LazMapViewer: Add distance measurement between user-provided points (https://forum.lazarus.freepascal.org/index.php/topic,12674.msg319269.html, patch by sstvmaster).

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@6879 8e941d3f-bd1b-0410-a28a-d453659cc2b4

components/lazmapviewer/example/MapViewer_Demo.lpi

@@ -34,7 +34,7 @@
         <PackageName Value="LCL"/>
       </Item2>
     </RequiredPackages>
-    <Units Count="3">
+    <Units Count="4">
       <Unit0>
         <Filename Value="MapViewer_Demo.lpr"/>
         <IsPartOfProject Value="True"/>
@@ -54,6 +54,10 @@
         <HasResources Value="True"/>
         <ResourceBaseClass Value="Form"/>
       </Unit2>
+      <Unit3>
+        <Filename Value="globals.pas"/>
+        <IsPartOfProject Value="True"/>
+      </Unit3>
     </Units>
   </ProjectOptions>
   <CompilerOptions>

components/lazmapviewer/example/MapViewer_Demo.lpr

@@ -5,7 +5,7 @@ program MapViewer_Demo;
 uses
   {$IFDEF UNIX}cthreads,{$ENDIF}
   Interfaces, // this includes the LCL widgetset
-  Forms, Main, gpslistform
+  Forms, Main, gpslistform, globals
   { you can add units after this };
 
 {$R *.res}

components/lazmapviewer/example/globals.pas

@@ -0,0 +1,19 @@
+unit globals;
+
+{$mode objfpc}{$H+}
+
+interface
+
+uses
+  Classes, SysUtils, mvEngine;
+
+const
+  DistanceUnit_Names: array[TDistanceUnits] of string = ('m', 'km', 'miles');
+
+var
+  DistanceUnit: TDistanceUnits = duKilometers;
+
+implementation
+
+end.
+

components/lazmapviewer/example/gpslistform.lfm

@@ -2,20 +2,21 @@ object GPSListViewer: TGPSListViewer
   Left = 282
   Height = 352
   Top = 135
-  Width = 483
+  Width = 557
   Caption = 'GPS points'
   ClientHeight = 352
-  ClientWidth = 483
+  ClientWidth = 557
   LCLVersion = '2.1.0.0'
   object ListView: TListView
     Left = 6
     Height = 308
     Top = 6
-    Width = 471
+    Width = 545
     Align = alClient
     BorderSpacing.Left = 6
     BorderSpacing.Top = 6
     BorderSpacing.Right = 6
+    Checkboxes = True
     Columns = <    
       item
         Caption = 'ID'
@@ -41,12 +42,12 @@ object GPSListViewer: TGPSListViewer
     Left = 0
     Height = 38
     Top = 314
-    Width = 483
+    Width = 557
     Align = alBottom
     AutoSize = True
     BevelOuter = bvNone
     ClientHeight = 38
-    ClientWidth = 483
+    ClientWidth = 557
     TabOrder = 1
     object BtnDeletePoint: TBitBtn
       AnchorSideLeft.Control = BtnGoToPoint
@@ -151,7 +152,7 @@ object GPSListViewer: TGPSListViewer
       AnchorSideTop.Control = Panel1
       AnchorSideRight.Control = Panel1
       AnchorSideRight.Side = asrBottom
-      Left = 402
+      Left = 476
       Height = 26
       Top = 6
       Width = 75
@@ -198,5 +199,19 @@ object GPSListViewer: TGPSListViewer
       OnClick = BtnCloseClick
       TabOrder = 2
     end
+    object BtnCalcDistance: TButton
+      AnchorSideLeft.Control = BtnDeletePoint
+      AnchorSideLeft.Side = asrBottom
+      AnchorSideTop.Control = Panel1
+      Left = 234
+      Height = 25
+      Top = 6
+      Width = 203
+      AutoSize = True
+      BorderSpacing.Around = 6
+      Caption = 'Calc distance between two points'
+      OnClick = BtnCalcDistanceClick
+      TabOrder = 3
+    end
   end
 end

components/lazmapviewer/example/gpslistform.pas

@@ -6,7 +6,7 @@ interface
 
 uses
   Classes, SysUtils, Forms, Controls, Graphics, Dialogs, ButtonPanel, ComCtrls,
-  ExtCtrls, Buttons, mvGpsObj, mvMapViewer;
+  ExtCtrls, Buttons, StdCtrls, mvGpsObj, mvMapViewer;
 
 const
   // IDs of GPS items
@@ -20,8 +20,10 @@ type
     BtnDeletePoint: TBitBtn;
     BtnGoToPoint: TBitBtn;
     BtnClose: TBitBtn;
+    BtnCalcDistance: TButton;
     ListView: TListView;
     Panel1: TPanel;
+    procedure BtnCalcDistanceClick(Sender: TObject);
     procedure BtnCloseClick(Sender: TObject);
     procedure BtnDeletePointClick(Sender: TObject);
     procedure BtnGoToPointClick(Sender: TObject);
@@ -46,7 +48,8 @@ implementation
 {$R *.lfm}
 
 uses
-  mvTypes, mvEngine;
+  mvTypes, mvEngine,
+  globals;
 
 destructor TGPSListViewer.Destroy;
 begin
@@ -92,6 +95,57 @@ begin
   Close;
 end;
 
+procedure TGPSListViewer.BtnCalcDistanceClick(Sender: TObject);
+type
+  TCoorRec = record
+    Lon: Double;
+    Lat: Double;
+    Name: String;
+  end;
+var
+  i, iChecked: Integer;
+  gpsObj: TGpsObj;
+  gpsPt: TGpsPoint;
+  TCoorArr: array[0..1] of TCoorRec;
+begin
+  // count checked items
+  iChecked := 0;
+  for i:=0 to ListView.Items.Count - 1 do begin
+    if ListView.Items.Item[i].Checked then Inc(iChecked);
+  end;
+  //
+  if iChecked <> 2 then begin
+    ShowMessage('Please select 2 items to calculate the distance.');
+  end
+  else begin
+    iChecked := 0;
+    for i:=0 to ListView.Items.Count - 1 do begin
+      if ListView.Items.Item[i].Checked then begin
+        gpsObj := FList.Items[i];
+        if gpsObj is TGpsPoint then begin
+          gpsPt := TGpsPoint(gpsObj);
+          TCoorArr[iChecked].Lat := gpsPt.Lat;
+          TCoorArr[iChecked].Lon := gpsPt.Lon;
+          TCoorArr[iChecked].Name:= gpsPt.Name;
+          Inc(iChecked);
+        end;
+      end;
+    end;
+    // show distance between selected items
+    ShowMessage('Distance between ' + TCoorArr[0].Name + ' and ' + TCoorArr[1].Name + ' is: ' +
+    Format('%.2n %s.', [
+      CalcGeoDistance(
+        TCoorArr[0].Lat,
+        TCoorArr[0].Lon,
+        TCoorArr[1].Lat,
+        TCoorArr[1].Lon,
+        DistanceUnit
+      ),
+      DistanceUnit_Names[DistanceUnit]
+      ]));
+  end;
+end;
+
 procedure TGPSListViewer.BtnDeletePointClick(Sender: TObject);
 var
   gpsObj: TGpsObj;

components/lazmapviewer/example/main.pas

@@ -99,7 +99,7 @@ implementation
 uses
   LCLType, IniFiles, Math, FPCanvas, FPImage, IntfGraphics,
   mvEngine, mvExtraData,
-  gpslistform;
+  globals, gpslistform;
 
 type
   TLocationParam = class
@@ -241,6 +241,7 @@ end;
 
 procedure TMainForm.CbDistanceUnitsChange(Sender: TObject);
 begin
+  DistanceUnit := TDistanceUnits(CbDistanceUnits.ItemIndex);
   UpdateViewPortSize;
 end;
 
@@ -414,6 +415,7 @@ var
   i: Integer;
   s: String;
   pt: TRealPoint;
+  du: TDistanceUnits;
 begin
   ini := TMemIniFile.Create(CalcIniName);
   try
@@ -435,6 +437,16 @@ begin
     pt.Lat := StrToFloatDef(ini.ReadString('MapView', 'Center.Latitude', ''), 0.0, PointFormatSettings);
     MapView.Center := pt;
 
+    s := ini.ReadString('MapView', 'DistanceUnits', '');
+    if s <> '' then begin
+      for du in TDistanceUnits do
+        if DistanceUnit_Names[du] = s then begin
+          DistanceUnit := du;
+          CbDistanceUnits.ItemIndex := ord(du);
+          break;
+        end;
+    end;
+
     List := TStringList.Create;
     try
       ini.ReadSection('Locations', List);
@@ -518,9 +530,9 @@ begin
       MapView.GetVisibleArea.TopLeft.Lon,
       MapView.GetVisibleArea.TopLeft.Lat,
       MapView.GetVisibleArea.BottomRight.Lon,
-      TDistanceUnits(cbDistanceUnits.ItemIndex)
+      DistanceUnit
     ),
-    cbDistanceUnits.Items[cbDistanceUnits.ItemIndex]
+    DistanceUnit_Names[DistanceUnit]
   ]);
   InfoViewportHeight.Caption := Format('%.2n %s', [
     CalcGeoDistance(
@@ -528,9 +540,9 @@ begin
       MapView.GetVisibleArea.TopLeft.Lon,
       MapView.GetVisibleArea.BottomRight.Lat,
       MapView.GetVisibleArea.TopLeft.Lon,
-      TDistanceUnits(cbDistanceUnits.ItemIndex)
+      DistanceUnit
     ),
-    cbDistanceUnits.Items[cbDistanceUnits.ItemIndex]
+    DistanceUnit_Names[DistanceUnit]
   ]);
 end;
 
@@ -552,6 +564,8 @@ begin
     ini.WriteString('MapView', 'Center.Longitude', FloatToStr(MapView.Center.Lon, PointFormatSettings));
     ini.WriteString('MapView', 'Center.Latitude', FloatToStr(MapView.Center.Lat, PointFormatSettings));
 
+    ini.WriteString('MapView', 'DistanceUnits', DistanceUnit_Names[DistanceUnit]);
+
     ini.EraseSection('Locations');
     for i := 0 to CbLocations.Items.Count-1 do
       ini.WriteString('Locations', 'Item'+IntToStr(i), CbLocations.Items[i]);