Question

如何转换C＃代码

bmd是BitmapData

 byte* scanline = (byte*)bmd.Scan0 + (y * bmd.Stride);

到VB.NET？

在线C＃到VB.net转换器给了我这一行

Dim scanline As Pointer(Of Byte) = CType(bmd.Scan0, Pointer(Of Byte)) + (y * bmd.Stride)

但未定义类型'指针'。在 VB.Net？

我有什么选择？感谢您的建议。

Answer 1

VB.NET不支持指针。只要VB.NET是你的要求，替代品就会非常慢，Marshal类就是你所拥有的。它不应该是，在您的解决方案中添加C＃类库并在Visual Studio中使用其VB.NET代码中的类。

Answer 2

元帅是这里唯一的方式。我之前已经取得了很大的成功，但这很烦人。

http://msdn.microsoft.com/en-us/library/system.drawing.imaging.bitmapdata.scan0.aspx

' Get the address of the first line.
Dim ptr As IntPtr = bmpData.Scan0

' Declare an array to hold the bytes of the bitmap.
' This code is specific to a bitmap with 24 bits per pixels.
Dim bytes As Integer = Math.Abs(bmpData.Stride) * bmp.Height
Dim rgbValues(bytes - 1) As Byte

' Copy the RGB values into the array.
System.Runtime.InteropServices.Marshal.Copy(ptr, rgbValues, 0, bytes)

Answer 3

这是我得到的确切但一次通过后失败了。关于数组超出界限的东西可能与y * bmd.Stride有关（但我不明白为什么会出现越界错误，因为它应该只复制原始内存字节而不使用数组！）

  Public Function findImages(ByVal bmd As BitmapData) As List(Of Point)
    Dim results As New List(Of Point)()
    foundRects = New List(Of Rectangle)()

    For y As Integer = 0 To bmd.Height - 1
        'oringinal code
        'Dim scanline As Pointer(Of Byte) = CType(bmd.Scan0, Pointer(Of Byte)) + (y * bmd.Stride)

        'mess is here
        ' gets address of the first line
        'Dim ptr As IntPtr = bmd.Scan0
        'Dim bytes As Integer = (y * bmd.Stride)
        'If bytes = 0 Then bytes = bmd.Stride
        Dim scanline(bmd.Width * PIXLESIZE) As Byte

        'Copy the RGB values into the array.
        Runtime.InteropServices.Marshal.Copy(bmd.Scan0, scanline, (y * bmd.Stride), bmd.Width * PIXLESIZE)
        ' --------------------------------

        For x As Integer = 0 To bmd.Width - 1
            Dim xo As Integer = x * PIXLESIZE
            Dim buff As Byte() = {scanline(xo), scanline(xo + 1), scanline(xo + 2), &HFF}
            Dim val As Integer = BitConverter.ToInt32(buff, 0)

            ' Pixle value from subimage in desktop image
            If pixels.ContainsKey(val) AndAlso notFound(x, y) Then
                Dim loc As Point = DirectCast(pixels(val), Point)

                Dim sx As Integer = x - loc.X
                Dim sy As Integer = y - loc.Y
                ' Subimage occurs in desktop image 
                If imageThere(bmd, sx, sy) Then
                    Dim p As New Point(x - loc.X, y - loc.Y)
                    results.Add(p)
                    foundRects.Add(New Rectangle(x, y, bmImage.Width, bmImage.Height))
                End If
            End If
        Next
    Next

    Return results
End Function

C＃byte *到VB.NET BitmapData scanline

3 个答案: