WIA driver services library
The WIA driver services library contains functions that a WIA minidriver can call for assistance in performing the following tasks:
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 It is obsolete and is no longer supported.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. |