LazMapViewer: Fixes issues with painting/multithreading. Issue #39063, patch by Yuliyan Ivanov.

git-svn-id: https://svn.code.sf.net/p/lazarus-ccr/svn@9092 8e941d3f-bd1b-0410-a28a-d453659cc2b4

components/lazmapviewer/source/mvcache.pas

@@ -60,8 +60,12 @@ Type
 implementation
 
 uses
-  FPimage, GraphType, FPReadJPEG;
+  FPimage, GraphType, FPReadJPEG, DateUtils;
 
+const
+  MEMCACHE_MAX = 64; // Tiles kept in memory
+  MEMCACHE_SWEEP_CNT = 10; // Max tiles to be swept at once
+  DISKCACHE_MAXAGE = 10 * 86400; // 10 days
 
 { TPictureCache }
 
@@ -104,7 +108,7 @@ end;
 constructor TPictureCache.Create(aOwner: TComponent);
 begin
   inherited Create(aOwner);
-  FMemMaxElem := 2048 div 256;
+  FMemMaxElem := MEMCACHE_MAX;
   Cache := TStringList.create;
 end;
 
@@ -200,11 +204,13 @@ end;
 function TPictureCache.DiskCached(const aFileNAme: String): Boolean;
 var
   FullFileName: string;
+  Age: LongInt;
 begin
   if UseDisk then
   begin
     FullFileName := BasePath + aFileName;
-    Result := FileExists(FullFileName);
+    Age := FileAge(fullFileName);
+    Result := Age > (DateTimeToUnix(Now, False) - DISKCACHE_MAXAGE);
   end
   else
     Result := False;
@@ -217,9 +223,9 @@ var
   lStream: TFileStream;
 begin
   img := nil;
-  FullFileName := BasePath + aFileName;
+  if DiskCached(aFileName) then
-  if FileExists(fullFileName) then
   begin
+    FullFileName := BasePath + aFileName;
     lStream := TFileStream.Create(FullFileName, fmOpenRead);
     try
       try
@@ -258,7 +264,7 @@ begin
   try
     if Cache.Count > FMemMaxElem then
     begin
-      for i:=1 to 10 do
+      for i := 1 to MEMCACHE_SWEEP_CNT do
       begin
         idx := pred(Cache.Count);
         if idx > 1 then
@@ -311,9 +317,6 @@ begin
       end;
     end;
   end;
-
-  if not FUseThreads then
-    CheckCacheSize(self);
 end;
 
 procedure TPictureCache.GetFromCache(MapProvider: TMapProvider;

components/lazmapviewer/source/mvengine.pas

@@ -36,6 +36,8 @@ type
   TDrawStretchedTileEvent = procedure (const TileId: TTileId; X,Y: Integer;
     TileImg: TLazIntfImage; const R: TRect) of object;
 
+  TTileDownloadedEvent = procedure (const TileId: TTileId) of object;
+
   TTileIdArray = Array of TTileId;
 
   TDistanceUnits = (duMeters, duKilometers, duMiles);
@@ -71,6 +73,7 @@ type
       FOnChange: TNotifyEvent;
       FOnDrawTile: TDrawTileEvent;
       FOnDrawStretchedTile: TDrawStretchedTileEvent;
+      FOnTileDownloaded: TTileDownloadedEvent;
       FOnZoomChange: TNotifyEvent;
       lstProvider : TStringList;
       Queue : TJobQueue;
@@ -106,7 +109,7 @@ type
       procedure CalculateWin(var AWin: TMapWindow);
       function DegreesToPixelsEPSG3395(const AWin: TMapWindow; ALonLat: TRealPoint): TPoint;
       function DegreesToPixelsEPSG3857(const AWin: TMapWindow; ALonLat: TRealPoint): TPoint;
-      procedure Redraw(const aWin: TMapWindow);
+      procedure Redraw(const aWin: TMapWindow; const paintOnly: Boolean = False);
       function CalculateVisibleTiles(const aWin: TMapWindow) : TArea;
       function IsCurrentWin(const aWin: TMapWindow) : boolean;
     protected
@@ -115,6 +118,7 @@ type
       function GetTileName(const Id: TTileId): String;
       procedure evDownload(Data: TObject; Job: TJob);
       procedure TileDownloaded(Data: PtrInt);
+      procedure DrawTileFromCache(constref ATile: TTileId; constref AWin: TMapWindow);
       procedure DrawStretchedTile(const TileId: TTileID; X, Y: Integer; TileImg: TLazIntfImage; const R: TRect);
       Procedure DrawTile(const TileId: TTileId; X,Y: integer; TileImg: TLazIntfImage);
       Procedure DoDrag(Sender: TDragObj);
@@ -176,6 +180,7 @@ type
       property OnChange: TNotifyEvent Read FOnChange write FOnchange; //called when visiable area change
       property OnDrawStretchedTile: TDrawStretchedTileEvent read FOnDrawStretchedTile write FOnDrawStretchedTile;
       property OnDrawTile: TDrawTileEvent read FOnDrawTile write FOnDrawTile;
+      property OnTileDownloaded: TTileDownloadedEvent read FOnTileDownloaded write FOnTileDownloaded;
       property OnZoomChange: TNotifyEvent read FOnZoomChange write FOnZoomChange;
   end;
 
@@ -233,32 +238,8 @@ begin
     Result := round(IntPower(2, AZoomLevel));
 end;
 
-
 type
 
-  { TLaunchDownloadJob }
-
-  TLaunchDownloadJob = class(TJob)
-  private
-    AllRun: boolean;
-    Win: TMapWindow;
-    Engine: TMapViewerEngine;
-    FRunning: boolean;
-    FTiles: TTileIdArray;
-    FStates: Array of integer;
-  protected
-    function pGetTask: integer; override;
-    procedure pTaskStarted(aTask: integer); override;
-    procedure pTaskEnded(aTask: integer; aExcept: Exception); override;
-  public
-    procedure ExecuteTask(aTask: integer; FromWaiting: boolean); override;
-    function Running: boolean; override;
-  public
-    constructor Create(Eng: TMapViewerEngine; const Tiles: TTileIdArray;
-      const aWin: TMapWindow);
-  end;
-
-
   { TEnvTile }
 
   TEnvTile = Class(TBaseTile)
@@ -285,90 +266,6 @@ type
   end;
 
 
-{ TLaunchDownloadJob }
-
-function TLaunchDownloadJob.pGetTask: integer;
-var
-  i: integer;
-begin
-  if not AllRun and not Cancelled then
-  begin
-    for i:=Low(FStates) to High(FStates) do
-      if FStates[i] = 0 then
-      begin
-        Result := i + 1;
-        Exit;
-      end;
-    AllRun := True;
-  end;
-  Result := ALL_TASK_COMPLETED;
-  for i := Low(FStates) to High(FStates) do
-    if FStates[i] = 1 then
-    begin
-      Result := NO_MORE_TASK;
-      Exit;
-    end;
-end;
-
-procedure TLaunchDownloadJob.pTaskStarted(aTask: integer);
-begin
-  FRunning := True;
-  FStates[aTask-1] := 1;
-end;
-
-procedure TLaunchDownloadJob.pTaskEnded(aTask: integer; aExcept: Exception);
-begin
-  if Assigned(aExcept) then
-    FStates[aTask - 1] := 3
-  Else
-    FStates[aTask - 1] := 2;
-end;
-
-procedure TLaunchDownloadJob.ExecuteTask(aTask: integer; FromWaiting: boolean);
-var
-  iTile: integer;
-  lJob: TEventJob;
-  lTile: TEnvTile;
-begin
-  iTile := aTask - 1;
-  lTile:=TEnvTile.Create(FTiles[iTile], Win);
-  lJob := TEventJob.Create
-    (
-      @Engine.evDownload,
-      lTile,
-      false,                                    // owns data
-      Engine.GetTileName(FTiles[iTile])
-    );
-  if not Queue.AddUniqueJob(lJob  ,
-    Launcher
-  ) then
-     begin
-       FreeAndNil(lJob);
-       FreeAndNil(lTile);
-     end;
-end;
-
-function TLaunchDownloadJob.Running: boolean;
-begin
-  Result := FRunning;
-end;
-
-constructor TLaunchDownloadJob.Create(Eng: TMapViewerEngine;
-  const Tiles: TTileIdArray; const aWin: TMapWindow);
-var
-  i: integer;
-begin
-  Engine := Eng;
-  SetLength(FTiles, Length(Tiles));
-  For i:=Low(FTiles) to High(FTiles) do
-    FTiles[i] := Tiles[i];
-  SetLength(FStates, Length(Tiles));
-  AllRun := false;
-  Name := 'LaunchDownload';
-  Win := aWin;
-end;
-
-
 { TEnvTile }
 
 constructor TEnvTile.Create(const aTile: TTileId; const aWin: TMapWindow);
@@ -392,7 +289,6 @@ begin
   FBkColor := colWhite;
   RegisterProviders;
   Queue := TJobQueue.Create(8);
-  Queue.OnIdle := @Cache.CheckCacheSize;
 
   inherited Create(aOwner);
 
@@ -531,8 +427,8 @@ begin
     MoveMapCenter(Sender);
 end;
 
-procedure TMapViewerEngine.DrawStretchedTile(const TileID: TTileID; X, Y: Integer;
+procedure TMapViewerEngine.DrawStretchedTile(const TileId: TTileID; X,
-  TileImg: TLazIntfImage; const R: TRect);
+  Y: Integer; TileImg: TLazIntfImage; const R: TRect);
 begin
   if Assigned(FOnDrawStretchedTile) then
     FOnDrawStretchedTile(TileId, X, Y, TileImg, R);
@@ -652,7 +548,7 @@ begin
 end;
 
 function TMapViewerEngine.IsValidTile(const aWin: TMapWindow;
-  const aTile: TTileId): boolean;
+  const aTile: TTIleId): boolean;
 var
   tiles: int64;
 begin
@@ -806,7 +702,8 @@ begin
   Result.Lon := Math.EnsureRange(Result.Lon, MIN_LONGITUDE, MAX_LONGITUDE);
 end;
 
-Function TMapViewerEngine.PixelsToDegreesEPSG3395(APoint: TPoint; Zoom: Integer): TRealPoint;
+function TMapViewerEngine.PixelsToDegreesEPSG3395(APoint: TPoint; Zoom: Integer
+  ): TRealPoint;
 
   function PhiIteration(y, phi: Extended): Extended;
   var
@@ -1048,18 +945,33 @@ begin
   Redraw(MapWin);
 end;
 
-procedure TMapViewerEngine.Redraw(const AWin: TMapWindow);
+procedure TMapViewerEngine.Redraw(const aWin: TMapWindow;
+  const paintOnly: Boolean);
 var
   TilesVis: TArea;
-  x, y : Integer; //int64;
+  x, y, px, py: Integer;
+  iTile, numTiles: Integer;
   Tiles: TTileIdArray = nil;
-  iTile: Integer;
   tile: TTileID;
-  numTiles: Integer;
-  px, py: Integer;
   previewDrawn: Boolean;
   previewImg: TLazIntfImage;
   R: TRect;
+
+  procedure AddJob;
+  var
+    lTile: TEnvTile;
+    lJob: TEventJob;
+  begin
+    lTile:=TEnvTile.Create(Tiles[iTile], aWin);
+    lJob := TEventJob.Create(@evDownload, lTile, False,                                    // owns data
+      GetTileName(Tiles[iTile]));
+    if not Queue.AddUniqueJob(lJob, Self) then
+    begin
+      FreeAndNil(lJob);
+      FreeAndNil(lTile);
+    end;
+  end;
+
 begin
   if not(Active) then
     Exit;
@@ -1082,9 +994,11 @@ begin
       Tiles[iTile].Y := Y;
       Tiles[iTile].Z := AWin.Zoom;
 
+      if Cache.InCache(AWin.MapProvider, Tiles[iTile]) then
+        DrawTileFromCache(Tiles[iTile], AWin)
+      else
       // Avoid tiling artefacts when a tile does not exist (lowest zoom) or
       // is not valid
-      if not Cache.InCache(AWin.MapProvider, Tiles[iTile]) then
       begin
         previewdrawn := False;
         py := AWin.Y + Y * TILE_SIZE;
@@ -1104,14 +1018,17 @@ begin
         end;
         if not previewDrawn then
           DrawTile(Tiles[iTile], px, py, nil);  // Draw blank tile if preview cannot be generated
-      end;
 
         if IsValidTile(AWin, Tiles[iTile]) then
+        begin
+          AddJob;
           inc(iTile);
         end;
+      end;
+    end;
   SetLength(Tiles, iTile);
-  if Length(Tiles) > 0 then
+  if Length(Tiles) < 1 then
-    Queue.AddJob(TLaunchDownloadJob.Create(self, Tiles, AWin), self);
+    Cache.CheckCacheSize(Nil);
 end;
 
 procedure TMapViewerEngine.RegisterProviders;
@@ -1270,48 +1187,57 @@ end;
 procedure TMapViewerEngine.TileDownloaded(Data: PtrInt);
 var
   EnvTile: TEnvTile;
+begin
+  EnvTile := TEnvTile(Data);
+  try
+    if Assigned(FOnTileDownloaded) then
+      FOnTileDownloaded(EnvTile.Tile);
+  finally
+    FreeAndNil(EnvTile);
+  end;
+end;
+
+procedure TMapViewerEngine.DrawTileFromCache(constref ATile: TTileId; constref
+  AWin: TMapWindow);
+var
   img: TLazIntfImage;
   X, Y: integer;
   worldWidth : Integer;
   numTiles : Integer;
   baseX : Integer;
 begin
-  EnvTile := TEnvTile(Data);
+  if IsCurrentWin(AWin)then
-  try
-    if IsCurrentWin(EnvTile.Win)then
   begin
-       Cache.GetFromCache(EnvTile.Win.MapProvider, EnvTile.Tile, img);
+     Cache.GetFromCache(AWin.MapProvider, ATile, img);
-       Y := EnvTile.Win.Y + EnvTile.Tile.Y * TILE_SIZE; // begin of Y
+     Y := AWin.Y + ATile.Y * TILE_SIZE; // begin of Y
      if Cyclic then
      begin
-         baseX := EnvTile.Win.X + EnvTile.Tile.X * TILE_SIZE; // begin of X
+       baseX := AWin.X + ATile.X * TILE_SIZE; // begin of X
-         numTiles := 1 shl EnvTile.Win.Zoom;
+       numTiles := 1 shl AWin.Zoom;
        worldWidth := numTiles * TILE_SIZE;
        // From the center to the left (western) hemisphere
        X := baseX;
        while (X+TILE_SIZE >= 0) do
        begin
-           DrawTile(EnvTile.Tile, X, Y, img);
+         DrawTile(ATile, X, Y, img);
          X := X - worldWidth;
        end;
        // From the center to the right (eastern) hemisphere
        X := baseX + worldWidth;
-         while ((X-TILE_SIZE) <= EnvTile.Win.Width) do
+       while ((X-TILE_SIZE) <= AWin.Width) do
        begin
-           DrawTile(EnvTile.Tile, X, Y, img);
+         DrawTile(ATile, X, Y, img);
          X := X + worldWidth;
        end;
      end else
      begin
-         X := EnvTile.Win.X + EnvTile.Tile.X * TILE_SIZE; // begin of X
+       X := AWin.X + ATile.X * TILE_SIZE; // begin of X
-         DrawTile(EnvTile.Tile, X, Y, img);
+       DrawTile(ATile, X, Y, img);
      end;
   end;
-  finally
-    FreeAndNil(EnvTile);
-  end;
 end;
 
+
 function TMapViewerEngine.WorldScreenToLonLat(aPt: TPoint): TRealPoint;
 begin
   aPt.X := aPt.X - MapWin.X;

components/lazmapviewer/source/mvgpsobj.pas

@@ -30,21 +30,20 @@ type
   TGPSObj = class
   private
     BBoxSet: Boolean;
-    FBoundingBox: TRealArea;
     FExtraData: TObject;
     FName: String;
     FIdOwner: integer;
     function GetBoundingBox: TRealArea;
-    procedure SetBoundingBox(AValue: TRealArea);
     procedure SetExtraData(AValue: TObject);
   public
     destructor Destroy; override;
     procedure Assign(AObj: TGPSObj); virtual;
     procedure GetArea(out Area: TRealArea); virtual; abstract;
+    procedure Draw(AView: TObject; Area: TRealArea); virtual; abstract;
     property Name: String read FName write FName;
     property ExtraData: TObject read FExtraData write SetExtraData;
     property IdOwner: Integer read FIdOwner;
-    property BoundingBox: TRealArea read GetBoundingBox write SetBoundingBox;
+    property BoundingBox: TRealArea read GetBoundingBox;
   end;
 
   TGPSObjarray = Array of TGPSObj;
@@ -66,6 +65,7 @@ type
 
     procedure Assign(AObj: TGPSObj); override;
     procedure GetArea(out Area: TRealArea);override;
+    procedure Draw({%H-}AView: TObject; {%H-}Area: TRealArea); override;
     function HasElevation: boolean;
     function HasDateTime: Boolean;
     function DistanceInKmFrom(OtherPt: TGPSPoint; UseElevation: boolean=true): double;
@@ -89,6 +89,7 @@ type
   public
     constructor Create(ALon, ALat: Double; AElevation: Double = NO_ELE;
       ADateTime: TDateTime = NO_DATE);
+    procedure Draw({%H-}AView: TObject; {%H-}Area: TRealArea); override;
     property ImageIndex: Integer read FImageIndex write FImageIndex default -1;
   end;
   { TGPSTrack }
@@ -106,6 +107,7 @@ type
     destructor Destroy; override;
 
     procedure GetArea(out Area: TRealArea); override;
+    procedure Draw({%H-}AView: TObject; {%H-}Area: TRealArea); override;
     function TrackLengthInKm(UseEle: Boolean=true): double;
 
     property Points: TGPSPointList read FPoints;
@@ -155,6 +157,7 @@ type
     procedure ClearExcept(OwnedBy: integer; const ExceptLst: TIdArray;
       out Notfound: TIdArray);
     procedure GetArea(out Area: TRealArea); override;
+    procedure Draw({%H-}AView: TObject; {%H-}Area: TRealArea); override;
     function GetObjectsInArea(const Area: TRealArea): TGPSObjList;
     function GetIdsArea(const Ids: TIdArray; AIdOwner: integer): TRealArea;
 
@@ -184,7 +187,7 @@ function GetAreaOf(objs: TGPSObjList): TRealArea;
 implementation
 
 uses
-  mvExtraData;
+  mvExtraData, mvMapViewer;
 
 function hasIntersectArea(const Area1: TRealArea; const Area2: TRealArea): boolean;
 begin
@@ -249,19 +252,11 @@ begin
 end;
 
 function TGPSObj.GetBoundingBox: TRealArea;
+var
+  A: TRealArea;
 begin
-  if not(BBoxSet) then
+  GetArea(A);
-  begin
+  Result := A;
-    GetArea(FBoundingBox);
-    BBoxSet := true;
-  end;
-  Result := FBoundingBox;
-end;
-
-procedure TGPSObj.SetBoundingBox(AValue: TRealArea);
-begin
-  FBoundingBox := AValue;
-  BBoxSet := true;
 end;
 
 destructor TGPSObj.Destroy;
@@ -408,6 +403,11 @@ begin
   end;
 end;
 
+procedure TGPSObjectList.Draw(AView: TObject; Area: TRealArea);
+begin
+  //;
+end;
+
 function TGPSObjectList.GetObjectsInArea(const Area: TRealArea): TGPSObjList;
 var
   i: integer;
@@ -628,7 +628,7 @@ begin
   end;
 end;
 
-function TGPSObjectList.FindTrackByID(const ID: Integer): TGpsTrack;
+function TGPSObjectList.FindTrackByID(const id: Integer): TGpsTrack;
 var
   i: Integer;
 begin
@@ -686,6 +686,11 @@ begin
   end;
 end;
 
+procedure TGPSTrack.Draw(AView: TObject; Area: TRealArea);
+begin
+  TMapView(AView).DrawTrack(Area, Self);
+end;
+
 function TGPSTrack.TrackLengthInKm(UseEle: Boolean): double;
 var
   i: integer;
@@ -698,7 +703,7 @@ end;
 
 { TGPSPoint }
 
-procedure TGPSPoint.Assign(AObj: TGpsObj);
+procedure TGPSPoint.Assign(AObj: TGPSObj);
 begin
   if (AObj is TGPSPoint) then
   begin
@@ -725,6 +730,11 @@ begin
   Area.BottomRight := FRealPt;
 end;
 
+procedure TGPSPoint.Draw(AView: TObject; Area: TRealArea);
+begin
+  TMapView(AView).DrawPt(Area, Self);
+end;
+
 function TGPSPoint.HasElevation: boolean;
 begin
   Result := FElevation <> NO_ELE;
@@ -796,6 +806,11 @@ begin
   FImageIndex := -1;
 end;
 
+procedure TGPSPointOfInterest.Draw(AView: TObject; Area: TRealArea);
+begin
+  TMapView(AView).DrawPointOfInterest(Area, Self);
+end;
+
 
 end.
 

components/lazmapviewer/source/mvjobqueue.pas

@@ -107,8 +107,8 @@ type
 implementation
 
 const
-  WAIT_TIME = 3000;
+  WAIT_TIME = 300;
-  TERMINATE_TIMEOUT = 1000;
+  TERMINATE_TIMEOUT = WAIT_TIME * 2;
 
 type
 
@@ -297,7 +297,6 @@ begin
         end
         else
         begin
-          MyQueue.FEvent.ResetEvent;
           if not(RestartTask) then
             MyQueue.pTaskStarted(aJob, TaskId);
         end;
@@ -366,7 +365,7 @@ var
 begin
   Jobs := TObjectList.Create(true);
   Threads := TObjectList.Create(true);
-  FEvent := TEvent.Create(nil,true,false,'');
+  FEvent := TEvent.Create(Nil, False, False,'');
   FSect := TCriticalSection.Create;
   TerminatedThread := 0;
   for i:=1 to FNbThread do
@@ -383,9 +382,11 @@ begin
     try
       FEvent.SetEvent;
       TerminatedThread := 0;
-      for i:=0 to pred(Threads.Count) do
+      for i := 0 to Pred(Threads.Count) do
         TQueueThread(Threads[i]).Terminate;
       TerminateEvent.WaitFor(TERMINATE_TIMEOUT);
+      for i := 0 to Pred(Threads.Count) do
+        TQueueThread(Threads[i]).WaitFor;
       FreeAndNil(FSect);
       FreeAndNil(FEvent);
       FreeAndNil(Threads);

components/lazmapviewer/source/mvmapviewer.pas

@@ -23,7 +23,7 @@ interface
 
 uses
   Classes, SysUtils, Controls, Graphics, FPImage, IntfGraphics, Forms, ImgList, LCLVersion,
-  MvTypes, MvGPSObj, MvEngine, MvMapProvider, MvDownloadEngine, MvDrawingEngine;
+  MvTypes, MvGPSObj, MvEngine, MvMapProvider, MvDownloadEngine, MvDrawingEngine, mvCache;
 
 Type
 
@@ -54,9 +54,7 @@ Type
       procedure CallAsyncInvalidate;
       procedure DoAsyncInvalidate({%H-}Data: PtrInt);
       procedure DrawObjects(const {%H-}TileId: TTileId; aLeft, aTop, aRight,aBottom: integer);
-      procedure DrawPointOfInterest(const {%H-}Area: TRealArea; APt: TGPSPointOfInterest);
+      procedure DrawGpsObj(const {%H-}Area: TRealArea; AObj: TGPSObj);
-      procedure DrawPt(const {%H-}Area: TRealArea; APt: TGPSPoint);
-      procedure DrawTrack(const Area: TRealArea; trk: TGPSTrack);
       function GetCacheOnDisk: boolean;
       function GetCachePath: String;
       function GetCenter: TRealPoint;
@@ -108,6 +106,7 @@ Type
       procedure DoDrawStretchedTile(const TileId: TTileID; X, Y: Integer; TileImg: TLazIntfImage; const R: TRect);
       procedure DoDrawTile(const TileId: TTileId; X,Y: integer; TileImg: TLazIntfImage);
       procedure DoDrawTileInfo(const {%H-}TileID: TTileID; X,Y: Integer);
+      procedure DoTileDownloaded(const TileId: TTileId);
       function DoMouseWheel(Shift: TShiftState; WheelDelta: Integer;
         MousePos: TPoint): Boolean; override;
       procedure DoOnResize; override;
@@ -124,6 +123,9 @@ Type
     public
       constructor Create(AOwner: TComponent); override;
       destructor Destroy; override;
+      procedure DrawPointOfInterest(const {%H-}Area: TRealArea; APt: TGPSPointOfInterest);
+      procedure DrawPt(const {%H-}Area: TRealArea; APt: TGPSPoint);
+      procedure DrawTrack(const Area: TRealArea; trk: TGPSTrack);
       procedure ClearBuffer;
       procedure GetMapProviders(lstProviders: TStrings);
       function GetVisibleArea: TRealArea;
@@ -266,13 +268,7 @@ var
 begin
   iObj := aTask-1;
   Obj := FLst[iObj];
-  if Obj.InheritsFrom(TGPSTrack) then
+  Viewer.DrawGpsObj(FArea, Obj);
-    Viewer.DrawTrack(FArea, TGPSTrack(Obj));
-  if Obj.InheritsFrom(TGPSPointOfInterest) then
-    Viewer.DrawPointOfInterest(FArea, TGPSPointOfInterest(Obj))
-  else
-  if Obj.InheritsFrom(TGPSPoint) then
-    Viewer.DrawPt(FArea, TGPSPoint(Obj));
 end;
 
 function TDrawObjJob.Running: boolean;
@@ -295,8 +291,6 @@ destructor TDrawObjJob.Destroy;
 begin
   inherited Destroy;
   FreeAndNil(FLst);
-  if not(Cancelled) then
-    Viewer.CallAsyncInvalidate;
 end;
 
 
@@ -557,6 +551,7 @@ begin
   Result:=inherited DoMouseWheel(Shift, WheelDelta, MousePos);
   if IsActive then
     Engine.MouseWheel(self,Shift,WheelDelta,MousePos,Result);
+  Invalidate;
 end;
 
 procedure TMapView.MouseDown(Button: TMouseButton; Shift: TShiftState;
@@ -565,6 +560,7 @@ begin
   inherited MouseDown(Button, Shift, X, Y);
   if IsActive then
     Engine.MouseDown(self,Button,Shift,X,Y);
+  Invalidate;
 end;
 
 procedure TMapView.MouseUp(Button: TMouseButton; Shift: TShiftState;
@@ -573,6 +569,7 @@ begin
   inherited MouseUp(Button, Shift, X, Y);
   if IsActive then
     Engine.MouseUp(self,Button,Shift,X,Y);
+  Invalidate;
 end;
 
 procedure TMapView.MouseMove(Shift: TShiftState; X, Y: Integer);
@@ -580,6 +577,7 @@ begin
   inherited MouseMove(Shift, X, Y);
   if IsActive then
     Engine.MouseMove(self,Shift,X,Y);
+  Invalidate;
 end;
 
 procedure TMapView.Notification(AComponent: TComponent; Operation: TOperation);
@@ -594,6 +592,7 @@ begin
   inherited DblClick;
   if IsActive then
     Engine.DblClick(self);
+  Invalidate;
 end;
 
 procedure TMapView.DoOnResize;
@@ -604,13 +603,18 @@ begin
   DrawingEngine.CreateBuffer(ClientWidth, ClientHeight);
   if IsActive then
     Engine.SetSize(ClientWidth, ClientHeight);
+  Invalidate;
 end;
 
 procedure TMapView.Paint;
 begin
   inherited Paint;
   if IsActive then
-    DrawingEngine.PaintToCanvas(Canvas)
+  begin
+    Engine.Redraw;
+    DrawObjects(Default(TTileId), 0, 0, Canvas.Width, Canvas.Height);
+    DrawingEngine.PaintToCanvas(Canvas);
+  end
   else
   begin
     Canvas.Brush.Color := InactiveColor;
@@ -631,7 +635,7 @@ begin
     if hasIntersectArea(objArea, visArea) then
     begin
       Area := IntersectArea(objArea, visArea);
-      Engine.Jobqueue.AddJob(TDrawObjJob.Create(self, Objs, Area), Engine);
+      Invalidate;
     end
     else
       objs.Free;
@@ -654,8 +658,6 @@ begin
   if not trk.Visible or (trk.Points.Count = 0) then
     exit;
 
-  GPSItems.Lock;
-  try
     // Determine track color
     if trk.LineColor = clDefault then
     begin
@@ -687,9 +689,6 @@ begin
       pt1 := pt2;
       iPt1 := iPt2;
     end;
-  finally
-    GPSItems.Unlock;
-  end;
 end;
 
 procedure TMapView.DrawPointOfInterest(const Area: TRealArea; APt: TGPSPointOfInterest);
@@ -701,8 +700,6 @@ var
   bmp: TBitmap;
   w, h: Integer;
 begin
-  GPSItems.Lock;
-  try
     pt := Engine.LonLatToScreen(APt.RealPoint);
 
     // Draw point as symbol from image list ...
@@ -746,9 +743,6 @@ begin
     end;
     extent := DrawingEngine.TextExtent(s);
     DrawingEngine.TextOut(pt.X - extent.CX div 2, pt.Y + 5, s);
-  finally
-    GPSItems.Unlock;
-  end;
 end;
 
 procedure TMapView.DrawPt(const Area: TRealArea; APt: TGPSPoint);
@@ -758,8 +752,6 @@ var
   extent: TSize;
   s: String;
 begin
-  GPSItems.Lock;
-  try
     if Assigned(FOnDrawGpsPoint) then begin
       FOnDrawGpsPoint(Self, DrawingEngine, APt);
       exit;
@@ -796,6 +788,13 @@ begin
     extent := DrawingEngine.TextExtent(s);
     DrawingEngine.Textout(Pt.X - extent.CX div 2, Pt.Y + 5, s);
 
+end;
+
+procedure TMapView.DrawGpsObj(const Area: TRealArea; AObj: TGPSObj);
+begin
+  GPSItems.Lock;
+  try
+    AObj.Draw(Self, Area);
   finally
     GPSItems.Unlock;
   end;
@@ -815,22 +814,25 @@ procedure TMapView.DrawObjects(const TileId: TTileId;
 var
   Area: TRealArea;
   lst: TGPSObjList;
+  I: Integer;
 begin
   Area.TopLeft := Engine.ScreenToLonLat(Point(aLeft, aTop));
   Area.BottomRight := Engine.ScreenToLonLat(Point(aRight, aBottom));
   if GPSItems.Count > 0 then
   begin
     lst := GPSItems.GetObjectsInArea(Area);
+    try
       if lst.Count > 0 then
-      Engine.Jobqueue.AddJob(TDrawObjJob.Create(self, lst, Area), Engine)
-    else
       begin
+        for I := 0 to Pred(lst.Count) do
+          DrawGpsObj(Area, lst[I]);
+      end;
+    finally
       FreeAndNil(Lst);
-      CallAsyncInvalidate;
     end;
   end
   else
-    CallAsyncInvalidate;
+    ;
 end;
 
 procedure TMapView.DoAsyncInvalidate(Data: PtrInt);
@@ -839,7 +841,7 @@ Begin
   AsyncInvalidate := false;
 end;
 
-procedure TMapView.DoDrawStretchedTile(const TileId: TTileId; X, Y: Integer;
+procedure TMapView.DoDrawStretchedTile(const TileId: TTileID; X, Y: Integer;
   TileImg: TLazIntfImage; const R: TRect);
 begin
   if Assigned(TileImg) then
@@ -850,7 +852,6 @@ begin
   if FDebugTiles then
     DoDrawTileInfo(TileID, X, Y);
 
-  DrawObjects(TileId, X, Y, X + TILE_SIZE, Y + TILE_SIZE);
 end;
 
 procedure TMapView.DoDrawTile(const TileId: TTileId; X, Y: integer;
@@ -864,7 +865,6 @@ begin
   if FDebugTiles then
     DoDrawTileInfo(TileID, X, Y);
 
-  DrawObjects(TileId, X, Y, X + TILE_SIZE, Y + TILE_SIZE);
 end;
 
 procedure TMapView.DoDrawTileInfo(const TileID: TTileID; X, Y: Integer);
@@ -877,6 +877,12 @@ begin
   DrawingEngine.Line(X, Y + TILE_SIZE, X + TILE_SIZE, Y + TILE_SIZE);
 end;
 
+procedure TMapView.DoTileDownloaded(const TileId: TTileId);
+begin
+  // TODO: Include tile information to optimize redraw.
+  CallAsyncInvalidate;
+end;
+
 function TMapView.IsActive: Boolean;
 begin
   if not(csDesigning in ComponentState) then
@@ -911,6 +917,7 @@ begin
   FEngine.CacheOnDisk := true;
   FEngine.OnDrawTile := @DoDrawTile;
   FEngine.OnDrawStretchedTile := @DoDrawStretchedTile;
+  FEngine.OnTileDownloaded := @DoTileDownloaded;
   FEngine.DrawPreviewTiles := True;
   FEngine.DrawTitleInGuiThread := false;
   FEngine.DownloadEngine := FBuiltinDownloadEngine;
@@ -1054,7 +1061,7 @@ end;
 
 procedure TMapView.Redraw;
 begin
-  Engine.Redraw;
+  Invalidate;
 end;
 
 function TMapView.GetVisibleArea: TRealArea;