GetRootItem Method

Visual Basic
C#
WinRT C#
WinRT JavaScript
C++

public object GetRootItem( 
   object item
)

'Declaration
 
Public Function GetRootItem( _
   ByVal item As Object _
) As Object

'Usage
 
Dim instance As WiaSession
Dim item As Object
Dim value As Object
 
value = instance.GetRootItem(item)

public object GetRootItem( 
   object item
)

 function Leadtools.Wia.WiaSession.GetRootItem( 
   item 
)

public:
Object^ GetRootItem( 
   Object^ item
)

Parameters

item: Handle to the item which represents the item for which you wish to retrieve its root item. You can retrieve this parameter by either calling the GetRootItem method to get the device's root item itself or by enumerating the child items of the device through a call to EnumChildItems method.

Return Value

The WIA root item handle.

Gets the root item for the item passed through the item parameter. If item parameters is null then the retrieved item will be the devices root item (which represents the device itself). This is the first function you need to call to get a handle to the devices root item. Then pass that handle to the EnumChildItems method to enumerate all of the devices child items. Then call this function again for any child item of the enumerated items to retrieve its root item if needed.

Visual Basic
C#
WinRT C#
WinRT JavaScript
Silverlight C#
Silverlight VB

Dim wiaSession As WiaSession
Public Sub GetRootItemExample(ByVal parent As IWin32Window)
   If (Not WiaSession.IsAvailable(WiaVersion.Version1)) Then
      MessageBox.Show("WIA version 1.0 not installed.")
      Return
   End If

   wiaSession = New WiaSession()
   wiaSession.Startup(WiaVersion.Version1)

   Dim res As DialogResult = wiaSession.SelectDeviceDlg(parent, WiaDeviceType.Default, WiaSelectSourceFlags.NoDefault)
   If res <> DialogResult.OK Then
      MessageBox.Show("Error selecting WIA device.")
      wiaSession.Shutdown()
      Return
   End If

   Dim rootItem As Object = wiaSession.GetRootItem(Nothing)
   If Not rootItem Is Nothing Then
      AddHandler wiaSession.EnumItemsEvent, AddressOf session_EnumItemsEvent

      wiaSession.EnumChildItems(rootItem)

      RemoveHandler wiaSession.EnumItemsEvent, AddressOf session_EnumItemsEvent
   End If

   wiaSession.Shutdown()
End Sub

Private Sub session_EnumItemsEvent(ByVal sender As Object, ByVal e As WiaEnumItemsEventArgs)
   If Not e.Item Is Nothing Then
      Dim dataTransfer As WiaDataTransferProperties = WiaDataTransferProperties.Empty
      Dim imageEffects As WiaImageEffectsProperties = WiaImageEffectsProperties.Empty

      Dim properties As WiaProperties = wiaSession.GetProperties(e.Item)

      properties.MaximumNumberOfPages = 0 ' scan all pages in feeder
      dataTransfer.ImageDataType = WiaImageDataType.Grayscale
      imageEffects.Brightness = 250

      properties.DataTransfer = dataTransfer
      properties.ImageEffects = imageEffects

      AddHandler wiaSession.SetPropertiesEvent, AddressOf session_SetPropertiesEvent

      wiaSession.SetProperties(e.Item, properties)

      RemoveHandler wiaSession.SetPropertiesEvent, AddressOf session_SetPropertiesEvent

      wiaSession.FreeItem(e.Item)
   End If
End Sub

Private Sub session_SetPropertiesEvent(ByVal sender As Object, ByVal e As WiaSetPropertiesEventArgs)
   If e.Error <= 0 Then
      Console.WriteLine("Failed to set the below property:" & Constants.vbLf + Constants.vbTab & "Property Id: {0}" & Constants.vbLf + Constants.vbTab & "Property Value: {1}" & Constants.vbLf + Constants.vbTab & "Error: {2}" & Constants.vbLf + Constants.vbLf, e.PropertyId.ToString(), Convert.ToInt32(e.Value).ToString(), e.Error.ToString())
   End If
End Sub

WiaSession wiaSession;
public void GetRootItemExample(IWin32Window parent)
{
   if (!WiaSession.IsAvailable(WiaVersion.Version1))
   {
      MessageBox.Show("WIA version 1.0 not installed.");
      return;
   }

   wiaSession = new WiaSession();
   wiaSession.Startup(WiaVersion.Version1);

   DialogResult res = wiaSession.SelectDeviceDlg(parent, WiaDeviceType.Default, WiaSelectSourceFlags.NoDefault);
   if (res != DialogResult.OK)
   {
      MessageBox.Show("Error selecting WIA device.");
      wiaSession.Shutdown();
      return;
   }

   object rootItem = wiaSession.GetRootItem(null);
   if (rootItem != null)
   {
      wiaSession.EnumItemsEvent += new EventHandler<WiaEnumItemsEventArgs>(wiaSession_EnumItemsEvent);

      wiaSession.EnumChildItems(rootItem);

      wiaSession.EnumItemsEvent -= new EventHandler<WiaEnumItemsEventArgs>(wiaSession_EnumItemsEvent);
   }

   wiaSession.Shutdown();
}

void wiaSession_EnumItemsEvent(object sender, WiaEnumItemsEventArgs e)
{
   if(e.Item != null)
   {
      WiaDataTransferProperties dataTransfer = WiaDataTransferProperties.Empty;
      WiaImageEffectsProperties imageEffects = WiaImageEffectsProperties.Empty;

      WiaProperties properties = wiaSession.GetProperties(e.Item);

      properties.MaximumNumberOfPages = 0;   // scan all pages in feeder
      dataTransfer.ImageDataType = WiaImageDataType.Grayscale;
      imageEffects.Brightness = 250;

      properties.DataTransfer = dataTransfer;
      properties.ImageEffects = imageEffects;

      wiaSession.SetPropertiesEvent += new EventHandler<WiaSetPropertiesEventArgs>(wiaSession_SetPropertiesEvent);

      wiaSession.SetProperties(e.Item, properties);

      wiaSession.SetPropertiesEvent -= new EventHandler<WiaSetPropertiesEventArgs>(wiaSession_SetPropertiesEvent);

      wiaSession.FreeItem(e.Item);
   }
}

void wiaSession_SetPropertiesEvent(object sender, WiaSetPropertiesEventArgs e)
{
   if(e.Error <= 0)
   {
      Console.WriteLine("Failed to set the below property:\n\tProperty Id: {0}\n\tProperty Value: {1}\n\tError: {2}\n\n", e.PropertyId.ToString(), Convert.ToInt32(e.Value).ToString(), e.Error.ToString());
   }
}

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

WiaSession Class
WiaSession Members
Startup Method
Shutdown Method
EnumChildItems Method
GetProperties Method
SetProperties Method
GetPropertyLong Method
SetPropertyLong Method
GetPropertyBuffer Method
SetPropertyBuffer Method
GetPropertyString Method
SetPropertyString Method
GetPropertyGuid Method
SetPropertyGuid Method
GetPropertySystemTime Method
SetPropertySystemTime Method