VbPointerT Structure

Public Structure VbPointer(Of T As IConvertible)

Dim instance As VbPointer(Of T)

generic<typename T>
where T : IConvertible
public value class VbPointer

[<SealedAttribute>]
type VbPointer<'T when 'T : IConvertible> = 
    struct
        inherit ValueType
    end

No code example is currently available or this language may not be supported.

' C# original source code that use pointers to invert the colors of a image:
'
' private static Image InvertImageColorsUnsafe(Image img) {
' 
'     Bitmap bmp = new Bitmap(img);
' 
'     //Format is BGRA, NOT ARGB.
'     BitmapData bmData = bmp.LockBits(new Rectangle(0, 0, bmp.Width, bmp.Height),
'                                      ImageLockMode.ReadWrite,
'                                      PixelFormat.Format32bppArgb);
' 
'     int stride = bmData.Stride;
'     IntPtr Scan0 = bmData.Scan0;
' 
'     unsafe {
'         byte* p = (byte*)(void*)Scan0;
' 
'         int nOffset = stride - bmp.Width * 4;
'         int nWidth = bmp.Width;
' 
'         for (int y = 0; y < bmp.Height; y++) {
'             for (int x = 0; x < nWidth; x++) {
'                 p[0] = (byte)(255 - p[0]); // Red
'                 p[1] = (byte)(255 - p[1]); // Green
'                 p[2] = (byte)(255 - p[2]); // Blue
'                 //p[3] is alpha, don't want to invert alpha
'                 p += 4;
'             }
'             p += nOffset;
'         }
'     }
' 
'     bmp.UnlockBits(bmData);
'     return (Image)bmp;
' }

' VB.NET equivalency using the VbPointer class:
Private Shared Function InvertImageColorsUnsafe(originalImg As Image) As Image

    Dim bmp As New Bitmap(originalImg)

    ' Format is BGRA, NOT ARGB.
    Dim bmData As BitmapData =
        bmp.LockBits(New Rectangle(0, 0, bmp.Width, bmp.Height),
                     ImageLockMode.ReadWrite, PixelFormat.Format32bppArgb)

    Dim stride As Integer = bmData.Stride
    Dim p As New VbPointer(Of Byte)(bmData.Scan0)

    Dim nOffset As Integer = stride - bmp.Width * 4
    Dim nWidth As Integer = bmp.Width

    For y As Integer = 0 To (bmp.Height - 1)
        For x As Integer = 0 To (nWidth - 1)
            p(0) = CByte(255 - p(0)) ' Red
            p(1) = CByte(255 - p(1)) ' Green
            p(2) = CByte(255 - p(2)) ' Blue
            'p(3) is alpha, don't want to invert alpha
            p += 4
        Next
        p += nOffset
    Next
    bmp.UnlockBits(bmData)

    Return DirectCast(bmp, Image)
End Function

No code example is currently available or this language may not be supported.

No code example is currently available or this language may not be supported.

No code example is currently available or this language may not be supported.

No code example is currently available or this language may not be supported.