Optional ByVal lSrcHeight As Long = -1, _
        Optional ByVal eRop As RasterOpConstants = vbSrcCopy _
    )
    If lSrcWidth < 0 Then lSrcWidth = m_tBI.bmiHeader.biWidth
    If lSrcHeight < 0 Then lSrcHeight = m_tBI.bmiHeader.biHeight
    BitBlt m_hDC, 0, 0, lSrcWidth, lSrcHeight, lhDC, lSrcLeft, lSrcTop, eRop
End Sub
Public Function SavePicture(ByVal sFileName As String) As Boolean
Dim lC As Long, i As Long

   ' Save to BMP:
   SavePicture = SaveToBitmap(m_lPtr, sFileName)

End Function
Private Function SaveToBitmap(ByVal lPtrBits As Long, ByVal sFileName As String)
Dim tBH As BITMAPFILEHEADER
Dim tRGBQ As RGBQUAD
Dim hFile As Long
Dim lBytesWritten As Long
Dim lSize As Long
Dim lR As Long
Dim bErr As Boolean
Dim hMem As Long, lPtr As Long
Dim lErr As Long

   ' Prepare the BITMAPFILEHEADER
   With tBH
      .bfType = BITMAPTYPE
      .bfOffBits = 14 + Len(m_tBI)
      .bfSize = .bfOffBits + m_tBI.bmiHeader.biSizeImage
   End With
   hFile = CreateFile(sFileName, _
                 GENERIC_READ Or GENERIC_WRITE, _
                  ByVal 0&, _
                  ByVal 0&, _
                  CREATE_ALWAYS, _
                  FILE_ATTRIBUTE_NORMAL, _
                  0)
   lErr = Err.LastDllError
   If (hFile = INVALID_HANDLE_VALUE) Then
      ' error
      Err.Raise 17, App.EXEName & ".cDIBSection", ApiError(lErr)
   Else
      
      ' Writing the BITMAPFILEINFOHEADER is somewhat painful
      ' due to non-byte alignment of structure...
      hMem = GlobalAlloc(GPTR, 14)
      lPtr = GlobalLock(hMem)
      CopyMemory ByVal lPtr, tBH.bfType, 2
      CopyMemory ByVal lPtr + 2, tBH.bfSize, 4
      CopyMemory ByVal lPtr + 6, 0&, 4
      CopyMemory ByVal lPtr + 10, tBH.bfOffBits, 4
      lSize = 14
      lR = WriteFile(hFile, ByVal lPtr, lSize, lBytesWritten, ByVal 0&)
      GlobalUnlock hMem
      GlobalFree hMem
      
      ' Add the BITMAPINFOHEADER and colour palette:
      bErr = FileErrHandler(lR, lSize, lBytesWritten)
      If Not bErr Then
         lSize = Len(m_tBI)
         lR = WriteFile(hFile, m_tBI, lSize, lBytesWritten, ByVal 0&)
         bErr = FileErrHandler(lR, lSize, lBytesWritten)
      End If
      
      If Not bErr Then
         ' Its easy to write the bitmap data, though...
         lSize = m_tBI.bmiHeader.biSizeImage
         lR = WriteFile(hFile, ByVal lPtrBits, lSize, lBytesWritten, ByVal 0&)
         bErr = FileErrHandler(lR, lSize, lBytesWritten)
      End If
      
      
      CloseHandle hFile
      SaveToBitmap = Not (bErr)
   End If

End Function
Private Function ApiError(ByVal e As Long) As String
    Dim s As String, c As Long
    s = String(256, 0)
    c = FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM Or _
                      FORMAT_MESSAGE_IGNORE_INSERTS, _
                      0, e, 0&, s, Len(s), ByVal 0)
    If c Then ApiError = left$(s, c)
End Function

Private Function FileErrHandler( _
   ByVal lR As Long, ByVal lSize As Long, _
   ByVal lBytes As Long) As Boolean
   If (lR = 0) Or Not (lSize = lBytes) Then
      'Err.Raise
      FileErrHandler = True
   End If
End Function


Public Sub PaintPicture( _
        ByVal lhDC As Long, _
        Optional ByVal lDestLeft As Long = 0, _
        Optional ByVal lDestTop As Long = 0, _
        Optional ByVal lDestWidth As Long = -1, _
        Optional ByVal lDestHeight As Long = -1, _
        Optional ByVal lSrcLeft As Long = 0, _
        Optional ByVal lSrcTop As Long = 0, _
        Optional ByVal eRop As RasterOpConstants = vbSrcCopy _
    )
   If (lDestWidth < 0) Then lDestWidth = m_tBI.bmiHeader.biWidth
   If (lDestHeight < 0) Then lDestHeight = m_tBI.bmiHeader.biHeight
   If Not (m_hDD = 0) Then
      ' DrawDib method:
      DrawDibDraw m_hDD, lhDC, lDestLeft, lDestTop, _
         lDestWidth, lDestHeight, _
         m_tBI, ByVal m_lPtr, lSrcLeft, lSrcTop, lDestWidth, lDestHeight, 0
   Else
      BitBlt lhDC, lDestLeft, lDestTop, _
         lDestWidth, lDestHeight, m_hDC, _
         lSrcLeft, lSrcTop, eRop
   End If
End Sub
Public Sub AlphaPaintPicture( _
        ByVal lhDC As Long, _
        Optional ByVal lDestLeft As Long = 0, _
        Optional ByVal lDestTop As Long = 0, _
        Optional ByVal lDestWidth As Long = -1, _
        Optional ByVal lDestHeight As Long = -1, _
        Optional ByVal lSrcLeft As Long = 0, _
        Optional ByVal lSrcTop As Long = 0, _
        Optional ByVal lConstantAlpha As Byte = 255 _
    )
   If (lDestWidth < 0) Then lDestWidth = m_tBI.bmiHeader.biWidth
   If (lDestHeight < 0) Then lDestHeight = m_tBI.bmiHeader.biHeight
   
   Dim lBlend As Long
   Dim bf As BLENDFUNCTION
   bf.BlendOp = AC_SRC_OVER
   bf.BlendFlags = 0
   bf.SourceConstantAlpha = lConstantAlpha
   bf.AlphaFormat = AC_SRC_ALPHA
   CopyMemory lBlend, bf, 4
   
   Dim lR As Long
   lR = AlphaBlend( _
      lhDC, _
      lDestLeft, lDestTop, lDestWidth, lDestHeight, _
      m_hDC, _
      lSrcLeft, lSrcTop, lDestWidth, lDestHeight, _
      lBlend)
   If (lR = 0) Then
      Debug.Print ApiError(Err.LastDllError)
   End If
End Sub

Public Property Get hDC() As Long
    hDC = m_hDC
End Property
Public Property Get hDib() As Long
    hDib = m_hDIb
End Property
Public Property Get DIBSectionBitsPtr() As Long
    DIBSectionBitsPtr = m_lPtr
End Property
Public Sub RandomiseBits( _
        Optional ByVal bGray As Boolean = False _
    )
Dim bDib() As Byte
Dim x As Long, y As Long
Dim lC As Long
Dim tSA As SAFEARRAY2D
    
    ' Get the bits in the from DIB section:
    With tSA
        .cbElements = 1
        .cDims = 2
        .Bounds(0).lLbound = 0
        .Bounds(0).cElements = m_tBI.bmiHeader.biHeight
        .Bounds(1).lLbound = 0
        .Bounds(1).cElements = BytesPerScanLine()
        .pvData = m_lPtr
    End With
    CopyMemory ByVal VarPtrArray(bDib()), VarPtr(tSA), 4

    ' random:
    Randomize Timer
    
    If (bGray) Then
        For y = 0 To m_tBI.bmiHeader.biHeight - 1
            For x = 0 To BytesPerScanLine - 1 Step 4
                lC = Rnd * 255
                bDib(x + 3, y) = Rnd * 255 '255 * (y / m_tBI.bmiHeader.biHeight)
                bDib(x, y) = lC * bDib(x + 3, y) / 255
                bDib(x + 1, y) = lC * bDib(x + 3, y) / 255
                bDib(x + 2, y) = lC * bDib(x + 3, y) / 255
            Next x
        Next y
    Else
         For y = 0 To m_tBI.bmiHeader.biHeight - 1
            For x = 0 To BytesPerScanLine - 1 Step 4
                bDib(x + 3, y) = Rnd * 255 '255 * (y / m_tBI.bmiHeader.biHeight)
                bDib(x, y) = Rnd * 255 * bDib(x + 3, y) / 255
                bDib(x + 1, y) = Rnd * 255 * bDib(x + 3, y) / 255
                bDib(x + 2, y) = Rnd * 255 * bDib(x + 3, y) / 255
            Next x
        Next y
    End If
    
    ' Clear the temporary array descriptor
    ' (This does not appear to be necessary, but
    ' for safety do it anyway)
    CopyMemory ByVal VarPtrArray(bDib), 0&, 4
    
End Sub

Public Sub PreMultiplyAlpha()
Dim bDib() As Byte
Dim x As Long, y As Long
Dim lC As Long
Dim tSA As SAFEARRAY2D
Dim bAlpha As Long
    
    ' Get the bits in the from DIB section:
    With tSA
        .cbElements = 1
        .cDims = 2
        .Bounds(0).lLbound = 0
        .Bounds(0).cElements = m_tBI.bmiHeader.biHeight
        .Bounds(1).lLbound = 0
        .Bounds(1).cElements = BytesPerScanLine()
        .pvData = m_lPtr
    End With
    CopyMemory ByVal VarPtrArray(bDib()), VarPtr(tSA), 4
   For x = 0 To Me.BytesPerScanLine - 4 Step 4 ' each item has 4 bytes:
      For y = 0 To m_tBI.bmiHeader.biHeight - 1
         ' Get the red value from the mask to use as the alpha
         ' value:
         bAlpha = bDib(x + 3, y)
         ' Now premultiply the r/g/b values by the alpha divided
         ' by 255.  This is required for the AlphaBlend GDI function,
         ' see MSDN/Platform SDK/GDI/BLENDFUNCTION for more
         ' details:
         bDib(x, y) = (bDib(x, y) * bAlpha) \ 255
         bDib(x + 1, y) = (bDib(x + 1, y) * bAlpha) \ 255
         bDib(x + 2, y) = (bDib(x + 2, y) * bAlpha) \ 255
         
         'Debug.Print "A:"; bAlpha, "B:"; bDib(x, y), "G:"; bDib(x + 1, y),
          "R:"; bDib(x + 2, y)
      Next y
   Next x

    ' Clear the temporary array descriptor
    ' (This does not appear to be necessary, but
    ' for safety do it anyway)
    CopyMemory ByVal VarPtrArray(bDib), 0&, 4

End Sub
Public Function AreAllAlphaBytesZero() As Boolean
Dim bDib() As Byte
Dim x As Long, y As Long
Dim lC As Long
Dim tSA As SAFEARRAY2D
Dim r As Boolean
        
   r = True
    ' Get the bits in the from DIB section:
    With tSA
        .cbElements = 1
        .cDims = 2
        .Bounds(0).lLbound = 0
        .Bounds(0).cElements = m_tBI.bmiHeader.biHeight
        .Bounds(1).lLbound = 0
        .Bounds(1).cElements = BytesPerScanLine()
        .pvData = m_lPtr
    End With
    CopyMemory ByVal VarPtrArray(bDib()), VarPtr(tSA), 4
    
   For x = 0 To Me.BytesPerScanLine - 4 Step 4 ' each item has 4 bytes:
      For y = 0 To m_tBI.bmiHeader.biHeight - 1
         ' Get the red value from the mask to use as the alpha
         ' value:
         If Not (bDib(x + 3, y) = 0) Then
            r = False
            Exit For
         End If
      Next y
      If Not (r) Then Exit For
   Next x

    ' Clear the temporary array descriptor
    ' (This does not appear to be necessary, but
    ' for safety do it anyway)
    CopyMemory ByVal VarPtrArray(bDib), 0&, 4
    
   AreAllAlphaBytesZero = r
End Function

Public Sub SetColourTransparent( _
      ByVal oColor As OLE_COLOR, _
      Optional ByVal lOtherColorAlpha As Long = -1, _
      Optional ByVal bPreMult = False _
   )
Dim bDib() As Byte
Dim x As Long, y As Long
Dim lR As Long
Dim lG As Long
Dim lB As Long
Dim lC As Long
Dim tSA As SAFEARRAY2D
Dim bAlpha As Long
    
    OleTranslateColor oColor, 0, lC
    lR = (lC And &HFF&)
    lG = (lC And &HFF00&) \ &H100&
    lB = (lC And &HFF0000) \ &H10000
    
    ' Get the bits in the from DIB section:
    With tSA
        .cbElements = 1
        .cDims = 2
        .Bounds(0).lLbound = 0
        .Bounds(0).cElements = m_tBI.bmiHeader.biHeight
        .Bounds(1).lLbound = 0
        .Bounds(1).cElements = BytesPerScanLine()
        .pvData = m_lPtr
    End With
    CopyMemory ByVal VarPtrArray(bDib()), VarPtr(tSA), 4
   For x = 0 To Me.BytesPerScanLine - 4 Step 4 ' each item has 4 bytes:
      For y = 0 To m_tBI.bmiHeader.biHeight - 1
         If (bDib(x, y) = lB) And _
            (bDib(x + 1, y) = lG) And _
            (bDib(x + 2, y) = lR) Then
            ' Set alpha to 0:
            bDib(x + 3, y) = 0
            If (bPreMult) Then
               bDib(x, y) = 0
               bDib(x + 1, y) = 0
               bDib(x + 2, y) = 0
            End If
         ElseIf (lOtherColorAlpha > 0) Then
            bDib(x + 3, y) = lOtherColorAlpha
            If (bPreMult) Then
               bDib(x, y) = bDib(x, y) * lOtherColorAlpha / 255
               bDib(x + 1, y) = bDib(x + 1, y) * lOtherColorAlpha / 255
               bDib(x + 2, y) = bDib(x + 2, y) * lOtherColorAlpha / 255
            End If
         End If
      Next y
   Next x

    ' Clear the temporary array descriptor
    ' (This does not appear to be necessary, but
    ' for safety do it anyway)
    CopyMemory ByVal VarPtrArray(bDib), 0&, 4

End Sub

Public Sub SetAlpha(ByVal bAlphaSet As Byte)
Dim bDib() As Byte
Dim x As Long, y As Long
Dim lC As Long
Dim tSA As SAFEARRAY2D
Dim bAlpha As Long
      
   bAlpha = bAlphaSet
    
    ' Get the bits in the from DIB section:
    With tSA
        .cbElements = 1
        .cDims = 2
        .Bounds(0).lLbound = 0
        .Bounds(0).cElements = m_tBI.bmiHeader.biHeight
        .Bounds(1).lLbound = 0
        .Bounds(1).cElements = BytesPerScanLine()
        .pvData = m_lPtr
    End With
    CopyMemory ByVal VarPtrArray(bDib()), VarPtr(tSA), 4
   For x = 0 To Me.BytesPerScanLine - 4 Step 4 ' each item has 4 bytes:
      For y = 0 To m_tBI.bmiHeader.biHeight - 1
         ' Set alpha to the specified alpha & premultiply:
         bDib(x, y) = bDib(x, y) * bAlpha \ 255
         bDib(x + 1, y) = bDib(x + 1, y) * bAlpha \ 255
         bDib(x + 2, y) = bDib(x + 2, y) * bAlpha \ 255
         bDib(x + 3, y) = bAlpha
      Next y
   Next x
    
    ' Clear the temporary array descriptor
    ' (This does not appear to be necessary, but
    ' for safety do it anyway)
    CopyMemory ByVal VarPtrArray(bDib), 0&, 4

End Sub
Public Sub ClearUp()
    If (m_hDC <> 0) Then
        If (m_hDIb <> 0) Then
            SelectObject m_hDC, m_hBmpOld
            DeleteObject m_hDIb
        End If
        DeleteObject m_hDC
    End If
    m_hDC = 0: m_hDIb = 0: m_hBmpOld = 0: m_lPtr = 0
    If Not (m_hDD = 0) Then
      DrawDibClose m_hDD
      m_hDD = 0
   End If
End Sub
Public Function Clone() As cAlphaDibSection
Dim cDibTo As cAlphaDibSection
Dim tSA As SAFEARRAY2D
Dim tSATo As SAFEARRAY2D
Dim lDib() As Long
Dim lDibTo() As Long
Dim x As Long
Dim y As Long
   
   Set cDibTo = New cAlphaDibSection
   cDibTo.Create Width, Height
   
   With tSA
      .cbElements = 4
      .cDims = 2
      .Bounds(0).lLbound = 0
      .Bounds(0).cElements = m_tBI.bmiHeader.biHeight
      .Bounds(1).lLbound = 0
      .Bounds(1).cElements = BytesPerScanLine() \ 4
      .pvData = m_lPtr
   End With
   CopyMemory ByVal VarPtrArray(lDib()), VarPtr(tSA), 4
    
   With tSATo
      .cbElements = 4
      .cDims = 2
      .Bounds(0).lLbound = 0
      .Bounds(0).cElements = tSA.Bounds(0).cElements
      .Bounds(1).lLbound = 0
      .Bounds(1).cElements = tSA.Bounds(1).cElements
      .pvData = cDibTo.DIBSectionBitsPtr
   End With
   CopyMemory ByVal VarPtrArray(lDibTo()), VarPtr(tSATo), 4
   
   For x = 0 To m_tBI.bmiHeader.biWidth - 1
      For y = 0 To m_tBI.bmiHeader.biHeight - 1
         lDibTo(x, y) = lDib(x, y)
      Next y
   Next x
   
   ' Clear the temporary array descriptors
   ' (This does not appear to be necessary, but
   ' for safety do it anyway)
   CopyMemory ByVal VarPtrArray(lDib), 0&, 4
   CopyMemory ByVal VarPtrArray(lDibTo), 0&, 4
   
   Set Clone = cDibTo
   
End Function
Public Function AlphaResample( _
      ByVal lNewWidth As Long _
   ) As cAlphaDibSection
Dim x As Long
Dim y As Long
Dim i As Long
Dim j As Long
Dim lBuf() As Long
Dim lColorCount() As Long
Dim bDib() As Byte
Dim bDibTo() As Byte
Dim tSA As SAFEARRAY2D
Dim tSATo As SAFEARRAY2D
Dim cDibTo As cAlphaDibSection
Dim bIntegral As Boolean
Dim scaleX As Long
Dim scaleY As Long
Dim xDest As Long
Dim xDestWithScan As Long
Dim yDest As Long
Dim yDestWithScan As Long
Dim xDestAlso As Long
Dim xDestAlsoWithScan As Long
Dim yDestAlso As Long
Dim yDestAlsoWithScan As Long
Dim xDestTmp As Long
Dim yDestTmp As Long
Dim lModX As Single
Dim lModY As Single
Dim lR As Long
Dim lG As Long
Dim lB As Long
Dim lA As Long
Dim lAMult As Long
Dim lTotAlpha As Long
Dim lTotColour As Long
Dim xStep As Long
Dim lNewHeight As Long
   
   ' Check if the new height will be an integral number of pixels:
   If ((m_tBI.bmiHeader.biHeight * lNewWidth) Mod m_tBI.bmiHeader.biWidth) = 0
    Then
      bIntegral = True
      lNewHeight = (Height * lNewWidth) \ Width
   Else
      lNewHeight = (Height * lNewWidth) \ Width + 1
   End If
   
   Set cDibTo = New cAlphaDibSection
   cDibTo.Create lNewWidth, lNewHeight
   
   With tSA
      .cbElements = 1
      .cDims = 2
      .Bounds(0).lLbound = 0
      .Bounds(0).cElements = m_tBI.bmiHeader.biHeight
      .Bounds(1).lLbound = 0
      .Bounds(1).cElements = BytesPerScanLine()
      .pvData = m_lPtr
   End With
   CopyMemory ByVal VarPtrArray(bDib()), VarPtr(tSA), 4
    
   With tSATo
      .cbElements = 1
      .cDims = 2
      .Bounds(0).lLbound = 0
      .Bounds(0).cElements = cDibTo.Height
      .Bounds(1).lLbound = 0
      .Bounds(1).cElements = cDibTo.BytesPerScanLine()
      .pvData = cDibTo.DIBSectionBitsPtr
   End With
   CopyMemory ByVal VarPtrArray(bDibTo()), VarPtr(tSATo), 4
   
   If ((m_tBI.bmiHeader.biWidth Mod cDibTo.Width) = 0) And _
      ((m_tBI.bmiHeader.biHeight Mod cDibTo.Height) = 0) Then
      
      ' Integral scale.  This means every pixel of the
      ' source image only needs to be used once for
      ' each destination pixel
      
      scaleX = m_tBI.bmiHeader.biWidth \ cDibTo.Width
      scaleY = m_tBI.bmiHeader.biHeight \ cDibTo.Height
      lTotAlpha = scaleX * scaleY
      xStep = (scaleX - 1) * 4
      For x = 0 To BytesPerScanLine - 4 Step 4 * scaleX
         yDest = 0
         For y = 0 To m_tBI.bmiHeader.biHeight - 1 Step scaleY
            lR = 0: lG = 0: lB = 0: lA = 0
            lTotColour = 0
            For i = 0 To xStep Step 4
               For j = 0 To scaleY - 1
                  lAMult = bDib(x + i + 3, y + j)
                  If (lAMult > 0) Then
                     lB = lB + (bDib(x + i, y + j) * lAMult) \ 255
                     lG = lG + (bDib(x + i + 1, y + j) * lAMult) \ 255
                     lR = lR + (bDib(x + i + 2, y + j) * lAMult) \ 255
                     lTotColour = lTotColour + 1
                  End If
                  lA = lA + lAMult
               Next j
            Next i
            If (lTotColour > 0) Then
               bDibTo(xDest, yDest) = (lB \ lTotColour)
               bDibTo(xDest + 1, yDest) = (lG \ lTotColour)
               bDibTo(xDest + 2, yDest) = (lR \ lTotColour)
            End If
            bDibTo(xDest + 3, yDest) = (lA \ lTotAlpha)
            'Debug.Print xDest, yDest, lA, lB, g, lR
            yDest = yDest + 1
         Next y
         xDest = xDest + 4
      Next x
      
   Else
      ' Non-Integral scale.  This means a source pixel may
      ' have a contribution to more than one destination
      ' pixel.
      ReDim lBuf(0 To cDibTo.BytesPerScanLine + 4, 0 To cDibTo.Height) As Long
      ReDim lColorCount(0 To cDibTo.Width, 0 To cDibTo.Height) As Long
      Dim xStart As Single
      Dim yStart As Single
      Dim size As Single
      Dim xOut As Long
      Dim fContrib As Single
      Dim fContribX As Single
      Dim fContribY As Single
      
      size = lNewWidth / m_tBI.bmiHeader.biWidth
      
      For x = 0 To BytesPerScanLine - 4 Step 4
         
         xStart = ((x \ 4) * lNewWidth) / m_tBI.bmiHeader.biWidth
         xDest = Int(xStart)
         xOut = xDest * 4
         
         For y = 0 To m_tBI.bmiHeader.biHeight - 1
            
            yStart = y * lNewWidth / m_tBI.bmiHeader.biWidth
            yDest = Int(yStart)
                        
            ' Check whether we get all of this pixel or not:
            If (xStart + size > xDest + 1) Then
               ' only a proportion in x:
               If (yStart + size > yDest + 1) Then
                  ' proportion in x and a proportion in y:
                  
                  ' This pixel gets a contribution:
                  fContribX = (1# - (xStart + size - (xDest + 1)) / size)
                  fContribY = 1# - (yStart + size - (yDest + 1)) / size
                  
                  fContrib = fContribX * fContribY
                  If (bDib(x + 3, y) > 0) Then
                     lBuf(xOut, yDest) = lBuf(xOut, yDest) + bDib(x, y) *
                      fContrib
                     lBuf(xOut + 1, yDest) = lBuf(xOut + 1, yDest) + bDib(x +
                      1, y) * fContrib
                     lBuf(xOut + 2, yDest) = lBuf(xOut + 2, yDest) + bDib(x +
                      2, y) * fContrib
                     lColorCount(xDest, yDest) = lColorCount(xDest, yDest) + 1
                  End If
                  lBuf(xOut + 3, yDest) = lBuf(xOut + 3, yDest) + bDib(x + 3,
                   y) * fContrib
                  
                  ' The next one along in x gets a contribution:
                  fContrib = (1# - fContribX) * fContribY
                  If (bDib(x + 3, y) > 0) Then
                     lBuf(xOut + 4, yDest) = lBuf(xOut + 4, yDest) + bDib(x, y)
                      * fContrib
                     lBuf(xOut + 5, yDest) = lBuf(xOut + 5, yDest) + bDib(x +
                      1, y) * fContrib
                     lBuf(xOut + 6, yDest) = lBuf(xOut + 6, yDest) + bDib(x +
                      2, y) * fContrib
                     lColorCount(xDest + 1, yDest) = lColorCount(xDest + 1,
                      yDest) + 1
                  End If
                  lBuf(xOut + 7, yDest) = lBuf(xOut + 7, yDest) + bDib(x + 3,
                   y) * fContrib
                  
                  ' The next one along in y gets a contribution:
                  fContrib = fContribX * (1# - fContribY)
                  If (bDib(x + 3, y) > 0) Then
                     lBuf(xOut, yDest + 1) = lBuf(xOut, yDest + 1) + bDib(x, y)
                      * fContrib
                     lBuf(xOut + 1, yDest + 1) = lBuf(xOut + 1, yDest + 1) +
                      bDib(x + 1, y) * fContrib
                     lBuf(xOut + 2, yDest + 1) = lBuf(xOut + 2, yDest + 1) +
                      bDib(x + 2, y) * fContrib
                     lColorCount(xDest, yDest + 1) = lColorCount(xDest, yDest +
                      1) + 1
                  End If
                  lBuf(xOut + 3, yDest + 1) = lBuf(xOut + 3, yDest + 1) +
                   bDib(x + 3, y) * fContrib
                  
                  ' The next one along in x and y gets a contribution:
                  fContrib = (1# - fContribX) * (1# - fContribY)
                  If (bDib(x + 3, y) > 0) Then
                     lBuf(xOut + 4, yDest + 1) = lBuf(xOut + 4, yDest + 1) +
                      bDib(x, y) * fContrib
                     lBuf(xOut + 5, yDest + 1) = lBuf(xOut + 5, yDest + 1) +
                      bDib(x + 1, y) * fContrib
                     lBuf(xOut + 6, yDest + 1) = lBuf(xOut + 6, yDest + 1) +
                      bDib(x + 2, y) * fContrib
                     lColorCount(xDest, yDest + 1) = lColorCount(xDest, yDest +
                      1) + 1
                  End If
                  lBuf(xOut + 7, yDest + 1) = lBuf(xOut + 7, yDest + 1) +
                   bDib(x + 3, y) * fContrib
                  
                  
               Else
                  ' proportion in x, whole lot in y
                  'Debug.Assert (bDib(x + 2, y) = 0)
                  
                  ' This pixel gets a contribution:
                  fContrib = 1# - (xStart + size - (xDest + 1)) / size
                  'fContrib = 1
                  If (bDib(x + 3, y) > 0) Then
                     lBuf(xOut, yDest) = lBuf(xOut, yDest) + bDib(x, y) *
                      fContrib
                     lBuf(xOut + 1, yDest) = lBuf(xOut + 1, yDest) + bDib(x +
                      1, y) * fContrib
                     lBuf(xOut + 2, yDest) = lBuf(xOut + 2, yDest) + bDib(x +
                      2, y) * fContrib
                     lColorCount(xDest, yDest) = lColorCount(xDest, yDest) + 1
                  End If
                  lBuf(xOut + 3, yDest) = lBuf(xOut + 3, yDest) + bDib(x + 3,
                   y) * fContrib
                  
                  ' And so does the next one along:
                  fContrib = 1# - fContrib
                  If (bDib(x + 3, y) > 0) Then
                     lBuf(xOut + 4, yDest) = lBuf(xOut + 4, yDest) + bDib(x, y)
                      * fContrib
                     lBuf(xOut + 5, yDest) = lBuf(xOut + 5, yDest) + bDib(x +
                      1, y) * fContrib
                     lBuf(xOut + 6, yDest) = lBuf(xOut + 6, yDest) + bDib(x +
                      2, y) * fContrib
                     lColorCount(xDest + 1, yDest) = lColorCount(xDest + 1,
                      yDest) + 1
                  End If
                  lBuf(xOut + 7, yDest) = lBuf(xOut + 7, yDest) + bDib(x + 3,
                   y) * fContrib
               End If
               
            Else
               If (yStart + size > yDest + 1) Then
                  ' All in x, only a proportion in y.
                  
                  ' This pixel gets a contribution:
                  fContrib = 1# - (yStart + size - (yDest + 1)) / size
                  If (bDib(x + 3, y) > 0) Then
                     lBuf(xOut, yDest) = lBuf(xOut, yDest) + bDib(x, y) *
                      fContrib
                     lBuf(xOut + 1, yDest) = lBuf(xOut + 1, yDest) + bDib(x +
                      1, y) * fContrib
                     lBuf(xOut + 2, yDest) = lBuf(xOut + 2, yDest) + bDib(x +
                      2, y) * fContrib
                     lColorCount(xDest, yDest) = lColorCount(xDest, yDest) + 1
                  End If
                  lBuf(xOut + 3, yDest) = lBuf(xOut + 3, yDest) + bDib(x + 3,
                   y) * fContrib
                  
                  ' And so does the next one along:
                  fContrib = (1# - fContrib)
                  If (bDib(x + 3, y) > 0) Then
                     lBuf(xOut, yDest + 1) = lBuf(xOut, yDest + 1) + bDib(x, y)
                      * fContrib
                     lBuf(xOut + 1, yDest + 1) = lBuf(xOut + 1, yDest + 1) +
                      bDib(x + 1, y) * fContrib
                     lBuf(xOut + 2, yDest + 1) = lBuf(xOut + 2, yDest + 1) +
                      bDib(x + 2, y) * fContrib
                     lColorCount(xDest, yDest + 1) = lColorCount(xDest, yDest +
                      1) + 1
                  End If
                  lBuf(xOut + 3, yDest + 1) = lBuf(xOut + 3, yDest + 1) +
                   bDib(x + 3, y) * fContrib
                  
               Else
                  ' All in x and y:
                  If (bDib(x + 3, y) > 0) Then
                     lBuf(xOut, yDest) = lBuf(xOut, yDest) + bDib(x, y)
                     lBuf(xOut + 1, yDest) = lBuf(xOut + 1, yDest) + bDib(x +
                      1, y)
                     lBuf(xOut + 2, yDest) = lBuf(xOut + 2, yDest) + bDib(x +
                      2, y)
                     lColorCount(xDest, yDest) = lColorCount(xDest, yDest) + 1
                  End If
                  lBuf(xOut + 3, yDest) = lBuf(xOut + 3, yDest) + bDib(x + 3, y)
               End If
            End If
            
         Next y
      Next x
      
      ' Swap buffer into the dib:
      'On Error Resume Next
      For x = 0 To cDibTo.BytesPerScanLine - 4 Step 4
         For y = 0 To cDibTo.Height - 1
            lB = (((lBuf(x, y) * lNewWidth) \ m_tBI.bmiHeader.biWidth) *
             lNewWidth) \ m_tBI.bmiHeader.biWidth
            If (lB > 255) Then lB = 255
            bDibTo(x, y) = lB
            lG = (((lBuf(x + 1, y) * lNewWidth) \ m_tBI.bmiHeader.biWidth) *
             lNewWidth) \ m_tBI.bmiHeader.biWidth
            If (lG > 255) Then lG = 255
            bDibTo(x + 1, y) = lG
            lR = (((lBuf(x + 2, y) * lNewWidth) \ m_tBI.bmiHeader.biWidth) *
             lNewWidth) \ m_tBI.bmiHeader.biWidth
            If (lR > 255) Then lR = 255
            bDibTo(x + 2, y) = lR
            lA = (((lBuf(x + 3, y) * lNewWidth) \ m_tBI.bmiHeader.biWidth) *
             lNewWidth) \ m_tBI.bmiHeader.biWidth
            If (lA > 255) Then lA = 255
            bDibTo(x + 3, y) = lA
         Next y
      Next x
      
   End If
   
   ' Clear the temporary array descriptor
   ' (This does not appear to be necessary, but
   ' for safety do it anyway)
   CopyMemory ByVal VarPtrArray(bDib), 0&, 4
   CopyMemory ByVal VarPtrArray(bDibTo), 0&, 4
   
   Set AlphaResample = cDibTo
   
End Function

Private Sub Class_Terminate()
    ClearUp
End Sub