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Hello,
I found an article on Codeproject which gives a comprehensive example of scanning an image and loading it directly into a window.http://www.codeproject.com/KB/dotnet/twaindotnet.aspx
When saving, however it will always save as 96 dpi. Is there any way of upping this?
I looked at GdipSaveImageToFile and saw the last argument is an IntPtr based on an EncoderParameters variable, but couldn’t figure how to massage that in. Any attempt at a Marshal.StructureToPtr failed miserably.
But also, is there any way of getting the scan directly into a file from the Twain, without getting the Image and saving that?
Any help gratefully appreciated.
ZiggyShort
You can scan direct into an image file if you select the FILE MODE as TWAIN transfer mode. Refer also to the TWAIN spec. The supported file formats are depending on the TWAIN data source.
Best regards,
Kaijyou’ll have to tweak this from vb.net, but for managed code this works.
'TW_SETUPFILEXFER
'''
''' Describes the file format and file specification information for a transfer through a disk file.
'''
'''TW_SETUPFILEXFER from TWAIN Spec
Public Structure twSetupFileXfer
#Region " C++ Reference "
'/* DAT_SETUPFILEXFER. Sets up DS to application data transfer via a file. */
'typedef struct {
' TW_STR255 FileName;
' TW_UINT16 Format; /* Any TWFF_ constant */
' TW_INT16 VRefNum; /* Used for Mac only */
'} TW_SETUPFILEXFER, FAR * pTW_SETUPFILEXFER;
#End Region
'''
''' A complete file specifier to the target file. On Windows, be sure to include the
''' complete pathname.
'''
'''Original type was TW_STR255.
Public FileName As String
'''
''' The format of the file the Source is to fill. Fill with the correct constant—as
''' negotiated with the Source—of type TWFF_xxxx.
'''
'''Original type was TW_UINT16
Public Format As Enumerations.ImageFileFormat
'''
''' The volume reference number for the file. This applies to Macintosh only. On
''' Windows, fill the field with TWON_DONTCARE16.
'''
'''Original type was TW_INT16
Public VrefNum As Int16
End Structure
and like Kaij said, you’ll have to set XferMode to File.
.
nope, that tells the source where to put the file after the you’ve been notified that the source is ready to deliver the file to you
to tell the source to use file for the XferMode I use something like:
Public Function SetXferMech(ByVal value As String) As Boolean
Dim xferMechVal As Enumerations.XferMech
Select Case value
Case Enumerations.XferMech.File.ToString
xferMechVal = Enumerations.XferMech.File
Case Enumerations.XferMech.Memory.ToString
xferMechVal = Enumerations.XferMech.Memory
Case Else
xferMechVal = Enumerations.XferMech.Native
End Select
'SetXferMode(_Profile.TransferMode)
'//
alias the namespace for shorter calls (not needed, just prettier)
Dim cap_XferMech As Enumerations.Capability = Enumerations.Capability.Icap_XferMech
'//
prep the container
Dim XferMechOneval As New DataStructures.twOneValue
XferMechOneval.ItemType = DataStructures.twCapability.CapType(cap_XferMech)
XferMechOneval.Item = xferMechVal
'//
create the CapStruc with the container
Dim capXferMech As New DataStructures.twCapability(cap_XferMech, XferMechOneval)
'//
set the Cap
Dim retBool As Boolean = OperationTriplets.Control.Capability.Set(capXferMech)
Return retBool
End Function
and I call that function after/If OpenDs returns twSuccess but before EnableDs gets called
.
they’re all in the opentwain project:
http://www.codeplex.com/opentwainon the releases tab, I think the most current one is named december 2007
.
I don’t know if it is going to make a different but I define twSetupFileXfer a little different,
'TW_SETUPFILEXFER
'''
''' Describes the file format and file specification information for a transfer through a disk file.
'''
'''TW_SETUPFILEXFER from TWAIN Spec
Public Structure twSetupFileXfer
#Region " C++ Reference "
'/* DAT_SETUPFILEXFER. Sets up DS to application data transfer via a file. */
'typedef struct {
' TW_STR255 FileName;
' TW_UINT16 Format; /* Any TWFF_ constant */
' TW_INT16 VRefNum; /* Used for Mac only */
'} TW_SETUPFILEXFER, FAR * pTW_SETUPFILEXFER;
#End Region
'''
''' A complete file specifier to the target file. On Windows, be sure to include the
''' complete pathname.
'''
'''Original type was TW_STR255.
Public FileName As String
'''
''' The format of the file the Source is to fill. Fill with the correct constant—as
''' negotiated with the Source—of type TWFF_xxxx.
'''
'''Original type was TW_UINT16
Public Format As Enumerations.ImageFileFormat
'''
''' The volume reference number for the file. This applies to Macintosh only. On
''' Windows, fill the field with TWON_DONTCARE16.
'''
'''Original type was TW_INT16
Public VrefNum As Int16
End Structure
then ::GetLastError *may* provide some information, but if memory serves GetLastError didn’t always return the stuff you thought it should when called from .net depending on how you you’re pinvoke was defined.
that said, if you’ve already pulled down the openTwain a working model of the code you’re looking for is in the cTwain.vb file in a method named TransferPicturesAsFile.
.
yes. but our class and structure don’t look alike.
my structure is decorated with
your class isn’t
and you’re welcome to open an IM.
you have my gmail address.and while we’re at it some of this is coming back to me (probably because I had a look thru the source code)
I don’t save the image from the DIB the way NetMaster shows in his interop artacle. …It didn’t do what I wanted for some reason ( but honestly that part hasn’t come back to me yet), and I switched to using SetDIBitsToDevice, but the part that struck me was that I don’t update the dpi with the GdipBitmapSetResolution call because I never got the drivers that I test with to give me dpi in a way that makes sense.
I did however build the project at one time with an option to update the resolution but I just used the SetResolution method (System.Drawing.Bitmap.SetResolution).
I know why I don’t fiddle with the resolution (my scanner’s driver wanted to tell me that the x and yResolution was 7432 or something when I thought it was 300) but why don’t you use SetResolution from the framework instead?
just wondering, it shouldn’t impact your current error.