private MapShapeModelCollection ProcessItems(IRandomAccessStream shapeStream, ShapefileRecordInfoCollection recordInfos, CancellationTokenSource cancellationTokenSource)
{
if (cancellationTokenSource.IsCancellationRequested)
{
return(null);
}
int itemCount = recordInfos.Count;
int maxDegreeOfParallelism = Environment.ProcessorCount;
if (itemCount < maxDegreeOfParallelism)
{
maxDegreeOfParallelism = itemCount;
}
int remainder = itemCount % maxDegreeOfParallelism;
int multiplier = (itemCount / maxDegreeOfParallelism) + (remainder > 0 ? 1 : 0);
var token = cancellationTokenSource.Token;
List <Task <MapShapeModelCollection> > tasks = new List <Task <MapShapeModelCollection> >();
for (int i = 0; i < maxDegreeOfParallelism; i++)
{
int start = i * multiplier;
int end = Math.Min((i + 1) * multiplier, itemCount);
ParseShapeTaskState taskState = new ParseShapeTaskState()
{
Start = start,
End = end,
Records = recordInfos,
Stream = shapeStream,
CancellationTokenSource = cancellationTokenSource,
CoordinateConverter = this.CoordinateValueConverter
};
var task = Task.Factory.StartNew <Task <MapShapeModelCollection> >(ParseShapes, taskState, token, TaskCreationOptions.AttachedToParent, TaskScheduler.Current).Unwrap();
tasks.Add(task);
}
Task.WaitAll(tasks.ToArray());
MapShapeModelCollection models = tasks[0].Result;
for (int i = 1; i < maxDegreeOfParallelism; i++)
{
var modelsToMerge = tasks[i].Result;
if (modelsToMerge == null)
{
continue;
}
foreach (var model in modelsToMerge)
{
models.Add(model);
}
}
models.BoundingRect = recordInfos.BoundingRect;
return(models);
}
private static Task <MapShapeModelCollection> ParseShapes(object state)
{
ParseShapeTaskState taskState = (ParseShapeTaskState)state;
var cancellationTokenSource = taskState.CancellationTokenSource;
var token = cancellationTokenSource.Token;
var task = Task.Factory.StartNew(async() =>
{
using (var shapeStream = taskState.Stream.CloneStream())
{
int start = taskState.Start;
int end = taskState.End;
var coordinateConverter = taskState.CoordinateConverter;
var records = taskState.Records;
MapShapeModelCollection shapeModels = new MapShapeModelCollection();
for (int i = start; i < end; i++)
{
if (cancellationTokenSource.IsCancellationRequested)
{
return(null);
}
int contentOffset = records[i].ContentOffset;
shapeStream.Seek((ulong)contentOffset);
int contentLength = records[i].ContentLength;
byte[] content = new byte[contentLength];
await shapeStream.ReadAsync(content.AsBuffer(), (uint)contentLength, InputStreamOptions.Partial);
EsriShapeType shapeType = (EsriShapeType)BitConverter.ToInt32(content, 0);
if (shapeModels.Type == EsriShapeType.NullShape)
{
shapeModels.Type = shapeType;
}
// TODO: Consider specific support for "M" types (PointM, MultipointM, PolygonM) that support measure coordinate -- is this the Bubble visualization?.
switch (shapeType)
{
case EsriShapeType.NullShape:
shapeModels.Add(new NullShapeModel());
break;
case EsriShapeType.Point:
case EsriShapeType.PointM:
case EsriShapeType.PointZ:
CreatePoint(content, shapeModels, 4, coordinateConverter);
break;
case EsriShapeType.Polyline:
case EsriShapeType.PolylineM:
case EsriShapeType.PolylineZ:
CreatePolyline(content, shapeModels, coordinateConverter);
break;
case EsriShapeType.Polygon:
case EsriShapeType.PolygonM:
case EsriShapeType.PolygonZ:
CreatePolygon(content, shapeModels, coordinateConverter);
break;
default:
throw new NotSupportedException("The supported ESRI shape types are Point(MZ), Polyline(MZ), and Polygon(MZ).");
}
}
return(shapeModels);
}
},
token).Unwrap();
return(task);
}
