pass mat from dll c++ to imagesource c#

Question

I'm working with Visual C# 2010, and I like to send an image from DLL C++ to my Visual C# 2010. The image has 166*166*24 to send the image from DLL C++ to C#. I'm using this code:

main.cpp

unsigned char*   test()
        {
read image from filename
        Mat OriginalImg = imread(fileName, CV_LOAD_IMAGE_COLOR); 
         return (OriginalImg.data);} 
  OriginalImg.data return the pointer to the image.

main.h

 extern "C" { __declspec(dllexport) unsigned char* test();}

and in my program Visual C#, I use this code:

 [DllImport("testng.dll", CallingConvention = CallingConvention.Cdecl)]
               private static extern IntPtr test();

        IntPtr intPtr1;

                    BitmapImage bitmapImage;
        calling the c++ dll
                    intPtr1 = test(1);

                    if (intPtr1.ToString().CompareTo("0") != 0)         
                    {     
create a bitmap with the pointer         
                    Bitmap bitmap = new Bitmap(166, 166, 3 * 166, System.Drawing.Imaging.PixelFormat.Format24bppRgb, intPtr1);
to show the bitmap i need to convert it to a bitmap image
                    bitmapImage=convertBitmapToBitmapImage(bitmap); 
                    System.Windows.Media.ImageBrush ib = new System.Windows.Media.ImageBrush();
                    ib.ImageSource = bitmapImage;
i put the image received from c++ dll like a background to my canvas: canvasImage
                    windows.canvasImage.Background = ib;
                    }

         BitmapImage convertBitmapToBitmapImage(Bitmap bitmap)
                {

                   IntPtr hBitmap = bitmap.GetHbitmap();

                   BitmapSource retval;

                     try
                        {
                             retval = Imaging.CreateBitmapSourceFromHBitmap(
                             hBitmap,
                             IntPtr.Zero,
                             Int32Rect.Empty,
                             BitmapSizeOptions.FromEmptyOptions());
                        }
                    finally
                       {
                           //DeleteObject(hBitmap);

                        }

                     return (BitmapImage)retval;



                }

sorry is the first time i ask a question here, the problem is that this line : Bitmap bitmap = new Bitmap(166, 166, 3 * 166, System.Drawing.Imaging.PixelFormat.Format24bppRgb, intPtr1); return a error : invalid parameter so i don´t know what is the problem exactly. — roma, Mar 24 '14 at 10:57
So you've got compilation problem? Please paste compiler error message. — marol, Mar 24 '14 at 11:16
when i debug the file it stop at this line :Bitmap bitmap = new Bitmap(166, 166, 3 * 166, System.Drawing.Imaging.PixelFormat.Format24bppRgb, intPtr1); pointing to fromat24bppRgb showing invalid parameter message — roma, Mar 24 '14 at 11:59

score 0 · Accepted Answer · edited May 23 '17 at 11:59

0

My guess is the pointer to the cv::Mat data is no longer valid after function test() returns, because variable OriginalImg gets out of scope, destructors have cleaned OriginalImg data. Try making OriginalImg global if it is possible to prevent automatic destroy of the variable.

In general, I recommend making a generic C++/CLI wrapper for OpenCV. A made a post about that. For example, I'm working now on the same problem as you and I'm creating a System.Drawing.Bitmap object in C++/CLI without any DllImports...

edited May 23 '17 at 11:59

Community

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answered Mar 24 '14 at 12:00

marol

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But if you have more issues, post it here. – marol Mar 24 '14 at 12:24

pass mat from dll c++ to imagesource c#

1 Answers1