Show Current Selection of a Multiple Feature Selection

[steveg]

The change request RFC 71 ​http://trac.osgeo.org/mapguide/wiki/MapGuideRfc71 was implemented to display the properties of individual features of a multiple feature selection in the properties pane of the AJAX viewer. However, once a multiple feature selection is made and the user selects one of the features from the dropdown list, it is difficult to determine from the map which feature's properties are being displayed.

One proposal would be to have a secondary selection color that would be used to show which feature's properties is active in the properties pane (i.e. selection color blue to show all selected features and yellow to show the active feature in the properties pane)

[jng]

The ideal solution (whatever that may be. I haven't put much thought into it) is one that requires no roundtrips back to the MapGuide server for extra information. Whatever is returned by getselectedfeatures.aspx/php.jsp should provide sufficient information to render sub-selected features.

Keep in mind that the selection that you see in the viewer is a dumb image returned by the MapGuide Server. To change the selection color for the subselected feature in the naively classical sense, would require another roundtrip to the MapGuide Server for the new selection image. This is woefully inefficient.

So in terms of showing a sub-selected feature, the best bet is to put a client-side marker (eg. A css-styled div) of some sort on top of the feature in question, that moves when panning and zooming and is cleared when either the selection is cleared or a different selected feature is sub-selected.

[jng]

Now that QUERYMAPFEATURES for all intents and purposes works as originally designed (there has been many design/implementation defects), I've got an easy idea on how to do this. We can implement sub-selections as renderings of transient (temporary) selections.

We can render transient selections by simply issuing a v2.6.0 QUERYMAPFEATURES with PERSIST=0 and with a different selection color, sending up the selection XML fragment of the current feature and require an inline selection image as part of the response, which we can then overlay on top of the current map image.

We can send this request on any change of map view or change of active feature in the property palette. However, because it is transient it means that if you plot the map there will be no active sub-selection included as we never persist that active sub-selection server-side.

How does that sound?

[jng]

Ticket retargeted after milestone closed

[jng]

Milestone renamed

[jng]

This is already handled by external viewers like ​https://github.com/jumpinjackie/mapguide-react-layout

Won't be handled in the AJAX or Fusion viewer