包含類型不實現接口IMessageFilter

Question

我仍然試圖找出與此錯誤發生：

OCR.test.IMessageFilter.PreFilterMessage(ref System.Windows.Forms.Message): containing type does not implement interface System.Windows.Forms.IMessageFilter

這裏是我的代碼：

bool IMessageFilter.PreFilterMessage(ref Message m) // Error with this line 
{ 
    TwainCommand cmd = tw.PassMessage(ref m); 
    if (cmd == TwainCommand.Not) 
     return false; 

    switch (cmd) 
    { 
     case TwainCommand.CloseRequest: 
     { 
      EndingScan(); 
      tw.CloseSrc(); 
      break; 
     } 
     case TwainCommand.CloseOk: 
     { 
      EndingScan(); 
      tw.CloseSrc(); 
      break; 
     } 
     case TwainCommand.DeviceEvent: 
     { 
      break; 
     } 
     case TwainCommand.TransferReady: 
     { 
      ArrayList pics = tw.TransferPictures(); 
      EndingScan(); 
      tw.CloseSrc(); 
      picnumber++; 
      for (int i = 0; i < pics.Count; i++) 
      { 
       IntPtr img = (IntPtr)pics[i]; 
       PicForm newpic = new PicForm(img); 
       newpic.MdiParent = this; 
       int picnum = i + 1; 
       //newpic.Text = "ScanPass " + picnumber.ToString() + "_Pic " + picnum.ToString(); 
       newpic.Show(); 
      } 
      break; 
     } 
    } 

    return true; 
} 

Answer 1

類，你實現PreFilterMessage方法需要從IMessageFilter接口派生。你可能錯過了它

public class Foo: IMessageFilter 
{ 
    bool IMessageFilter.PreFilterMessage(ref Message m) 
    { 
     // your code 
    } 
}