您可以尝试添加自定义代码,并在Image.Value属性中使用它,以便在找不到图像时加载默认图像:
Public Function GetImage(ByRef CustomerNumber As String) As String
' Customer image
Dim ImageCustomerURL As String
ImageCustomerURL = "http://localhost/images/" + CustomerNumber + "/logo.gif"
' Default Image if customer image does not exist
Dim ImageDefaultURL As String
ImageDefaultURL = "http://localhost/images/default.gif"
' Create a web request to see if customer image exists
Dim m_Req As System.Net.HttpWebRequest = System.Net.HttpWebRequest.Create(ImageCustomerURL)
Try
Dim HttpWResp As System.Net.HttpWebResponse = CType(m_Req.GetResponse(), System.Net.HttpWebResponse)
If HttpWResp.StatusCode = System.Net.HttpStatusCode.OK
Return ImageCustomerURL
Else
Return ImageDefaultURL
End If
Catch ex As System.Net.WebException
If ex.Status = System.Net.WebExceptionStatus.ProtocolError Then
Return ImageDefaultURL
End If
End Try
Return ImageDefaultURL
End Function
那么你的Image.Value属性表达式应该是:
=Code.GetImage(iCustomerNumber.ToString())
编辑:设置Visibility.Hidden属性而不是使用默认图像
我认为使用默认图像比空白更好看,但实际上这两种方法是相同的:
Public Function HideImage(ByRef CustomerNumber As String) As Boolean
' Customer image
Dim ImageCustomerURL As String
ImageCustomerURL = "http://localhost/images/" + CustomerNumber + "/logo.gif"
' Create a web request to see if customer image exists
Dim m_Req As System.Net.HttpWebRequest = System.Net.HttpWebRequest.Create(ImageCustomerURL)
Try
Dim HttpWResp As System.Net.HttpWebResponse = CType(m_Req.GetResponse(), System.Net.HttpWebResponse)
If HttpWResp.StatusCode = System.Net.HttpStatusCode.OK
Return False
Else
Return True
End If
Catch ex As System.Net.WebException
If ex.Status = System.Net.WebExceptionStatus.ProtocolError Then
Return True
End If
End Try
Return True
End Function
那么你的Visibility.Hidden属性表达式是:
=Code.HideImage(iCustomerNumber.ToString())