ObjectLand provides the user with a possibility to add, change, remove map features during browsing a theme based on this map. These operations have a general name – map editing. All the operations of editing can be performed only with features of such layers and types which are displayed in the present theme.
In this chapter operations of adding and editing features are described. ObjectLand provides the user with two methods for performing these operations:
coordinate feature editing which essence is in entering coordinate values which determine the position of the feature on the map (coordinates are entered from the keyboard).
interactive feature editing, that is, their visual building (drawing) and changing them using a mouse.
Both methods allow the user to create a feature located in the specified position on a map. The advantage of coordinate editing is a higher precision of specifying coordinates, the advantage of interactive editing – visualization of actions being performed. The feature which was created by one of the methods can be further edited by the same method or a different one.
To begin the operation of adding a feature in the mode of coordinate editing the menu item Feature+Add should be performed. From the opened nested menu it is necessary to select the spatial category of the feature which is being added: point, line, area, text or image. A dialog box for input of coordinates and other parameters of the feature being created will be opened. The form of this dialog box and operations with it depend on the selected spatial category. While working with the dialog box, the user selects the layer and the type of feature being added (from the list of feature types of the present category displayed in the browsed theme), enters coordinates and other feature parameters. As a result of these actions, if the user doesn't cancel the operation of adding, a new feature will be created.
To start coordinate editing of the existing feature, this feature should be selected at first. It is possible to use any selecting mode, but only one feature should be selected. Then the menu command Feature+Edit should be performed. The system determines the spatial category of the selected feature and depending on this type opens a dialog box of editing a point, line, area, text or image feature. All these dialog boxes differ from dialog boxes of adding a feature only in the title (“Editing” instead of “Adding”) and also in one more parameter: the layer and feature type are specified already and cannot be changed in this dialog box.
When a dialog box of editing is opened, the current values of parameters, point coordinates, etc. are displayed in its panes. The user can make the necessary changes using all the operations which are described for dialog boxes of adding features. After pushing the button OK a dialog box of editing is closed and the system redraws the displaying pane with the changed feature. After pushing the button Cancel all the made changes are canceled and the selected feature remains without changes.
If the user prefers to draw the feature being added in interactive mode, he should push the button 
at the bottom of the mode pane. The system switches over to the mode Adding new feature, the cursor takes the form of a cross (
). After completing creation of one feature the system remains in the adding mode allowing the user to add more features. It is possible to leave the adding mode by pushing the button of any mode in the upper part of the mode toolbar (for example, Selection).
To change the existing feature in interactive mode, it should be selected for editing. To do this the required feature (or group of features) should be selected and the mode Edit should be turned on (the button 
in the mode toolbar). Another sequence of actions is also possible: switching over the mode Edit at first, then selecting the feature for editing by clicking it. In any case the feature selected for editing is highlighted by color. By default bright blue color is used (unlike the red color set by default for selected features in other modes). It is possible to select a group of several features for editing, it is enough to select features by clicking them while holding down the key Ctrl. Selection of individual features can be reset by clicking while holding down the key Alt.
For adding a new inner boundary of the existing area feature a special mode Adding inner boundary is provided (the button 
). This mode is used similarly to the mode Adding new feature.
When one of the modes Adding new feature, Edit or Adding inner boundary is turned on, the system opens an auxiliary window “Editor control” which permits the user to control some editing parameters and also receive the information about feature coordinates in the process of editing.
Further possible actions with the selected feature depend on the spatial category of the feature which is being edited and on the selected variant of the mode Edit.
ObjectLand enables the user to undo any operations of changing features not depending on the method of editing.
 |  |
