[2005] Creating a Pointer to a Array of Bytes

Hi!!!

I have this code:

vb 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??

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

Watch this code:

vb 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.

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

Code:

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Public Sub New(ByVal myByteArray As Byte())

End Sub

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

Quote:

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Originally Posted by Lasering

Watch this code:

vb 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.

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

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.

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

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.

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:

Code:

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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)

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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.

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.