事件處理程序

Question

我真的很新的WinForms和此刻的我有以下的錯誤使用的事件處理程序在C＃：

Error 1 The type 'DotFlickScreenCapture.ScreenCapture' cannot be used as type parameter 'TEventArgs' in the generic type or method 'System.EventHandler'. There is no implicit reference conversion from 'DotFlickScreenCapture.ScreenCapture' to 'System.EventArgs'.

我試圖尋找一種方法來打敗這個錯誤，但到目前爲止，我的谷歌搜索沒有發現任何東西。

線這個錯誤點是這個：

public EventHandler<ScreenCapture> capture; 

，從我可以告訴，這個類：

public class ScreenCapture 
{ 
    public delegate void StatusUpdateHandler(object sender, ProgressEventArgs e); 
    public event StatusUpdateHandler OnUpdateStatus; 

    public bool saveToClipboard = true; 

    public void CaptureImage(bool showCursor, Size curSize, Point curPos, Point SourcePoint, Point DestinationPoint, Rectangle SelectionRectangle, string FilePath, string extension) 
    { 
     Bitmap bitmap = new Bitmap(SelectionRectangle.Width, SelectionRectangle.Height); 

     using (Graphics g = Graphics.FromImage(bitmap)) 
     { 
      g.CopyFromScreen(SourcePoint, DestinationPoint, SelectionRectangle.Size); 

      if (showCursor) 
      { 
       Rectangle cursorBounds = new Rectangle(curPos, curSize); 
       Cursors.Default.Draw(g, cursorBounds); 
      } 
     } 

     if (saveToClipboard) 
     { 

      Image img = (Image)bitmap; 
      Clipboard.SetImage(img); 

      if (OnUpdateStatus == null) return; 

      ProgressEventArgs args = new ProgressEventArgs(img); 
      OnUpdateStatus(this, args); 
     } 
     else 
     { 
      switch (extension) 
      { 
       case ".bmp": 
        bitmap.Save(FilePath, ImageFormat.Bmp); 
        break; 
       case ".jpg": 
        bitmap.Save(FilePath, ImageFormat.Jpeg); 
        break; 
       case ".gif": 
        bitmap.Save(FilePath, ImageFormat.Gif); 
        break; 
       case ".tiff": 
        bitmap.Save(FilePath, ImageFormat.Tiff); 
        break; 
       case ".png": 
        bitmap.Save(FilePath, ImageFormat.Png); 
        break; 
       default: 
        bitmap.Save(FilePath, ImageFormat.Jpeg); 
        break; 
      } 
     } 
    } 
} 


public class ProgressEventArgs : EventArgs 
{ 
    public Image CapturedImage { get; private set; } 
    public ProgressEventArgs(Image img) 
    { 
     CapturedImage = img; 
    } 
} 

有沒有人經歷過這個錯誤？是的，我如何克服它？

Answer 1

ScreenCapture類必須從EventArgs類派生出來才能以您想要的方式使用。

public class ScreenCapture : EventArgs 

然後（避免誤解），它應該被命名ScreenCaptureEventArgs。考慮到這一點，創建一個ScreenCaptureEventArgs的類將更容易，該類衍生自EventArgs並且包含屬性ScreenCapture，這是您已擁有的類的實例。

就像是：

public class ScreenCaptureEventArgs : EventArgs 
{ 
    public ScreenCaptureEventArgs(ScreenCapture c) 
    { 
     Capture = c; 
    } 

    public ScreenCapture Capture { get; private set; } 
} 

public event EventHandler<ScreenCaptureEventArgs> ScreenCaptured;