Map flashes to white on each pan/zoom

Patrick · March 22, 2016, 7:24am

Dear all,

I'm looking to speed up the display of our map and tried to use overlay.tile cache.

Unfortunatly, this does not speed up the process as the map flashes to white (background color) on each pan/zoom.

Can you help me, this is my code, based on a sample.

        private void TestForm_Load(object sender, EventArgs e)
        {
          winformsMap1.ThreadingMode = MapThreadingMode.Multithreaded;

          winformsMap1.MapResizeMode = MapResizeMode.PreserveExtent;
          winformsMap1.MapFocusMode = MapFocusMode.ManuallyFocused;

          winformsMap1.AdornmentOverlay.ShowLogo = false;
          winformsMap1.ZoomLevelSnapping = ZoomLevelSnappingMode.SnapUp;
          winformsMap1.MapUnit = GeographyUnit.Meter;

           OpenStreetMapOverlay osmOvelerlay = new OpenStreetMapOverlay();
            osmOvelerlay.CacheDirectory = @"C:\temp\OpenStreetMapLayerCache1";

            winformsMap1.Overlays.Add(osmOvelerlay);

            LayerOverlay m_GeosetOverlay = new LayerOverlay();
            m_GeosetOverlay.TileCache = new InMemoryBitmapTileCache();  // <=== this is the line which causes the flash

            winformsMap1.Overlays.Add(m_GeosetOverlay);

            winformsMap1.CurrentExtent = new RectangleShape(-4352400.53526627, 8867834.11959479, 10425951.3896003, -2890780.54967516);
            winformsMap1.Refresh();
        }

Clint · March 22, 2016, 9:05am

Patrick,

Thanks for your post, I noticed that if i used the FileBitMapTileCache instead of an InMemoryBitMapTile Cache the flash no longer occurs. I pulled the code I used below from the "UsingTileCache" How Do I sample under the "Getting Started" section.

winformsMap1.ThreadingMode = MapThreadingMode.Multithreaded; winformsMap1.MapResizeMode = MapResizeMode.PreserveExtent; winformsMap1.MapFocusMode = MapFocusMode.ManuallyFocused; winformsMap1.AdornmentOverlay.ShowLogo = false; winformsMap1.ZoomLevelSnapping = ZoomLevelSnappingMode.SnapUp; winformsMap1.MapUnit = GeographyUnit.Meter; OpenStreetMapOverlay osmOvelerlay = new OpenStreetMapOverlay(); osmOvelerlay.CacheDirectory = @"C:\temp\OpenStreetMapLayerCache1"; winformsMap1.Overlays.Add(osmOvelerlay); LayerOverlay m_GeosetOverlay = new LayerOverlay(); FileBitmapTileCache bitmapTileCache = new FileBitmapTileCache(); bitmapTileCache.CacheDirectory = @"..\..\SampleData\Data\SampleCacheTiles"; bitmapTileCache.CacheId = "World02CachedTiles"; bitmapTileCache.TileAccessMode = TileAccessMode.ReadOnly; bitmapTileCache.ImageFormat = TileImageFormat.Png; m_GeosetOverlay.TileCache = bitmapTileCache; //m_GeosetOverlay.TileCache = new InMemoryBitmapTileCache(); // <=== this is the line which causes the flash winformsMap1.Overlays.Add(m_GeosetOverlay); winformsMap1.CurrentExtent = new RectangleShape(-4352400.53526627, 8867834.11959479, 10425951.3896003, -2890780.54967516); winformsMap1.Refresh();

Hope this helps, but let us know if you have any questions!

Thanks!

Patrick · March 22, 2016, 9:05am

Clint,

you are using pre-calculated tiles and it works, but it’s not at all what I’m trying to do.
I’m trying to generate the map tile on the fly, in order to speed up the redraw.

Trying to change
m_GeosetOverlay.TileCache = new InMemoryBitmapTileCache();
to
  m_GeosetOverlay.TileCache = new FileBitmapTileCache(@"c:\temp\test");

gives the same flashing effect.

Please advise.

Regards,
Patrick.

Ben · March 22, 2016, 9:05am

Patrick,

We’ve confirmed this is a bug and will fix it since 5.5.36.0 (Dev Branch) and 5.5.0.36(Release Branch) revision. Please get the latest daily build and have another try.

Thanks,

Ben

Ben · March 22, 2016, 9:05am

Patrick,

We’ve confirmed this is a bug and will fix it since 5.5.36.0 (Dev Branch) and 5.5.0.36(Release Branch) revision. Please get the latest daily build and have another try.

Thanks,

Ben

Patrick · March 22, 2016, 9:05am

Ben,

In 5.5.0.36, in multithread mode (Map.ThreadingMode = MapThreadingMode.Multithreaded;) the background layer is not refreshed anymore when user zoom with wheel.

Please advise.
Patrick.

Ben · March 22, 2016, 9:05am

Patrick,

Thanks for the report. We’ve fixed this and please try the latest Daily Build. (5.5.40.0 (Dev Branch) or 5.5.0.40(Release Branch))

Thanks,

Ben

Patrick · March 22, 2016, 9:05am

Ben,

The background layer not displayed issue is fixed with 5.5.0.40, thank you.
The flashing issue is partially fixed.

when you zoom/pan to an area already displayed, it does not occur anymore.
However, if you pan/zoom to an area not yet displayed, the flash is still there.

please advise
Patrick.

Ben · March 22, 2016, 9:05am

Patrick,

Thanks for the reporting. It might take some time to have a really good solution, we are on it and I’ll let you know after we have a result.

Thanks,

Ben

Patrick · March 22, 2016, 9:05am

I’m not in rush Ben, but i would be cool if this can be fixed by 6.0.

Patrick.

Gary2 · March 22, 2016, 9:05am

Hello Patrick,

Thanks for your patience and understanding, please feel free to let us know your problems.

Regards,

Gary

Gary2 · March 22, 2016, 9:05am

Hello Patrick,

Sorry to say, we can’t recreate it. Please look for an e-mail from our support team with information on how to download a video of our attempt to recreate this. It shows how we were trying to recreate it but failed, could you please provide a video shows how you can recreate it?

I appreciate your help.

Regards,

Gary

Patrick · March 22, 2016, 9:05am

Gary,

it works perfectly with the DVT version 5.5.48.0;
however, the issue is still there with the latest PRD version 5.5.0.33

any chance to have this fix in the PRD branch ?

Best regards,
Patrick.

Gary2 · March 22, 2016, 9:05am

Hello Patrick,

We have a plan to release the new PRD version, but didn’t have details now.

Please subscribe our forums, we will post news as soon as we planed it.

Regards,

Gary

Patrick · March 22, 2016, 9:05am

Hi,

it works fine with 5.5.0.50
thank you.

Patrick.

Gary2 · March 22, 2016, 9:05am

Hello Patrick,

Any more questions please feel free to let us know.

Regards,

Gary

Muneswar_Rao · March 22, 2016, 9:05am

Hi Gary,

We see similar flash in silverlight edition as well. To improve the speed, we just added server cache. Below is the way we create server cache for each instance of ServerLayerOverlay.

layerOverlay.ServerCache =

new ServerCache("somepath");But still, we could see sometimes it flashes when we pan/zoom. Since the cache is maintained at the server, we may not achieve the performance/speed that we do in windows edition where the cache is maintained on the client machine. I am just guessing. Is there a way to improve it further?

Ben · March 22, 2016, 9:05am

Muneswar,

I guess the “flash” you mean here is the tile not loading fast enough even it’s in the cache, right?  As you said it may not achieve the same performance as Desktop Edition where client cache is maintained, but after some checking I think we still have some space to improve. We’ve added it to our issue tracking system and will work on it pretty soon, and I will keep you updated here.

Thanks,

Ben

Ben · March 22, 2016, 9:05am

Muneswar,

We’ve completed this issue in the latest Daily Build (5.5.113.0) which would be available to download in one or two days, please have another try then.

Thanks,

Bai

Ben · March 22, 2016, 9:05am

Muneswar,

We’ve completed this issue in the latest Daily Build (5.5.113.0) which would be available to download in one or two days, please have another try then.

Thanks,

Ben