UWP C++ PrintTask PreviewPage Duplication Error - c++

Question

I'm currently working on a print task within my app to print a couple of pages to either printer or PDF. I'm using the microsoft printsample as the basis for my code and it all works with the exception of one thing. When I change printers, the printer preview creates duplicate pages of the content I sent to the printer preview.
Here is all my code that handles the printing. Does anyone know what might be causing the print UI to create duplicate preview pages when changing between printers and or print to PDF? thanks.
void MainPage::Print_Test_Button_Click(Platform::Object^ sender, Windows::UI::Xaml::RoutedEventArgs^ e)
{
if (isPrinting) {
pDocument->InvalidatePreview();
printMan = Windows::Graphics::Printing::PrintManager::GetForCurrentView();
printMan->PrintTaskRequested -= printTaskRequestedEventToken;
isPrinting = false;
}
this->Certificate_SV_1->ScrollToVerticalOffset(0.0);
this->Certificate_SV_2->ScrollToVerticalOffset(0.0);
// CREATE THE PRINT DOCUMENT
pDocument = ref new Windows::UI::Xaml::Printing::PrintDocument();
// SAVE DOCUMENT SOURCE
pDocumentSource = pDocument->DocumentSource;
// CLEAR CACHE OF PREVIEW PAGES
printPreviewPages.clear();
// Add an event handler which creates preview pages.
pDocument->Paginate += ref new Windows::UI::Xaml::Printing::PaginateEventHandler(this, &MainPage::CreatePrintPreviewPages);
// Add an event handler which provides a specified preview page.
pDocument->GetPreviewPage += ref new Windows::UI::Xaml::Printing::GetPreviewPageEventHandler(this, &MainPage::GetPrintPreviewPage);
// Add an event handler which provides all final print pages.
pDocument->AddPages += ref new Windows::UI::Xaml::Printing::AddPagesEventHandler(this, &MainPage::AddPrintPages);
// PRINT MANAGER
printMan = Windows::Graphics::Printing::PrintManager::GetForCurrentView();
// RAISE NEW PRINT TASK REQUEST
printTaskRequestedEventToken = printMan->PrintTaskRequested += ref new Windows::Foundation::TypedEventHandler<Windows::Graphics::Printing::PrintManager^, Windows::Graphics::Printing::PrintTaskRequestedEventArgs^>(this, &MainPage::PrintTaskRequested);
// SHOWS THE PRINTER UI
printMan->ShowPrintUIAsync();
}
.
void MainPage::CreatePrintPreviewPages(Object^ sender, Windows::UI::Xaml::Printing::PaginateEventArgs^ e)
{
Windows::UI::Xaml::Printing::PrintDocument^ printDocument = safe_cast<Windows::UI::Xaml::Printing::PrintDocument^>(sender);
hasOverFlow = false;
StackPanel^ PrinterPage = ref new StackPanel();
PrinterPage->Width = 794; PrinterPage->Height = 1123;
PrinterPage = safe_cast<StackPanel^>(this->Certificate_Page_1);
// ADD PAGE TO THE COLLECTION
printPreviewPages.push_back(PrinterPage);
PrinterPage = safe_cast<StackPanel^>(this->Certificate_Page_2);
printPreviewPages.push_back(PrinterPage);
// Report the number of preview pages created
printDocument->SetPreviewPageCount(printPreviewPages.size(), Windows::UI::Xaml::Printing::PreviewPageCountType::Final);
}
.
void MainPage::GetPrintPreviewPage(Object^ sender, Windows::UI::Xaml::Printing::GetPreviewPageEventArgs^ e)
{
Windows::UI::Xaml::Printing::PrintDocument^ localprintDocument = safe_cast<Windows::UI::Xaml::Printing::PrintDocument^>(sender);
localprintDocument->SetPreviewPage(e->PageNumber, printPreviewPages[e->PageNumber - 1]);
}
.
void MainPage::AddPrintPages(Object^ sender, Windows::UI::Xaml::Printing::AddPagesEventArgs^ e)
{
Windows::UI::Xaml::Printing::PrintDocument^ printDocument = safe_cast<Windows::UI::Xaml::Printing::PrintDocument^>(sender);
for (uint8_t i = 0; i < printPreviewPages.size(); i++) {
printDocument->AddPage(printPreviewPages[i]);
}
// Indicate that all of the print pages have been provided
printDocument->AddPagesComplete();
}
.
void MainPage::PrintTaskRequested(Windows::Graphics::Printing::PrintManager^ sender, Windows::Graphics::Printing::PrintTaskRequestedEventArgs^ e) {
Windows::Graphics::Printing::PrintTask^ printTask = e->Request->CreatePrintTask("PRINT TASK", ref new Windows::Graphics::Printing::PrintTaskSourceRequestedHandler([=](Windows::Graphics::Printing::PrintTaskSourceRequestedArgs^ args)
{
args->SetSource(pDocumentSource);
}));
// Print Task event handler is invoked when the print job is completed.
printTask->Completed += ref new Windows::Foundation::TypedEventHandler<Windows::Graphics::Printing::PrintTask^, Windows::Graphics::Printing::PrintTaskCompletedEventArgs^>([=](Windows::Graphics::Printing::PrintTask^ sender, Windows::Graphics::Printing::PrintTaskCompletedEventArgs^ e)
{
// Notify the user when the print operation fails.
if (e->Completion == Windows::Graphics::Printing::PrintTaskCompletion::Failed)
{
auto callback = ref new Windows::UI::Core::DispatchedHandler([=]()
{
this->DataStreamWindow->Text = "Printing Failed!";
pDocument->InvalidatePreview();
printMan = Windows::Graphics::Printing::PrintManager::GetForCurrentView();
printMan->PrintTaskRequested -= printTaskRequestedEventToken;
isPrinting = false;
});
Dispatcher->RunAsync(Windows::UI::Core::CoreDispatcherPriority::Normal, callback);
}
else if (e->Completion == Windows::Graphics::Printing::PrintTaskCompletion::Canceled)
{
auto callback = ref new Windows::UI::Core::DispatchedHandler([=]()
{
this->DataStreamWindow->Text = "Printing Cancelled!";
pDocument->InvalidatePreview();
printMan = Windows::Graphics::Printing::PrintManager::GetForCurrentView();
printMan->PrintTaskRequested -= printTaskRequestedEventToken;
isPrinting = false;
});
Dispatcher->RunAsync(Windows::UI::Core::CoreDispatcherPriority::Normal, callback);
}
pDocument->InvalidatePreview();
printMan = Windows::Graphics::Printing::PrintManager::GetForCurrentView();
printMan->PrintTaskRequested -= printTaskRequestedEventToken;
isPrinting = false;
});
}