Map View
User Guide GeoDMS GUI - map view
introduction
The map view presents data items that can be geographically located. Each map view has a projection, indicating a coordinate system. For instance in Dutch applications usually the “Rijks Driehoek (RD)” coordinate system is used. EPSG codes are used as identifiers for the most common coordinate systems. The EPSG code is shown in the title of each map view, if configured as SpatialReference Property for the base unit of the coordinate system.
Since GeoDMS 20.19.2 the title of a map view names the view itself first, then the coordinate system and the active layer: MapView with EPSG:28992 - Active layer: buurt (#buurt = 14,262). When the base unit declares neither a SpatialReference nor a Label property to stand in for it, the title reads MapView No SpatialReference, followed by the active layer as usual. Up to and including GeoDMS 20.19.1 nothing at all was written for the coordinate system in that case, so the title began with a bare comma and gave no indication that the SpatialReference was missing.
A map view consists of layers, each layer is related to one or more data items. All geographically related data items using the same projection can be combined in the same map view window. They can also be opened in multiple separate map views. The number of opened map views is not limited.
By double clicking on an element, a ValueInfo window appears.
activate map view
To view data in a map view, first activate a tree item that can be geographically related (indicated with a map icon 
).
A new map can be created or a layer can be added to an existing map by activating one of the following actions listed in the table.
| action | no active map view | active map view |
|---|---|---|
| double click on active item | new map window | added to active map view with same coordinate system |
| main/pop-up menu option default view | new map window | added to active map view with same coordinate system |
| main/pop-up menu option map view | new map window | new map window |
| Ctrl-M on active item | new map window | new map window |
| drag and drop to view | new map window | added to active map view with same coordinate system |
navigate in the map view
Next to the tools in the toolbar, the visible part of the map (the region of interest) can be changed with the mouse and with the keyboard:
| action | effect |
|---|---|
| mouse wheel | zoom in/out, keeping the location under the mouse pointer at the same position |
| + and - | zoom in/out around the center of the map view. Both the keys of the numeric keypad and the +/- keys of the main keyboard can be used |
| arrow keys | pan the map one step to the left, right, up or down |
| Ctrl-L | zoom to the extent of all layers |
| Ctrl-Y | zoom to the extent of the active layer |
| Ctrl-F | zoom to the extent of the selected elements |
| Ctrl-0 | copy the current location and zoomlevel to the clipboard |
| Ctrl-1, Ctrl-2, Ctrl-3 | go to the location, the zoomlevel, or both, as stored in the clipboard. Add Shift to apply this to all opened map views |
These keyboard shortcuts are sent to the desktop component that has the keyboard focus. Click in the map view to give it the focus; other components use the same keys for their own purposes, the treeview for instance expands and collapses an item with + and -.
Ctrl-Shift-Left and Ctrl-Shift-Right do not move the map but change the width of the legend column, in steps of 10 pixels; see Map view Legend.
Since GeoDMS 20.15.1 a click in a map view always moves the keyboard focus to that view. In the versions 20.0.0 up to and including 20.15.0 the focus could remain on the component that was used before — usually the treeview, after activating another item there — so the keyboard shortcuts silently stopped working, while the mouse wheel kept zooming. This was most noticeable in a remote desktop session, in which the mouse wheel is often not forwarded to the application.
tooltip
Resting the mouse pointer on a layer raises a tooltip describing what is under it. For a grid layer it names the grid location as [column, row], followed by the index of that cell in the grid domain, the row it occupies in the data when the domain is tiled and that row differs from the index, and the value of the active Attribute there:
GridLayer [15, 19], Index: 15,215, DataRow: 3,815, Value: 34
A tooltip is only raised for a layer the pointer is actually on, so a position outside the extent of every layer raises none at all.
Since GeoDMS 20.19.3 a position that is inside a grid layer but on no cell of it reports the grid location and stops, with not in any tile in place of the data row and the value:
GridLayer [382, 60], Index: 48,382, not in any tile
This is possible only for a domain tiled with the irregular form of TiledUnit, whose tiles are not required to cover the source range without gaps — a TiledUnit over a sparse study area, one tile per continent for instance, leaves the sea uncovered. Up to and including GeoDMS 20.19.2 moving the mouse over such a position terminated the GeoDMS GUI, with no error message and without writing a crash dump: the engine looked the cell up anyway and read past the end of the tile administration. To a user this looked like the window simply disappearing. Selecting a rectangle, circle or polygon that reached across an uncovered part of such a grid could end the same way, and no longer does.