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|Home GeoPack GeoAtlas How to Use TGeoAtlas|
|See also: Interface of SDL_GeoAtlas|
TGeoAtlas is a visual component for displaying maps of a geographical atlas. It consists of a command panel and a GeoMap display component. The command panel which can be accessed via the property CmdPanel contains three elements: the map selector (property MapSelector) which is a dropdown listbox containing all registered map names; a pointer button (property PointerButton) which activates the normal pointer-like cursor behavior. If the pointer button is active, the current map may be panned by dragging it with the mouse. The third element is the ZoomButton. If the zoom button is active you can zoom into and out of a map by clicking it with the left or the right mouse button. The activity of the PointerButton and ZoomButton is mutually exclusive - only one of them can be active (=pressed). You can switch off the command panel by setting the property CmdPanelVisible to FALSE.
In order to use a map within the atlas each map has to be registered using the method RegisterMap. The number of registered maps can be obtained from the property NumRegMaps. If a map is no longer needed in the atlas, you can remove it by calling UnregisterMap. The list of registered maps is available via the array property Maps. You can select a particular map by calling the method SelectMap. The currently loaded map can be accessed via the property CurrentMap.
If the property MapOutlineVisible is TRUE, the atlas component indicates all overlapping maps of the current map by drawing thin outlines. The color of the map outlines can be controlled by the property MapOutlineColor.
There are two ways to zoom into a map or out of a map: you may either achieve this interactively (activating the ZoomButton and clicking the map) of by using the methods ZoomIn and ZoomOut. The ZoomIn method is controlled by the property MinResDiff which specifies the minimum required resolution difference for zooming into a region.