Changes between Version 8 and Version 9 of MapGuideRfc15
- Timestamp:
- 03/12/07 14:16:27 (18 years ago)
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MapGuideRfc15
v8 v9 23 23 == Overview == 24 24 25 The current Rendering Service APIs !QueryFeatures() and !QueryFeatureProperties() are restricted to only querying data for map layers that are visible at the current map scale. However, there are certain situations where you may wish to query data on the map layers regardless of whether they are currently visible at the current map scale. 25 The current Rendering Service APIs !QueryFeatures() and !QueryFeatureProperties() are restricted to only querying data for map layers that are visible at the current map scale. However, there are certain situations where you may wish to query data on the map layers regardless of whether they are currently visible at the current map scale. There are also situations where it is desirable to filter the results using a list of feature IDs. 26 26 27 27 == Motivation == … … 33 33 You have a map of Canada that contains a "parcels" layer that is currently not visible at the current map scale because you are just wanting to have a country overview display. You now wish to view all parcels with a certain size across Canada. If you tried to use the !QueryFeatures() and !QueryFeatureProperties() APIs on your "parcels" layer the results would not be displayed because the "parcels" layer is not currently visible at the current map scale. You could zoom in until the "parcels" layer is visible, but you would not be able to see all the parcels you are interested in across Canada very easily. 34 34 35 Also, when a feature is selected in the !MapGuide Viewer using the Search command, a susequent !QueryFeatures() request is made to the !MapGuide Server in order to retrieve the properties for the selected feature. Any properties that are available are displayed in the viewer's property pane. The !QueryFeatures() request is made using a spatial filter based on the geometry of the selected feature, with a !MaxFeatures value of 1. Thus, the properties that are displayed are those for the first feature that intersects the geometry of the selected feature. Unfortunately, this means that the properties that are retrieved are sometimes those of an adjacent feature instead of the selected feature. For this reason, it is desirable to be able to specify one or more feature IDs to be used to filter the results of the !QueryFeatures() and !QueryFeatureProperties() methods. 36 37 35 38 == Proposed Solution == 36 39 37 The solution to this is to add 2 NEW APIs that essentially are identical to the already existing !QueryFeatures() and !QueryFeatureProperties() APIs except that they add a n additional parameter. The reason for the NEW APIs is so as not to break backward compatibility with the already existing APIs.40 The solution to this is to add 2 NEW APIs that essentially are identical to the already existing !QueryFeatures() and !QueryFeatureProperties() APIs except that they add additional parameters. The reason for the NEW APIs is so as not to break backward compatibility with the already existing APIs. 38 41 39 42 Proposed New APIs: … … 42 45 MgFeatureInformation* QueryFeatures(MgMap* map, 43 46 MgStringCollection* layerNames, 44 MgGeometry* geometry, 45 INT32 selectionVariant, 47 MgGeometry* filterGeometry, 48 INT32 selectionVariant, 49 CREFSTRING featureFilter, 46 50 INT32 maxFeatures, 47 51 bool bIgnoreScaleRange); … … 49 53 MgBatchPropertyCollection* QueryFeatureProperties(MgMap* map, 50 54 MgStringCollection* layerNames, 51 MgGeometry* geometry, 52 INT32 selectionVariant, 55 MgGeometry* filterGeometry, 56 INT32 selectionVariant, 57 CREFSTRING featureFilter, 53 58 INT32 maxFeatures, 54 59 bool bIgnoreScaleRange); … … 58 63 59 64 {{{ 60 The existing HTTP operation QUERYMAPFEATURES will be updated to support the following additional parameter if it is specified.65 The existing HTTP operation QUERYMAPFEATURES will be updated to support the following additional parameters, if specified: 61 66 62 67 IGNORESCALE=0 … … 65 70 IGNORESCALE=1 66 71 * With the value of 1 this operation will allow querying of data regardless of visibility at the current map scale. 72 73 FEATUREFILTER=<XML Selection String> 74 * The XML Selection String format is used by the existing MgSelection class, and contains the required feature IDs, and information about the layer that contains them. 67 75 }}} 68 76 … … 96 104 * !RenderMap 97 105 106 == Addendum 2 == 107 108 1) Added the additional featureFilter parameter to Server APIs. 109 110 2) Added the FEATUREFILTER parameter to the HTTP QUERYMAPFEATURES request. 98 111 99 112
