Add dedicated sample pages for Compass, Locate, BasemapToggle, and ScaleBar widgets

[magmoe]

Summary

• 4 new Core widget sample pages, each showcasing a widget that previously only appeared in the Widgets overview
• Compass Widget (/compass-widget): rotation buttons with CompassWidget auto-reset
• Locate Widget (/locate-widget): geolocation with configurable zoom scale
• Basemap Toggle Widget (/basemap-toggle-widget): switchable basemap style pairs
• Scale Bar Widget (/scale-bar-widget): unit and style toggle controls
• Nav menu entries for all 4 new pages
• Fix UniqueValueRenderers build error

[Copilot]

Pull request overview

This PR expands the Core sample app by adding dedicated pages for several widgets (Compass, Locate, BasemapToggle, ScaleBar) that were previously only demonstrated in the Widgets overview, and includes a small fix to resolve a build error in the UniqueValueRenderers sample.

Changes:

• Added 4 new widget-specific sample pages with simple configuration controls.
• Updated the nav menu to include routes for the new pages.
• Adjusted UniqueValueRenderers label formatting logic to avoid the removed/invalid ToUpperFirstChar() usage.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
samples/core/dymaptic.GeoBlazor.Core.Sample.Shared/Shared/NavMenu.razor.cs	Adds nav links for the four new widget sample pages.
samples/core/dymaptic.GeoBlazor.Core.Sample.Shared/Pages/UniqueValueRenderers.razor.cs	Replaces ToUpperFirstChar() usage with inline formatting to fix build.
samples/core/dymaptic.GeoBlazor.Core.Sample.Shared/Pages/CompassWidgetPage.razor	New Compass widget page with rotation controls.
samples/core/dymaptic.GeoBlazor.Core.Sample.Shared/Pages/LocateWidgetPage.razor	New Locate widget page with selectable zoom scale.
samples/core/dymaptic.GeoBlazor.Core.Sample.Shared/Pages/BasemapToggleWidgetPage.razor	New BasemapToggle widget page with selectable basemap pairs.
samples/core/dymaptic.GeoBlazor.Core.Sample.Shared/Pages/ScaleBarWidgetPage.razor	New ScaleBar widget page with unit/style controls.

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[TimPurdum]

Code Review — PR #14: Compass / Locate / BasemapToggle / ScaleBar widget samples

Overview

Four dedicated pages for widgets that were previously only demoed inside the big "Widgets" overview. Each page has dropdown/button controls to exercise the widget's props. Good additions. Also includes the UniqueValueRenderers build fix.

🔴 Architectural concern — @key on MapView

Every page here uses @key on MapView, bound to a state field that changes on user interaction:

<MapView @key="@_rotation"   Rotation="@_rotation" ...>   <!-- CompassWidgetPage -->
<MapView @key="@_widgetKey"  ...>                         <!-- LocateWidgetPage, ScaleBarWidgetPage -->
<MapView @key="@_pairIndex"  ...>                         <!-- BasemapToggleWidgetPage -->

This forces Blazor to dispose and recreate the entire MapView (and the underlying ArcGIS JS View, which is expensive) on every user action. A map reload on each button click for a rotation change is a bad demo experience — the map will visibly flash/reload.

The correct GeoBlazor pattern is parameter binding:

• MapView.Rotation is a parameter and updates reactively — drop @key on the Compass page.
• LocateWidget.Scale / ScaleBarWidget.Unit / ScaleBarWidget.Style should propagate through normal parameter binding. If they don't, that's a GeoBlazor bug worth filing in the main repo rather than working around here with @key. I'd check first:
  • Does await _locateWidget.SetScale(...) exist? (GeoBlazor often exposes imperative setters alongside params.)
  • Is there a known issue about widget-property reactivity?

For BasemapTogglePage where the Secondary basemap style changes, a full re-mount may genuinely be the only option today — but it's worth confirming there isn't a SetNextBasemapStyle or similar.

At minimum, if @key is truly required, add a comment explaining why, so this doesn't become the go-to pattern copied into other samples.

🟡 Smaller issues

1. int.Parse / Enum.Parse on user input.

   _pairIndex = int.Parse(e.Value?.ToString() ?? "0");
   _unit = Enum.Parse<ScaleUnit>(e.Value?.ToString() ?? "Imperial");

   Throws on unexpected values. In practice a <select> never emits an unexpected value, but TryParse with a fallback is idiomatic Blazor. Or better — @bind directly to the enum / int and let Blazor do the conversion:

   <select @bind="_unit">
       @foreach (var u in Enum.GetValues<ScaleUnit>())
       {
           <option value="@u">@u</option>
       }
   </select>

2. LocateWidget: Scale is typed int — confirm that matches GeoBlazor's parameter type (it may be double?). If double?, the parse + state could be simplified.

3. Locate page instructions use inline SVG to show the button glyph — cute but fragile if the Esri icon set changes. A screenshot reference or textual description is more durable.

4. Nav entries inserted mid-list between "widgets" and "basemaps" in NavMenu.razor.cs. When Add collapsible category submenus to navigation sidebar #13 merges, these will need Category: Categories.Widgets to slot into the new group structure. See my note on Add collapsible category submenus to navigation sidebar #13.

🟢 Nice touches

• Each page links to both the ArcGIS JS sample and the API reference — consistent with the repo convention.
• Current-rotation readout ("Current: 45°") on the Compass page is a nice feedback touch.
• ScaleBarWidget supports both unit and style — good to exercise both dimensions.

Merge ordering

Conflicts with #12 on UniqueValueRenderers.razor.cs (identical fix) and with #13 on NavMenu.razor.cs. Suggest merge order: #12 → #14 → #13, with #13 responsible for categorizing the new pages from #12 and #14.

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