List transformations by suitability

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
// Copyright 2018 Esri.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
// You may obtain a copy of the License at: http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific
// language governing permissions and limitations under the License.

using Android.App;
using Android.OS;
using Android.Views;
using Android.Widget;
using Esri.ArcGISRuntime;
using Esri.ArcGISRuntime.Geometry;
using Esri.ArcGISRuntime.Mapping;
using Esri.ArcGISRuntime.Symbology;
using Esri.ArcGISRuntime.UI;
using Esri.ArcGISRuntime.UI.Controls;
using System;
using System.Collections.Generic;
using System.Drawing;

namespace ArcGISRuntime.Samples.ListTransformations
{
    [Activity (ConfigurationChanges=Android.Content.PM.ConfigChanges.Orientation | Android.Content.PM.ConfigChanges.ScreenSize)]
	[ArcGISRuntime.Samples.Shared.Attributes.OfflineData()]
    [ArcGISRuntime.Samples.Shared.Attributes.Sample(
        name: "List transformations by suitability",
        category: "Geometry",
        description: "Get a list of suitable transformations for projecting a geometry between two spatial references with different horizontal datums.",
        instructions: "Select a transformation from the list to see the result of projecting the point from EPSG:27700 to EPSG:3857 using that transformation. The result is shown as a red cross; you can visually compare the original blue point with the projected red cross.",
        tags: new[] { "datum", "geodesy", "projection", "spatial reference", "transformation" })]
    public class ListTransformations : Activity
    {
        // Hold a reference to the map view.
        private MapView _myMapView;

        // Point whose coordinates will be projected using a selected transform.
        private MapPoint _originalPoint;

        // Graphic representing the projected point.
        private Graphic _projectedPointGraphic;

        // GraphicsOverlay to hold the point graphics.
        private GraphicsOverlay _pointsOverlay;

        // Text view to display messages to the user (exceptions, etc.).
        private TextView _messagesTextView;

        // Labels to display the input/output spatial references (WKID).
        private TextView _inWkidLabel;
        private TextView _outWkidLabel;

        // Spinner to display the datum transformations suitable for the input/output spatial references.
        private Spinner _transformationsPicker;

        // Switch to toggle suitable transformations for the current extent.
        private Switch _useExtentSwitch;

        protected override void OnCreate(Bundle bundle)
        {
            base.OnCreate(bundle);

            Title = "List transformations by suitability";

            // Create the UI.
            CreateLayout();

            // Create a new map, add a point graphic, and fill the datum transformations list.
            Initialize();
        }

        private void Initialize()
        {
            // Create the map and add it to the map view control.
            Map myMap = new Map(BasemapStyle.ArcGISImagery);

            // Create a point in the Greenwich observatory courtyard in London, UK, the location of the prime meridian.
            _originalPoint = new MapPoint(538985.355, 177329.516, SpatialReference.Create(27700));

            // Set the initial extent to an extent centered on the point.
            Viewpoint initialViewpoint = new Viewpoint(_originalPoint, 5000);
            myMap.InitialViewpoint = initialViewpoint;

            // Handle the map loading to fill the UI controls.
            myMap.Loaded += MyMap_Loaded;

            // Add the map to the map view.
            _myMapView.Map = myMap;

            // Create a graphics overlay to hold the original and projected points.
            _pointsOverlay = new GraphicsOverlay();
            _myMapView.GraphicsOverlays.Add(_pointsOverlay);

            // Add the point as a graphic with a blue square.
            SimpleMarkerSymbol markerSymbol = new SimpleMarkerSymbol(SimpleMarkerSymbolStyle.Square, Color.Blue, 15);
            Graphic originalGraphic = new Graphic(_originalPoint, markerSymbol);
            _pointsOverlay.Graphics.Add(originalGraphic);

            // Get the path to the projection engine data (if it exists).
            string peFolderPath = GetProjectionDataPath();
            if (!String.IsNullOrEmpty(peFolderPath))
            {
                TransformationCatalog.ProjectionEngineDirectory = peFolderPath;
                _messagesTextView.Text = "Using projection data found at '" + peFolderPath + "'";
            }
            else
            {
                _messagesTextView.Text = "Projection engine data not found.";
            }
        }

        private void MyMap_Loaded(object sender, EventArgs e)
        {
            // Get the map's spatial reference.
            SpatialReference mapSpatialReference = ((Map)sender).SpatialReference;

            // Run on the UI thread.
            RunOnUiThread(() =>
            {
                // Show the input and output spatial reference (WKID) in the labels.
                _inWkidLabel.Text = "In WKID = " + _originalPoint.SpatialReference.Wkid;
                _outWkidLabel.Text = "Out WKID = " + mapSpatialReference.Wkid;

                // Call a function to create a list of transformations to fill the picker.
                GetSuitableTransformations(_originalPoint.SpatialReference, mapSpatialReference, _useExtentSwitch.Checked);
            });
        }

        private void CreateLayout()
        {
            // View for the input/output wkid labels.
            LinearLayout wkidLabelsStackView = new LinearLayout(this) { Orientation = Orientation.Horizontal };
            wkidLabelsStackView.SetPadding(10, 10, 0, 10);

            // Create a label for the input spatial reference.
            _inWkidLabel = new TextView(this)
            {
                Text = "In WKID = ",
                TextAlignment = TextAlignment.ViewStart
            };

            // Create a label for the output spatial reference.
            _outWkidLabel = new TextView(this)
            {
                Text = "Out WKID = ",
                TextAlignment = TextAlignment.ViewStart
            };

            // Create some horizontal space between the labels.
            Space space = new Space(this);
            space.SetMinimumWidth(30);

            // Add the Wkid labels to the stack view.
            wkidLabelsStackView.AddView(_inWkidLabel);
            wkidLabelsStackView.AddView(space);
            wkidLabelsStackView.AddView(_outWkidLabel);

            // Create the 'use extent' switch.
            _useExtentSwitch = new Switch(this)
            {
                Checked = false,
                Text = "Use extent"
            };

            // Handle the checked change event for the switch.
            _useExtentSwitch.CheckedChange += UseExtentSwitch_CheckedChange;

            // Create a picker (Spinner) for datum transformations.
            _transformationsPicker = new Spinner(this);
            _transformationsPicker.SetPadding(5, 10, 0, 10);

            // Handle the selection event to work with the selected transformation.
            _transformationsPicker.ItemSelected += TransformationsPicker_ItemSelected;

            // Create a text view to show messages.
            _messagesTextView = new TextView(this);

            // Create a new vertical layout for the app UI.
            LinearLayout mainLayout = new LinearLayout(this) { Orientation = Orientation.Vertical };

            // Create a layout for the app tools.
            LinearLayout toolsLayout = new LinearLayout(this) { Orientation = Orientation.Vertical };
            toolsLayout.SetPadding(10, 0, 0, 0);
            toolsLayout.SetMinimumHeight(320);

            // Add the transformation UI controls to the tools layout.
            toolsLayout.AddView(wkidLabelsStackView);
            toolsLayout.AddView(_useExtentSwitch);
            toolsLayout.AddView(_transformationsPicker);
            toolsLayout.AddView(_messagesTextView);

            // Add the tools layout and map view to the main layout.
            mainLayout.AddView(toolsLayout);
            _myMapView = new MapView(this);
            mainLayout.AddView(_myMapView);

            // Show the layout in the app.
            SetContentView(mainLayout);
        }

        // Function to get suitable datum transformations for the specified input and output spatial references.
        private void GetSuitableTransformations(SpatialReference inSpatialRef, SpatialReference outSpatialRef, bool considerExtent)
        {
            // Get suitable transformations. Use the current extent to evaluate suitability, if requested.
            IReadOnlyList<DatumTransformation> transformations;
            if (considerExtent)
            {
                Envelope currentExtent = _myMapView.GetCurrentViewpoint(ViewpointType.BoundingGeometry).TargetGeometry as Envelope;
                transformations = TransformationCatalog.GetTransformationsBySuitability(inSpatialRef, outSpatialRef, currentExtent);
            }
            else
            {
                transformations = TransformationCatalog.GetTransformationsBySuitability(inSpatialRef, outSpatialRef);
            }

            // Get the default transformation for the specified input and output spatial reference.
            DatumTransformation defaultTransform = TransformationCatalog.GetTransformation(inSpatialRef, outSpatialRef);

            // Create a list of transformations.
            List<DatumTransformation> transformsList = new List<DatumTransformation>();
            foreach(DatumTransformation transformation in transformations)
            {
                transformsList.Add(transformation);
            }

            // Create an adapter for showing the spinner list.
            TransformationsAdapter transformationsAdapter = new TransformationsAdapter(this, transformsList)
            {
                DefaultTransformation = defaultTransform
            };

            // Apply the adapter to the spinner.
            _transformationsPicker.Adapter = transformationsAdapter;
        }

        private void TransformationsPicker_ItemSelected(object sender, AdapterView.ItemSelectedEventArgs e)
        {
            // Get the selected transform from the spinner. Return if none is selected.
            TransformationsAdapter adapter = (TransformationsAdapter)_transformationsPicker.Adapter;
            DatumTransformation selectedTransform = adapter[e.Position];
            if (selectedTransform == null) { return; }

            try
            {
                // Project the original point using the selected transform.
                MapPoint projectedPoint = (MapPoint)GeometryEngine.Project(_originalPoint, _myMapView.SpatialReference, selectedTransform);

                // Update the projected graphic (if it already exists), create it otherwise.
                if (_projectedPointGraphic != null)
                {
                    _projectedPointGraphic.Geometry = projectedPoint;
                }
                else
                {
                    // Create a symbol to represent the projected point (a cross to ensure both markers are visible).
                    SimpleMarkerSymbol projectedPointMarker = new SimpleMarkerSymbol(SimpleMarkerSymbolStyle.Cross, Color.Red, 15);

                    // Create the point graphic and add it to the overlay.
                    _projectedPointGraphic = new Graphic(projectedPoint, projectedPointMarker);
                    _pointsOverlay.Graphics.Add(_projectedPointGraphic);
                }

                _messagesTextView.Text = "Projected point using transform: " + selectedTransform.Name;
            }
            catch (ArcGISRuntimeException ex)
            {
                // Exception if a transformation is missing grid files.
                _messagesTextView.Text = "Error using selected transformation: " + ex.Message;

                // Remove the projected point graphic (if it exists).
                if (_projectedPointGraphic != null && _pointsOverlay.Graphics.Contains(_projectedPointGraphic))
                {
                    _pointsOverlay.Graphics.Remove(_projectedPointGraphic);
                    _projectedPointGraphic = null;
                }
            }
        }

        private void UseExtentSwitch_CheckedChange(object sender, CompoundButton.CheckedChangeEventArgs e)
        {
            // Call a function to create a list of transformations to fill the picker.
            GetSuitableTransformations(_originalPoint.SpatialReference, _myMapView.Map.SpatialReference, _useExtentSwitch.Checked);
        }

        private string GetProjectionDataPath()
        {
            // Return the projection data path; note that this is not valid by default.
            // You must manually download the projection engine data and update the path returned here.
            return "";
        }
    }

    // An Adapter class to provide a list of datum transformations for display in a Spinner control.
    public class TransformationsAdapter : BaseAdapter<DatumTransformation>
    {
        // Property to expose the default datum transformation (will be displayed with different text color).
        public DatumTransformation DefaultTransformation { get; set; }

        // Fields to store the list of transformations and the current context.
        private List<DatumTransformation> _transformations;
        private Activity _context;

        // Constructor for the adapter. Store the context and the list of transformations to display.
        public TransformationsAdapter(Activity context, List<DatumTransformation> items) : base()
        {
            _transformations = items;
            _context = context;
        }

        // Provide an ID for an item at a given position (just return the position).
        public override long GetItemId(int position)
        {
            return position;
        }

        // Provide the datum transformation at this position in the list.
        public override DatumTransformation this[int position]
        {
            get { return _transformations[position]; }
        }

        // Provide the number of items (datum transformations) in the list.
        public override int Count
        {
            get
            {
                return _transformations.Count;
            }
        }

        // Override the GetView method to provide a custom (formatted) text view for each transformation in the list.
        public override View GetView(int position, View convertView, ViewGroup parent)
        {
            // Create a new text view to display the transformation name with the proper formatting.
            TextView transformTextView = new TextView(_context);

            // Get the datum transformation being displayed.
            DatumTransformation thisTransform = _transformations[position];

            // Set the text with the transformation name.
            transformTextView.SetText(thisTransform.Name, TextView.BufferType.Normal);

            // Use white as the default text color (available transforms).
            transformTextView.SetTextColor(Android.Graphics.Color.White);
            transformTextView.SetBackgroundColor(Android.Graphics.Color.DarkGray);

            // See if the transform is missing required projection engine files. If so, display the text in gray.
            if (thisTransform.IsMissingProjectionEngineFiles)
            {
                transformTextView.SetTextColor(Android.Graphics.Color.Gray);
            }

            // If this is the default transformation, show it in blue.
            if(thisTransform.Name == DefaultTransformation.Name)
            {
                transformTextView.SetTextColor(Android.Graphics.Color.Blue);
            }

            // Pass back the text view.
            return transformTextView;
        }
    }
}