lazmapviewer: Add geo distance calculation (patch by sstvmaster, https://forum.lazarus.freepascal.org/index.php/topic,12674.msg318879.html#msg318879).

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@6865 8e941d3f-bd1b-0410-a28a-d453659cc2b4

components/lazmapviewer/example/gpslistform.pas

@@ -56,7 +56,7 @@ end;
 
 procedure TGPSListViewer.Populate;
 const
-  GPS_FORMAT = '0.000000';
+  GPS_FORMAT = '0.00000°';
 var
   i: Integer;
   item: TListItem;

components/lazmapviewer/example/main.lfm

@@ -1,10 +1,10 @@
 object MainForm: TMainForm
   Left = 345
-  Height = 545
+  Height = 581
   Top = 121
   Width = 869
   Caption = 'MainForm'
-  ClientHeight = 545
+  ClientHeight = 581
   ClientWidth = 869
   OnCreate = FormCreate
   OnDestroy = FormDestroy
@@ -13,11 +13,11 @@ object MainForm: TMainForm
   LCLVersion = '2.1.0.0'
   object ControlPanel: TPanel
     Left = 592
-    Height = 545
+    Height = 581
     Top = 0
     Width = 277
     Align = alRight
-    ClientHeight = 545
+    ClientHeight = 581
     ClientWidth = 277
     TabOrder = 1
     object CbProviders: TComboBox
@@ -145,11 +145,11 @@ object MainForm: TMainForm
         Left = 16
         Height = 15
         Top = 23
-        Width = 46
+        Width = 43
         BorderSpacing.Left = 16
         BorderSpacing.Top = 4
         BorderSpacing.Bottom = 8
-        Caption = 'Latitude:'
+        Caption = 'Latitude'
         ParentColor = False
       end
       object InfoPositionLongitude: TLabel
@@ -195,11 +195,11 @@ object MainForm: TMainForm
       AnchorSideRight.Side = asrBottom
       Left = 9
       Height = 66
-      Top = 185
+      Top = 181
       Width = 259
       Anchors = [akTop, akLeft, akRight]
       AutoSize = True
-      BorderSpacing.Top = 12
+      BorderSpacing.Top = 8
       Caption = 'Center'
       ClientHeight = 46
       ClientWidth = 255
@@ -223,11 +223,11 @@ object MainForm: TMainForm
         Left = 16
         Height = 15
         Top = 23
-        Width = 46
+        Width = 43
         BorderSpacing.Left = 16
         BorderSpacing.Top = 4
         BorderSpacing.Bottom = 8
-        Caption = 'Latitude:'
+        Caption = 'Latitude'
         ParentColor = False
       end
       object InfoCenterLongitude: TLabel
@@ -272,7 +272,7 @@ object MainForm: TMainForm
       AnchorSideRight.Control = BtnSearch
       Left = 9
       Height = 23
-      Top = 264
+      Top = 334
       Width = 190
       Anchors = [akTop, akLeft, akRight]
       BorderSpacing.Right = 8
@@ -283,13 +283,13 @@ object MainForm: TMainForm
       Text = 'New York'
     end
     object BtnSearch: TButton
-      AnchorSideTop.Control = GbCenterCoords
+      AnchorSideTop.Control = GbScreenSize
       AnchorSideTop.Side = asrBottom
       AnchorSideRight.Control = GbCenterCoords
       AnchorSideRight.Side = asrBottom
       Left = 207
       Height = 25
-      Top = 263
+      Top = 333
       Width = 61
       Anchors = [akTop, akRight]
       AutoSize = True
@@ -305,7 +305,7 @@ object MainForm: TMainForm
       AnchorSideRight.Control = BtnGoTo
       Left = 9
       Height = 21
-      Top = 318
+      Top = 388
       Width = 196
       Anchors = [akTop, akLeft, akRight]
       BorderSpacing.Top = 4
@@ -325,7 +325,7 @@ object MainForm: TMainForm
       AnchorSideTop.Side = asrBottom
       Left = 9
       Height = 15
-      Top = 299
+      Top = 369
       Width = 177
       BorderSpacing.Top = 12
       Caption = 'Select one of the found locations:'
@@ -338,7 +338,7 @@ object MainForm: TMainForm
       AnchorSideRight.Side = asrBottom
       Left = 213
       Height = 25
-      Top = 316
+      Top = 386
       Width = 55
       Anchors = [akTop, akRight]
       AutoSize = True
@@ -354,7 +354,7 @@ object MainForm: TMainForm
       AnchorSideRight.Side = asrBottom
       Left = 8
       Height = 52
-      Top = 380
+      Top = 450
       Width = 260
       Anchors = [akTop, akLeft, akRight]
       AutoSize = False
@@ -368,7 +368,7 @@ object MainForm: TMainForm
       AnchorSideTop.Side = asrBottom
       Left = 8
       Height = 25
-      Top = 347
+      Top = 417
       Width = 92
       AutoSize = True
       BorderSpacing.Top = 8
@@ -383,8 +383,8 @@ object MainForm: TMainForm
       AnchorSideRight.Control = InfoBtnGPSPoints
       AnchorSideRight.Side = asrBottom
       Left = 8
-      Height = 80
+      Height = 64
-      Top = 432
+      Top = 502
       Width = 260
       Anchors = [akTop, akLeft, akRight]
       AutoSize = False
@@ -498,7 +498,7 @@ object MainForm: TMainForm
       AnchorSideTop.Control = BtnGPSPoints
       Left = 108
       Height = 25
-      Top = 347
+      Top = 417
       Width = 110
       AutoSize = True
       BorderSpacing.Left = 8
@@ -506,10 +506,110 @@ object MainForm: TMainForm
       OnClick = BtnSaveToFileClick
       TabOrder = 11
     end
+    object GbScreenSize: TGroupBox
+      AnchorSideLeft.Control = GbCenterCoords
+      AnchorSideTop.Control = GbCenterCoords
+      AnchorSideTop.Side = asrBottom
+      AnchorSideRight.Control = GbCenterCoords
+      AnchorSideRight.Side = asrBottom
+      Left = 9
+      Height = 66
+      Top = 255
+      Width = 259
+      Anchors = [akTop, akLeft, akRight]
+      AutoSize = True
+      BorderSpacing.Top = 8
+      Caption = 'Viewport size'
+      ClientHeight = 46
+      ClientWidth = 255
+      TabOrder = 12
+      object LblViewportWidth: TLabel
+        AnchorSideLeft.Control = GbScreenSize
+        AnchorSideTop.Control = GbScreenSize
+        Left = 16
+        Height = 15
+        Top = 4
+        Width = 32
+        BorderSpacing.Left = 16
+        BorderSpacing.Top = 4
+        Caption = 'Width'
+        ParentColor = False
+      end
+      object LblViewportHeight: TLabel
+        AnchorSideLeft.Control = GbScreenSize
+        AnchorSideTop.Control = LblViewportWidth
+        AnchorSideTop.Side = asrBottom
+        Left = 16
+        Height = 15
+        Top = 23
+        Width = 36
+        BorderSpacing.Left = 16
+        BorderSpacing.Top = 4
+        BorderSpacing.Bottom = 8
+        Caption = 'Height'
+        ParentColor = False
+      end
+      object InfoViewportWidth: TLabel
+        AnchorSideTop.Control = GbScreenSize
+        AnchorSideRight.Control = GbScreenSize
+        AnchorSideRight.Side = asrBottom
+        Left = 205
+        Height = 15
+        Top = 4
+        Width = 34
+        Alignment = taRightJustify
+        Anchors = [akTop, akRight]
+        BorderSpacing.Top = 4
+        BorderSpacing.Right = 16
+        Caption = 'Label2'
+        ParentColor = False
+      end
+      object InfoViewportHeight: TLabel
+        AnchorSideTop.Control = InfoViewportWidth
+        AnchorSideTop.Side = asrBottom
+        AnchorSideRight.Control = GbScreenSize
+        AnchorSideRight.Side = asrBottom
+        Left = 205
+        Height = 15
+        Top = 23
+        Width = 34
+        Alignment = taRightJustify
+        Anchors = [akTop, akRight]
+        BorderSpacing.Top = 4
+        BorderSpacing.Right = 16
+        BorderSpacing.Bottom = 8
+        Caption = 'Label2'
+        ParentColor = False
+      end
+    end
+    object CbDistanceUnits: TComboBox
+      AnchorSideTop.Control = GbCenterCoords
+      AnchorSideTop.Side = asrBottom
+      AnchorSideRight.Control = GbCenterCoords
+      AnchorSideRight.Side = asrBottom
+      Left = 176
+      Height = 23
+      Top = 253
+      Width = 76
+      Anchors = [akTop, akLeft, akRight]
+      BorderSpacing.Top = 6
+      BorderSpacing.Right = 16
+      ItemHeight = 15
+      ItemIndex = 1
+      Items.Strings = (
+        'm'
+        'km'
+        'miles'
+      )
+      OnChange = CbDistanceUnitsChange
+      Style = csDropDownList
+      TabOrder = 13
+      Text = 'km'
+    end
   end
   object MapView: TMapView
     Left = 0
-    Height = 545
+    Height = 581
     Hint = 'Displays the map'
     Top = 0
     Width = 592
@@ -523,6 +623,7 @@ object MainForm: TMainForm
     UseThreads = True
     Zoom = 0
     OnZoomChange = MapViewZoomChange
+    OnChange = MapViewChange
     OnDrawGpsPoint = MapViewDrawGpsPoint
     OnMouseMove = MapViewMouseMove
     OnMouseUp = MapViewMouseUp

components/lazmapviewer/example/main.pas

@@ -24,13 +24,19 @@ type
     CbProviders: TComboBox;
     CbUseThreads: TCheckBox;
     CbMouseCoords: TGroupBox;
+    CbDistanceUnits: TComboBox;
     GbCenterCoords: TGroupBox;
+    GbScreenSize: TGroupBox;
     InfoCenterLatitude: TLabel;
+    InfoViewportHeight: TLabel;
     InfoCenterLongitude: TLabel;
     InfoBtnGPSPoints: TLabel;
     GPSPointInfo: TLabel;
+    InfoViewportWidth: TLabel;
     Label8: TLabel;
     LblCenterLatitude: TLabel;
+    LblViewportHeight: TLabel;
+    LblViewportWidth: TLabel;
     LblPositionLongitude: TLabel;
     LblPositionLatitude: TLabel;
     InfoPositionLongitude: TLabel;
@@ -53,11 +59,13 @@ type
       ARect: TRect; State: TOwnerDrawState);
     procedure CbProvidersChange(Sender: TObject);
     procedure CbUseThreadsChange(Sender: TObject);
+    procedure CbDistanceUnitsChange(Sender: TObject);
     procedure FormCreate(Sender: TObject);
     procedure FormDestroy(Sender: TObject);
     procedure FormShow(Sender: TObject);
     procedure GeoNamesNameFound(const AName: string; const ADescr: String;
       const ALoc: TRealPoint);
+    procedure MapViewChange(Sender: TObject);
     procedure MapViewDrawGpsPoint(Sender, ACanvas: TObject; APoint: TGpsPoint);
     procedure MapViewMouseMove(Sender: TObject; Shift: TShiftState; X,
       Y: Integer);
@@ -72,6 +80,7 @@ type
     procedure ClearFoundLocations;
     procedure UpdateDropdownWidth(ACombobox: TCombobox);
     procedure UpdateLocationHistory(ALocation: String);
+    procedure UpdateViewportSize;
 
   public
     procedure ReadFromIni;
@@ -88,7 +97,7 @@ implementation
 
 uses
   LCLType, IniFiles, Math, FPCanvas, FPImage, IntfGraphics,
-  mvExtraData,
+  mvEngine, mvExtraData,
   gpslistform;
 
 type
@@ -227,6 +236,11 @@ begin
   MapView.UseThreads := CbUseThreads.Checked;
 end;
 
+procedure TMainForm.CbDistanceUnitsChange(Sender: TObject);
+begin
+  UpdateViewPortSize;
+end;
+
 procedure TMainForm.ClearFoundLocations;
 var
   i: Integer;
@@ -276,6 +290,11 @@ begin
   CbFoundLocations.Items.AddObject(AName, P);
 end;
 
+procedure TMainForm.MapViewChange(Sender: TObject);
+begin
+  UpdateViewportSize;
+end;
+
 procedure TMainForm.MapViewDrawGpsPoint(Sender, ACanvas: TObject;
   APoint: TGpsPoint);
 const
@@ -332,12 +351,20 @@ var
   i: Integer;
 begin
   rPt := MapView.Center;
+  InfoCenterLongitude.Caption := Format('%.6f° = %s', [rPt.Lon, GPSToDMS(rPt.Lon)]);
+  InfoCenterLatitude.Caption := Format('%.6f° = %s', [rPt.Lat, GPSToDMS(rPt.Lat)]);
+  {
   InfoCenterLongitude.Caption := Format('%.6f°', [rPt.Lon]);
   InfoCenterLatitude.Caption := Format('%.6f°', [rPt.Lat]);
+  }
 
   rPt := MapView.ScreenToLonLat(Point(X, Y));
+  InfoPositionLongitude.Caption := Format('%.6f° = %s', [rPt.Lon, GPSToDMS(rPt.Lon)]);
+  InfoPositionLatitude.Caption := Format('%.6f° = %s', [rPt.Lat, GPSToDMS(rPt.Lat)]);
+  {
   InfoPositionLongitude.Caption := Format('%.6f°', [rPt.Lon]);
   InfoPositionLatitude.Caption  := Format('%.6f°', [rPt.Lat]);
+  }
 
   rArea.TopLeft := MapView.ScreenToLonLat(Point(X-DELTA, Y-DELTA));
   rArea.BottomRight := MapView.ScreenToLonLat(Point(X+DELTA, Y+DELTA));
@@ -349,7 +376,11 @@ begin
         for i:=0 to gpsList.Count-1 do
           if gpsList[i] is TGpsPoint then
             with TGpsPoint(gpsList[i]) do
-              L.Add(Format('%s' + Lineending + '  (lat=%.6f°, lon=%.6f°)', [Name, Lat, Lon]));
+              L.Add(Format('%s' + Lineending + '  (lat=%.6f°=%s, lon=%.6f°=%s°)', [
+                Name, Lat, GPSToDMS(Lat), Lon, GPSToDMS(Lon)
+              ]));
+              //L.Add(Format('%s' + Lineending + '  (lat=%.6f°, lon=%.6f°)', [Name, Lat, Lon]));
+
         GPSPointInfo.Caption := L.Text;
       finally
         L.Free;
@@ -470,6 +501,30 @@ begin
   CbLocations.Text := ALocation;
 end;
 
+procedure TMainForm.UpdateViewportSize;
+begin
+  InfoViewportWidth.Caption := Format('%.2n %s', [
+    CalcGeoDistance(
+      MapView.GetVisibleArea.TopLeft.Lat,
+      MapView.GetVisibleArea.TopLeft.Lon,
+      MapView.GetVisibleArea.TopLeft.Lat,
+      MapView.GetVisibleArea.BottomRight.Lon,
+      TDistanceUnits(cbDistanceUnits.ItemIndex)
+    ),
+    cbDistanceUnits.Items[cbDistanceUnits.ItemIndex]
+  ]);
+  InfoViewportHeight.Caption := Format('%.2n %s', [
+    CalcGeoDistance(
+      MapView.GetVisibleArea.TopLeft.Lat,
+      MapView.GetVisibleArea.TopLeft.Lon,
+      MapView.GetVisibleArea.BottomRight.Lat,
+      MapView.GetVisibleArea.TopLeft.Lon,
+      TDistanceUnits(cbDistanceUnits.ItemIndex)
+    ),
+    cbDistanceUnits.Items[cbDistanceUnits.ItemIndex]
+  ]);
+end;
+
 procedure TMainForm.WriteToIni;
 var
   ini: TCustomIniFile;

components/lazmapviewer/source/mvengine.pas

@@ -44,6 +44,8 @@ Type
 
   TTileIdArray = Array of TTileId;
 
+  TDistanceUnits = (duMeters, duKilometers, duMiles);
+
   { TMapWindow }
 
   TMapWindow = Record
@@ -161,6 +163,13 @@ Type
       property OnZoomChange: TNotifyEvent read FOnZoomChange write FOnZoomChange;
   end;
 
+function CalcGeoDistance(Lat1, Lon1, Lat2, Lon2: double;
+  AUnits: TDistanceUnits = duKilometers): double;
+
+function GPSToDMS(Angle: Double): string;
+
+procedure SplitGps(AValue: Double; out ADegs, AMins, ASecs: Double);
+
 
 implementation
 
@@ -1090,5 +1099,65 @@ begin
 end;
 
 
+//------------------------------------------------------------------------------
+
+procedure SplitGps(AValue: Double; out ADegs, AMins: Double);
+begin
+  AValue := abs(AValue);
+  AMins := frac(AValue) * 60;
+  ADegs := trunc(AValue);
+end;
+
+procedure SplitGps(AValue: Double; out ADegs, AMins, ASecs: Double);
+begin
+  SplitGps(AValue, ADegs, AMins);
+  ASecs := frac(AMins) * 60;
+  AMins := trunc(AMins);
+end;
+
+function GPSToDMS(Angle: Double): string;
+var
+  deg, min, sec: Double;
+begin
+  SplitGPS(Angle, deg, min, sec);
+  Result := Format('%.0f° %.0f'' %.1f"', [deg, min, sec]);
+end;
+
+{ Returns the direct distance (air-line) between two geo coordinates
+ If latitude NOT between -90°..+90° and longitude NOT between -180°..+180°
+ the function returns -1.
+ Usage: FindDistance(51.53323, -2.90130, 51.29442, -2.27275, duKilometers);
+}
+function CalcGeoDistance(Lat1, Lon1, Lat2, Lon2: double;
+  AUnits: TDistanceUnits = duKilometers): double;
+const
+  raduis_km: double = 6371.0; // generalized radius of earth
+var
+  d_radians: double; // distance in radians
+  lat1r, lon1r, lat2r, lon2r: double;
+begin
+  // Validate
+  if (Lat1 < -90.0) or (Lat1 > 90.0) then exit(-1);
+  if (Lon1 < -180.0) or (Lon1 > 180.0) then exit(-1);
+  if (Lat2 < -90.0) or (Lat2 > 90.0) then exit(-1);
+  if (Lon2 < -180.0) or (Lon2 > 180.0) then exit(-1);
+
+  // Turn lat and lon into radian measures
+  lat1r := (PI / 180.0) * Lat1;
+  lon1r := (PI / 180.0) * Lon1;
+  lat2r := (PI / 180.0) * Lat2;
+  lon2r := (PI / 180.0) * Lon2;
+
+  // calc
+  d_radians := arccos(Sin(lat1r) * sin(lat2r) + cos(lat1r) * cos(lat2r) * cos(lon1r - lon2r));
+  Result := EARTH_RADIUS * d_radians;
+
+  case AUnits of
+    duMeters: ;
+    duKilometers: Result := Result * 1E-3;
+    duMiles: Result := Result * 0.62137E-3;
+  end;
+end;
+
 end.