C＃和AForge - 使用未分配的局部變量edgePoints的

Question

我試圖編譯這段代碼（最後一個）： http://www.aforgenet.com/framework/features/blobs_processing.html

但它拋出：使用未分配的局部變量的「edgePoints」 ..

這裏是代碼：

 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); 

這是他有問題的行：

  edgePoints.AddRange(leftPoints); 

我綁分配null以edgePoints但它失敗：

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

什麼問題？我沒有修改源代碼，這樣就可以工作了..

Answer 1

您需要，以及 - 一個值分配給它：

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

在打電話的方法在該實例上。

你leftPoints和rightPoints可能是由

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

調用（注意out關鍵字）初始化，但edgePoints是不是 - 你需要做的是自己。