[API] Source/OSM.TilesProvider.Google.pas: + Add Google maps provider

Source/OSM.TilesProvider.Google.pas

@@ -0,0 +1,62 @@
+{
+  Google tile image provider.
+  https://gis.stackexchange.com/questions/225098/using-google-maps-static-tiles-with-leaflet
+  - should be an official description but I didn't find it.
+
+  (c) Fr0sT-Brutal https://github.com/Fr0sT-Brutal/Delphi_OSMMap
+
+  @author(Fr0sT-Brutal (https://github.com/Fr0sT-Brutal))
+  @author(Martin (https://github.com/array81))
+}
+unit OSM.TilesProvider.Google;
+
+interface
+
+uses
+  SysUtils,
+  OSM.SlippyMapUtils, OSM.TilesProvider;
+
+type
+  // Google tile image provider
+  TGoogleTilesProvider = class(TTilesProvider)
+  const
+    //~ global defaults
+    // Default copyright text
+    DefTilesCopyright = '(c) Google';
+    {~ TODO: Note that difference in the "lyrs" parameter in the URL:
+      Hybrid: s,h;
+      Satellite: s;
+      Streets: m;
+      Terrain: p;
+    }
+    // Default pattern of tile URL. Placeholders are for: Random subdomain (0..MaxSubdomainNum), X, Y, Zoom
+    DefTileURLPatt = 'http://mt%d.google.com/vt/lyrs=m&hl=en&x=%d&y=%d&z=%d';
+    // Maximal subdomain number
+    MaxSubdomainNum = 3;
+  public
+    // Pattern of tile URL. Placeholders are for: Random subdomain (0..MaxSubdomainNum), X, Y, Zoom
+    TileURLPatt: string;
+
+    constructor Create;
+    function GetTileURL(const Tile: TTile): string; override;
+  end;
+
+implementation
+
+constructor TGoogleTilesProvider.Create;
+begin
+  MinZoomLevel := Low(TMapZoomLevel);
+  MaxZoomLevel := 19;
+//  TileFormat.Format := 'png';
+//  TileFormat.Width := 256;
+//  TileFormat.Height := 256;
+  TilesCopyright := DefTilesCopyright;
+  TileURLPatt := DefTileURLPatt;
+end;
+
+function TGoogleTilesProvider.GetTileURL(const Tile: TTile): string;
+begin
+  Result := Format(TileURLPatt, [Random(MaxSubdomainNum), Tile.ParameterX, Tile.ParameterY, Tile.Zoom]);
+end;
+
+end.