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Add BackgroundImage with EPPlus only allows path but cannot get path in Blazor WASM

This may not be 100% an EPPlus issue, but since it is Blazor WASM it appears I cannot get the file path to a static image in the wwwroot/images folder. I can get the url and paste it into a browser and that works, even adding that same path to the src attribute of an img works, neither of those helps me.
FYI "background" in this context means a watermark.
It appears that the EPPlus dev team only wants a drive path the file (ex. C:\SomeFolder\SomeFile.png), and I am not seeing how to get that within Blazor WASM. I can get the bytes of the file in c# and even a stream, but no direct path.
My code is the following:
using (var package = new ExcelPackage(fileName))
{
var sheet = package.Workbook.Worksheets.Add(exportModel.OSCode);
sheet.BackgroundImage.SetFromFile("https://localhost:44303/images/Draft.png");
...
}
This returns an exception:
Unhandled exception rendering component: Can't find file /https:/localhost:44303/images/Draft.png
Noticing that leading / I even tried:
sheet.BackgroundImage.SetFromFile("images/Draft.png");
Which returned the same error:
Unhandled exception rendering component: Can't find file /images/Draft.png
So, I am perhaps needing 1 of 2 possible answers:
A way to get a local drive path to the file so the .SetFromFile method is not going to error.
To have a way to set that BackgroundImage property with a byte array or stream of the image. There is this property BackgroundImage.Image but it is readonly.

Thanks to a slap in the face from #Panagiotis-Kanavos I wound up taking the processing out of the client and moving it to the server. With that, I was able to use Static Files to add the watermark with relatively little pain.
In case anyone may need the full solution (which I always find helpful) here it is:
Here is the code within the button click on the Blazor component or page:
private async Task GenerateFile(bool isFinal)
{
...
var fileStream = await excelExportService.ProgramMap(exportModel);
var fileName = "SomeFileName.xlsx";
using var streamRef = new DotNetStreamReference(stream: fileStream);
await jsRuntime.InvokeVoidAsync("downloadFileFromStream", fileName, streamRef);
}
That calls a client-side service that really just passes control over to the server:
public class ExcelExportService : IExcelExportService
{
private const string baseUri = "api/excel-export";
private readonly IHttpService httpService;
public ExcelExportService(IHttpService httpService)
{
this.httpService = httpService;
}
public async Task<Stream> ProgramMap(ProgramMapExportModel exportModel)
{
return await httpService.PostAsJsonForStreamAsync<ProgramMapExportModel>($"{baseUri}/program-map", exportModel);
}
}
Here is the server-side controller that catches the call from the client:
[Route("api/excel-export")]
[ApiController]
public class ExcelExportController : ControllerBase
{
private readonly ExcelExportService excelExportService;
public ExcelExportController(ExcelExportService excelExportService)
{
this.excelExportService = excelExportService;
}
[HttpPost]
[Route("program-map")]
public async Task<Stream> ProgramMap([FromBody] ProgramMapExportModel exportModel)
{
return await excelExportService.ProgramMap(exportModel);
}
}
And that in-turn calls the server-side service where the magic happens:
public async Task<Stream> ProgramMap(ProgramMapExportModel exportModel)
{
var result = new MemoryStream();
ExcelPackage.LicenseContext = LicenseContext.Commercial;
var fileName = #$"Gets Overwritten";
using (var package = new ExcelPackage(fileName))
{
var sheet = package.Workbook.Worksheets.Add(exportModel.OSCode);
if (!exportModel.IsFinal)
{
var pathToDraftImage = #$"{Directory.GetCurrentDirectory()}\StaticFiles\Images\Draft.png";
sheet.BackgroundImage.SetFromFile(pathToDraftImage);
}
...
sheet.Cells.AutoFitColumns();
package.SaveAs(result);
}
result.Position = 0; // Without this, data does not get written
return result;
}
For some reason, this next method was not needed when doing this on the client-side but now that it is back here, I had to add a method that returned a stream specifically and used the ReadAsStreamAsync instead of ReadAsJsonAsync:
public async Task<Stream> PostAsJsonForStreamAsync<TValue>(string requestUri, TValue value, CancellationToken cancellationToken = default)
{
Stream result = default;
var responseMessage = await httpClient.PostAsJsonAsync(requestUri, value, cancellationToken);
try
{
result = await responseMessage.Content.ReadAsStreamAsync(cancellationToken: cancellationToken);
}
catch (HttpRequestException e)
{
...
}
return result;
}
Lastly, in order for it to give the end-user a download link, this was used (taken from the Microsoft Docs):
window.downloadFileFromStream = async (fileName, contentStreamReference) => {
const arrayBuffer = await contentStreamReference.arrayBuffer();
const blob = new Blob([arrayBuffer]);
const url = URL.createObjectURL(blob);
const anchorElement = document.createElement("a");
anchorElement.href = url;
anchorElement.download = fileName ?? "";
anchorElement.click();
anchorElement.remove();
URL.revokeObjectURL(url);
}

Windows 10 Iot Core app crashes if I try to open a PWM pin

I want to open a PWM pin to my buzzer. But If I try to call the pwmController.OpenPin(6) method, the app crashes with an System.Runtime.InteropServices.SEHException.
I had already double checked the sample sources like the ms-iot-samples. But I cannot see what my problems are.
An idea was that some permissions are missing, but if I try to add for exmaple <iot:Capability Name="lowLevelDevices" />, I cannot longer build the application.
Source
private PwmPin buzzerPin;
private PwmController pwmController;
public RainbowHAT()
{
// ... do something else
InitAsync();
}
private async void InitAsync()
{
Logger.Log(this, "Init");
// Setup PWM controller.
if (LightningProvider.IsLightningEnabled)
{
LowLevelDevicesController.DefaultProvider = LightningProvider.GetAggregateProvider();
}
var pwmControllers = await PwmController.GetControllersAsync(LightningPwmProvider.GetPwmProvider());
if (pwmControllers == null || pwmControllers.Count < 2)
{
throw new OperationCanceledException("Operation canceled due missing GPIO controller");
}
pwmController = pwmControllers[1];
pwmController.SetDesiredFrequency(50);
// Setup buzzer
buzzerPin = pwmController.OpenPin(13); <-- CRASH
buzzerPin.SetActiveDutyCyclePercentage(0.05);
buzzerPin.Start();
}
I also tried the following tip to reduce the min required Windows version, but this does not help, too.

PWM Controller needs Lightning support. So you need to set the controller driver as Direct Memory Mapped Driver. Here is a sample about PWM on Raspberry Pi.
You also need to modify the code as following:
private async void InitAsync()
{
Logger.Log(this, "Init");
// Setup PWM controller.
if (LightningProvider.IsLightningEnabled)
{
var pwmControllers = await PwmController.GetControllersAsync(LightningPwmProvider.GetPwmProvider());
if (pwmControllers == null || pwmControllers.Count < 2)
{
throw new OperationCanceledException("Operation canceled due missing GPIO controller");
}
pwmController = pwmControllers[1];
pwmController.SetDesiredFrequency(50);
// Setup buzzer
buzzerPin = pwmController.OpenPin(13);
buzzerPin.SetActiveDutyCyclePercentage(0.05);
buzzerPin.Start();
}
}

CefSharp how to rename and embed BrowserSubProcess.exe

iam quite desperate here. I couldn't find any example code for this in C#.
I want to rename BrowserSubProcess.exe and i want it to embed my main exe, if possible.
I am aware of this solution;
https://github.com/cefsharp/CefSharp/issues/1149#issuecomment-225547869
Rename CefSharp.BrowserSubprocess winforms
but i couldn't implemented it. I need sample program or code to understand. I hope #amaitland will see this and helps me.

I embed the BrowserSubProcess Program.cs to my Program.cs so it is embedded now.
static class Program
{
/// <summary>
/// The main entry point for the application.
/// </summary>
[STAThread]
static void Main(string[] args)
{
if (args.Count() < 5)
{
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new LoginForm());
}
else
{
MyBrowserSubProcess(args);
}
}
static int MyBrowserSubProcess(string[] args)
{
Debug.WriteLine("BrowserSubprocess starting up with command line: " + String.Join("\n", args));
SubProcess.EnableHighDPISupport();
int result;
var type = args.GetArgumentValue(CefSharpArguments.SubProcessTypeArgument);
var parentProcessId = -1;
// The Crashpad Handler doesn't have any HostProcessIdArgument, so we must not try to
// parse it lest we want an ArgumentNullException.
if (type != "crashpad-handler")
{
parentProcessId = int.Parse(args.GetArgumentValue(CefSharpArguments.HostProcessIdArgument));
if (args.HasArgument(CefSharpArguments.ExitIfParentProcessClosed))
{
Task.Factory.StartNew(() => AwaitParentProcessExit(parentProcessId), TaskCreationOptions.LongRunning);
}
}
// Use our custom subProcess provides features like EvaluateJavascript
if (type == "renderer")
{
var wcfEnabled = args.HasArgument(CefSharpArguments.WcfEnabledArgument);
var subProcess = wcfEnabled ? new WcfEnabledSubProcess(parentProcessId, args) : new SubProcess(args);
using (subProcess)
{
result = subProcess.Run();
}
}
else
{
result = SubProcess.ExecuteProcess();
}
Debug.WriteLine("BrowserSubprocess shutting down.");
return result;
}
private static async void AwaitParentProcessExit(int parentProcessId)
{
try
{
var parentProcess = Process.GetProcessById(parentProcessId);
parentProcess.WaitForExit();
}
catch (Exception e)
{
//main process probably died already
Debug.WriteLine(e);
}
await Task.Delay(1000); //wait a bit before exiting
Debug.WriteLine("BrowserSubprocess shutting down forcibly.");
Environment.Exit(0);
}
}
And my BrowserSubprocessPath is my main exe.
settings.BrowserSubprocessPath = System.AppDomain.CurrentDomain.FriendlyName;

I finally managed to rename this sub process! Haven't found any solution how to do it through the CefSharp API, but found my own worked solution.
So, In your code that uses CefSharp add one setting to the Cef Settings, before Cef.Initialize()
using CefSharp;
using CefSharp.Wpf;
using System.IO;
using System.Reflection;
using System.Windows;
public App()
{
var settings = new CefSettings
{
BrowserSubprocessPath = Path.Combine(GetAppPath(), $#"runtimes\win-x64\native{ GetAppName() }.exe")
};
Cef.InitializeAsync(settings);
}
private static string GetAppPath()
{
return new FileInfo(Assembly.GetExecutingAssembly().Location).DirectoryName;
}
private static string GetAppName()
{
return Assembly.GetExecutingAssembly().GetName().Name;
}
After this go to the bin\Debug\net6.0-windows\runtimes\win-x64\native\ and rename CefSharp.BrowserSubprocess.exe to Name you want to use.
Done. Now it will use this file with custom name you need.
P.S. For the auto name set you can always use Post-Build event with command to rename the file after project built and set the name same as your assembly name. I use this approach for my needs.

UWP FolderPicker window opens but is frozen

The basic idea is I have a UWP app pulling user data from a json file saved locally, and at various times it may pull that full list of objects from the file, but it always checks that the user has set the location for the data, and if not, prompts via a FolderPicker for the user to set the location. In this case, I have combobox that helps filter the objects after selecting a criteria and entering text.
Here's the call stack:
UWPMiniatures.exe!UWPMiniatures.Data.MiniDAL.SetSaveFolder() Line 98 C# Symbols loaded.
UWPMiniatures.exe!UWPMiniatures.Data.MiniDAL.LoadAllAsync() Line 71 C# Symbols loaded.
UWPMiniatures.exe!UWPMiniatures.Data.MiniDataService.Load() Line 36 C# Symbols loaded.
UWPMiniatures.exe!UWPMiniatures.MainPage.FilterGridView(string submission) Line 156 C# Symbols loaded.
UWPMiniatures.exe!UWPMiniatures.MainPage.SearchIcon_Click(object sender, Windows.UI.Xaml.RoutedEventArgs e) Line 95 C# Symbols loaded.
So, working backwords, the FolderPicker is being called here:
private async Task SetSaveFolder()
{
if(!StorageApplicationPermissions.FutureAccessList.ContainsItem("PickedFolderToken"))
{
FolderPicker folderPicker = new FolderPicker();
folderPicker.SuggestedStartLocation = PickerLocationId.Desktop;
folderPicker.FileTypeFilter.Add("*");
folderPicker.CommitButtonText = "Pick A Folder To Save Your Data";
StorageFolder folder = await folderPicker.PickSingleFolderAsync();
if (folder != null)
{
// Application now has read/write access to all contents in the picked folder (including other sub-folder contents)
StorageApplicationPermissions.FutureAccessList.AddOrReplace("PickedFolderToken", folder);
var userFolder = await StorageApplicationPermissions.FutureAccessList.GetFolderAsync("PickedFolderToken");
var file = await userFolder.CreateFileAsync("AllMinisList.json",CreationCollisionOption.OpenIfExists);
var imagefolder = await userFolder.CreateFolderAsync("Images");
}
}
}
The folder picker dialog opens, with a blinking cursor next to Folder:, but nothing happens when I click anywhere, nor can i type in Folder: textbox. Now, putting this identical code in a new project and calling it in response to a click event works fine: Dialog opens, I make a new folder or pick an existing one, it gets added to future access list. Not sure how to else to troubleshoot this but the problem seems to lie out side the actual code calling the FolderPicker.
here is the code for the other calling function
private void SearchIcon_Click(object sender, RoutedEventArgs e)
{
FilterGridView(SearchTextBox.Text);
SearchTextBox.Text = "";
}
private async void FilterGridView(string submission)
{
var selected = FilterComboBox.SelectedValue;
miniDS = new MiniDataService();
if(selected.ToString()=="All")
{
MiniList.Clear();
List<Miniature> fullList = await miniDS.Load();
fullList.ForEach(m => MiniList.Add(m));
}
else if (selected.ToString() == "Quantity")
{
List<Miniature> fullList = await miniDS.Load();
var templist = fullList.AsQueryable()
.Where($"{selected} = #0", submission); ;
MiniList.Clear();
templist.ToList<Miniature>()
.ForEach(m => MiniList.Add(m));
}
else
{
List<Miniature> fullList = await miniDS.Load();
var templist = fullList.AsQueryable()
.Where($"{selected}.StartsWith(#0)", submission);
MiniList.Clear();
templist.ToList<Miniature>()
.ForEach(m => MiniList.Add(m));
}
}
MiniDataService and MiniDal don't do much here other than pass the call along.
Any ideas where I can look to troubleshoot this?
UPDATE: Some additional info, I copied the code from SetSaveFolder() directly into a new event handler for a button, clicked it, I get FolderPicker, functions perfectly. But thats not at all the functionality needed. I need it to be called, directly or indirectly from my Data Service. So here's where its created:
public sealed partial class MainPage : Page
{
/// <summary>
/// MiniList is the list of minis currently being displayed
/// </summary>
private ObservableCollection<Miniature> MiniList;
private MiniDataService miniDS;
private List<string> FilterComboList;
private Miniature NewMini;
public MainPage()
{
this.InitializeComponent();
miniDS = new MiniDataService();
MiniList = new ObservableCollection<Miniature>();
FilterComboList = PopulateFilterCombo();
NewMini = new Miniature();
MyFrame.Navigate(typeof(MiniListPage), MiniList);
}
...
So the problem seems to have something to do with the fact that FolderPicker is being called from this "static" object. Is this a thread issue? I thought in UWP I am always on the UI threadm and since at the top level an event handler is calling folderPicker I can't understand why the UI seems locked.

So i think I figured it out, though I have no idea why this happened. If anyone can clue me in, id appreciate it.
So from the call List<Miniature> fullList = await miniDS.Load();
Here's that method:
public async Task<List<Miniature>> Load()
{
return await minidal.LoadAllAsync();
}
public async Task<List<Miniature>> LoadAllAsync()
{
List<Miniature> MiniCollection = new List<Miniature>();
if (StorageApplicationPermissions.FutureAccessList.ContainsItem("PickedFolderToken"))
{
try
{
var userFolder = await StorageApplicationPermissions.FutureAccessList.GetFolderAsync("PickedFolderToken");
var file = await userFolder.GetFileAsync("AllMinisList.json");
var data = await file.OpenReadAsync();
using (StreamReader stream = new StreamReader(data.AsStream()))
{
string text = stream.ReadToEnd();
MiniCollection = JsonConvert.DeserializeObject<List<Miniature>>(text);
}
}
catch(Exception e)
{
throw e;
}
}
else
{
SetSaveFolder().Wait();
return MiniCollection;
}
return MiniCollection;
}
So the problem was right here:
SetSaveFolder().Wait();
When I replace that with
await SetSaveFolder();
it works fine. I can click in the folderPicker, and it does what it's supposed to. I guess I though .Wait() was used when you aren't return anything other than but it seems there is more too it than that!

C# TPL: Possible to restart a failed Pipeline at an arbitrary step?

I have a data processing job that consists of about 20 sequential steps. The steps all fall under one of three categories:
do some file manipulation
import / export data from a database
make a call to a 3rd party web API
I've refactored the code from one long, awful looking method to a pipeline pattern, using examples here and here. All of the steps are TransformBlock, such as
var stepThirteenPostToWebApi = new TransformBlock<FileInfo, System.Guid>(async csv =>
{
dynamic task = await ApiUtils.SubmitData(csv.FullName);
return task.guid;
});
The code works most of the time, but occasionally a step in the pipeline fails for whatever reason - let's say a corrupt file can't be read in step 6 of 20 (just an example - any step could fail). The pipeline stops running further tasks, as it should.
However, the 3rd party web API introduces a challenge - we are charged for each job we initiate whether we execute all 20 steps or just the first one.
I would like to be able to fix whatever went wrong in the problem step (again, for our example let's say I fix the corrupt file in step 6 of 20), then pick back up at step 6. The 3rd party web API has a GUID for each job, and is asynchronous, so that should be fine - after the problem is fixed, it will happily let a job resume with remaining steps.
My question: Is it possible (and if so advisable?) to design a pipeline that could begin at any step, assuming the pre-requisites for that step were valid?
It would look something like:
job fails on step 6 and logs step 5 as the last successful step
a human comes along and fixes whatever caused step 6 to fail
a new pipeline is started at step 6
I realize a brute-force way would be to have StartAtStep2(), StartAtStep3(), StartAtStep4() methods. That doesn't seem like a good design, but I'm a bit new at this pattern so maybe that's acceptable.

The brute force way is not that bad, for example your above code would just need to be
bool StartAtStepThirteen(FileInfo csv)
{
return stepThirteenPostToWebApi.Post(csv);
}
The setup of the chain should be a separate method than the executing of the chain. You should save stepThirteenPostToWebApi in a class level variable in a class that represent's the entire chain, the setup of the chain could be done in the class's constructor.
Here is a simple 3 step version of the process. When a error happens instead of faulting the task chain I log the error and pass null along the chain for invalid entries. You could make that log method raise a event and then the user can decide what to do with the bad entry.
public class WorkChain
{
private readonly TransformBlock<string, FileInfo> stepOneGetFileInfo;
private readonly TransformBlock<FileInfo, System.Guid?> stepTwoPostToWebApi;
private readonly ActionBlock<System.Guid?> stepThreeDisplayIdToUser;
public WorkChain()
{
stepOneGetFileInfo = new TransformBlock<string, FileInfo>(new Func<string, FileInfo>(GetFileInfo));
stepTwoPostToWebApi = new TransformBlock<FileInfo, System.Guid?>(new Func<FileInfo, Task<Guid?>>(PostToWebApi));
stepThreeDisplayIdToUser = new ActionBlock<System.Guid?>(new Action<Guid?>(DisplayIdToUser));
stepOneGetFileInfo.LinkTo(stepTwoPostToWebApi, new DataflowLinkOptions() {PropagateCompletion = true});
stepTwoPostToWebApi.LinkTo(stepThreeDisplayIdToUser, new DataflowLinkOptions() {PropagateCompletion = true});
}
public void PostToStepOne(string path)
{
bool result = stepOneGetFileInfo.Post(path);
if (!result)
{
throw new InvalidOperationException("Failed to post to stepOneGetFileInfo");
}
}
public void PostToStepTwo(FileInfo csv)
{
bool result = stepTwoPostToWebApi.Post(csv);
if (!result)
{
throw new InvalidOperationException("Failed to post to stepTwoPostToWebApi");
}
}
public void PostToStepThree(Guid id)
{
bool result = stepThreeDisplayIdToUser.Post(id);
if (!result)
{
throw new InvalidOperationException("Failed to post to stepThreeDisplayIdToUser");
}
}
public void CompleteAdding()
{
stepOneGetFileInfo.Complete();
}
public Task Completion { get { return stepThreeDisplayIdToUser.Completion; } }
private FileInfo GetFileInfo(string path)
{
try
{
return new FileInfo(path);
}
catch (Exception ex)
{
LogGetFileInfoError(ex, path);
return null;
}
}
private async Task<Guid?> PostToWebApi(FileInfo csv)
{
if (csv == null)
return null;
try
{
dynamic task = await ApiUtils.SubmitData(csv.FullName);
return task.guid;
}
catch (Exception ex)
{
LogPostToWebApiError(ex, csv);
return null;
}
}
private void DisplayIdToUser(Guid? obj)
{
if(obj == null)
return;
Console.WriteLine(obj.Value);
}
}