i have these 2 functions for get pixels:
Code:
Public Sub GetImageData(ByRef SourcehBitmap As Long, ByRef SourceHDC As Long, ByRef ImageData() As Byte)

    'Declare variables of the necessary bitmap types
    Dim bm As BITMAP
    Dim bmi As BITMAPINFO
    
    'Now we fill up the bmi (Bitmap information variable) with all the necessary data
    bmi.bmHeader.bmSize = 40 'Size, in bytes, of the header (always 40)
    bmi.bmHeader.bmPlanes = 1 'Number of planes (always one)
    bmi.bmHeader.bmBitCount = 24 'Bits per pixel (always 24 for image processing)
    bmi.bmHeader.bmCompression = 0 'Compression: none or RLE (always zero)
    
    'Calculate the size of the bitmap type (in bytes)
    Dim bmLen As Long
    bmLen = Len(bm)
    
    'Get the picture box information from SrcPictureBox and put it into our 'bm' variable
    GetObject SourcehBitmap, bmLen, bm
    bm.bmBitsPixel = 32
    
    'Build a correctly sized array.
    ReDim ImageData(0 To (bm.bmBitsPixel \ 8) - 1, 0 To bm.bmWidth - 1, 0 To bm.bmHeight - 1)
    
    'Finish building the 'bmi' variable we want to pass to the GetDIBits call
    bmi.bmHeader.bmWidth = bm.bmWidth
    bmi.bmHeader.bmHeight = bm.bmHeight
    
    'Now that we've filled the 'bmi' variable, we use GetDIBits to take the data from SrcPictureBox and put
    '  it into the ImageData() array using the settings specified in 'bmi'
    GetDIBits SourceHDC, SourcehBitmap, 0, bm.bmHeight, ImageData(0, 0, 0), bmi, 0


End Sub


Public Sub SetImageData(ByRef HBitmap As Long, ByRef DestinationHDC As Long, ByRef ImageData() As Byte)


    'Variables for the necessary bitmap types
    Dim bm As BITMAP
    Dim bmi As BITMAPINFO
    
    'Fill the bmi (Bitmap information variable) with appropriate values
    bmi.bmHeader.bmSize = 40
    bmi.bmHeader.bmPlanes = 1
    bmi.bmHeader.bmBitCount = 24
    bmi.bmHeader.bmCompression = 0
    
    'Calculate the size of the bitmap type (in bytes)
    Dim bmLen As Long
    bmLen = Len(bm)
    
    'Get the picture box information from DstPictureBox and put it into our 'bm' variable
    GetObject HBitmap, bmLen, bm
    
    'Now that we know the object's size, finish building the temporary header to pass to StretchDIBits
    bmi.bmHeader.bmWidth = bm.bmWidth
    bmi.bmHeader.bmHeight = bm.bmHeight
    bm.bmBitsPixel = 32
    'Use StretchDIBits to take the data from the ImageData() array and put it into SrcPictureBox using
    '  the settings specified in 'bmi'
    StretchDIBits DestinationHDC, 0, 0, bm.bmWidth, bm.bmHeight, 0, 0, bm.bmWidth, bm.bmHeight, _
      ImageData(0, 0, 0), bmi, 0, vbSrcCopy
End Sub
i get the array... but when i try change something:
Code:
Public Sub DrawAlphaBlend(ByRef DestinationDC As Long, AlphaValue As Long)        Dim BF As Long
        Const USE_BITMAP_ALPHA = &H1000000 'AC_SRC_ALPHA scaled up to the 4th byte of a long
        'BF = 128 * &H10000  'semi transparent ignoring bitmaps alpha channel
        BF = AlphaValue * &H10000 Or USE_BITMAP_ALPHA 'fully opaque using bitmaps alpha channel
        'AlphaBlend DestinationDC, 0, 0, Width, Height, hdc, 0, 0, Width, Height, BF
        GetImageData HBitmap, hdc, Pixels()
        Dim x As Long, y As Long
        For x = 0 To Width - 1
            For y = 0 To Height - 1
                If Pixels(2, x, y) = 255 And Pixels(1, x, y) = 0 And Pixels(0, x, y) = 0 Then
                    Pixels(2, x, y) = 0
                    Pixels(1, x, y) = 255
                    Pixels(0, x, y) = 0
                End If
            Next y
        Next x
        SetImageData HBitmap, DestinationDC, Pixels
End Sub
i get these result(tested with gif file):
Name:  imagem_2020-12-08_201343.jpg
Views: 68
Size:  27.4 KB
how can i fix these bug?
in these case i'm changing the red to green.. even if i change the alpha, i will get the same result
i use GDIPLUS for get the image:
Code:
Public Sub FromFile(FileName As String)    If FileName = "" Then Exit Sub
    DeleteObjects
    hdc = CreateCompatibleDC(GetDC(GetForegroundWindow()))
    GdipCreateFromHDC hdc, Graphics
    
    If Graphics Then
        Call GdipLoadImageFromFile(StrPtr(FileName), BITMAP)
        If BITMAP Then
            GdipGetImageHeight BITMAP, Height
            GdipGetImageWidth BITMAP, Width
            GdipCreateHBITMAPFromBitmap BITMAP, HBitmap, &O0
            SelectObject hdc, HBitmap
        End If
    End If
End Sub