Question

I think this must be an easy question for somebody who uses bitmap in C++. I have my a working code in C# – how to do something simillar in C++ ?? Thanks for your codes (help) :-))

public Bitmap Visualize ()
{


  PixelFormat fmt = System.Drawing.Imaging.PixelFormat.Format24bppRgb;
  Bitmap result = new Bitmap( Width, Height, fmt );

  BitmapData data = result.LockBits( new Rectangle( 0, 0, Width, Height ), ImageLockMode.ReadOnly, fmt );
  unsafe
  {
    byte* ptr;

    for ( int y = 0; y < Height; y++ )
    {
      ptr = (byte*)data.Scan0 + y * data.Stride;

      for ( int x = 0; x < Width; x++ )
      {
          float num = 0.44;
          byte c = (byte)(255.0f * num);
          ptr[0] = ptr[1] = ptr[2] = c;


          ptr += 3;
      }
    }
  }
  result.UnlockBits( data );

  return result;

}

Answer 1

Raw translation to C++/CLI, I didn’t run the example so it may contains some typo. Anyway there are different ways to get the same result in C++ (because you can use the standard CRT API).

Bitmap^ Visualize ()
{
  PixelFormat fmt = System::Drawing::Imaging::PixelFormat::Format24bppRgb;
  Bitmap^ result = gcnew Bitmap( Width, Height, fmt );

  BitmapData^ data = result->LockBits( Rectangle( 0, 0, Width, Height ), ImageLockMode::ReadOnly, fmt );
  for ( int y = 0; y < Height; y++ )
  {
    unsigned char* ptr = reinterpret_cast<unsigned char*>((data->Scan0 + y * data->Stride).ToPointer());

    for ( int x = 0; x < Width; x++ )
    {
        float num = 0.44f;
        unsigned char c = static_cast<unsigned char>(255.0f * num);
        ptr[0] = ptr[1] = ptr[2] = c;

        ptr += 3;
    }
  }

  result->UnlockBits( data );

  return result;

}