Add Date/Time XMP Property

C++ sample program to add date/time properties to an existing XMP embedded in a JPG or TIF image file.

void XmpAddSimpleDate(void)
    {
    // Adds a simple XMP date/time property to XMP metadata embedded
    // in a JPG or TIF.
    CkXmp xmp;
    xmp.UnlockComponent("anything for 30-day trial");

    bool success = xmp.LoadAppFile("AgencyPhotographer-Example.jpg");
    if (!success)
	{
	xmp.SaveLastError("lastError.txt");
	return;
	}

    // Get the 1st XMP metadata document contained within the JPG.
    // (It is unusual to have more than a single XMP embedded in a JPG or TIFF)
    CkXml *xml = xmp.GetEmbedded(0);
    if (!xml)
	{
	printf("XMP not found!\n");
	return;
	}

    // Set this: <xap:MetadataDate>2005-03-13T02:00:54-06:00</xap:MetadataDate>
    SYSTEMTIME sysTime;

    // Get the current date/time.
    GetSystemTime(&sysTime);

    // If the property already exists, it is updated.
    xmp.AddSimpleDate(*xml,"xap:MetadataDate",sysTime);

    // Save the JPG with its updated XMP metadata.
    xmp.SaveAppFile("out.jpg");

    // Save the XMP to an XML file so we can review the changes in a text editor
    xml->SaveXml("newXmp.xml");

    delete xml;
    
    return;
    }