In ImageGear for Silverlight, an array container (see ImGearCapArray) or an enumeration container (see ImGearCapEnumeration) cannot be used to set a capability with string values. If calling code attempts to do this, then an exception will be thrown from the ImGearTWAIN.SetCapability method. However, when getting the value of a string capability, an array or enumeration can be returned with string values, from the ImGearTWAIN.GetCapability method.

The following example demonstrates attempting to set a capability with a string in an array container.

C#

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<code> ImGearCapArray arrayCapContainer = new ImGearCapArray(ImGearCapabilities.ICAP_HALFTONES); ImGearCapOneValueString oneValueCapContainer = new ImGearCapOneValueString(ImGearCapabilities.ICAP_HALFTONES); oneValueCapContainer.Value = "NONE"; arrayCapContainer.Values.Add(oneValueCapContainer); myImGearTWAIN.SetCapability(arrayCapContainer); // this line results in an ImGearException being thrown </code>

Alternative

An alternative to setting a string capability with an array or enumeration container would be to set the capability with a one-value container. The following code demonstrates setting a capability with a one-value container.

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<code> ImGearCapOneValueString oneValueCapContainer = new ImGearCapOneValueString(ImGearCapabilities.ICAP_HALFTONES); oneValueCapContainer.Value = “NONE”; myImGearTWAIN.SetCapability(oneValueCapContainer); </code>

How does this effect you?

In the TWAIN 2.0 specification, the only capabilities that are string value types and can be set with an array or enumeration container are ICAP_HALFTONES and CAP_PRINTERSTRING.

For ICAP_HALFTONES this will prevent you from setting the legal values of the capability.

For CAP_PRINTERSTRING this will restrict you to specifying printer strings of one line.