/// <summary>
/// Begin creating and displaying WPF shapes on the canvas.
/// </summary>
private void DisplayShapes(ShapeFileReadInfo info)
{
// Create shape brushes.
if (this.shapeBrushes == null)
this.CreateShapeBrushes(0.40, 45);
// Set up the transformation for WPF shapes.
if (this.shapeTransform == null)
this.shapeTransform = this.CreateShapeTransform(info);
// Schedule display of the first block of shapefile records
// using the dispatcher.
this.dispatcher.BeginInvoke(DispatcherPriority.Normal, new DisplayNextPrototype(this.DisplayNextShapeRecord), info);
}
/// <summary>
/// Display a block of shape records as WPF shapes, and schedule
/// the next display with the dispatcher if needed.
/// </summary>
/// <param name="info">Shapefile read information.</param>
private void DisplayNextShapeRecord(ShapeFileReadInfo info)
{
if (this.cancelReadShapeFile)
return;
// Create a block of WPF shapes and add them to the shape list.
this.shapeList.Clear();
int index = info.RecordIndex;
for (; index < (info.RecordIndex + ShapeDisplay.displayShapesBlockingFactor); index++)
{
if (index >= info.ShapeFile.Records.Count)
break;
ShapeFileRecord record = info.ShapeFile.Records[index];
// Set the name of the WPF shape.
++this.wpfShapeCount;
string shapeName = String.Format(System.Globalization.CultureInfo.InvariantCulture, "Shape{0}", this.wpfShapeCount);
// Create the WPF shape.
Shape shape;
if (record.NumberOfParts == 0)
shape = this.CreateWPFPoint(shapeName, record);
else
shape = this.CreateWPFShape(shapeName, record);
// Set a tooltip for the shape that displays up to 5 attribute values.
shape.ToolTip = shape.Name;
if (record.Attributes != null)
{
string attr = String.Empty;
for (int i = 0; i < Math.Min(5, record.Attributes.ItemArray.GetLength(0)); i++)
{
attr += (", " + record.Attributes[i].ToString());
}
shape.ToolTip += attr;
}
// Add the shape to the shape list.
//this.shapeList.Add(shape);
// If the record just processed is very large, then don't process
// any further records.
if (record.Points.Count > 5000)
{
++index;
break;
}
}
// Set the record index to read next (as part of the
// next dispatched task).
info.RecordIndex = index;
// Add the newly created WPF shapes to the canvas.
foreach (Shape shape in this.shapeList)
{
this.canvas.Children.Add(shape);
}
this.shapeList.Clear();
// Display the current progress.
double progressValue = (index * 100.0) / info.ShapeFile.Records.Count;
progressValue = Math.Min(100, progressValue);
this.ShowProgress("Creating WPF shapes...", progressValue);
// See if we need to dispatch another display operation.
if (index < info.ShapeFile.Records.Count)
{
// Schedule the next display at Background priority.
this.dispatcher.BeginInvoke(DispatcherPriority.Background, new DisplayNextPrototype(this.DisplayNextShapeRecord), info);
}
else
{
// End the progress.
this.ShowProgress("Creating WPF shapes...", 100);
this.EndReadShapeFile(info);
}
}
/// <summary>
/// Read dBASE file attributes.
/// </summary>
/// <param name="info">Shapefile read information.</param>
private void ReadDbaseAttributes(ShapeFileReadInfo info)
{
// Read attributes from the associated dBASE file.
try
{
string dbaseFile = info.FileName.Replace(".shp", ".dbf");
dbaseFile = dbaseFile.Replace(".SHP", ".DBF");
info.ShapeFile.ReadAttributes(dbaseFile);
}
catch (OleDbException ex)
{
// Note: An exception will occur if the filename of the dBASE
// file does not follow 8.3 naming conventions. In this case,
// you must use its short (MS-DOS) filename.
MessageBox.Show(ex.Message);
// Activate the window.
this.owner.Activate();
}
}
/// <summary>
/// Perform some cleanup at the end of reading a shapefile.
/// </summary>
/// <param name="info">Shapefile read information.</param>
private void EndReadShapeFile(ShapeFileReadInfo info)
{
if (info != null && info.Stream != null)
{
info.Stream.Close();
info.Stream.Dispose();
info.Stream = null;
}
this.EndReadShapeFile();
}
/// <summary>
/// Read a block of shape file records and possibly schedule
/// the next read with the dispatcher.
/// </summary>
/// <param name="info">Shapefile read information.</param>
private void ReadNextShapeRecord(ShapeFileReadInfo info)
{
if (this.cancelReadShapeFile)
return;
try
{
// Read a block of shape records.
for (int i = 0; i < ShapeDisplay.readShapesBlockingFactor; i++)
{
ShapeFileRecord record = info.ShapeFile.ReadShapeFileRecord(info.Stream);
info.NumberOfBytesRead += (4 + record.ContentLength) * 2;
}
}
catch (FileFormatException ex)
{
this.EndReadShapeFile(info);
MessageBox.Show(ex.Message);
return;
}
catch (IOException)
{
// Display the end progress (100 percent).
this.ShowProgress("Reading shapefile...", 100);
// Read attributes from the associated dBASE file.
this.ReadDbaseAttributes(info);
// Display shapes on the canvas.
if (info.ShapeFile.Records.Count > 0)
this.DisplayShapes(info);
else
this.EndReadShapeFile(info);
return;
}
// Display the current progress.
double progressValue = info.NumberOfBytesRead * 100.0 / (info.ShapeFile.FileHeader.FileLength * 2);
progressValue = Math.Min(100, progressValue);
this.ShowProgress("Reading shapefile...", progressValue);
// Schedule the next read at Background priority.
this.dispatcher.BeginInvoke(DispatcherPriority.Background, new ReadNextPrototype(this.ReadNextShapeRecord), info);
}
/// <summary>
/// Computes a transformation so that the shapefile geometry
/// will maximize the available space on the canvas and be
/// perfectly centered as well.
/// </summary>
/// <param name="info">Shapefile information.</param>
/// <returns>A transformation object.</returns>
private TransformGroup CreateShapeTransform(ShapeFileReadInfo info)
{
// Bounding box for the shapefile.
double xmin = info.ShapeFile.FileHeader.XMin;
double xmax = info.ShapeFile.FileHeader.XMax;
double ymin = info.ShapeFile.FileHeader.YMin;
double ymax = info.ShapeFile.FileHeader.YMax;
// Width and height of the bounding box.
double width = Math.Abs(xmax - xmin);
double height = Math.Abs(ymax - ymin);
// Aspect ratio of the bounding box.
double aspectRatio = width / height;
// Aspect ratio of the canvas.
double canvasRatio = this.canvas.ActualWidth / this.canvas.ActualHeight;
// Compute a scale factor so that the shapefile geometry
// will maximize the space used on the canvas while still
// maintaining its aspect ratio.
double scaleFactor = 1.0;
if (aspectRatio < canvasRatio)
scaleFactor = this.canvas.ActualHeight / height;
else
scaleFactor = this.canvas.ActualWidth / width;
// Compute the scale transformation. Note that we flip
// the Y-values because the lon/lat grid is like a cartesian
// coordinate system where Y-values increase upwards.
ScaleTransform xformScale = new ScaleTransform(scaleFactor, -scaleFactor);
// Compute the translate transformation so that the shapefile
// geometry will be centered on the canvas.
TranslateTransform xformTrans = new TranslateTransform();
xformTrans.X = (this.canvas.ActualWidth - (xmin + xmax) * scaleFactor) / 2;
xformTrans.Y = (this.canvas.ActualHeight + (ymin + ymax) * scaleFactor) / 2;
// Add the two transforms to a transform group.
TransformGroup xformGroup = new TransformGroup();
xformGroup.Children.Add(xformScale);
xformGroup.Children.Add(xformTrans);
return xformGroup;
}
/// <summary>
/// Read shapes and attributes from the given shapefile.
/// </summary>
/// <param name="fileName">Full pathname of a shapefile.</param>
public void ReadShapeFile(string fileName)
{
this.isReadingShapeFile = true;
this.cancelReadShapeFile = false;
// Create an object to store shapefile info during the read.
ShapeFileReadInfo info = new ShapeFileReadInfo();
info.FileName = fileName;
info.ShapeFile = new ShapeFile();
info.Stream = null;
info.NumberOfBytesRead = 0;
info.RecordIndex = 0;
try
{
// Read the File Header first.
info.Stream = new FileStream(fileName, FileMode.Open, FileAccess.Read);
info.ShapeFile.ReadShapeFileHeader(info.Stream);
info.NumberOfBytesRead = ShapeFileHeader.Length;
// Schedule the first read of shape file records using the dispatcher.
this.dispatcher.BeginInvoke(DispatcherPriority.Normal, new ReadNextPrototype(this.ReadNextShapeRecord), info);
}
catch (IOException ex)
{
this.EndReadShapeFile(info);
MessageBox.Show(ex.Message);
}
}
