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How can I print a pdf document from Xamarin.Forms UWP?

I have a Xamarin.Forms application that supports only UWP. I cannot find a way to print a pdf document. Whatever I have seen on the web, for some reason doesn't work for me. E.g. I tried
https://www.syncfusion.com/kb/8767/how-to-print-pdf-documents-in-xamarin-forms-platform
It lets me print, but the preview in the print dialog never shows up, and the progress indicator just keeps rotating forever.
I also tried http://zawayasoft.com/2018/03/13/uwp-print-pdf-files-silently-without-print-dialog/
This gives me errors that I cannot fix.
So I wonder if somebody can suggest something else that would actually work. Maybe something newer than what I have tried (I use VS 2017). Printing without the printing dialog would be preferable.
Thank you in advance.

I used a very dirty hack to do that!
What I had to do was to try to print the image version of the pdf (I did the conversion in backend) and then used the following DependencyInjection:
Inside my Print class in UWP project:
class Print : IPrint
{
void IPrint.Print(byte[] content)
{
Print_UWP printing = new Print_UWP();
printing.PrintUWpAsync(content);
}
}
and the class responsible for printing in uwp:
public class Print_UWP
{
PrintManager printmgr = PrintManager.GetForCurrentView();
PrintDocument PrintDoc = null;
PrintDocument printDoc;
PrintTask Task = null;
Windows.UI.Xaml.Controls.Image ViewToPrint = new Windows.UI.Xaml.Controls.Image();
public Print_UWP()
{
printmgr.PrintTaskRequested += Printmgr_PrintTaskRequested;
}
public async void PrintUWpAsync(byte[] imageData)
{
int i = 0;
while (i < 5)
{
try
{
BitmapImage biSource = new BitmapImage();
using (InMemoryRandomAccessStream stream = new InMemoryRandomAccessStream())
{
await stream.WriteAsync(imageData.AsBuffer());
stream.Seek(0);
await biSource.SetSourceAsync(stream);
}
ViewToPrint.Source = biSource;
if (PrintDoc != null)
{
printDoc.GetPreviewPage -= PrintDoc_GetPreviewPage;
printDoc.Paginate -= PrintDoc_Paginate;
printDoc.AddPages -= PrintDoc_AddPages;
}
this.printDoc = new PrintDocument();
try
{
printDoc.GetPreviewPage += PrintDoc_GetPreviewPage;
printDoc.Paginate += PrintDoc_Paginate;
printDoc.AddPages += PrintDoc_AddPages;
bool showprint = await PrintManager.ShowPrintUIAsync();
}
catch (Exception e)
{
Debug.WriteLine(e.ToString());
}
// printmgr = null;
// printDoc = null;
// Task = null;
PrintDoc = null;
GC.Collect();
printmgr.PrintTaskRequested -= Printmgr_PrintTaskRequested;
break;
}
catch (Exception e)
{
i++;
}
}
}
private void Printmgr_PrintTaskRequested(PrintManager sender, PrintTaskRequestedEventArgs args)
{
var deff = args.Request.GetDeferral();
Task = args.Request.CreatePrintTask("Invoice", OnPrintTaskSourceRequested);
deff.Complete();
}
async void OnPrintTaskSourceRequested(PrintTaskSourceRequestedArgs args)
{
var def = args.GetDeferral();
await Windows.ApplicationModel.Core.CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
{
args.SetSource(printDoc.DocumentSource);
});
def.Complete();
}
private void PrintDoc_AddPages(object sender, AddPagesEventArgs e)
{
printDoc.AddPage(ViewToPrint);
printDoc.AddPagesComplete();
}
private void PrintDoc_Paginate(object sender, PaginateEventArgs e)
{
PrintTaskOptions opt = Task.Options;
printDoc.SetPreviewPageCount(1, PreviewPageCountType.Final);
}
private void PrintDoc_GetPreviewPage(object sender, GetPreviewPageEventArgs e)
{
printDoc.SetPreviewPage(e.PageNumber, ViewToPrint);
}
}
Please note that this is not a perfect solution and sometimes it crashes without actually being able to trace the exception (which is really strange) so I am sure there must be better answers even though it does the job.

Google Places Autocomplete does not populate the address

I have an active Google Places autocomplete working with Xamarin Forms or Cross Platform. I have a working solution that auto populates the address when the user types in the address. My problem is when the user selects it from the list the address does not go to the search_bar.text… The search bar just remains with the text that was typed? how can I get the text when selected to populate in the search bar.
I am new to Xamarin forms and C#.
public Createbusinessaccount ()
{
InitializeComponent ();
search_bar.ApiKey = GooglePlacesApiKey;
search_bar.Type = PlaceType.Address;
search_bar.Components = new Components("country:us"); // Restrict results to Australia and New Zealand
search_bar.PlacesRetrieved += Search_Bar_PlacesRetrieved;
search_bar.TextChanged += Search_Bar_TextChanged;
search_bar.MinimumSearchText = 2;
results_list.ItemSelected += Results_List_ItemSelected;
}
void Search_Bar_PlacesRetrieved(object sender, AutoCompleteResult result)
{
results_list.ItemsSource = result.AutoCompletePlaces;
spinner.IsRunning = false;
spinner.IsVisible = false;
if (result.AutoCompletePlaces != null && result.AutoCompletePlaces.Count > 0)
results_list.IsVisible = true;
}
void Search_Bar_TextChanged(object sender, TextChangedEventArgs e)
{
if (!string.IsNullOrEmpty(e.NewTextValue))
{
results_list.IsVisible = false;
spinner.IsVisible = true;
spinner.IsRunning = true;
}
else
{
results_list.IsVisible = true;
spinner.IsRunning = false;
spinner.IsVisible = false;
}
}
async void Results_List_ItemSelected(object sender, SelectedItemChangedEventArgs e)
{
if (e.SelectedItem == null)
return;
var prediction = (AutoCompletePrediction)e.SelectedItem;
results_list.SelectedItem = null;
var place = await Places.GetPlace(prediction.Place_ID, GooglePlacesApiKey);
if (place != null)
await DisplayAlert(
place.Name, string.Format("Lat: {0}\nLon: {1}", place.Latitude, place.Longitude), "OK");
}

In your ItemSelected method, you need to set the text of the searchbar:
async void Results_List_ItemSelected(object sender, SelectedItemChangedEventArgs e)
{
if (e.SelectedItem == null)
return;
var prediction = (AutoCompletePrediction)e.SelectedItem;
search_bar.Text = prediction.Name? // Your property here
results_list.SelectedItem = null;
var place = await Places.GetPlace(prediction.Place_ID, GooglePlacesApiKey);
if (place != null)
await DisplayAlert(
place.Name, string.Format("Lat: {0}\nLon: {1}", place.Latitude, place.Longitude), "OK");
}

I am still trying to fix this, it only adds the street name and number not the whole address

ZXing.Net Back Navigation C#

I am using ZXing.Net camera barcode scanner, xamarin forms, and C# and it appears to be working good. But I have an issue where if I go the the next page via Navigation.PushAsync(), then click the Back Navigation Button, the ZXingScannerPage camera will not reload...(it will only be a still image of the last pic taken)...how do I reload the ZXingScannerPage so that the camera is actively upon pressing the Back Navigation? Is the anyway to refresh the camera view attached to the page?

Use the following code. Stop the scanning as soon as scanning is done. Don't do a manual manuver.
Entry objScanner= new Entry();
objScanner.Placeholder = "Barcode";
objScanner.Keyboard = Keyboard.Numeric;
objScanner.HorizontalOptions = LayoutOptions.StartAndExpand;
objScanner.WidthRequest = Application.Current.MainPage.Width - 40;
objScanner.SetBinding(Entry.TextProperty, "ElementValue", BindingMode.TwoWay);
objScanner.BindingContext = control;
layout.Children.Add(objScanner);
objScanner.Focused += async (s, e) =>
{
var scanPage = new ZXingScannerPage();
await Navigation.PushAsync(scanPage);
scanPage.OnScanResult += (result) =>
{
// Stop scanning
scanPage.IsScanning = false;
// Pop the page and show the result
Device.BeginInvokeOnMainThread(async () =>
{
await Navigation.PopAsync();
objScanner.Text = result.Text;
// await DisplayAlert("Scanned Barcode", result.Text, "OK");
});
};
};

The solution that I found that works for me to allow back navigation using ZXing Scanner page is to remove all instances of ZXing Scanner page before push a new instance of the page to the navigation stack. In your navigation.cs, when you get ready to push the page, use this:
foreach(var x in _navigation.Navigation.NavigationStack.ToList())
{
if((x.GetType() == typeof(/* name of your scanner page */)))
{
_navigation.Navigation.RemovePage(x);
}
}
var page = new /* your scanner page */();
_navigation.PushAsync( /* your scanner page */);

I have found a workaround which may be useful.
On content page, create a local content variable.
If I instantiate the scanner and add it to Content in OnAppearing method, then set Content = null OnDisappearing method. Nulling the Content seems to trigger the necessary cleanups up the stack.
Here's my code:
public class QrCodeScanPage : ZXingScannerPage
{
View _content;
public QrCodeScanPage()
{
InitScanner();
}
void InitScanner()
{
IsAnalyzing = true;
IsScanning = true;
DefaultOverlayTopText = "Align the barcode within the frame";
DefaultOverlayBottomText = string.Empty;
OnScanResult += ScanPage_OnScanResult;
Title = "Scan Code";
var item = new ToolbarItem
{
Text = "Cancel",
Command = new Command(async () =>
{
IsScanning = false;
await Navigation.PopAsync();
})
};
if (Device.RuntimePlatform != Device.iOS)
item.IconImageSource = "toolbar_close.png";
ToolbarItems.Add(item);
}
void ScanPage_OnScanResult(ZXing.Result result)
{
Device.BeginInvokeOnMainThread(async () =>
{
IsScanning = false;
IsAnalyzing = false;
await Navigation.PushAsync(new QrCodeScanResultPage());
});
}
protected override void OnAppearing()
{
IsScanning = true;
IsAnalyzing = true;
base.OnAppearing();
if (Content != null)
{
_content = Content;
}
if (Content == null)
{
Content = _content;
}
}
protected override void OnDisappearing()
{
base.OnDisappearing();
Content = null;
}
}

Video recorder app in Windows Phone 8.1

I am going to write a Video Recorder app in Windows Phone 8.1 (RT).
I used the example provided in Windows Reference.
public sealed partial class CamcorderMainPage : Page
{
StatusBar StatusBarObject = Windows.UI.ViewManagement.StatusBar.GetForCurrentView();
string StatusBarHeader = "Firefly Moments";
MediaCaptureInitializationSettings _captureInitSettings;
List<Windows.Devices.Enumeration.DeviceInformation> _deviceList;
Windows.Media.MediaProperties.MediaEncodingProfile _profile;
Windows.Media.Capture.MediaCapture _mediaCapture;
bool _recording = false;
bool _previewing = false;
string NoCameraError = "No camera device is found ";
public CamcorderMainPage()
{
this.InitializeComponent();
this.Loaded += CamcorderMainPage_Loaded;
}
void CamcorderMainPage_Loaded(object sender, RoutedEventArgs e)
{
//throw new NotImplementedException();
EnumerateCameras();
}
private async void EnumerateCameras()
{
var devices = await Windows.Devices.Enumeration.DeviceInformation.FindAllAsync(
Windows.Devices.Enumeration.DeviceClass.VideoCapture);
_deviceList = new List<Windows.Devices.Enumeration.DeviceInformation>();
// Add the devices to deviceList
if (devices.Count > 0)
{
for (var i = 0; i < devices.Count; i++)
{
_deviceList.Add(devices[i]);
}
InitCaptureSettings();
InitMediaCapture();
// rootPage.NotifyUser("Initialization complete.", NotifyType.StatusMessage);
}
else
{
StatusBarObject.ProgressIndicator.Text = NoCameraError;
//rootPage.NotifyUser("No camera device is found ", NotifyType.ErrorMessage);
}
}
private void InitCaptureSettings()
{
_captureInitSettings = null;
_captureInitSettings = new Windows.Media.Capture.MediaCaptureInitializationSettings();
_captureInitSettings.AudioDeviceId = "";
_captureInitSettings.VideoDeviceId = "";
_captureInitSettings.StreamingCaptureMode = Windows.Media.Capture.StreamingCaptureMode.AudioAndVideo;
_captureInitSettings.PhotoCaptureSource = Windows.Media.Capture.PhotoCaptureSource.VideoPreview;
if (_deviceList.Count > 0)
_captureInitSettings.VideoDeviceId = _deviceList[0].Id;
}
// Create a profile.
private void CreateProfile()
{
_profile = Windows.Media.MediaProperties.MediaEncodingProfile.CreateMp4(
Windows.Media.MediaProperties.VideoEncodingQuality.Qvga);
}
// Create and initialze the MediaCapture object.
public async void InitMediaCapture()
{
_mediaCapture = null;
_mediaCapture = new Windows.Media.Capture.MediaCapture();
// Set the MediaCapture to a variable in App.xaml.cs to handle suspension.
(App.Current as App).MediaCapture = _mediaCapture;
await _mediaCapture.InitializeAsync(_captureInitSettings);
CreateProfile();
}
// Start the video capture.
private async void StartMediaCaptureSession()
{
var storageFile = await Windows.Storage.KnownFolders.VideosLibrary.CreateFileAsync(
"cameraCapture.mp4", Windows.Storage.CreationCollisionOption.GenerateUniqueName);
await _mediaCapture.StartRecordToStorageFileAsync(_profile, storageFile);
_recording = true;
}
// Stop the video capture.
private async void StopMediaCaptureSession()
{
await _mediaCapture.StopRecordAsync();
_recording = false;
(App.Current as App).IsRecording = false;
}
private async void ShowFireFlyStatusBar()
{
//this will show the Status Bar
Windows.UI.ViewManagement.ApplicationView.GetForCurrentView().SetDesiredBoundsMode(ApplicationViewBoundsMode.UseVisible);
StatusBarObject.ProgressIndicator.Text = StatusBarHeader;
StatusBarObject.ProgressIndicator.ProgressValue = 0;
StatusBarObject.ForegroundColor = Colors.MintCream;
StatusBarObject.BackgroundColor = Color.FromArgb(255, 166, 62, 59);
StatusBarObject.BackgroundOpacity = .6;
await StatusBarObject.ProgressIndicator.ShowAsync();
}
/// <summary>
/// Invoked when this page is about to be displayed in a Frame.
/// </summary>
/// <param name="e">Event data that describes how this page was reached.
/// This parameter is typically used to configure the page.</param>
protected override void OnNavigatedTo(NavigationEventArgs e)
{
ShowFireFlyStatusBar();
}
private void Camcorder_StartCapture_Click(object sender, RoutedEventArgs e)
{
StartMediaCaptureSession();
}
private void Camcorder_StopCapture_Click(object sender, RoutedEventArgs e)
{
StopMediaCaptureSession();
}
}
Its working fine as I am getting the video file from Photos App .
Now how to enable live preview while recording in app? Which control to use for it?

You're looking for the CaptureElement. Once you add it to your XAML, connect it to your MediaCapture object and start preview like so:
PreviewControl.Source = _mediaCapture;
await _mediaCapture.StartPreviewAsync();
Have a look at the UniversalCameraSample posted on the Microsoft github page for more information. It targets Windows 10, but most of the patterns should work on 8/8.1 as well.

Previous Page state lost on back key press

I am creating a Windows Phone 8.1 Universal App. There are some screens on my app. On the first screen, i am navigate my screen to second screen. When i press hardware back button on second screen. My previous page state lost.
I am unable to rectify where was the problem. Here is the code below:
Screen 1 Code
protected override void OnNavigatedTo(NavigationEventArgs e)
{
this.navigationHelper.OnNavigatedTo(e);
this.NavigationCacheMode = NavigationCacheMode.Enabled;
if (e.NavigationMode == NavigationMode.New)
{
BindQuickDateComboBox();
if (Frame.BackStack.Count > 0)
{
var lastPage = Frame.BackStack.Last().SourcePageType;
if (lastPage != null && lastPage.FullName == "Cryoserver.AppLogin")
{
Frame.BackStack.Clear();
}
}
}
}
async private void appBarSearch_Click(object sender, RoutedEventArgs e)
{
try
{
if (IsValidateForm())
{
ProgressBar.IsVisible = true;
cmdBarSearch.IsEnabled = false;
if (await conn.Table<SearchQuery>().CountAsync() > 0)
{
await conn.DropTableAsync<SearchQuery>();
await conn.CreateTableAsync<SearchQuery>();
}
var searchTerms = new SearchQuery();
if (Convert.ToString(cmbQuickDate.SelectedItem) != "Any Date")
{
searchTerms.FromDate = pickerFromDate.Date.ToString("d MMM yyyy");
searchTerms.FromTime = pickerFromTime.Time.ToString();
searchTerms.ToDate = pickerToDate.Date.ToString("d MMM yyyy");
searchTerms.ToTime = pickerToTime.Time.ToString();
}
searchTerms.SearchKeywords = txtKeywords.Text;
searchTerms.Parties = txtParties.Text;
searchTerms.Contributer = txtFrom.Text;
searchTerms.Viewer = txtTo.Text;
searchTerms.AttachmentName = txtAttName.Text;
searchTerms.AttachmentKeywords = txtAttKeywords.Text;
searchTerms.SearchReason = txtSearchReason.Text;
searchTerms.IsHighLight = "false";
await conn.InsertAsync(searchTerms);
object resultMails = await SearchEmailArchive();
if (!String.IsNullOrEmpty(Convert.ToString(resultMails)))
{
GlobalInfo.SelectedRow = -1;
GlobalInfo.SearchPageIndex = -1;
GlobalInfo.IsFindKeyword = false;
var archiveMails = JsonConvert.DeserializeObject<SearchResult>(resultMails.ToString());
Frame.Navigate(typeof(MailList), archiveMails);
}
ProgressBar.IsVisible = false;
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
ProgressBar.IsVisible = false;
}
cmdBarSearch.IsEnabled = true;
}
private void Page_Loaded(object sender, RoutedEventArgs e)
{
}
Screen 2
I too used this code in second screen and also after removing this code. But it didn't work for me. Still the same problem.
void HardwareButtons_BackPressed(object sender, BackPressedEventArgs e)
{
if (Frame.CanGoBack)
{
e.Handled = true;
Frame.GoBack();
}
}
Screen 1 state is Blank and behaves as a freshly loaded screen. Why?
Any help would be much appreciated.

I would try setting NavigationCacheMode="Required" in the constructor/XAML instead.