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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.

Convert onvif stream to rtsp address in c#

I am developing a project using c#.in my project i should get the camera stream .So i use onvif to get the stream but i faced a problem .some of my camera can't support onvif and they support RTSP,and i have to use rtsp in my project to :
Here is my onvif code to get the camera stream :
async void StartCameraAfterLogin()
{
//Dooooorbin
await ProcessConnect("http://172.16.0.52/onvif/device_service"
, Properties.Settings.Default.CameraUserName, Properties.Settings.Default.CameraPassword);
}
async Task ProcessConnect(string addr, string name, string pass)
{
//Release();
//ctrlInfo.Content = new ProgressControl();
var account = new System.Net.NetworkCredential(name, pass);
NvtSessionFactory factory = new NvtSessionFactory(account);
////This is syncronouse ui blokking call
//var session = factory.CreateSession(new Uri(addr);
try
{
var session = factory.CreateSession(new Uri(addr));
ss = session;
await FillInfoArea(session);
}
catch (Exception err)
{
Algoa.Utilities.Logger.ToDebug(err);
//ctrlInfo.Content = new ErrorControl(err);
}
}
string profie;
private async Task FillInfoArea(INvtSession session)
{
var profInfo = new ProfieInfoControl();
try
{
var streamData = await profInfo.Init(session);
//sp.Children.Add(profInfo);
profie = profInfo.valueToken.Text;
InitVideoControl(streamData.Item1, streamData.Item4, session.credentials);
//InitPtzControl(session, streamData.Item2, streamData.Item3);
}
catch (Exception err)
{
Algoa.Utilities.Logger.ToDebug(err);
}
//ctrlInfo.Content = sp;
}
private void InitVideoControl(string suri, System.Windows.Size size, System.Net.NetworkCredential networkCredential)
{
InitPlayer(suri, networkCredential, size);
}
public void InitPlayer(string videoUri, NetworkCredential account, System.Windows.Size sz = default(System.Windows.Size))
{
player = new HostedPlayer();
playerDisposable.Add(player);
if (sz != default(System.Windows.Size))
videoBuff = new VideoBuffer((int)sz.Width, (int)sz.Height);
else
{
videoBuff = new VideoBuffer(720, 576);
}
player.SetVideoBuffer(videoBuff);
MediaStreamInfo.Transport transp = MediaStreamInfo.Transport.Udp;
MediaStreamInfo mstrInfo = null;
if (account != null)
{
mstrInfo = new MediaStreamInfo(videoUri, transp, new UserNameToken(account.UserName, account.Password));//, transp, null);
}
else
{
mstrInfo = new MediaStreamInfo(videoUri, transp);
}
playerDisposable.Add(
player.Play(mstrInfo, this)
);
InitPlayback(videoBuff, true);
//{ // playing controls
// btnPause.Click += play;
// btnResume.Click += play;
//}
}
How can i convert my onvif url to rtsp url ?Is there any solution or i should change all part of my code?
I am new in camera stream coding .

I downloaded the OZEKI-SDK
private IIPCamera _camera;
private DrawingImageProvider _imageProvider = new DrawingImageProvider();
private MediaConnector _connector = new MediaConnector();
private VideoViewerWF _videoViewerWF1;
public Form1()
{
InitializeComponent();
// Create video viewer UI control
_videoViewerWF1 = new VideoViewerWF();
_videoViewerWF1.Name = "videoViewerWF1";
_videoViewerWF1.Size = panel1.Size;
panel1.Controls.Add(_videoViewerWF1);
// Bind the camera image to the UI control
_videoViewerWF1.SetImageProvider(_imageProvider);
}
// Connect camera video channel to image provider and start
private void connectBtn_Click(object sender, EventArgs e)
{
_camera = IPCameraFactory.GetCamera("rtsp://192.168.113.150:554/ufirststream", "root", "pass");
_connector.Connect(_camera.VideoChannel, _imageProvider);
_camera.Start();
_videoViewerWF1.Start();
}
As a another solution i finally used Accord.net library to capture rtsp stream.

Why value does not fall within the expected range when setting Value Changed for Gatt Characteristic

I would like to keep on reading characteristic/set value changed event handlers for characteristics from my BLE 4.0 device, by using the ValueChanged callback in Universal Windows Platform C# in Visual Studio 2017.
I followed some tutorial from these sites: Damian Blog's Windows Universal with BLE, Bluetooth Gatt's Git Hub, Bluetooth Generic Attribute Profile - Heart Rate Service and Dr. Jukka's mobile Blog on BLE. All of them are using ValueChanged and I have tried to follow what they did.
Unfortunately, instead of ValueChanged being triggered, I receive the following error when using the ValueChanged callback.
System.ArgumentException: 'Value does not fall within the expected range.'
This line of code is producing the error:
characteristic.ValueChanged += Oncharacteristic_ValueChanged;
Here is more details of my source code:
NOTE: I am using COM 7 for my dongler and my program could discover the BLE's device name, and could discover the Uuid of the services and characteristics.
public List<string> serviceList = new List<string>();
public List<string> characteristicList = new List<string>();
public BluetoothLEDevice myDevice { get; set; }
public MainPage()
{
this.InitializeComponent();
}
private async void Page_Loaded(object sender, RoutedEventArgs e)
{
// Find the com port
string selector = SerialDevice.GetDeviceSelector("COM7");
DeviceInformationCollection devices = await DeviceInformation.FindAllAsync(selector);
if (devices.Count > 0)
{
var dialog = new MessageDialog("Com Device found");
await dialog.ShowAsync();
DeviceInformation deviceInfo = devices[0];
SerialDevice serialDevice = await SerialDevice.FromIdAsync(deviceInfo.Id);
serialDevice.BaudRate = 9600;
serialDevice.DataBits = 8;
serialDevice.StopBits = SerialStopBitCount.One;
serialDevice.Parity = SerialParity.None;
}
else
{
MessageDialog popup = new MessageDialog("Sorry, no device found.");
await popup.ShowAsync();
}
// After com port is found, search for device
foreach (DeviceInformation di in await DeviceInformation.FindAllAsync(BluetoothLEDevice.GetDeviceSelector()))
{
BluetoothLEDevice bleDevice = await BluetoothLEDevice.FromIdAsync(di.Id);
// Display BLE device name
var dialogBleDeviceName = new MessageDialog("BLE Device Name " + bleDevice.Name);
await dialogBleDeviceName.ShowAsync();
myDevice = bleDevice;
}
// Check device connection
myDevice.ConnectionStatusChanged += OnConnectionStatusChanged;
foreach (var service in myDevice.GattServices)
{
serviceList.Add(service.Uuid.ToString());
// Verify if service is discovered by displaying a popup
MessageDialog serviceUuidPopUp = new MessageDialog("Adding Service Uuid to list " + service.Uuid.ToString() );
await serviceUuidPopUp.ShowAsync();
foreach (var characteristic in service.GetAllCharacteristics())
{
var characteristicUuid = characteristic.Uuid.ToString().ToLowerInvariant();
characteristicList.Add(characteristicUuid);
// Verify if characteristic is discovered by displaying a popup
MessageDialog charUuidPopUp = new MessageDialog("Adding characteristic Uuid to list " + characteristicUuid);
await charUuidPopUp.ShowAsync();
// set value changed event handlers for characteristics
characteristic.ValueChanged += Oncharacteristic_ValueChanged;
}
}
}
private void OnConnectionStatusChanged(BluetoothLEDevice sender, object args)
{
if (sender.ConnectionStatus == BluetoothConnectionStatus.Connected)
{
System.Diagnostics.Debug.WriteLine("Connected");
}
else
{
System.Diagnostics.Debug.WriteLine("Disconnected");
}
}
private void Oncharacteristic_ValueChanged(GattCharacteristic sender, GattValueChangedEventArgs args)
{
byte[] data = new byte[args.CharacteristicValue.Length];
DataReader.FromBuffer(
args.CharacteristicValue).ReadBytes(data);
string text = Encoding.UTF8.GetString(data, 0, data.Length);
}
UPDATE 1
I tried to check Characteristic Properties before set value changed event handlers for my characteristics by following the answer given by rudi belt on SO.
if (characteristic.CharacteristicProperties == (GattCharacteristicProperties.Read | GattCharacteristicProperties.Notify))
{
characteristic.ValueChanged += Oncharacteristic_ValueChanged;
}
Unfortunately, this IF statement is not executed.
UPDATE 2
I have tried to remove ALL the codes inside Oncharacteristic_ValueChanged method. But it still gives me the same error
System.ArgumentException: 'Value does not fall within the expected range.'
I have been spending a lot of time trying to solve this problem. I will be very happy if anyone can help me on this. Thank you!

Reading your efforts in the former question I can provide a working example, but first some explanation.
myDevice.ConnectionStatusChanged is not needed, it is only used to notice a connection is lost or connected. You have to connect to your device first and handle things in the connection method.
After you have succeeded in connecting you have to get the service that contains the characteristic you want to use for read, write, notify or indicate.
When you have selected the service You can get the characteristics of that service.
Select the characteristic by Uuid, or in my example with CharacteristicProperties.HasFlag.
This flag in my example is Notify.
In the code comments you find extra info.
using System;
using System.Diagnostics;
using System.Threading.Tasks;
using Windows.Devices.Bluetooth;
using Windows.Devices.Bluetooth.GenericAttributeProfile;
using Windows.Devices.Enumeration;
using Windows.UI.Popups;
using Windows.UI.Xaml.Controls;
namespace App1
{
public sealed partial class MainPage : Page
{
GattDeviceServicesResult serviceResult = null;
private BluetoothLEDevice myDevice;
private GattCharacteristic selectedCharacteristic;
public MainPage()
{
this.InitializeComponent();
ConnectDevice();
}
private async void ConnectDevice()
{
//This works only if your device is already paired!
foreach (DeviceInformation di in await DeviceInformation.FindAllAsync(BluetoothLEDevice.GetDeviceSelector()))
{
BluetoothLEDevice bleDevice = await BluetoothLEDevice.FromIdAsync(di.Id);
// Display BLE device name
var dialogBleDeviceName = new MessageDialog("BLE Device Name " + bleDevice.Name);
await dialogBleDeviceName.ShowAsync();
myDevice = bleDevice;
}
if (myDevice != null)
{
int servicesCount = 3;//Fill in the amount of services from your device!!!!!
int tryCount = 0;
bool connected = false;
while (!connected)//This is to make sure all services are found.
{
tryCount++;
serviceResult = await myDevice.GetGattServicesAsync();
if (serviceResult.Status == GattCommunicationStatus.Success && serviceResult.Services.Count >= servicesCount)
{
connected = true;
Debug.WriteLine("Connected in " + tryCount + " tries");
}
if (tryCount > 5)//make this larger if faild
{
Debug.WriteLine("Failed to connect to device ");
return;
}
}
if (connected)
{
for (int i = 0; i < serviceResult.Services.Count; i++)
{
var service = serviceResult.Services[i];
//This must be the service that contains the Gatt-Characteristic you want to read from or write to !!!!!!!.
string myServiceUuid = "0000ffe0-0000-1000-8000-00805f9b34fb";
if (service.Uuid.ToString() == myServiceUuid)
{
Get_Characteriisics(service);
break;
}
}
}
}
}
private async void Get_Characteriisics(GattDeviceService myService)
{
var CharResult = await myService.GetCharacteristicsAsync();
if (CharResult.Status == GattCommunicationStatus.Success)
{
foreach (GattCharacteristic c in CharResult.Characteristics)
{
if (c.CharacteristicProperties.HasFlag(GattCharacteristicProperties.Notify))
{
selectedCharacteristic = c;
break;
}
}
try
{
// Write the ClientCharacteristicConfigurationDescriptor in order for server to send notifications.
var result = await selectedCharacteristic.WriteClientCharacteristicConfigurationDescriptorAsync(
GattClientCharacteristicConfigurationDescriptorValue.Notify);
if (result == GattCommunicationStatus.Success)
{
var dialogNotifications = new MessageDialog("Successfully registered for notifications");
await dialogNotifications.ShowAsync();
selectedCharacteristic.ValueChanged += SelectedCharacteristic_ValueChanged;
}
else
{
var dialogNotifications = new MessageDialog($"Error registering for notifications: {result}");
await dialogNotifications.ShowAsync();
}
}
catch (Exception ex)
{
// This usually happens when not all characteristics are found
// or selected characteristic has no Notify.
var dialogNotifications = new MessageDialog(ex.Message);
await dialogNotifications.ShowAsync();
await Task.Delay(100);
Get_Characteriisics(myService); //try again
//!!! Add a max try counter to prevent infinite loop!!!!!!!
}
}
else
{
var dialogNotifications = new MessageDialog("Restricted service. Can't read characteristics");
await dialogNotifications.ShowAsync();
}
}
private void SelectedCharacteristic_ValueChanged(GattCharacteristic sender, GattValueChangedEventArgs args)
{
}
}
}
If you have problems with this code feel free to ask in comments.

Download txt file from google drive in windows phone 8.1

I'm doing a windows phone project, and need to download a text file from the internet and read its content.
This is what I have tried (but it didn't work)
private async Task pobierz()
{
string source = "https://drive.google.com/file/d/0BzgKBwKyU4oORkxxSlVITGswb1E/view?usp=sharing";
string LocalName = "hej.txt";
var srce = new Uri(source, UriKind.Absolute);
// var destinationFile =await KnownFolders.PicturesLibrary.CreateFileAsync()
StorageFile file = await StorageFile.GetFileFromApplicationUriAsync(new Uri(#"ms-appx:///Assets/hej.txt"));
var downloader = new BackgroundDownloader();
DownloadOperation download = downloader.CreateDownload(srce,file);
}

Please see https://msdn.microsoft.com/en-us/library/windows/apps/xaml/jj152726.aspx?f=255&MSPPError=-2147217396 for detailed description of how to use the BackgroundDownloader.
You need to implement and call the following method:
private async void HandleDownloadAsync(DownloadOperation download, bool start)
{
try
{
// Store the download so we can pause/resume.
activeDownloads.Add(download);
Progress<DownloadOperation> progressCallback = new Progress<DownloadOperation>(DownloadProgress);
if (start)
{
// Start the download and attach a progress handler.
await download.StartAsync().AsTask(cts.Token, progressCallback);
}
else
{
// The download was already running when the application started, re-attach the progress handler.
await download.AttachAsync().AsTask(cts.Token, progressCallback);
}
ResponseInformation response = download.GetResponseInformation();
Log(String.Format("Completed: {0}, Status Code: {1}", download.Guid, response.StatusCode));
}
catch (TaskCanceledException)
{
Log("Download cancelled.");
}
catch (Exception ex)
{
LogException("Error", ex);
}
finally
{
activeDownloads.Remove(download);
}
}

How to handle prepopulated database in Windows Phone 8.1

I need to use a prepopulated database in my Xamarin.Forms application, so I searched for possible solutions.
I've found this article and tested with Android - it worked okay.
However, it uses Windows Phone 8 - that is not compatible with Windows 8.1.
So I tried to modify this Windows Phone 8 code:
public static void CopyDatabaseIfNotExists(string dbPath)
{
var storageFile = IsolatedStorageFile.GetUserStoreForApplication();
if (!storageFile.FileExists(dbPath))
{
using (var resourceStream = Application.GetResourceStream(new Uri("people.db3", UriKind.Relative)).Stream)
{
using (var fileStream = storageFile.CreateFile(dbPath))
{
byte[] readBuffer = new byte[4096];
int bytes = -1;
while ((bytes = resourceStream.Read(readBuffer, 0, readBuffer.Length)) > 0)
{
fileStream.Write(readBuffer, 0, bytes);
}
}
}
}
}
Into this code:
public static async void CopyDatabaseIfNotExists(string dbPath)
{
IStorageFolder applicationFolder = ApplicationData.Current.LocalFolder;
StorageFile existingFile = await Windows.Storage.StorageFile.GetFileFromPathAsync("prep.db");
IStorageFile storageFile = await applicationFolder.GetFileAsync(dbPath);
if (storageFile == null)
{
await existingFile.CopyAndReplaceAsync(storageFile);
However, it does not work, I can't provide a proper filepath for my existing db file (it is in the root of the project), it always gives me this error:
Value does not fall within the expected range.
How could I get a proper path to my prepopulated file?
Also, why do I need to use a stream based "copy" when I could simply copy the file itself?

The following code works for Windows Phone 8.1 and UWP:
public async void CopyDatabaseIfNotExists(string dbPath)
{
IStorageFolder applicationFolder = ApplicationData.Current.LocalFolder;
var existingFile = await Windows.ApplicationModel.Package.Current.InstalledLocation.GetFileAsync(myDBFileName);
if (!await CheckForExistingFile(myDBFileName))
await existingFile.CopyAsync(applicationFolder);
}
private async Task<bool> CheckForExistingFile(string filePath)
{
try
{
var file = await ApplicationData.Current.LocalFolder.GetFileAsync(Uri.EscapeDataString(filePath));
//no exception means file exists
return true;
}
catch (FileNotFoundException ex)
{
//find out through exception
return false;
}
}