Working with Error Handling

When an error condition is detected during call to any ImageGear property/method, an error code and all necessary error information is placed in an internal memory area called the ImageGear error stack. You can analyze the error stack for the error count and error information.

The error stack information is available via an object IGResult Object that is belongs to the Core type library.

Information about any error is available via IGResultRecord Object.

IGResult Object has the following properties and methods:

Name	Prop/Method	Description
IsOK Property	Method	Returns True if there is no errors, False otherwise.
ErrorCount Property	Prop, Get	Returns a count of error on the error stack (count of records of the level 0).
NotificationFlags Property	Prop, Get/Put	Specifies a method to inform the customer about an error. See examples below.
RecordCount Property	Prop, Get	Returns a count of records of the specified level on the error stack.
RecordsTotal Property	Prop, Get	Returns a total count of the records on the error stack.
GetError Method	Method	Returns IGResultRecord Object describing the specified error.
GetRecordWithLevel Method	Method	Returns IGResultRecord Object describing the specified record of the specified level.
Clear Method	Method	Clears all records on the error stack.

The NotificationFlags Property allows to choose a way how the customer will be informed about an error. It can take the following values:

IG_ERR_NO_ACTION	No action in case of error. The customer should analyze an error stack after call to the any property/methods. See Example 1. No Action when Error Occurs.
IG_ERR_OLE_ERROR	An OLE container is informed about an error via IErrorInfo interface. See Example 2. OLE Error.
IG_ERR_EVENT_ERROR	ImageGear will fire IGError Event event every time the error (record of level 0) is added to the error stack. Information about the error is located in the ResRec parameter. See Example 3. Error Events.
IG_ERR_EVENT_WARNING	ImageGear will fire IGError Event event every time the warning (record of level 1) is added to the error stack. Information about the warning is located in the ResRec parameter. See Example 3. Error Events.

Below is a brief description of properties of IGResultRecord Object:

Name	Description
FileName Property	The name of the file where an error/warning has been set.
LineNumber Property	The number of the line.
ErrCode Property	The code of the error.
Level Property	The level of the record. 0 - error, 1- warning.
Value1 Property	First attribute of the error/warning.
Value2 Property	Second attribute of the error/warning.
ExtraText Property	Extra text string describing an error.

Example 1. No Action when Error Occurs

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Public page as IGPage ` Set notification flags to IG_ERR_NO_ACTION IGCoreCtl1.Result.NotificationFlags = IG_ERR_NO_ACTION `Create a page and load an image Set page = IGCoreCtl1.CreatePage IGFormatsCtl1.LoadPageFromFile page, "myimage.jpg", 0 `check for error if not IGCoreCtl1.Result.IsOk() then `Get error count Dim errcount as Long errount = IGCoreCtl1.Result.ErrorCount `Get error description Dim rec as IGResultRecord Set rec = IGCoreCtl1.Result.GetError(errount - 1) `Get error code Dim errcode as enumIGErrorCodes Errcode = rec.ErrCode `Some error processing ... `Clear error stack IGCoreCtl1.Result.Clear End if

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Public page as IGPage
` Set notification flags to IG_ERR_NO_ACTION
IGCoreCtl1.Result.NotificationFlags = IG_ERR_NO_ACTION
`Create a page and load an image
Set page = IGCoreCtl1.CreatePage
IGFormatsCtl1.LoadPageFromFile page, "myimage.jpg", 0
`check for error
if not IGCoreCtl1.Result.IsOk() then
`Get error count
Dim errcount as Long
errount = IGCoreCtl1.Result.ErrorCount
`Get error description
Dim rec as IGResultRecord
Set rec = IGCoreCtl1.Result.GetError(errount - 1)
`Get error code 
Dim errcode as enumIGErrorCodes
Errcode = rec.ErrCode
`Some error processing
...
`Clear error stack
IGCoreCtl1.Result.Clear
End if

Example 2. OLE Error

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Dim errorRecord As IGResultRecord Dim i As Integer On Error GoTo ErrorHandler IGCoreCtl1.Result.NotificationFlags = IG_ERR_OLE_ERROR Set page = IGCoreCtl1.CreatePage IGFormatsCtl1.LoadPageFromFile page, "myimage.jpg", 0 Exit Sub ErrorHandler: If IGCoreCtl1.Result.IsOk() then `Internal COM error MsgBox "VB returned an error (" + Hex(Err.Number) + "):" + vbCrLf + Err.Description, vbExclamation, "Internal COM Error" Else `IG error For i = 0 To IGCoreCtl1.Result.RecordsTotal - 1 Set errorRecord = IGCoreCtl1.Result.GetRecord(i) MsgBox "ImageGear returned an error (" + errorRecord.ErrCode + "):" + vbCrLf + errorRecord.ExtraText, vbExclamation, "ImageGear Error" Next i End If Exit Sub

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Dim errorRecord As IGResultRecord
Dim i As Integer
On Error GoTo ErrorHandler
IGCoreCtl1.Result.NotificationFlags = IG_ERR_OLE_ERROR
Set page = IGCoreCtl1.CreatePage
IGFormatsCtl1.LoadPageFromFile page, "myimage.jpg", 0 
Exit Sub
ErrorHandler:
If IGCoreCtl1.Result.IsOk() then
   `Internal COM error
    MsgBox "VB returned an error (" + Hex(Err.Number) + "):" +
vbCrLf +
Err.Description, vbExclamation, "Internal COM Error" 
Else
  `IG error
   For i = 0 To IGCoreCtl1.Result.RecordsTotal - 1
   Set errorRecord = IGCoreCtl1.Result.GetRecord(i)
   MsgBox "ImageGear returned an error (" + errorRecord.ErrCode
+ "):" +
vbCrLf + errorRecord.ExtraText, vbExclamation, "ImageGear
Error" 
   Next i
End If
Exit Sub

Example 3. Error Events

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Public page as IGPage ` Set notification flags to IG_ERR_EVENT_ERROR or IG_ERR_EVENT_WARNING IGCoreCtl1.Result.NotificationFlags = IG_ERR_EVENT_ERROR or IG_ERR_EVENT_WARNING `Create a page and load an image Set page = IGCoreCtl1.CreatePage IGFormatsCtl1.LoadPageFromFile page, "myimage.jpg", 0 Exit Sub ` error processing Private Sub IGCoreCtl1_IGError(ByVal ResRec As GearCORELibCtl.IIGResultRecord) MsgBox "Event: " & ResRec.ExtraText End Sub

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Public page as IGPage
` Set notification flags to IG_ERR_EVENT_ERROR or
IG_ERR_EVENT_WARNING
IGCoreCtl1.Result.NotificationFlags = IG_ERR_EVENT_ERROR or
IG_ERR_EVENT_WARNING
`Create a page and load an image
Set page = IGCoreCtl1.CreatePage
IGFormatsCtl1.LoadPageFromFile page, "myimage.jpg", 0
Exit Sub
` error processing
Private Sub IGCoreCtl1_IGError(ByVal ResRec As
GearCORELibCtl.IIGResultRecord)
MsgBox "Event: " & ResRec.ExtraText
End Sub