// Process elevation data requests by the user
private async Task ProcessUserRequests()
{
try
{
// Get user rectangle
var userEnvelope = await MyMapView.Editor.RequestShapeAsync(DrawShape.Envelope) as Envelope;
if (userEnvelope.Height == 0 || userEnvelope.Width == 0)
{
throw new ArgumentNullException("Please click and drag a box to define an extent.");
}
// Display the graphics
_graphicsLayer.Graphics.Add(new Graphic(userEnvelope));
// Take account of WrapAround
var polygon = GeometryEngine.NormalizeCentralMeridian(userEnvelope) as Polygon;
Envelope envelope = polygon.Extent;
// Retrieve elevation data from the service
ElevationData elevationData = await GetElevationData(envelope);
// Create the image for the display
WriteableBitmap writeableBitmapElevation = await CreateElevationImageAsync(elevationData);
ElevationImage.Source = writeableBitmapElevation;
ElevationView.Visibility = Visibility.Visible;
}
catch (Exception ex)
{
var _x = new MessageDialog(ex.Message, "Sample Error").ShowAsync();
}
}
// Call a REST SOE to get elevation data
private async Task <ElevationData> GetElevationData(Envelope rect)
{
string SOEurl = "http://sampleserver4.arcgisonline.com/ArcGIS/rest/services/Elevation/ESRI_Elevation_World/MapServer/exts/ElevationsSOE/ElevationLayers/1/GetElevationData?";
SOEurl += string.Format(CultureInfo.InvariantCulture,
"Extent={{\"xmin\" : {0}, \"ymin\" : {1}, \"xmax\" : {2}, \"ymax\" :{3},\"spatialReference\" : {{\"wkid\" : {4}}}}}&Rows={5}&Columns={6}&f=json",
rect.XMin, rect.YMin, rect.XMax, rect.YMax,
MyMapView.SpatialReference.Wkid, HeightTextBox.Text, WidthTextBox.Text);
/*
* e.g.
* http://sampleserver4.arcgisonline.com/ArcGIS/rest/services/Elevation/ESRI_Elevation_World/MapServer/exts/ElevationsSOE/ElevationLayers/1/GetElevationData?
* Extent={"xmin" : -1507310.85889877, "ymin" : 6406071.15031974, "xmax" : 879264.66769094, "ymax" :8164600.48570163,"spatialReference" : {"wkid" : 102100}}&Rows=15&Columns=15&f=json
*/
httpClient = new HttpClient();
var stream = await httpClient.GetStreamAsync(SOEurl);
DataContractJsonSerializer serializer = null;
ElevationData elevationData = null;
try
{
serializer = new DataContractJsonSerializer(typeof(ElevationData));
elevationData = serializer.ReadObject(stream) as ElevationData;
}
catch
{
// Check for a service error.
serializer = new DataContractJsonSerializer(typeof(ServiceError));
ServiceError serviceError = serializer.ReadObject(stream) as ServiceError;
// e.g. {"error":{"code":400,"message":"Value cannot be null.\r\nParameter name: Rows"}}
var _x = new MessageDialog(string.Format("Error: {0} meters", serviceError.error.message));
}
if (elevationData.data == null)
{
var _x = new MessageDialog("No Data Returned. Please try again.").ShowAsync();
}
return(elevationData);
}
// Create a bitmap image from the elevation data
private async Task <WriteableBitmap> CreateElevationImageAsync(ElevationData elevationData)
{
int thematicMin = elevationData.data[0];
int thematicMax = elevationData.data[0];
foreach (int elevValue in elevationData.data)
{
if (elevValue < thematicMin)
{
thematicMin = elevValue;
}
if (elevValue > thematicMax)
{
thematicMax = elevValue;
}
}
int totalRange = thematicMax - thematicMin;
int portion = totalRange / 5;
List <Color> cellColor = new List <Color>();
foreach (int elevValue in elevationData.data)
{
int startValue = thematicMin;
for (int i = 0; i < 5; i++)
{
if (Enumerable.Range(startValue, portion).Contains(elevValue))
{
cellColor.Add(colorRanges[i]);
break;
}
else if (i == 4)
{
cellColor.Add(colorRanges.Last());
}
startValue = startValue + portion;
}
}
int rows = Convert.ToInt32(HeightTextBox.Text);
int cols = Convert.ToInt32(WidthTextBox.Text);
byte[] pixelData = new byte[rows * cols * 4];
int cell = 0;
int pos = 0;
for (int x = 0; x < rows; x++)
{
for (int y = 0; y < cols; y++)
{
Color color = cellColor[cell++];
pixelData[pos++] = color.B;
pixelData[pos++] = color.G;
pixelData[pos++] = color.R;
pixelData[pos++] = (byte)255;
}
}
WriteableBitmap writeableBitmapElevation = new WriteableBitmap(rows, cols);
Stream stream = writeableBitmapElevation.PixelBuffer.AsStream();
await stream.WriteAsync(pixelData, 0, pixelData.Length);
stream.Flush();
return(writeableBitmapElevation);
}
// Create a bitmap image from the elevation data
private async Task<WriteableBitmap> CreateElevationImageAsync(ElevationData elevationData)
{
int thematicMin = elevationData.data[0];
int thematicMax = elevationData.data[0];
foreach (int elevValue in elevationData.data)
{
if (elevValue < thematicMin)
thematicMin = elevValue;
if (elevValue > thematicMax)
thematicMax = elevValue;
}
int totalRange = thematicMax - thematicMin;
int portion = totalRange / 5;
List<Color> cellColor = new List<Color>();
foreach (int elevValue in elevationData.data)
{
int startValue = thematicMin;
for (int i = 0; i < 5; i++)
{
if (Enumerable.Range(startValue, portion).Contains(elevValue))
{
cellColor.Add(colorRanges[i]);
break;
}
else if (i == 4)
cellColor.Add(colorRanges.Last());
startValue = startValue + portion;
}
}
int rows = Convert.ToInt32(HeightTextBox.Text);
int cols = Convert.ToInt32(WidthTextBox.Text);
byte[] pixelData = new byte[rows * cols * 4];
int cell = 0;
int pos = 0;
for (int x = 0; x < rows; x++)
{
for (int y = 0; y < cols; y++)
{
Color color = cellColor[cell++];
pixelData[pos++] = color.B;
pixelData[pos++] = color.G;
pixelData[pos++] = color.R;
pixelData[pos++] = (byte)255;
}
}
WriteableBitmap writeableBitmapElevation = new WriteableBitmap(rows, cols);
Stream stream = writeableBitmapElevation.PixelBuffer.AsStream();
await stream.WriteAsync(pixelData, 0, pixelData.Length);
stream.Flush();
return writeableBitmapElevation;
}