在Delphi TWebBrowser中按地址显示谷歌地图

Display Google Map by address in Delphi TWebBrowser

本文关键字：地址 显示 谷歌地图 Delphi TWebBrowser      更新时间：2023-09-26

我正试图在Delphi的Windows窗体上的TWebBrowser中显示谷歌地图。我可以使用地址点击按钮来显示地图，但不能在加载表单时显示。当表单最初显示时，如何获取显示地址的地图？

    private
    { Private declarations }
    HTMLWindow2: IHTMLWindow2;
  public
    { Public declarations }
  end;
var
  ViewMaps: TViewMaps;
  Flags: OLEVariant;
  address: string;
implementation
Uses ActiveX;
{$R *.dfm}
const
HTMLStr: AnsiString =
'<html> '+
'<head> '+
'<meta name="viewport" content="initial-scale=1.0, user-scalable=yes" /> '+
//'<meta http-equiv="X-UA-Compatible" content="IE=edge" />'+
'<script type="text/javascript" src="http://maps.google.com/maps/api/js?v=3"></script> '+
'<script type="text/javascript"> '+
''+
''+
'  var geocoder; '+
'  var map;  '+
//'  var address;  '+
'  var trafficLayer;'+
'  var bikeLayer;'+
'  var markersArray = [];'+
''+
''+
'  function initialize() { '+
'    geocoder = new google.maps.Geocoder();'+
'    var latlng = new google.maps.LatLng(40.714776,-74.019213); '+
//'    var address = "San Diego, CA";'+
'    var myOptions = { '+
'      zoom: 11, '+
'      center: latlng, '+
'      mapTypeId: google.maps.MapTypeId.ROADMAP '+
'    }; '+
'    map = new google.maps.Map(document.getElementById("map_canvas"), myOptions); '+
'    trafficLayer = new google.maps.TrafficLayer();'+
'    bikeLayer = new google.maps.BicyclingLayer();'+
'    map.set("streetViewControl", false);'+
'  } '+
''+
''+
'  function codeAddress(address) { '+
'    if (geocoder) {'+
'      geocoder.geocode( { address: address}, function(results, status) { '+
'        if (status == google.maps.GeocoderStatus.OK) {'+
'          map.setCenter(results[0].geometry.location);'+
'          PutMarker(results[0].geometry.location.lat(), results[0].geometry.location.lng(), results[0].geometry.location.lat()+","+results[0].geometry.location.lng());'+
'        } else {'+
'          alert("Geocode was not successful for the following reason: " + status);'+
'        }'+
'      });'+
'    }'+
'  }'+
''+
''+
'  function GotoLatLng(Lat, Lang) { '+
'   var latlng = new google.maps.LatLng(Lat,Lang);'+
'   map.setCenter(latlng);'+
'   PutMarker(Lat, Lang, Lat+","+Lang);'+
'  }'+
''+
''+
'function ClearMarkers() {  '+
'  if (markersArray) {        '+
'    for (i in markersArray) {  '+
'      markersArray[i].setMap(null); '+
'    } '+
'  } '+
'}  '+
''+
'  function PutMarker(Lat, Lang, Msg) { '+
'   var latlng = new google.maps.LatLng(Lat,Lang);'+
'   var marker = new google.maps.Marker({'+
'      position: latlng, '+
'      map: map,'+
'      title: Msg+" ("+Lat+","+Lang+")"'+
'  });'+
' markersArray.push(marker); '+
'  }'+
''+
''+
'  function TrafficOn()   { trafficLayer.setMap(map); }'+
''+
'  function TrafficOff()  { trafficLayer.setMap(null); }'+
''+''+
'  function BicyclingOn() { bikeLayer.setMap(map); }'+
''+
'  function BicyclingOff(){ bikeLayer.setMap(null);}'+
''+
'  function StreetViewOn() { map.set("streetViewControl", true); }'+
''+
'  function StreetViewOff() { map.set("streetViewControl", false); }'+
''+
''+'</script> '+
'</head> '+
'<body onload="initialize()"> '+
'  <div id="map_canvas" style="width:100%; height:100%"></div> '+
'</body> '+
'</html> ';
procedure TViewMaps.OnFormCreate(Sender: TObject);
var
  aStream: TMemoryStream;
begin
   WebBrowser1.Navigate('about:blank');
    if Assigned(WebBrowser1.Document) then
    begin
      aStream := TMemoryStream.Create;
      try
         aStream.WriteBuffer(Pointer(HTMLStr)^, Length(HTMLStr));
         //aStream.Write(HTMLStr[1], Length(HTMLStr));
         aStream.Seek(0, soFromBeginning);
         (WebBrowser1.Document as IPersistStreamInit).Load(TStreamAdapter.Create(aStream));
      finally
         aStream.Free;
      end;
      HTMLWindow2 := (WebBrowser1.Document as IHTMLDocument2).parentWindow;
    end;
end;
procedure TViewMaps.GoToAddressBtnClick(Sender: TObject);
begin
   address := MemoAddress.Lines.Text;
   address := StringReplace(StringReplace(Trim(address), #13, ' ', [rfReplaceAll]), #10, ' ', [rfReplaceAll]);
   HTMLWindow2.execScript(Format('codeAddress(%s)',[QuotedStr(address)]), 'JavaScript');
end;

您无法在创建网页时加载网页。相反，您可以使用TTimer在延迟时加载它。。。

procedure TForm1.Timer1Timer(Sender: TObject);
begin
  Timer1.Enabled:= False; //Disable timer so it doesn't fire again
  WebBrowser1.Navigate('about:blank');
  ...........  
end;
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