[GIS] Labeling Selected Features Only using ArcGIS Engine

arcgis-10.0arcgis-enginearcobjectsc

I've been labeling using the LabelEngine and simple expressions and it is working for every layer. I want to offer the option of labeling only selected features and thought it would be this simple:

annotateLayerProperties.LabelWhichFeatures = esriLabelWhichFeatures.esriSelectedFeatures;

Unfortunately that doesn't do it. Every polygon is still labeled. I verified that the features were selected (I have a routine that just returns the selected keys.) I also tried replacing the Engine labeling with a:

annotateLayerProperties.WhereClause = BuildWhere( keyName, selected );

using both my keys and the features OIDs – that does not label at all.

Does anyone know how to label only the selected features?

Best Answer

Labeling selected features is not currently possible in ArcGIS. The value you are setting on the property LabelWhichFeatures is overwritten by the labeling process and is not intended to be a persisted setting for this purpose. It main exists to power Convert Labels to Annotation which has a selected features option.

There is an existing enhancement request to provide labeling for selected features, but we'd like to understand the workflows that people are trying to fulfill with this requested functionality. If you can provide any details here, it would be helpful. <- If it is not obvious, I work on labeling at Esri.

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ArcGIS Progress – Showing Progress in ArcGIS Engine Application

The code below works for me. If you load a new map, you'll need to re-wire your events. Maybe try start animating when IDisplayEvents.Start fires (and IViewRefresh.Drawing is true). Then stop animating when IActiveViewEvents.AfterDraw fires with drawPhase == esriViewDrawPhase.esriViewForeground.

private IDisplayEvents_Event m_dispevt;
private IActiveViewEvents_Event m_avEvt;
private int m_lastTick;
private void WireEvents(IMap map)
{
    Debug.Print("wiring");
    m_dispevt = ((IActiveView)map).ScreenDisplay as IDisplayEvents_Event;
    m_dispevt.DisplayStarted += new IDisplayEvents_DisplayStartedEventHandler(MainForm_DisplayStarted);
    m_dispevt.DisplayFinished += new IDisplayEvents_DisplayFinishedEventHandler(MainForm_DisplayFinished);
    m_dispevt.DisplayInvalidated += new IDisplayEvents_DisplayInvalidatedEventHandler(MainForm_DisplayInvalidated);
    m_dispevt.DisplayScrolled += new IDisplayEvents_DisplayScrolledEventHandler(MainForm_DisplayScrolled);
    m_avEvt = (IActiveViewEvents_Event)map;
    m_avEvt.AfterDraw += new IActiveViewEvents_AfterDrawEventHandler(m_avEvt_AfterDraw);
    m_avEvt.AfterItemDraw += new IActiveViewEvents_AfterItemDrawEventHandler(m_avEvt_AfterItemDraw);
}

void m_avEvt_AfterItemDraw(short Index, IDisplay Display, esriDrawPhase phase)
{
    Debug.Print("afteritemdraw {0} {1}", Index, phase);
}

void m_avEvt_AfterDraw(IDisplay Display, esriViewDrawPhase phase)
{
    if(phase == esriViewDrawPhase.esriViewForeground)
        Debug.Print("foreground finished afterdraw {0} {1} msecs", phase, Environment.TickCount - m_lastTick);
    if (phase == esriViewDrawPhase.esriViewBackground)
        m_lastTick = Environment.TickCount;
}

void MainForm_DisplayScrolled(IDisplay Display, int deltaX, int deltaY)
{
    Debug.Print("scrolled");
}

void MainForm_DisplayInvalidated(IDisplay Display, ESRI.ArcGIS.Geometry.IEnvelope rect, bool erase, short cacheID)
{
    Debug.Print("invalidated");
}

void MainForm_DisplayFinished(IDisplay Display)
{
    Debug.Print("finished");
}

void MainForm_DisplayStarted(IDisplay Display)
{
    Debug.Print("started {0}", ((IViewRefresh)axMapControl1.Map).Drawing);
}

[GIS] How to use ArcGisServer from Engine

I've never tried this, but it seems like you could write a custom layer that uses webclient to access the mapservice via a REST API query, with returngeometry=true.

The returned json string could then be converted into a list of geometries using Json.NET. ILayer.Draw would loop through this list and draw the geometries.

If you need a legend, you could implement ILegendInfo so that it returns symbols that have been fetched via SOAP.

Best Answer

Related Solutions

ArcGIS Progress – Showing Progress in ArcGIS Engine Application

[GIS] How to use ArcGisServer from Engine

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