Exit condition for SketchEditor

JonasHashagen

I'm currently facing the problem that I need to add an exit condition for sketching geometries using the SketchEditor. The sketch editor should be finished/completed as soon as the sketched geometry fullfills the condition (e.g. has exactly 4 points).

To achieve this I registered to the GeometryChanged event, check for the exit condition and call the CompleteCommand if it mets the condition:

<SPAN class="keyword token">private</SPAN> <SPAN class="keyword token">void</SPAN> <SPAN class="token function">SketchEditorOnGeometryChanged</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="keyword token">object</SPAN> sender<SPAN class="punctuation token">,</SPAN> GeometryChangedEventArgs e<SPAN class="punctuation token">)</SPAN>
<SPAN class="punctuation token">{</SPAN>
&nbsp;&nbsp; <SPAN class="keyword token">if</SPAN> <SPAN class="punctuation token">(</SPAN><SPAN class="keyword token">this</SPAN><SPAN class="punctuation token">.</SPAN><SPAN class="token function">CheckValidity</SPAN><SPAN class="punctuation token">(</SPAN>e<SPAN class="punctuation token">.</SPAN>NewGeometry<SPAN class="punctuation token">)</SPAN> <SPAN class="operator token">&&</SPAN> <SPAN class="keyword token">this</SPAN><SPAN class="punctuation token">.</SPAN>sketchEditor<SPAN class="punctuation token">.</SPAN>CompleteCommand<SPAN class="punctuation token">.</SPAN><SPAN class="token function">CanExecute</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="keyword token">null</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">)</SPAN>
&nbsp;&nbsp; <SPAN class="punctuation token">{</SPAN>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; <SPAN class="keyword token">this</SPAN><SPAN class="punctuation token">.</SPAN>sketchEditor<SPAN class="punctuation token">.</SPAN>CompleteCommand<SPAN class="punctuation token">.</SPAN><SPAN class="token function">Execute</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="keyword token">null</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
&nbsp;&nbsp; <SPAN class="punctuation token">}</SPAN>
<SPAN class="punctuation token">}</SPAN><SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

However, the call to CompleteCommand will cause an NullReferenceException, because it will set the geometry of the SketchEditor to null, but the SketchEditor seems to use the value of geometry after the GeometryChanged event.

Am I missing something or is there no way to achieve such an exit condition?

JenniferNery

Oh that should not have happened, thank you for reporting this! I have logged an issue to fix NullRef exception.

The optional `drawAndEdit` parameter is to complete the task as soon as something is drawn. In the case of Polygon, after double-tap occurs and there's at least 3 vertices, it will be completed without going to edit mode or requiring Stop/Complete to be called.

Since you plan to complete the draw programmatically given your specific condition, you can alternatively use EditConfiguration to disable the edits you don't need, or

<SPAN class="keyword token">var</SPAN> config <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">SketchEditConfiguration</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">)</SPAN>
<SPAN class="punctuation token">{</SPAN>
&nbsp;&nbsp;&nbsp; AllowVertexEditing <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">false</SPAN><SPAN class="punctuation token">,</SPAN>
&nbsp;&nbsp;&nbsp; AllowMove <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">false</SPAN><SPAN class="punctuation token">,</SPAN>
&nbsp;&nbsp;&nbsp; AllowRotate <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">false</SPAN><SPAN class="punctuation token">,</SPAN>
&nbsp;&nbsp;&nbsp; ResizeMode <SPAN class="operator token">=</SPAN> SketchResizeMode<SPAN class="punctuation token">.</SPAN>None
<SPAN class="punctuation token">}</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="keyword token">var</SPAN> geom <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">await</SPAN> MyMapView<SPAN class="punctuation token">.</SPAN>SketchEditor<SPAN class="punctuation token">.</SPAN><SPAN class="token function">StartAsync</SPAN><SPAN class="punctuation token">(</SPAN>SketchCreationMode<SPAN class="punctuation token">.</SPAN>Polygon<SPAN class="punctuation token">,</SPAN> config<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN><SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

you can change the symbols in the Style.

MyMapView<SPAN class="punctuation token">.</SPAN>SketchEditor<SPAN class="punctuation token">.</SPAN>Style<SPAN class="punctuation token">.</SPAN>ShowNumbersForVertices <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">false</SPAN><SPAN class="punctuation token">;</SPAN>
MyMapView<SPAN class="punctuation token">.</SPAN>SketchEditor<SPAN class="punctuation token">.</SPAN>Style<SPAN class="punctuation token">.</SPAN>SelectionColor <SPAN class="operator token">=</SPAN> Color<SPAN class="punctuation token">.</SPAN>Red<SPAN class="punctuation token">;</SPAN>
MyMapView<SPAN class="punctuation token">.</SPAN>SketchEditor<SPAN class="punctuation token">.</SPAN>Style<SPAN class="punctuation token">.</SPAN>SelectedVertexSymbol <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">new</SPAN> <SPAN class="token class-name">SimpleMarkerSymbol</SPAN><SPAN class="punctuation token">(</SPAN>SimpleMarkerSymbolStyle<SPAN class="punctuation token">.</SPAN>Circle<SPAN class="punctuation token">,</SPAN> Color<SPAN class="punctuation token">.</SPAN>Red<SPAN class="punctuation token">,</SPAN> <SPAN class="number token">1</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN>
MyMapView<SPAN class="punctuation token">.</SPAN>SketchEditor<SPAN class="punctuation token">.</SPAN>Style<SPAN class="punctuation token">.</SPAN>VertexSymbol <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">null</SPAN><SPAN class="punctuation token">;</SPAN>
MyMapView<SPAN class="punctuation token">.</SPAN>SketchEditor<SPAN class="punctuation token">.</SPAN>Style<SPAN class="punctuation token">.</SPAN>MidVertexSymbol <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">null</SPAN><SPAN class="punctuation token">;</SPAN>
<SPAN class="keyword token">var</SPAN> geom <SPAN class="operator token">=</SPAN> <SPAN class="keyword token">await</SPAN> MyMapView<SPAN class="punctuation token">.</SPAN>SketchEditor<SPAN class="punctuation token">.</SPAN><SPAN class="token function">StartAsync</SPAN><SPAN class="punctuation token">(</SPAN>SketchCreationMode<SPAN class="punctuation token">.</SPAN>Polygon<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">;</SPAN><SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

We still need to fix the NullRef ex but meanwhile you have the option to use any of the above suggestions.