Display ActiveX Image on LabVIEW Front Panel [method returns"handler" (IPictureDisp - stdole.Picture)]
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From: LabBEAN on 24 Jan 2008 17:10 I'm acquiring images from a USB Microsoft Fingerprint Reader via ActiveX. The BiometricDisplay method outputs "handler" which is a reference, whose wire type is "stdole.Picture". I can create "Picture" property and invoke nodes using "handler" (in contrast to the "Pict" nodes used with LabVIEW picture indicator references) but do not see how they help. The SDK (Software Development Kit) explains that the BiometricDisplay method "Returns a picture display handle (IPictureDisp) to the supplied raw grayscale fingerprint image with its minutiae, segments and minutiae direction drawn." (Minutiae, segments, and direction are merely parts of the template, which is used for matching.) A couple of KnowledgeBase links make me wonder if porting the image to a standard LabVIEW indicator is even possible due to thread problems: <a href="http://digital.ni.com/public.nsf/allkb/62A407CAD9BC56BB862569C90055A3BE" target="_blank">http://digital.ni.com/public.nsf/allkb/62A407CAD9BC56BB862569C90055A3BE</a> <a href="http://digital.ni.com/public.nsf/allkb/9C4B1DC160DD5BF986256D6D00647526" target="_blank">http://digital.ni.com/public.nsf/allkb/9C4B1DC160DD5BF986256D6D00647526</a> Is it possible to port the image to a standard LabVIEW indicator? Are there ActiveX controls that could house the image? How would I find / install / use them? I've seen "Tree View Control" and "ImageList" mentioned elsewhere, but don't know if they're even applicable. Please speak slowly, as I am unfamiliar with the Picture data type. Thank you!
From: LabBEAN on 25 Jan 2008 12:10 Can I pass the ActiveX IPictureDisp handle to a front panel ActiveX control for display (e.g. the ActiveX equivalent of the LV Picture Indicator) to keep it in the ActiveX layer? Which control, and how do I install it? If not, have you successfully used OLE functions to convert the reference? Can this be done in LabVIEW? How would I load the libraries? Thank you for your comments! -B
From: zou on 25 Jan 2008 12:10 LabBEAN wrote: Can I pass the ActiveX IPictureDisp handle to a front panel ActiveX control for display (e.g. the ActiveX equivalent of the LV Picture Indicator) to keep it in the ActiveX layer? Which control, and how do I install it? I don't think that would work. If not, have you successfully used OLE functions to convert the reference? Yes. Can this be done in LabVIEW? How would I load the libraries? I don't think so. George Zou
From: LabBEAN on 25 Jan 2008 14:10 I am able to convert and pass the rawImage Variant to a LabVIEW Picture Indicator (see attached VI). The handle may be referencing a similar (standard?) rawImage Variant data type (albeit OLE), only this image would contain the overlayed template (explained above). I wonder if your DLL would parse the handle object correctly. Could you attach it / something similar as an example? Or, and please forgive me for continuing to beat this drum, maybe there's an ActiveX control that accepts the handle if it is to the rawImage type? -B rawImage to Picture.vi: http://forums.ni.com/attachments/ni/170/297562/1/rawImage to Picture.vi
From: zou on 25 Jan 2008 15:40
The OLE handle is not likely to be a raw image pointer. MS doesn't give the data structure of the handle. So you can't parse. You have to use OLE functions and other WinAPIs to get the raw image pointer. Can you give me the web page of the SDK you're using? I might have time to make a VI for you. George Zou |