topic Re: KmlNode - WriteToAsync() - doesnt included referenced image files in .NET Maps SDK Questions

KmlNode - WriteToAsync() - doesnt included referenced image files

justinfernandes — Fri, 29 Jan 2021 16:33:10 GMT

I am reading in a KmlGroundOverlay that references a tiff file.

I write the KmlGroundOverlay to a a Stream.

I save the Stream to a file.

Everything works as expected except the referenced tiff file is not included in the KMZ.

Is this because I'm importing into the incorrect place when i first read the file?

My KmlGroundOverlays are displayed as excepted over my basemaps in my app.

private async Task LoadAndSaveKmz(StorageFile file, StorageFolder exportFolder) { var localFile = await ApplicationData.Current.TemporaryFolder.CreateFileAsync( file.Name, Windows.Storage.CreationCollisionOption.ReplaceExisting); await file.CopyAndReplaceAsync(localFile); source = new Uri(localFile.Path); KmlLayer layer = new KmlLayer(source); await layer.LoadAsync(); //get access to kml node (omitting that code here) KmlNode node = GetNodeFromLayer(layer); string filename = "node.kmz"; StorageFile file = await exportFolder.CreateFileAsync(filename, CreationCollisionOption.ReplaceExisting); using (Stream stream = await file.OpenStreamForWriteAsync()) { await node.WriteToAsync(stream); } }

Re: KmlNode - WriteToAsync() - doesnt included referenced image files

MatveiStefarov — Mon, 01 Feb 2021 10:39:31 GMT

Hello Justin!

I'm guessing that the GroundOverlay references a remote file (i.e. GroundOverlay/Icon/href is an HTTP/HTTPS URL rather than a file path). This would explain why the TIFF is not being saved in the KMZ archive. When a KMLNode is saved, only the URLs to remote files are saved -- the remote content does not downloaded and does not get zipped up. You can find more details about the saving process in the remarks of KmlNode.SaveAsAsync(...) method.

As a workaround, you can edit the KMLGroundOverlay before saving. First get its Icon, then download the Uri to a temporary file, create a new KMLIcon with a path to the temporary file, and finally replace the overlay Icon. Here's an example of how you could do it:

// Ensures that GroundOverlays's image will be saved as an embedded file private async Task DownloadOverlayImageAsync(KmlGroundOverlay original) { var icon = original.Icon; if (icon == null || icon.Uri == null || !icon.Uri.IsAbsoluteUri) return; // Skip invalid and already-local overlays // Create a temporary file to save to. // Filename is based on the URL, with any invalid characters replaced by "_". var imageFileName = Regex.Replace(icon.Uri.LocalPath, @"[^a-zA-Z0-9_\-\.]", "_"); var temp = ApplicationData.Current.TemporaryFolder; var tempSubfolder = await temp.CreateFolderAsync("KmlGroundOverlayDownloads", CreationCollisionOption.OpenIfExists); var tempFile = await tempSubfolder.CreateFileAsync(imageFileName, CreationCollisionOption.GenerateUniqueName); // Download using Runtime's HTTP handler (to integrate with AuthenticationManager) var client = new System.Net.Http.HttpClient(new ArcGISHttpClientHandler()); using (var stream = await client.GetStreamAsync(icon.Uri)) { using (var fileStream = await tempFile.OpenStreamForWriteAsync()) { await stream.CopyToAsync(fileStream); } } // Replace existing remote-URL icon with new local-URL icon var newIcon = new KmlIcon(new Uri(tempFile.Path)); original.Icon = newIcon; }

Re: KmlNode - WriteToAsync() - doesnt included referenced image files

justinfernandes — Mon, 01 Feb 2021 18:45:56 GMT

Thanks for the detailed response! Lots of good stuff in there.

Unfortunately that is not my case. The image file is within a KMZ that was initially loaded by my App. The entire KMZ is copied to my Temporary Folder within my apps "sandbox".

I suppose i could manually unzip that kmz and move that file to somewhere in my local sandbox, and then specify a relative to path to that location.

So my main question becomes: How should i define the relative path within my new kml? where should the path be relative to such that WriteToSync() works successfully?

Also, is it possible to specify a path such that it finds a a file within another kmz (to prevent need for unzipping).

thanks!

Re: KmlNode - WriteToAsync() - doesnt included referenced image files

MichaelBranscomb — Mon, 01 Feb 2021 21:08:50 GMT

@justinfernandes One more thing to check - which version are you using? If it's not v100.10, can you update to 100.10 and retest?

Re: KmlNode - WriteToAsync() - doesnt included referenced image files

justinfernandes — Mon, 03 May 2021 18:45:06 GMT

changing versions did not help.

but i eventually solved the problem by reading the image file into a WriteableBitmap, writing that bitmap to my ApplicatoinData.Current.TemporaryFolder and then creating KmlGroundOverlay and writing that to the same folder.

code snippet:

public async Task ExportGroundOverlay(StorageFolder folder, WriteableBitmap image, KmlPlacemark placemark, string filename) { try { //dont know why we need to flip these! but we do for change detection ground overlays. image = image.Flip(WriteableBitmapExtensions.FlipMode.Horizontal); foreach (char c in System.IO.Path.GetInvalidFileNameChars()) { filename = filename.Replace(c, '_'); } StorageFile imageFile = await ApplicationData.Current.TemporaryFolder.CreateFileAsync(filename + ".jpg", CreationCollisionOption.ReplaceExisting); using (IRandomAccessStream stream = await imageFile.OpenAsync(FileAccessMode.ReadWrite)) { await image.ToStream(stream, BitmapEncoder.JpegEncoderId); } KmlIcon icon = new KmlIcon(new Uri(imageFile.Path)); KmlGroundOverlay groundOverlay = new KmlGroundOverlay(placemark.Geometries[0].Geometry, icon); StorageFile tempFile = await ApplicationData.Current.TemporaryFolder.CreateFileAsync(filename + ".kmz", CreationCollisionOption.ReplaceExisting); using (Stream stream = await tempFile.OpenStreamForWriteAsync()) { await groundOverlay.WriteToAsync(stream); } StorageFile file = await folder.CreateFileAsync(filename + ".kmz", CreationCollisionOption.ReplaceExisting); await tempFile.CopyAndReplaceAsync(file); } catch (Exception e) { Debug.WriteLine("ExportGroundOverlay() - exception = " + e.ToString()); } }