GetPropertyBuffer Method

Summary

Retrieves the Stream buffer for any WiaVariableTypes.UI1 or WiaVariableTypes.Vector property.

Syntax
C#
VB
C++
public Stream GetPropertyBuffer( 
   object item, 
   string propertyIdName, 
   WiaPropertyId propertyId 
) 
  
Public Function GetPropertyBuffer( _ 
   ByVal item As Object, _ 
   ByVal propertyIdName As String, _ 
   ByVal propertyId As WiaPropertyId _ 
) As Stream 
public: 
Stream^ GetPropertyBuffer(  
   Object^ item, 
   String^ propertyIdName, 
   WiaPropertyId propertyId 
)  

Parameters

item
Handle to the item which represents the item having the property. 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.

propertyIdName
This string should contain the equivalent property Id string for the WIA property ID. Use the GetPropertyIdString method to get this string for the property ID.

If you passed null for this parameter, then the WIA toolkit will use the property ID passed through the third parameter,

propertyId; otherwise, this parameter will be used whether or not you passed valid property ID through the propertyId parameter

propertyId
The property ID for the value being sought. For a list of available property IDs, see WiaPropertyId.

This parameter is required only if the second parameter, propertyIdName, is null; otherwise, you can pass 0 for this parameter.

Return Value

The WIA property buffer value.

Remarks

Any WIA property of type WiaVariableTypes.UI1 or WiaVariableTypes.Vector (for example, WiaPropertyId.CameraItemThumbnail, WiaPropertyId.ScannerDevicePadColor , ...etc) returns a Stream. In order to retrieve this type of buffer you need to call the function GetPropertyBuffer.

For more information, refer to Managing WIA Sources.

Example
C#
VB
using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Wia; 
 
WiaSession myWiaSession; 
public void GetPropertyBufferExample(IntPtr parent) 
{ 
   if (!WiaSession.IsAvailable(WiaVersion.Version1)) 
   { 
      MessageBox.Show("WIA version 1.0 not installed."); 
      return; 
   } 
 
   myWiaSession = new WiaSession(); 
   myWiaSession.Startup(WiaVersion.Version1); 
 
   DialogResult res = myWiaSession.SelectDeviceDlg(parent, WiaDeviceType.StreamingVideo, WiaSelectSourceFlags.NoDefault); 
   if (res != DialogResult.OK) 
   { 
      MessageBox.Show("Error selecting WIA device."); 
      myWiaSession.Shutdown(); 
      return; 
   } 
 
   object rootItem = myWiaSession.GetRootItem(null); 
   if (rootItem != null) 
   { 
      myWiaSession.EnumItemsEvent += new EventHandler<WiaEnumItemsEventArgs>(wiaSession_EnumItemsEvent2); 
 
      myWiaSession.EnumChildItems(rootItem); 
 
      myWiaSession.EnumItemsEvent -= new EventHandler<WiaEnumItemsEventArgs>(wiaSession_EnumItemsEvent2); 
   } 
 
   myWiaSession.Shutdown(); 
} 
 
void wiaSession_EnumItemsEvent2(object sender, WiaEnumItemsEventArgs e) 
{ 
   if (e.Item != null) 
   { 
      // Read the camera item thumbnail property. 
      Stream stream = myWiaSession.GetPropertyBuffer(e.Item, null, WiaPropertyId.CameraItemThumbnail); 
 
      // Read the camera thumbnail width property. 
      int nWidth = myWiaSession.GetPropertyLong(e.Item, null, WiaPropertyId.CameraItemThumbWidth); 
 
      // Read the camera thumbnail height property. 
      int nHeight = myWiaSession.GetPropertyLong(e.Item, null, WiaPropertyId.CameraItemThumbHeight); 
 
      int userDataLen = (int)stream.Length; 
      byte[] userData = new byte[userDataLen]; 
      stream.Read(userData, 0, userDataLen); 
 
      using (RasterImage thumbImage = new RasterImage( 
         RasterMemoryFlags.User, 
         nWidth, 
         nHeight, 
         24, 
         RasterByteOrder.Bgr, 
         RasterViewPerspective.LeftTop, 
         null, 
         userData, 
         userDataLen)) 
      { 
         using (RasterCodecs codecs = new RasterCodecs()) 
         { 
            codecs.Save(thumbImage, Path.Combine(LEAD_VARS.ImagesDir, "WiaThumb.jpg"), RasterImageFormat.Jpeg, 24); 
         } 
      } 
 
      myWiaSession.FreeItem(e.Item); 
   } 
} 
 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images"; 
} 
Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.Wia 
 
Dim myWiaSession As WiaSession 
<TestMethod()> _ 
Public Sub GetPropertyBufferExample(ByVal parent As IntPtr) 
   If (Not wiaSession.IsAvailable(WiaVersion.Version1)) Then 
      MessageBox.Show("WIA version 1.0 not installed.") 
      Return 
   End If 
 
   myWiaSession = New WiaSession() 
   myWiaSession.Startup(WiaVersion.Version1) 
 
   Dim res As DialogResult = myWiaSession.SelectDeviceDlg(parent, WiaDeviceType.StreamingVideo, WiaSelectSourceFlags.NoDefault) 
   If res <> DialogResult.OK Then 
      MessageBox.Show("Error selecting WIA device.") 
      myWiaSession.Shutdown() 
      Return 
   End If 
 
   Dim rootItem As Object = myWiaSession.GetRootItem(Nothing) 
   If Not rootItem Is Nothing Then 
      AddHandler myWiaSession.EnumItemsEvent, AddressOf session_EnumItemsEvent2 
 
      myWiaSession.EnumChildItems(rootItem) 
 
      RemoveHandler myWiaSession.EnumItemsEvent, AddressOf session_EnumItemsEvent2 
   End If 
 
   myWiaSession.Shutdown() 
End Sub 
 
Private Sub session_EnumItemsEvent2(ByVal sender As Object, ByVal e As WiaEnumItemsEventArgs) 
   If Not IsNothing(e.Item) Then 
      ' Read the camera item thumbnail property. 
      Dim stream As Stream = myWiaSession.GetPropertyBuffer(e.Item, Nothing, WiaPropertyId.CameraItemThumbnail) 
 
      ' Read the camera thumbnail width property. 
      Dim nWidth As Integer = myWiaSession.GetPropertyLong(e.Item, Nothing, WiaPropertyId.CameraItemThumbWidth) 
 
      ' Read the camera thumbnail height property. 
      Dim nHeight As Integer = myWiaSession.GetPropertyLong(e.Item, Nothing, WiaPropertyId.CameraItemThumbHeight) 
 
      Dim userDataLen As Integer = CType(stream.Length, Integer) 
      Dim userData(userDataLen - 1) As Byte 
      stream.Read(userData, 0, userDataLen) 
 
      Using thumbImage As New RasterImage( 
         RasterMemoryFlags.User, 
         nWidth, 
         nHeight, 
         24, 
         RasterByteOrder.Bgr, 
         RasterViewPerspective.LeftTop, 
         Nothing, 
         userData, 
         userDataLen) 
         Using codecs As New RasterCodecs() 
            codecs.Save(thumbImage, Path.Combine(LEAD_VARS.ImagesDir, "WiaThumb.jpg"), RasterImageFormat.Jpeg, 24) 
         End Using 
      End Using 
 
      myWiaSession.FreeItem(e.Item) 
   End If 
End Sub 
 
 
Public NotInheritable Class LEAD_VARS 
   Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images" 
End Class 

Requirements

Target Platforms

Help Version 20.0.2019.9.19
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Leadtools.Wia Assembly