[2005] Creating a Pointer to a Array of Bytes

[Lasering]

Hi!!!

I have this code:

Dim TGA As New TGAReader(Open.FileName)
Dim imagedata() As Byte = TGA.GetImageData(TGA.FileBytes)
Pic.Image = New Bitmap(TGA.ImageWidth, TGA.ImageHeight, TGA.ImageStride, Imaging.PixelFormat.Format24bppRgb, 'The pointer here)

The TGAReader class is a class made by me that reads a TGA file. As suggested the Method GetImageData retrieves a array of type byte.
This array contains three bytes for each pixel (The RGB intensities), thats why the pixelformat is 24bppRgb.
Now i want to create a pointer to that array of bytes. But i just dont know how. I know that a pointer can "be created" throw the IntPtr class. But I dont have any value to pass to the constructer. Can you help me??

[Atheist]

Does VB support pointers like these? I dont think so..C# does though.

[Lasering]

Watch this code:

Dim Bitma As New Bitmap(Open.FileName)
Dim imageData As System.Drawing.Imaging.BitmapData
imageData = Bitma.LockBits(New Rectangle(0, 0, Bitma.Width, Bitma.Height), Imaging.ImageLockMode.ReadWrite, Bitma.PixelFormat)
Pic.Image = New Bitmap(Bitma.Width, Bitma.Height, imageData.Stride, Bitma.PixelFormat, New IntPtr(CInt(imageData.Scan0)))

It reads a .jpg image and shows it using a pointer.

I want to do the same to my image. But my problem is that my image is TGA, and VB.net doesn't natively supports it, so i have to read the bytes where the pixel information is, and then create the image. I've tried the setpixel, but it takes like ages.

[robertx]

A Byte Array is a reference type so just pass the byte array to the constructor By Value (ByVal).

Public Sub New(ByVal myByteArray As Byte())

End Sub

This will pass a copy of a pointer to your byte array to the constructor.

[Atheist]

Watch this code:

Dim Bitma As New Bitmap(Open.FileName)
Dim imageData As System.Drawing.Imaging.BitmapData
imageData = Bitma.LockBits(New Rectangle(0, 0, Bitma.Width, Bitma.Height), Imaging.ImageLockMode.ReadWrite, Bitma.PixelFormat)
Pic.Image = New Bitmap(Bitma.Width, Bitma.Height, imageData.Stride, Bitma.PixelFormat, New IntPtr(CInt(imageData.Scan0)))

It reads a .jpg image and shows it using a pointer.

I want to do the same to my image. But my problem is that my image is TGA, and VB.net doesn't natively supports it, so i have to read the bytes where the pixel information is, and then create the image. I've tried the setpixel, but it takes like ages.

But thats not really creating a pointer is it? Its just locking the bitmap into the memory. Or... am I wrong?

[Lasering]

ur right! But by looking then into the memory u are then able to get its pointer.
Robertx, for that u would have to have the New sub for the bitmap class, because that is where i want to put the pointer.

[robertx]

Apologies - I now follow what you are trying to do. I was off in a completely different direction.

[Lasering]

lool :P
If u have any idea plz say. Because it seems that there is no way out of this, other then making a C# class, that is what i didnt want.

[robertx]

I have got no idea whether this will work but it's worth a try:

According to MSDN:

http://msdn2.microsoft.com/en-us/lib...shal.copy.aspx

The System.Runtime.InteropServices.Marshal.Copy Method

"Copies data from a managed array to an unmanaged memory pointer, or from an unmanaged memory pointer to a managed array."

This could be implemented as follows:

Dim imagedata() As Byte = TGA.GetImageData(TGA.FileBytes)

Dim lpimagedata As IntPtr = Marshal.AllocHGlobal(imagedata.Length)

Marshal.Copy(imagedata, 0, lpimagedata, imagedata.Length)

Pic.Image = New Bitmap(TGA.ImageWidth, TGA.ImageHeight, TGA.ImageStride, Imaging.PixelFormat.Format24bppRgb, lpimagedata)

The third parameter of the Marshal.Copy method ("destination") is a memory pointer (IntPtr) to which data is copied from the first parameter - the byte array containing the image data.

I hope that this somehow points you in the right direction.

[Lasering]

Thks, that helped. Since the image is stored backwards in the file (the end of the image is in the begining of the file), i get the last color. but i dont get the whole image but i dont understand why.