WIA driver services library

The WIA driver services library contains functions that a WIA minidriver can call for assistance in performing the following tasks:

• Build and maintain an item tree

• Log error and trace messages

• Read and store item properties

• Update and transfer data

A WIA minidriver calls most of these functions from its IWiaMiniDrv Interface methods as needed. Each WIA minidriver, however, must call the wiasCreateDrvItem function in the IWiaMiniDrv::drvInitializeWia method to create driver items. Each successful call to a wiasCreateDrvItem function creates an IWiaDrvItem item object, which is used in the minidriver's item tree. Several IWiaDrvItem Interface methods have a parameter of type IWiaDrvItem, including the IWiaDrvItem::AddItemToFolder, IWiaDrvItem::GetFirstChildItem, IWiaDrvItem::GetNextSiblingItem, and IWiaDrvItem::GetParentItem. Also, the wiasGetDrvItem function has a parameter of this type.

The driver services library provides the following functions.

Build and maintain an item tree

Function	Description
wiasCreateChildAppItem	Creates a new application item and inserts it as a child of the specified (parent) item.
wiasCreateDrvItem	Creates an IWiaDrvItem object.
wiasGetChildrenContexts	Retrieves an array of item contexts belonging to the current item's children.
wiasGetContextFromName	Retrieves the item context for an item name.
wiasGetDrvItem	Retrieves a driver item.
wiasGetRootItem	Retrieves the root item context of a specified WIA item.

Log error and trace messages

Function	Description
wiasCreateLogInstance	Creates an instance of a logging object.
wiasDebugError	Prints a debug error string in the Device Manager debug console. The output color is always red. This function is provided for compatibility only. It is recommended to use WIAS_ERROR instead.
wiasDebugTrace	Prints a debug trace string in the Device Manager debug console. This function is provided for compatibility only. It is recommended to use WIA_TRACE instead.
wiasFormatArgs	Formats an argument list into a packaged string for logging.
wiasPrintDebugHResult	Prints an HRESULT string on the Device Manager debug console. This function is provided for compatibility only. It is obsolete and is no longer supported. Use WIAS_LHRESULT instead.

Read and store item properties

Function	Description
wiasCreatePropContext	Allocates a property context to indicate which of an item's properties are changing.
wiasFreePropContext	Releases the memory occupied by a WIA_PROPERTY_CONTEXT structure.
wiasGetChangedValueFloat	Determines whether a property with a floating-point value has been changed by an application.
wiasGetChangedValueGuid	Determines whether a property with a GUID value has been changed by an application.
wiasGetChangedValueLong	Determines whether a property with a long integer value has been changed by an application.
wiasGetChangedValueStr	Determines whether a property with a string value has been changed by an application.
wiasGetItemType	Indicates a root or child item.
wiasGetPropertyAttributes	Retrieves the access flags and valid values for a set of properties.
wiasIsPropChanged	Tests whether the specified property has been changed by an application.
wiasReadMultiple	Reads multiple properties from a WIA item.
wiasReadPropBin	Reads a single binary property from a WIA item.
wiasReadPropFloat	Retrieves a floating-point property value from a WIA item.
wiasReadPropGuid	Retrieves a GUID property value from a WIA item.
wiasReadPropLong	Retrieves a long integer property value from a WIA item.
wiasReadPropStr	Retrieves a string property value from a WIA item.
wiasSetItemPropAttribs	Sets the access flags and valid values for an item's set of properties.
wiasSetItemPropNames	Writes property names to item properties.
wiasSetPropChanged	Modifies a property context to indicate that a property is being changed.
wiasSetPropertyAttributes	Sets the access flags and property values of an item's properties.
wiasSetValidFlag	Sets the valid values for a WIA_PROP_FLAG property.
wiasSetValidListFloat	Sets the valid values for a WIA_PROP_LIST property of type sub-VT_R4.
wiasSetValidListGuid	Sets the valid values for a WIA_PROP_LIST property of subtype VT_CLSID.
wiasSetValidListLong	Sets the valid values for a WIA_PROP_LIST property of type sub-VT_I4.
wiasSetValidListStr	Sets the valid values for a WIA_PROP_LIST property of type sub-VT_BSTR.
wiasSetValidRangeFloat	Specifies the range of valid values for a WIA_PROP_RANGE property of subtype VT_R4.
wiasSetValidRangeLong	Specifies the range of valid values for a WIA_PROP_RANGE property of subtype VT_I4.
wiasUpdateValidFormat	Updates the valid format of the property context for the current minidriver.
wiasValidateItemProperties	Validates a list of simple item properties against their current valid values.
wiasWriteMultiple	Writes multiple property values to a WIA item (the properties may be of different types).
wiasWritePropBin	Writes a single binary property value to a WIA item.
wiasWritePropFloat	Writes a floating-point property value to a WIA item.
wiasWritePropGuid	Writes a GUID property value to a WIA item.
wiasWritePropLong	Writes a long integer property value to a WIA item.
wiasWritePropStr	Writes a string property value to a WIA item.

Update and transfer data

Function	Description
wiasDownSampleBuffer	Takes in a buffer of pixel data and downsamples it to the specified size.
wiasGetImageInformation	Retrieves transfer context information from an item.
wiasParseEndorserString	Parses an endorser string, replacing WIA service-defined and vendor-defined tokens in the string with values associated with the tokens.
wiasSendEndOfPage	Calls the client callback routine during a data transfer, sending the current total page count.
wiasUpdateScanRect	Updates the scanning area sizes of the scanning device.
wiasWriteBufToFile	Writes the contents of a temporary page buffer to an image file.
wiasWritePageBufToFile	Writes the contents of a temporary page buffer to an image file. Use this function to write a page to a multi-page TIFF file.