?
Solved

BitmapData pointer in C#

Posted on 2007-03-30
2
Medium Priority
?
831 Views
Last Modified: 2013-12-17
In code I had in a Visual Studio C++ .NET Windows Form Application, I had a portion of code that looked like this:
bmd is a BitmapData object.

for(int y = 0; y < bmd->Height; y++)
{
      Byte* row = (Byte*)(void*)bmd->Scan0 +(y * bmd->Stride);
      for(int x = 0; x < bmd->Width*4; x++)
      {
              ...
        }
}

Now, I'm writing a function to do the same thing in C#.  However, I got a few errors.  I've been trying to find a C# equivalent that would give me the equivalent of the "Byte* row" line, but so far, I've got no luck.  This is what I have now, but its still not working. I've replaced that one entire line with this:

int rowPtr = y * bmd.Stride;
IntPtr scanPoint = bmd.Scan0;
Byte row;
unsafe
{
      void* bmdRow = scanPoint.ToPointer();
      //bmdRow+=rowPtr;   <- Gives error.
      row = (Byte)(bmdRow);
}

The code is basically supposed to give me a pointer to each row so I can set each pixel individually.  In that nested for loop was code that contained stuff like "row[x] = pixelvalue;"    If anyone can help me out with this, that'd be great.  Any questions to get a more detailed explanation of the problem, just ask.
0
Comment
Question by:raw_enha
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
2 Comments
 
LVL 11

Expert Comment

by:Babycorn-Starfish
ID: 18828275
Hi,

what error are you getting?
0
 
LVL 11

Accepted Solution

by:
Babycorn-Starfish earned 2000 total points
ID: 18828305
If you want to walk over the image, pixel by pixel i'd do something like this (i've assumed it's all in an unsafe block):

Byte bPP = (Byte)(aData.Stride / aWidth); //determine how many bytes per pixel there are  
Byte rowOffset = (Byte)(aData.Stride - (aBPP * aWidth)); // determine whether there is a row offset

Byte* p = (Byte*)aData.Scan0; //pointer to beginning of image

for (Int32 y = 0; y < height; y++)
{
    for (Int32 x = 0; x < width; x++)
    {
        //do something to this pixel
      //e.g. p[0] = 255 etc

      //update position of pointer
        p += bPP;    
    }
    p += rowOffset;
}
 
0

Featured Post

On Demand Webinar: Networking for the Cloud Era

Did you know SD-WANs can improve network connectivity? Check out this webinar to learn how an SD-WAN simplified, one-click tool can help you migrate and manage data in the cloud.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

IP addresses can be stored in a database in any of several ways.  These ways may vary based on the volume of the data.  I was dealing with quite a large amount of data for user authentication purpose, and needed a way to minimize the storage.   …
In my previous two articles we discussed Binary Serialization (http://www.experts-exchange.com/A_4362.html) and XML Serialization (http://www.experts-exchange.com/A_4425.html). In this article we will try to know more about SOAP (Simple Object Acces…
In this brief tutorial Pawel from AdRem Software explains how you can quickly find out which services are running on your network, or what are the IP addresses of servers responsible for each service. Software used is freeware NetCrunch Tools (https…
How to fix incompatible JVM issue while installing Eclipse While installing Eclipse in windows, got one error like above and unable to proceed with the installation. This video describes how to successfully install Eclipse. How to solve incompa…

777 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question