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C # ListBox how to export a file with the name I pass from the listbox

**sorry for my english but i don't know very well in google translate i do translation.
I want from my listbox the file that I choose to be exported with the same name that it has in my listbox**
private void downloadFile(object sender, EventArgs e)
{
string ip = txt_ip.Text;
string user = txt_user.Text;
string pass = txt_pass.Text;
//string pathLocalFile = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "download_sftp_file.txt");
try
{
SftpClient client = new SftpClient(ip, user, pass);
client.Connect();
string rmDer = dr_finder.Text;
var files = client.ListDirectory(rmDer);
if (rmDer == "")
{
client.Connect();
string rmDerNow = "/";
var filesName = client.ListDirectory(rmDerNow);
foreach (var file in filesName)
{
DirList.Items.Add(file.Name);
string result = Path.GetFileNameWithoutExtension(file.Name);
DirList.Items.Add(System.IO.Path.GetFileName(file.Name));
}
MessageBox.Show("List Directory Success!");
}
string pachRemFile = DirList.SelectedItem.ToString();
string pachlocalFile = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop),"Server Ftp File.txt");
Stream Filestream = File.OpenWrite(pachlocalFile);
client.DownloadFile(pachRemFile,Filestream);
client.Disconnect();
}
catch (Exception error)
{
MessageBox.Show(error.Message);
}
}

this object is the solution I finally didn't find anyone to help me. so I helped myself.
and I thought he had good programmers on this site
SaveFileDialog savefile = new SaveFileDialog(); /* this here is my solution get a save as. */
if (savefile.ShowDialog() == DialogResult.OK)
{
string pachRemFile = DirList.SelectedItem.ToString();
Stream Filestream = File.Open(savefile.FileName, FileMode.CreateNew);
StreamWriter sw = new StreamWriter(Filestream);
client.DownloadFile(pachRemFile, Filestream);
client.Disconnect();
}

Image does not display in gallery after download

I am developing a Xamarin app which retrives info from DB, take/choose photo and upload them to remote server, display this images from the remote server and the user can delete them by tap on and press a button and download the images from the remote server to the local device.
Everything works without problem, but when I download the image and after I go to the gallery for check it, the image does not appear, whereas I can see it and open in the file explorer. When I reboot the phone, the image appear in the gallery.
Below my current button download method:
private void button_download_image_Clicked(object sender, EventArgs e)
{
Uri image_url_format = new Uri(image_url);
WebClient webClient = new WebClient();
try
{
byte[] bytes_image = webClient.DownloadData(image_url_format);
Stream image_stream = new MemoryStream(bytes_image);
string dest_folder = Android.OS.Environment.GetExternalStoragePublicDirectory(Android.OS.Environment.DirectoryDownloads).ToString();
string file_name = System.IO.Path.GetFileName(image_url_format.LocalPath);
string dest_path = System.IO.Path.Combine(dest_folder, file_name);
using (var fileStream = new FileStream(dest_path, FileMode.Create, FileAccess.Write))
{
image_stream.CopyTo(fileStream);
}
}
catch (Exception ex)
{
DisplayAlert("Error", ex.ToString(), "OK");
}
DisplayAlert("Alert", "Download completed!", "OK");
}
I tried in another device, but I got the same behavior.
Probably there is a sort of thing which does not refresh the gallery.
Any idea how to force the gallery to refresh or something similar?

You need to refresh your gallery after inserting or deleting any pictures in storage.
You can try this.
var mediaScanIntent = new Intent(Intent.ActionMediaScannerScanFile);
mediaScanIntent.SetData(Android.Net.Uri.FromFile(new Java.IO.File(dest_path)));
Xamarin.Forms.Forms.Context.SendBroadcast(mediaScanIntent);
Add these lines below your code.
Make it like
private void button_download_image_Clicked(object sender, EventArgs e)
{
Uri image_url_format = new Uri(image_url);
WebClient webClient = new WebClient();
try
{
byte[] bytes_image = webClient.DownloadData(image_url_format);
Stream image_stream = new MemoryStream(bytes_image);
string dest_folder = Android.OS.Environment.GetExternalStoragePublicDirectory(Android.OS.Environment.DirectoryDownloads).ToString();
string file_name = System.IO.Path.GetFileName(image_url_format.LocalPath);
string dest_path = System.IO.Path.Combine(dest_folder, file_name);
using (var fileStream = new FileStream(dest_path, FileMode.Create, FileAccess.Write))
{
image_stream.CopyTo(fileStream);
}
var mediaScanIntent = new Intent(Intent.ActionMediaScannerScanFile);
mediaScanIntent.SetData(Android.Net.Uri.FromFile(new Java.IO.File(dest_path)));
//for old xamarin forms version
Xamarin.Forms.Forms.Context.SendBroadcast(mediaScanIntent);
//for new xamarin forms version
//Android.App.Application.SendBroadcast(mediaScanIntent);
}
catch (Exception ex)
{
DisplayAlert("Error", ex.ToString(), "OK");
return;
}
DisplayAlert("Alert", "Download completed!", "OK");
}

You need to just refresh the file you have downloaded. It's helpful.
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT){
Intent mediaScanIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
File f = new File("file://"+ Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES));
Uri contentUri = Uri.fromFile(f);
mediaScanIntent.setData(contentUri);
this.sendBroadcast(mediaScanIntent);
}else{
sendBroadcast(new Intent(Intent.ACTION_MEDIA_MOUNTED, Uri.parse("file://" + Environment.getExternalStorageDirectory())));
}

Make sure required permission given on both platforms.
Use in your class:
bool success = await DependencyService.Get<IPhotoLibrary>().SavePhotoAsync(data, folder, filename);
Common Interface
public interface IPhotoLibrary
{
Task<bool> SavePhotoAsync(byte[] data, string folder, string filename);
}
In Android service
public async Task<bool> SavePhotoAsync(byte[] data, string folder, string filename)
{
try
{
File picturesDirectory = Environment.GetExternalStoragePublicDirectory(Environment.DirectoryPictures);
File folderDirectory = picturesDirectory;
if (!string.IsNullOrEmpty(folder))
{
folderDirectory = new File(picturesDirectory, folder);
folderDirectory.Mkdirs();
}
using (File bitmapFile = new File(folderDirectory, filename))
{
bitmapFile.CreateNewFile();
using (FileOutputStream outputStream = new FileOutputStream(bitmapFile))
{
await outputStream.WriteAsync(data);
}
// Make sure it shows up in the Photos gallery promptly.
MediaScannerConnection.ScanFile(MainActivity.Instance,
new string[] { bitmapFile.Path },
new string[] { "image/png", "image/jpeg" }, null);
}
}
catch (System.Exception ex)
{
return false;
}
return true;
}
In iOS service:
public Task<bool> SavePhotoAsync(byte[] data, string folder, string filename)
{
NSData nsData = NSData.FromArray(data);
UIImage image = new UIImage(nsData);
TaskCompletionSource<bool> taskCompletionSource = new TaskCompletionSource<bool>();
image.SaveToPhotosAlbum((UIImage img, NSError error) =>
{
taskCompletionSource.SetResult(error == null);
});
return taskCompletionSource.Task;
}
also you can refer this one just to save an image and to reflect it in media, no need to use skiasharp for that. https://learn.microsoft.com/en-us/xamarin/xamarin-forms/user-interface/graphics/skiasharp/bitmaps/saving
Hope this may resolve your issue.

Refer to Blu's answer,
I changed this Xamarin.Forms.Forms.Context.SendBroadcast(mediaScanIntent); to Android.App.Application.Context.SendBroadcast(mediaScanIntent); and all works.

UWP IOT-Core App System.Exception: The application called an interface that was marshalled for a different thread

I'm stuck with an App that is running on Windows 10 IoT Core. All Classes are working fine, except for the one that is creating a CSV File via JSON and is supposed to send it as an Email.
When the Code reaches the "ReturnToMainPage()" Function the Exception "System.Exception: The application called an interface that was marshalled for a different thread" is thrown.
The "funny" thing is, the Mail is being send and i recieve it but the Program won't switch to back to the Main Page as intendet after sending the Email.
Here is the Code of the Class:
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Net.Http;
using System.Text;
using Windows.Storage;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using EASendMail;
namespace PratschZahlstation
{
public sealed partial class MailChoice : Page
{
private TextBlock _headerText;
private ComboBox _mailComboBox;
private Button _execute;
private Button _abort;
private EnDecode _coder = EnDecode.get_EnDecodeSingleton();
private string _mailto = null;
public MailChoice()
{
this.InitializeComponent();
Init();
}
private void Init()
{
_headerText = HeaderText;
_mailComboBox = MailAdresses;
_mailComboBox.Items.Add("---");
_mailComboBox.Items.Add("dummy#mail.com");
_mailComboBox.SelectedIndex = 0;
_execute = DoFunction;
_abort = DoExit;
}
private void DoFunction_Click(object sender, RoutedEventArgs e)
{
string selectedMail = this._mailComboBox.SelectedItem.ToString();
if(selectedMail == "---")
{
_headerText.Text = "Bitte eine Emailadresse aus der Liste auswählen.";
}
else
{
_headerText.Text = "CSV wird erstellt und per Mail versendet!";
_execute.IsEnabled = false;
_abort.IsEnabled = false;
_mailComboBox.IsEnabled = false;
_mailto = selectedMail;
DateTime date = DateTime.Now;
string strippedDate = date.ToString("yyyy-MM-dd") + " 00:00:01";
GetDataForCSV(strippedDate);
}
}
private async void GetDataForCSV(string dateAsString)
{
string correctedDate = "2019-07-01 00:00:01";//dateAsString;
string date = _coder.Base64Encode(correctedDate);
HttpClient _client = new HttpClient();
Uri _uri = new Uri("URI TO JSON-API");
_client.BaseAddress = _uri;
var request = new HttpRequestMessage(HttpMethod.Post, _uri);
var keyValues = new List<KeyValuePair<string, string>>();
keyValues.Add(new KeyValuePair<string, string>("mode", "10"));
keyValues.Add(new KeyValuePair<string, string>("date", date));
request.Content = new FormUrlEncodedContent(keyValues);
var response = await _client.SendAsync(request);
string sContent = await response.Content.ReadAsStringAsync();
keyValues = null;
if (sContent != null)
{
byte[] bytes = Encoding.UTF8.GetBytes(sContent);
string json = Encoding.UTF8.GetString(bytes);
if (!json.Contains("success"))
{
List<CSV_SQL_Json_Object> _Json = JsonConvert.DeserializeObject<List<CSV_SQL_Json_Object>>(json);
response.Dispose();
request.Dispose();
_client.Dispose();
if (_Json.Count == 0)
{
}
else
{
CreateCSV(_Json);
}
}
else
{
List<JSON_Status> _Json = JsonConvert.DeserializeObject<List<JSON_Status>>(json);
_headerText.Text = "Es ist der Folgender Fehler aufgetreten - Errorcode: \"" + _coder.Base64Decode(_Json[0].success) + "\"\r\nFehlermeldung: \"" + _coder.Base64Decode(_Json[0].message) + "\"";
_Json.Clear();
response.Dispose();
request.Dispose();
_client.Dispose();
}
}
}
private async void CreateCSV(List<CSV_SQL_Json_Object> contentForCSV)
{
DateTime date = DateTime.Now;
string csvName = date.ToString("yyyy-MM-dd") + ".csv";
StorageFolder storageFolder = KnownFolders.MusicLibrary;
StorageFile csvFile = await storageFolder.CreateFileAsync(csvName, CreationCollisionOption.OpenIfExists).AsTask().ConfigureAwait(false);
await FileIO.WriteTextAsync(csvFile, "Column1;Column2;Column3;Column4;\n");
foreach (var item in contentForCSV)
{
await FileIO.AppendTextAsync(csvFile, _coder.Base64Decode(item.Object1) + ";" + _coder.aesDecrypt(_coder.Base64Decode(item.Object2)) + ";" + _coder.aesDecrypt(_coder.Base64Decode(item.Object3)) + ";" + _coder.aesDecrypt(_coder.Base64Decode(item.Object4)) + "\n");
}
SendEmail(_mailto, csvName);
}
private async void SendEmail(string mailto, string csvName)
{
try
{
SmtpMail oMail = new SmtpMail("Mail");
SmtpClient oSmtp = new SmtpClient();
oMail.From = new MailAddress("noreply#dummy.com");
oMail.To.Add(new MailAddress(mailto));
oMail.Subject = "The Subject";
oMail.HtmlBody = "<font size=5>MailText</font>";
StorageFile file = await KnownFolders.MusicLibrary.GetFileAsync(csvName).AsTask().ConfigureAwait(false);
string attfile = file.Path;
Attachment oAttachment = await oMail.AddAttachmentAsync(attfile);
SmtpServer oServer = new SmtpServer("mail.dummy.com");
oServer.User = "dummyuser";
oServer.Password = "dummypass";
oServer.Port = 587;
oServer.ConnectType = SmtpConnectType.ConnectSSLAuto;
await oSmtp.SendMailAsync(oServer, oMail);
}
catch (Exception ex)
{
string error = ex.ToString();
_abort.IsEnabled = true;
}
ReturnToMainPage(); //This is where the Error Happens
}
private void ReturnToMainPage()
{
this.Frame.Navigate(typeof(MainPage));
}
private void DoExit_Click(object sender, RoutedEventArgs e)
{
this.Frame.Navigate(typeof(MainPage));
}
}
}

This could be an Threading issue. Navigation is only possible on the main-Thread.
You may want to try to marshal the call in:
Windows.ApplicationModel.Core.CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPriority.Normal,
() =>
{
// Your UI update code goes here!
}
);
Source:
The application called an interface that was marshalled for a different thread - Windows Store App

Like Tobonaut said, you can use the Dispatcher.RunAsync to call the Navigation, it worked.
But your problem may not be this.
I copied your code and reproduced your problem and found that you have problems with the calls to read and write files:
// Your code
StorageFile csvFile = await storageFolder.CreateFileAsync(csvName, CreationCollisionOption.OpenIfExists).AsTask().ConfigureAwait(false);
StorageFile file = await KnownFolders.MusicLibrary.GetFileAsync(csvName).AsTask().ConfigureAwait(false);
The Navigation will be work if you delete the .AsTask().ConfigureAwait(false).
Best regards.

How do I adjust the video quality from the camera in xamarin

I want to upload a video into server from my app, now I can upload small size video's, but in the case of larger size the video uploading is not done.How can I do this.
I found a reason that the 2 minutes video has the size 300 mb, so how can I reduce the size of the video with out losing the quality
Please somebody help me..
Here is my code for video taking
private async void TakeVideo_Clicked(object sender, EventArgs e)
{
if (!CrossMedia.Current.IsCameraAvailable || !CrossMedia.Current.IsTakeVideoSupported)
{
await DisplayAlert("No Camera", ":( No camera avaialble.", "OK");
return;
}
var _file = await CrossMedia.Current.TakeVideoAsync(new Plugin.Media.Abstractions.StoreVideoOptions
{
Name = "gtsvideo.mp4",
Directory = "GTSVideos",
});
if (_file == null)
{
return;
}
else
{
_path = _file.Path;
using (var _streamReader = new StreamReader(_file.GetStream()))
{
var _array = default(byte[]);
using (MemoryStream _memoryStream = new MemoryStream())
{
_streamReader.BaseStream.CopyTo(_memoryStream);
_array = _memoryStream.ToArray();
if (await DisplayAlert(App._confirmation, "It may take few Minutes..,Do you want to save the video?", "Yes", "Cancel"))
{
FileUploadAsync(_array, false);
activity_Indicator.IsVisible = true;
activity_Indicator.IsRunning = true;
}
else
{
return;
}
}
}
}
}
public async void FileUploadAsync(byte[] fileUpload, bool IsImage)
{
APIResponse _response = await App.DataManager.UpdateFilesAsync(_task.ID, fileUpload, IsImage);
if (IsImage == false)
{
await System.Threading.Tasks.Task.Delay(5000);
}
if (_response != null)
{
activity_Indicator.IsRunning = false;
if (IsImage)
{
DependencyService.Get<IAlertPlayer>().AlertMessege("Image upload successfully");
}
else
{
DependencyService.Get<IAlertPlayer>().AlertMessege("Video upload successfully");
}
}
else
{
DisplayAlertMessage();
}
}
UploadVideo
public async Task<APIResponse> UpdateFilesAsync(int id, byte[] file, bool IsImage)
{
Url _url = new Url(BaseURL).AppendPathSegment("tasks/UploadFiles");
_url.QueryParams["ID"] = id;
return await Service.POSTFILE<APIResponse>(_url, file, IsImage);
}
public async Task<T> POSTFILE<T>(Url url, byte[] uploadFile, bool IsImage)
{
try
{
using (MultipartFormDataContent _content = new MultipartFormDataContent())
{
ByteArrayContent _filecontent = new ByteArrayContent(uploadFile);
if (IsImage)
{
_filecontent.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment")
{
FileName = Guid.NewGuid().ToString() + ".png"
};
}
else
{
_filecontent.Headers.ContentDisposition = new System.Net.Http.Headers.ContentDispositionHeaderValue("attachment")
{
FileName = Guid.NewGuid().ToString() + ".mp4"
};
}
_content.Add(_filecontent);
using (HttpResponseMessage _response = await Client.PostAsync(url, _content))
{
string _result = await _response.Content.ReadAsStringAsync();
return JsonConvert.DeserializeObject<T>(_result);
}
}
}
catch (Exception ex)
{
}
return default(T);
}

Simple answer: Unless you implement some fancy lossless compression code yourself, you don't. You get what the operating system of your phone gives you.

The process cannot access the file because it is being used by another process

I am running a program where a file gets uploaded to a folder in IIS,and then is processed to extract some values from it. I use a WCF service to perform the process, and BackgroundUploader to upload the file to IIS. However, after the upload process is complete, I get the error "The process cannot access the file x because it is being used by another process." Based on similar questions asked here, I gathered that the file concerned needs to be in a using statement. I tried to modify my code to the following, but it didn't work, and I am not sure if it is even right.
namespace App17
{
public sealed partial class MainPage : Page, IDisposable
{
private CancellationTokenSource cts;
public void Dispose()
{
if (cts != null)
{
cts.Dispose();
cts = null;
}
GC.SuppressFinalize(this);
}
public MainPage()
{
this.InitializeComponent();
cts = new CancellationTokenSource();
}
public async void Button_Click(object sender, RoutedEventArgs e)
{
try
{
Uri uri = new Uri(serverAddressField.Text.Trim());
FileOpenPicker picker = new FileOpenPicker();
picker.FileTypeFilter.Add("*");
StorageFile file = await picker.PickSingleFileAsync();
using (var stream = await file.OpenAsync(FileAccessMode.Read))
{
GlobalClass.filecontent = file.Name;
GlobalClass.filepath = file.Path;
BackgroundUploader uploader = new BackgroundUploader();
uploader.SetRequestHeader("Filename", file.Name);
UploadOperation upload = uploader.CreateUpload(uri, file);
await HandleUploadAsync(upload, true);
stream.Dispose();
}
}
catch (Exception ex)
{
string message = ex.ToString();
var dialog = new MessageDialog(message);
await dialog.ShowAsync();
Log(message);
}
}
private void CancelAll(object sender, RoutedEventArgs e)
{
Log("Canceling all active uploads");
cts.Cancel();
cts.Dispose();
cts = new CancellationTokenSource();
}
private async Task HandleUploadAsync(UploadOperation upload, bool start)
{
try
{
Progress<UploadOperation> progressCallback = new Progress<UploadOperation>(UploadProgress);
if (start)
{
await upload.StartAsync().AsTask(cts.Token, progressCallback);
}
else
{
// The upload was already running when the application started, re-attach the progress handler.
await upload.AttachAsync().AsTask(cts.Token, progressCallback);
}
ResponseInformation response = upload.GetResponseInformation();
Log(String.Format("Completed: {0}, Status Code: {1}", upload.Guid, response.StatusCode));
cts.Dispose();
}
catch (TaskCanceledException)
{
Log("Upload cancelled.");
}
catch (Exception ex)
{
string message = ex.ToString();
var dialog = new MessageDialog(message);
await dialog.ShowAsync();
Log(message);
}
}
private void Log(string message)
{
outputField.Text += message + "\r\n";
}
private async void LogStatus(string message)
{
var dialog = new MessageDialog(message);
await dialog.ShowAsync();
Log(message);
}
private void UploadProgress(UploadOperation upload)
{
BackgroundUploadProgress currentProgress = upload.Progress;
MarshalLog(String.Format(CultureInfo.CurrentCulture, "Progress: {0}, Status: {1}", upload.Guid,
currentProgress.Status));
double percentSent = 100;
if (currentProgress.TotalBytesToSend > 0)
{
percentSent = currentProgress.BytesSent * 100 / currentProgress.TotalBytesToSend;
}
MarshalLog(String.Format(CultureInfo.CurrentCulture,
" - Sent bytes: {0} of {1} ({2}%), Received bytes: {3} of {4}", currentProgress.BytesSent,
currentProgress.TotalBytesToSend, percentSent, currentProgress.BytesReceived, currentProgress.TotalBytesToReceive));
if (currentProgress.HasRestarted)
{
MarshalLog(" - Upload restarted");
}
if (currentProgress.HasResponseChanged)
{
MarshalLog(" - Response updated; Header count: " + upload.GetResponseInformation().Headers.Count);
}
}
private void MarshalLog(string value)
{
var ignore = this.Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
{
Log(value);
});
}
}
}
After this is done, the file name is sent to a WCF service which will access and process the uploaded file to extract certain values. It is at this point I receive the error. I would truly appreciate some help.
public async void Extract_Button_Click(object sender, RoutedEventArgs e)
{
ServiceReference1.Service1Client MyService = new ServiceReference1.Service1Client();
string filename = GlobalClass.filecontent;
string filepath = #"C:\Users\R\Documents\Visual Studio 2015\Projects\WCF\WCF\Uploads\"+ filename;
bool x = await MyService.ReadECGAsync(filename, filepath);
}
EDIT: Code before I added the using block
try
{
Uri uri = new Uri(serverAddressField.Text.Trim());
FileOpenPicker picker = new FileOpenPicker();
picker.FileTypeFilter.Add("*");
StorageFile file = await picker.PickSingleFileAsync();
GlobalClass.filecontent = file.Name;
GlobalClass.filepath = file.Path;
BackgroundUploader uploader = new BackgroundUploader();
uploader.SetRequestHeader("Filename", file.Name);
UploadOperation upload = uploader.CreateUpload(uri, file);
await HandleUploadAsync(upload, true);
}

When you work with stream writers you actually create a process, which you can close it from task manager. And after stream.Dispose() put stream.Close().
This should solve your problem.

You should also close the stream that writes the file to disk (look at your implementation of CreateUpload).

i got such error in DotNet Core 2 using this code:
await file.CopyToAsync(new FileStream(fullFileName, FileMode.Create));
counter++;
and this is how I managed to get rid of message (The process cannot access the file x because it is being used by another process):
using (FileStream DestinationStream = new FileStream(fullFileName, FileMode.Create))
{
await file.CopyToAsync(DestinationStream);
counter++;
}