How do I parse a PolyPolygon16 metafile record out of a byte[] c#

Question

I need a little help in defining the following Windows GDI type in C#. I have the data in the form of a byte[] in C#, and I need to somehow marshal or cast it as the following in C#.

This is the type:

http://java.freehep.org/vectorgraphics/apidocs/org/freehep/graphicsio/emf/gdi/PolyPolygon16.html

http://msdn.microsoft.com/en-us/library/cc230665%28PROT.10%29.aspx

Edit: I have been able to get this far, close but not quite:

                    UInt32 rectLeft = BitConverter.ToUInt32(dataArray, 0);
                UInt32 rectTop = BitConverter.ToUInt32(dataArray, 4);
                UInt32 rectRight = BitConverter.ToUInt32(dataArray, 8);
                UInt32 rectBottom = BitConverter.ToUInt32(dataArray, 12);
                UInt32 rectNumberOfPolygons = BitConverter.ToUInt32(dataArray, 16);
                // Number of points in each polygon
                int l_nIndex = 20;
                UInt32[] lengths = new UInt32[rectNumberOfPolygons];
                for (int i = 0; i < lengths.Length; i++)
                {
                    lengths[i] = BitConverter.ToUInt32(dataArray, l_nIndex);
                    l_nIndex += 4;
                }
                // Extract points
                foreach (int l_nPolygonLength in lengths)
                {
                    List<Point> l_lstPoints = new List<Point>();
                    for (int i = 0; i < l_nIndex + l_nPolygonLength; i++)
                    {
                        UInt16 pointX = BitConverter.ToUInt16(dataArray, l_nIndex);
                        UInt16 pointY = BitConverter.ToUInt16(dataArray, l_nIndex + 2);
                        l_lstPoints.Add(new Point((int)pointX, (int)pointY));
                        l_nIndex += 4;
                    }
                }

Answer 1

That seems to be the method signature of Windows GDI function (not a type). It's second argument is a pointer to an array of points, you want to have drawn. Third argument is a pointer to an array of integers specifying how many points there are in each polygon, and the last argument is the number of polygons.

I could not find a Windows GDI function exactly named PolyPolygon16 when searching on Google, but I did find this.

Answer 2

RectL Object:

public static Rectangle ReadRectangle32(this BinaryReader reader)
{
    // Left (4 bytes)
    int left = reader.ReadInt32();

    // Top (4 bytes)
    int top = reader.ReadInt32();

    // Right (4 bytes)
    int right = reader.ReadInt32();

    // Bottom (4 bytes)
    int bottom = reader.ReadInt32();

    return Rectangle.FromLTRB(left, top, right, bottom);
}

PointS Object:

public static Point ReadPoint16(this BinaryReader reader)
{
    // x (2 bytes)
    int x = reader.ReadUInt16();

    // y (2 bytes)
    int y = reader.ReadUInt16();

    return new Point(x, y);
}

EMR_POLYPOLYGON16 Record (without type and size):

public static PolyPolygon ReadPolyPolygon16(this BinaryReader reader)
{
    // Bounds (16 bytes)
    Rectangle bounds = reader.ReadRectangle32();

    // NumberOfPolygons (4 bytes)
    int numberOfPolygons = reader.ReadInt32();

    // Count (4 bytes)
    int count = reader.ReadInt32();

    // PolygonPointCount (variable):
    //      A NumberOfPolygons length array of 32-bit unsigned integers
    var polygonPointCount = new int[numberOfPolygons];
    for (int i = 0; i < polygonPointCount.Length; i++)
    {
        polygonPointCount[i] = reader.ReadInt32();
    }

    // aPoints (variable):
    //      A Count length array of WMF PointS objects
    var points = new Point[count];
    for (int i = 0; i < points.Length; i++)
    {
        points[i] = reader.ReadPoint16();
    }

    return new PolyPolygon(bounds, numberOfPolygons, polygonPointCount, points);
}

Usage:

byte[] buffer;
using (var stream = new MemoryStream(buffer))
using (var reader = new BinaryReader(stream))
{
    var polypolygon = reader.ReadPolyPolygon16();
}

(Untested)