Feature Editing

Creating spatial objects

When the map is activated from a new database record, a dialogue box will inform the user that no linked GIS features can be found with this ID.  If the user chooses to create a feature the gazetteer opens (see The Gazetteer) which will help the user to navigate to the correct area of the map (although this feature can be disabled in the INI file).  The map layer corresponding to the record becomes the active layer and any features created are assigned the ID of the database record.

Once a drawing tool has been selected from the button bar an editing session is started and a temporary layer created for the digitised objects. Digitised objects remain on the temporary layer until they are saved by clicking on the Save button or by exiting the map when they are saved to the active layer.

New features can also be created with the ‘Copy and Merge Features’ command. See ‘Right-click menus’ for more information on this command.

Status bar information

The bottom right of the status bar displays either the current zoom as the distance in metres across the map window, the coordinates of the cursor or the map scale.  The map opens with the setting stored in the workspace file when it was last saved from MapInfo.  Double clicking on the display toggles it between the three modes.

Editing and deleting spatial objects

When you go to the map from a database record the associated layer becomes the active layer and map objects for that record are shown highlighted.  Note that highlighting is additive and if an even number of point objects are superimposed the highlighting is cancelled out.  To edit the map objects an editing session must be started by clicking on the ‘Edit the currently selected object’ button.  This launches the Edit Object dialogue which contains the warning that you must save your edits otherwise you risk losing them.  You may opt to suppress this dialogue.  You may also opt to show the location on disk of the temporary file in which the edits are stored before they are committed to the MapInfo layer.  Should the save fail for any reason the object may be retrieved from this file.

Edit object dialogue

If there are multiple map objects for the database record you may select an individual object to edit by clicking away from the objects to deselect them and then clicking on the one you wish to edit.  You can do this before or after starting the editing session

When the editing session has been started the polygons, lines and multiple objects may be in either move/resize/rotate or reshape mode.  Move/resize/rotate mode is indicated by black squares at the corners of the bounding rectangles and a black star (the rotation handle) near the bottom left bound.  In reshape mode each node on the object has a black square.  If there are multiple objects selected they will always be in move/resize/rotate mode. When a single object is selected you can toggle between the two modes using Control R or selecting Edit ‘Objects ► Reshape’ from the right click menu.


In move/resize/rotate mode clicking on the object gives a four pointed cursor which you can use to re-position the object or objects.  Dragging a black square allows you to resize the object(s).  Dragging the star allows you to rotate the object(s).

In reshape mode each node may be dragged to a new position.  New nodes can be added by selecting Edit ‘Objects ► Add Node’ from the right click menu.  To remove nodes first click on a node to highlight it and then press the backspace or the delete key.

To delete an object it must be selected in move/resize/rotate mode.  The object may then be deleted using the delete key or the backspace key.

Snapping to and tracing existing map objects

The standard Snap and Trace tools of MapInfo® are available through MapLink.

Snap is activated by pressing the ‘S’ key on the keyboard. When Snap is active the cursor changes to a circle containing a small cross. When the cursor is in range of a node to which you can snap it changes to a large cross. Clicking when the cursor is in range of a snap point forces the new node to that point.

When Snap is active you can also activate the Trace tool by pressing the ‘T’ key on the keyboard. Layers containing objects you wish to trace must be set as selectable. Once you have started drawing a line or polygon and have activated Trace then, as you move the cursor over the object you are tracing, each time you reach a snap node the shortest distance to that node is highlighted. If you hold down the Control key then the longest distance is highlighted. When you click on a node of the object you are tracing your line is drawn over the object to that point. If you need to change to a new object while tracing press ‘T’ to deactivate Trace mode, snap to a node on the new object, and then re-activate Trace.

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