C＃和AForge-使用未分配的局部变量edgePoints

Question

我正在尝试编译此代码（最后一个）： http : //www.aforgenet.com/framework/features/blobs_processing.html

但它抛出： 使用未分配的局部变量'edgePoints' ..

这是代码：

        BlobCounter blobCounter = new BlobCounter();
        blobCounter.ProcessImage(image23);
        Blob[] blobs = blobCounter.GetObjectsInformation();
        GrahamConvexHull hullFinder = new GrahamConvexHull();
        BitmapData data = image23.LockBits(new Rectangle(0, 0, image23.Width, image23.Height), ImageLockMode.ReadWrite, image23.PixelFormat);
        foreach (Blob blob in blobs)
        {
            List<IntPoint> leftPoints, rightPoints, edgePoints;
            blobCounter.GetBlobsLeftAndRightEdges(blob, out leftPoints, out rightPoints);
            edgePoints.AddRange(leftPoints);
            edgePoints.AddRange(rightPoints);
            List<IntPoint> hull = hullFinder.FindHull(edgePoints);
            Drawing.Polygon(data, hull, Color.Red);
        }
        image23.UnlockBits(data);

这是他有问题的那条线：

            edgePoints.AddRange(leftPoints);

我绑定将Null分配给edgePoints，但失败了：

List<IntPoint> leftPoints, rightPoints, edgePoints= null;

有什么问题？ 我没有修改源代码，所以一切正常。

Answer 1

您需要-为其分配一个值：

List<IntPoint> leftPoints, rightPoints, edgePoints;
edgePoints = new List<IntPoint>();

在该实例上调用方法之前。

您的leftPoints和rightPoints可能由初始化

blobCounter.GetBlobsLeftAndRightEdges(blob, out leftPoints, out rightPoints);

调用（请注意out关键字），但是edgePoints不是-您需要自己执行此操作。