How to get value of a variable from another class

Question

I am using Emgu CV's SURF and I used int j = CvInvoke.cvCountNonZero(mask); to find matched pair points. The problem how to return this value into main()?

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public static Image<Bgr, Byte> Draw(Image<Gray, Byte> modelImage, Image<Gray, byte> observedImage, out long matchTime)      
{
    HomographyMatrix homography;
    VectorOfKeyPoint modelKeyPoints;
    VectorOfKeyPoint observedKeyPoints;
    Matrix<int> indices;
    Matrix<byte> mask;

    FindMatch(modelImage, observedImage, out matchTime, out modelKeyPoints, out observedKeyPoints, out indices, out mask, out homography);

    //Draw the matched keypoints
    Image<Bgr, Byte> result = Features2DToolbox.DrawMatches(modelImage, modelKeyPoints, observedImage, observedKeyPoints, indices, new Bgr(255, 255, 255), new Bgr(255, 255, 255), mask, Features2DToolbox.KeypointDrawType.DEFAULT);

    int j = CvInvoke.cvCountNonZero(mask);
    return result;
}

Answer 1

You can create a simple result object:

public class DrawingResult {
    public Image<Bgr, Byte> Images { get; private set; }
    public int Count {get; private set; }

    public DrawingResult(Image<Bgr, Byte> images, int count) {
       Images = images;
       Count = count;
    }
}

And in your method:

public static DrawingResult Draw(Image<Gray, Byte> modelImage, Image<Gray, byte> observedImage, out long matchTime)
{
    HomographyMatrix homography;
    VectorOfKeyPoint modelKeyPoints;
    VectorOfKeyPoint observedKeyPoints;
    Matrix<int> indices;
    Matrix<byte> mask;

    FindMatch(modelImage, observedImage, out matchTime, out modelKeyPoints, out observedKeyPoints, out indices, out mask, out homography);

    //Draw the matched keypoints
    Image<Bgr, Byte> result = Features2DToolbox.DrawMatches(modelImage, modelKeyPoints, observedImage, observedKeyPoints,
       indices, new Bgr(255, 255, 255), new Bgr(255, 255, 255), mask, Features2DToolbox.KeypointDrawType.DEFAULT);

    int j = CvInvoke.cvCountNonZero(mask);
    return new DrawingResult(result, j);
}

And in the main method:

DrawingResult result = MyClass.Draw(...);
int count = result.Count;
Image<Bgr, Byte> images = result.Images;