This article describes how to use DotTwain’s SaveParameters,
LoadParameters, SaveXmlParameters and
LoadXmlParameters methods to allow your users to scan with
specific settings without having to change them every time in the scanner
interface.
If the Device.CustomDataSupported property returns true, you
should use the SaveParameters and LoadParameters methods. If the
CustomDataSupported property returns false, you must use the SaveXmlParameters
and LoadXmlParameters methods.
Difference Between Methods
The SaveParameters and LoadParameters methods use a special TWAIN operation
to tell the driver to save or load its settings. This means the file data is
created by the driver, not DotTwain.
The SaveXmlParameters and LoadXmlParameters methods work by saving/loading
all settable properties the driver provides in its CAP_SUPPORTEDCAPS.
Even through SaveXmlParameters will work with all drivers, it’s always best
to use SaveParameters when the driver supports it since that data usually
contains more information than DotTwain can access.
Saving Parameters
To save parameters you must show the driver interface so the user can select
the settings they want. If Device.EnabledInterfaceOnly returns
true, then the device is able to show its interface without scanning by calling
the ShowUserInterface method. If EnableInterfaceOnly returns
false, your only choice is to call Acquire and save the settings in the
AcquireFinished event.
Be sure to save the settings before calling the Close method
or they may be lost.
Loading Parameters
To load the parameters correctly, you must follow these steps:
- Open the device.
- Call LoadParameters (if CustomDataSupported) or LoadXmlParameters.
- Set the HideInterface property to true.
- Optionally set the DisplayProgressIndicator property to false.
- Call Acquire.
A demo project for Visual Studio 2008, both C# and VB, it attached to this
case to provide a working example on using these methods.
Original Article:
Q10271 - HOWTO: Proper use of Save/Load Parameters in TWAIN scanning