/// <summary>
/// Retrieve the packet description, packets data and XFORM which is the information the native recognizer needs.
/// The method is called from AddStrokes.
/// </summary>
private void GetPacketData
(
Stroke stroke,
out MS.Win32.Recognizer.PACKET_DESCRIPTION packetDescription,
out int countOfBytes,
out IntPtr packets,
out NativeMethods.XFORM xForm
)
{
int i;
countOfBytes = 0;
packets = IntPtr.Zero;
packetDescription = new MS.Win32.Recognizer.PACKET_DESCRIPTION();
Matrix matrix = Matrix.Identity;
xForm = new NativeMethods.XFORM((float)(matrix.M11), (float)(matrix.M12), (float)(matrix.M21),
(float)(matrix.M22), (float)(matrix.OffsetX), (float)(matrix.OffsetY));
StylusPointCollection stylusPoints = stroke.StylusPoints;
if (stylusPoints.Count == 0)
{
return; //we'll fail when the calling routine sees that packets is IntPtr.Zer
}
if (stylusPoints.Description.PropertyCount > StylusPointDescription.RequiredCountOfProperties)
{
//
// reformat to X, Y, P
//
StylusPointDescription reformatDescription
= new StylusPointDescription(
new StylusPointPropertyInfo[] {
new StylusPointPropertyInfo(StylusPointProperties.X),
new StylusPointPropertyInfo(StylusPointProperties.Y),
stylusPoints.Description.GetPropertyInfo(StylusPointProperties.NormalPressure)
});
stylusPoints = stylusPoints.Reformat(reformatDescription);
}
//
// now make sure we only take a finite amount of data for the stroke
//
if (stylusPoints.Count > MaxStylusPoints)
{
stylusPoints = stylusPoints.Clone(MaxStylusPoints);
}
Guid[] propertyGuids = new Guid[] { StylusPointPropertyIds.X, //required index for SPD
StylusPointPropertyIds.Y, //required index for SPD
StylusPointPropertyIds.NormalPressure }; //required index for SPD
Debug.Assert(stylusPoints != null);
Debug.Assert(propertyGuids.Length == StylusPointDescription.RequiredCountOfProperties);
// Get the packet description
packetDescription.cbPacketSize = (uint)(propertyGuids.Length * Marshal.SizeOf(typeof(Int32)));
packetDescription.cPacketProperties = (uint)propertyGuids.Length;
//
// use X, Y defaults for metrics, sometimes mouse metrics can be bogus
// always use NormalPressure metrics, though.
//
StylusPointPropertyInfo[] infosToUse = new StylusPointPropertyInfo[StylusPointDescription.RequiredCountOfProperties];
infosToUse[StylusPointDescription.RequiredXIndex] = StylusPointPropertyInfoDefaults.X;
infosToUse[StylusPointDescription.RequiredYIndex] = StylusPointPropertyInfoDefaults.Y;
infosToUse[StylusPointDescription.RequiredPressureIndex] =
stylusPoints.Description.GetPropertyInfo(StylusPointProperties.NormalPressure);
MS.Win32.Recognizer.PACKET_PROPERTY[] packetProperties =
new MS.Win32.Recognizer.PACKET_PROPERTY[packetDescription.cPacketProperties];
StylusPointPropertyInfo propertyInfo;
for (i = 0; i < packetDescription.cPacketProperties; i++)
{
packetProperties[i].guid = propertyGuids[i];
propertyInfo = infosToUse[i];
MS.Win32.Recognizer.PROPERTY_METRICS propertyMetrics = new MS.Win32.Recognizer.PROPERTY_METRICS( );
propertyMetrics.nLogicalMin = propertyInfo.Minimum;
propertyMetrics.nLogicalMax = propertyInfo.Maximum;
propertyMetrics.Units = (int)(propertyInfo.Unit);
propertyMetrics.fResolution = propertyInfo.Resolution;
packetProperties[i].PropertyMetrics = propertyMetrics;
}
unsafe
{
int allocationSize = (int)(Marshal.SizeOf(typeof(MS.Win32.Recognizer.PACKET_PROPERTY)) * packetDescription.cPacketProperties);
packetDescription.pPacketProperties = Marshal.AllocCoTaskMem(allocationSize);
MS.Win32.Recognizer.PACKET_PROPERTY *pPacketProperty =
(MS.Win32.Recognizer.PACKET_PROPERTY *)(packetDescription.pPacketProperties.ToPointer());
MS.Win32.Recognizer.PACKET_PROPERTY *pElement = pPacketProperty;
for (i = 0; i < packetDescription.cPacketProperties; i++)
{
Marshal.StructureToPtr(packetProperties[i], new IntPtr(pElement), false);
pElement++;
}
}
// Get packet data
int[] rawPackets = stylusPoints.ToHiMetricArray();
int packetCount = rawPackets.Length;
if (packetCount != 0)
{
countOfBytes = packetCount * Marshal.SizeOf(typeof(Int32));
packets = Marshal.AllocCoTaskMem(countOfBytes);
Marshal.Copy(rawPackets, 0, packets, packetCount);
}
}
