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CreateEmptyMapInMemory


Unit:SDL_geomap
Class: TGeoMap
Declaration: procedure CreateEmptyMapInMemory (LatLow, LongLow, LatHigh, LongHigh, dLat, dLong: double; Wid, Hgt: integer; ShowGrid: boolean; OnDrawMapData: TOnDrawMapDataEvent);

The method CreateEmptyMapInMemory creates a blank map in memory showing an area which is defined by the parameters LatLow, LongLow, LatHigh, LongHigh. If the parameter ShowGrid is TRUE a graticule is created. In this case the parameters dLat and dLong control the distance of displayed graticule lines. They may take any non-zero, positive value.

The parameters Wid and Hgt specify the width and the height of the map image (in pixels). They must not be less than 100 pixels.

The method CreateEmptyMapInMemory calls the routine OnDrawMapData after the map has been created in memory and before it is calibrated and displayed. It can be used to draw additional map features on the blank map (however, keep in mind that the map is not calibrated at this point, it is simply an image). It should be set to NIL if no additional drawing needs to be done.

Hint 1: In contrast to CreateAndLoadEmptyMap the created map image is a 24-bit (full color) bitmap.

Hint 2: You are responsible yourself to specify the range parameters and/or the width and height in a way that they correspond well to each other.

Example: The statement GeoMap1.CreateEmptyMapInMemory ('c:\temp\testmap',-5,10,10,35,5,5,500,300, true, nil); generates the following map in the memory (no map image is stored on disk):



Last Update: 2014-Sep-09