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WIA Camera Support in Windows Vista (Part 2 of 2)

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In the previous post, we gave an overview of the WIA-WPD Compatibility Layer and how WIA Applications can register for WIA_EVENT_DEVICE_CONNECTED events.

In this post, we will cover a more advanced topic: customization for PTP and MTP devices.   The WIA-WPD Compatibility Layer supports basic extensibility for custom WIA events and WIA properties.   These events and properties were provided in the PTP WIA class driver that shipped with Windows XP.  

Adding Custom PTP/MTP WIA Event Codes

To specify a list of supported PTP/MTP event codes the 'WiaEventCodes' entry should be provided. 

The following example shows 3 custom event codes being reported.

HKR,,"WiaEventCodes",”0x0001,0x0002,0x0003”

For each event code specified in the 'WiaEventCodes' entry, a corresponding 'WiaEventCodeXXX' entry must exist that specifies the name of the event and the GUID to use when reporting the event to WIA applications.  The entry should be constructed using the prefix ‘WiaEventCode + the event code specified in WiaEventCodes entry’ .  If the WiaEventCodeXXX entry is missing, the event will not be reported to WIA applications.

HKR,,"WiaEventCode0x0001”,”{20179E3D-139C-40D3-A0CA-962B33D67EE3},My Custom Event”
HKR,,"WiaEventCode0x0002”,”{259A62CF-D8FE-44D0-A747-B14F54A02133},My Amazing Event”
HKR,,"WiaEventCode0x0003”,”{639F80C6-94D1-48E2-9D8E-6D0F12237E48},My Super Event”

Adding Custom PTP/WIA Property Codes

To specify a list of supported PTP/MTP property codes the ‘WiaPropertyCodes’ entry should be provided. WIA properties will only appear on the root item.  These properties are commonly used to control/program the device. 

The following example shows 3 custom property codes being reported.

HKR,,"WiaPropertyCodes",”0x0001,0x0002,0x0003”

For each property code specified in the ‘WiaPropertyCodes’ entry, a corresponding ‘WiaPropertyCodeXXX’ entry must exist that specifies the name of the property and the WIA property code to use when reporting the property to WIA applications.  The entry should be constructed using the prefix ‘WiaPropertyCode + the property code specified in WiaPropertyCodes entry’ .  If the WiaPropertyCodeXXX entry is missing, the event will not be reported to WIA applications.

HKR,,"WiaPropertyCode0x0001”,”My Custom Device Property”
HKR,,"WiaPropertyCode0x0002”,”My Amazing Device Property”
HKR,,"WiaPropertyCode0x0003”,”My Super Device Property”

Sending PTP Custom Commands through WIA

PTP extension commands can be sent to the vendor's driver using IWiaItemExtras::Escape.   In Windows Vista, the WIA-WPD Compatibility Layer repackages PTP extension commands sent using this method into WPD MTP/PTP extension commands, which are dispatched to the WPD MTP class driver.   This mechanism exists to support legacy WIA vendor applications that relied on custom PTP commands from Windows XP. 

Sending MTP Custom Commands through WPD 

WPD supports sending of custom MTP commands to the MTP driver using the IPortableDevice::SendCommand API.   For a step-by-step description, visit DimeBy8's excellent post here.  

 

WIA to WPD Content Type and Format Mapping

The following table maps WIA Item Types to the WPD_OBJECT_CONTENT_TYPE. 

In addition to video and image content, the WIA-WPD Compatiliby Layer supports thumbnails and audio annotations for objects that have them.  Any data objects that do not fall under these categories (e.g. music files) will not appear in WIA applications.

 

WPD Object

WPD Content Type

WIA Item

WIA Item Type

Device object

N/A

Root item

(WiaItemTypeFolder | WiaItemTypeDevice | WiaItemTypeRoot)

Folder object

WPD_CONTENT_TYPE_FOLDER

Folder Item

WiaItemTypeFolder

Functional Object

WPD_CONTENT_TYPE_FUNCTIONAL_OBJECT

Folder Item

WiaItemTypeFolder

Image Object

WPD_CONTENT_TYPE_IMAGE

Image Item

(WiaItemTypeImage | WiaItemTypeFile | WiaItemTypeTransfer)

Video Object

WPD_CONTENT_TYPE_VIDEO

Video Item

(WiaItemTypeVideo | WiaItemTypeFile | WiaItemTypeTransfer)

Audio Object (used for annotations)

WPD_CONTENT_TYPE_AUDIO

Audio Item

(WiaItemTypeAudio | WiaItemTypeFile | WiaItemTypeTransfer)

Other objects

WPD_CONTENT_TYPE_XXXX

N/A (These are ignored)

N/A (These are ignored)

The following table maps the WIA_IPA_Format property to the WPD_OBJECT_FORMAT property:

 

WIA_IPA_FORMAT

The formats will be mapped as follows:

WiaImgFmt_EXIF

WPD_OBJECT_FORMAT_EXIF

WiaImgFmt_JPEG

WPD_OBJECT_FORMAT_JFIF

WiaImgFmt_PNG

WPD_OBJECT_FORMAT_PNG

WiaImgFmt_GIF

WPD_OBJECT_FORMAT_GIF

WiaImgFmt_TIFF

WPD_OBJECT_FORMAT_TIFF

WiaAudFmt_WAV

WPD_OBJECT_FORMAT_WAVE

WiaAudFmt_MP3

WPD_OBJECT_FORMAT_MP3

WiaAudFmt_AIFF

WPD_OBJECT_FORMAT_AIFF

WiaAudFmt_WMA

WPD_OBJECT_FORMAT_WMA

WiaImgFmt_MPG

WPD_OBJECT_FORMAT_MPEG

WiaImgFmt_AVI

WPD_OBJECT_FORMAT_AVI

WiaImgFmt_ASF

WPD_OBJECT_FORMAT_ASF

 

Configuration of the WIA-WPD Compatibility Layer

The following section lists the customization options in the WIA-WPD Compatibility Layer that can be disabled/enabled by the device's INF [AddReg] section:

Report EXIF Image Format as JPG

Some WIA applications expect the EXIF image format to be reported as WiaImgFmt_JPG and not WiaImgFmt_EXIF.   To "opt-in" for this functionality, vendors can add the following to your device's INF:

HKR,,"ReportJPGFormatForEXIF",0x10001,1

WIA Item Tree Behavior for DCF 

If the WIA-WPD Compatibility layer encounters a storage that supports DCF, it will ‘shift’ the WIA item tree contents closer to the root item so items are easily found.  This will reduce the number of folder levels an application or user will have to navigate to get to the image or video content stored on the device.  This functionality can be disabled by adding the following to your device’s .INF [AddReg] section.

HKR,,"DisableDCFSpecialProcessing",0x10001,1

 

This posting is provided "AS IS" with no warranties, and confers no rights.

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