When working with map browser window ObjectLand gives a possibility to select one feature or an arbitrary number of features by forming a set of selected features from them. It is possible to include features of different types or even features belonging to different map layers into the selection set. In the displaying pane selected area features change color, line features are displayed with red lines, point and text features are outlined by a red frame (if necessary, the user can change displaying style of selected features).
Including the feature into selection set is called selection, excluding – deselection or selection reset.
In information bar parameters of selected features are displayed. If one feature is selected, the names of its layer and type are indicated, for line feature – its length, for area one – its length (perimeter) and area. If several features are selected, the system displays more or less generalized data: if all the features belong to one layer, the name of the layer is displayed, if they belong to one type – the name of this type. The total area is displayed only if all the selected features are area features, and the total length – if every selected feature is either area or a line one.
Apart from getting information about features, the system allows performing some operations with all the set of selected features simultaneously.
The system provides several methods for selecting and deselecting features:
Use of selecting modes, turned on by mode toolbar buttons of map browser window, enables the user to specify features which are subject for selection or deselection using the mouse.
There is a possibility to use links between map features and table records to specify a set of features to be selected indirectly, by the set of records linked with them (chapter 33 “Table data in map display”).
It is possible to determine the set of selected features using the theme filter (chapter 34 “Filters and their structure”) by including those features which satisfy filter conditions or on the contrary, do not satisfy them, into this set.
A combination of all these methods is also possible when determining the set of selected features.
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