Rick Strahl's Web Log

Rick Strahl's Weblog

Wind, waves, code and everything in between...
.NET • C# • Markdown • WPF • All Things Web

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Centering a WPF TreeViewItem in the TreeView ScrollViewer

Tuesday - Hood River, Oregon

One of the annoying features of the TreeView in WPF is the inability to easily select and make an item prominently visible. While there is `TreeView.BringIntoView()` it doesn't do a good job dropping the item that the very bottom (or top) of the viewport with no way to center. In this post I show a few helper methods that facilitate this process and a few related tasks with some useful TreeView helpers.

Unpacking Zip Folders into Windows Long File Paths

June 22, 2025 - Hood River, Oregon

Ah, long file paths bit me again today - this time with `ZipFile.ExtractToDirectory()` not unzipping long path files, even when specifying long path syntax for the output folder. In this post I briefly review Windows long path issues again, and describe what doesn't work and how to work around this particular problem. While specific to `ExtractToDirectory()` a similar approach might apply to other batch file based operations.

Adding Runtime NuGet Package Loading to an Application

1 comment

June 09, 2025 - Hood River, Oregon

It's not a common use case, but if you need need to dynamically add external code at runtime, NuGet packages are the most familiar way for developers to add that functionality besides old-school direct assembly loading. In this post I look at my LiveReloadServer local Web Server tool and how I integrated both external assembly loading and NuGet package support to allow extensibility for the Razor (and Markdown) scripting functionality of LiveReloadServer.

Distinguished Name on FileZilla Server Self-Generated Certs

June 06, 2025 - Hood River, Oregon

Renewing Filezilla certificates I've run into a 'huh?' moment a few times trying to renew the self-signed certificates for the Administration interface. Trying the obvious entries of putting in the DNS names results in an error that's not perplexingly is fixed by providing a full Common Name instead.

Configuring Microsoft.AI.Extensions with multiple providers

May 30, 2025 - Hood River, Oregon

Microsoft.Extensions.AI is the new base library for creating AI clients in an abstracted way. While the library does a great job with the abstraction of the interfaces it works with, the provider interfaces that create the intial abstractions like IChatClient are a lot less user friendly with hard to discover syntax based on extension methods and different syntax for each provider. In this post I review three providers and how to get them instantiated along with a small streaming example to use them.

Lazy Loading the Mermaid Diagram Library

May 10, 2025 - Maui, Hawaii

The Mermaid library is a large beast, and if you're using it selectively in your Web content you probably want to make sure you don't load it unless you actually need it, due to it's download footprint and load time. If you're loading Mermaid with server only code it's pretty straight forward, but if you use it on the client there you may want to delay loading the library until you actually need to display a diagram.

WebView2: Waiting for Document Loaded

May 06, 2025 - Maui, Hawaii

WebBrowser loading is always async and the WebView2 control is no different - in fact it's more complex as there a number of events that need to be handled in order to properly handle loading the control. In this post I describe how you can create a simplified load checking routine, or use the Westwind.WebView library and WebViewHandler to wait on content and process document access using linear `await` syntax.

Avoiding WPF Image Control Local File Locking

April 28, 2025 - Maui, Hawaii

WPF locks local images when referenced via a Source attribute. In this post I discuss why this might be a problem and how you can work around it using native XAML and custom binding converter that provides a consolidated approach that includes image caching for better performance of reused images.

The Strong ARM of .NET: Wrestling with x64 and Arm64 Desktop App Deployment

1 comment

April 18, 2025 - Maui, Hawaii

.NET works great for cross-platform development making it easy to build apps that are cross-platform and cross-architecture specifically for x64 and Arm64. However, building a distributable application that can install and run out of box on both of these platforms, that's a bit more effort. In this post I discuss some of the gotchas and how to work around them to distribute apps that run out of the gate on both platforms.

Using Windows.Media SpeechRecognition in WPF

March 24, 2025 - Maui, Hawaii

Windows has a pretty capable SpeechRecognition engine built-in via Windows Media services. In .NET these features are accessible via the Windows SDK (WinSdk) that expose these Windows features to .NET applications. In this post I discuss how you can integrate these features into a WPF application, and discuss some of the pitfalls along the way that you have to watch out for related to the SDK integration 'features'.

Making Html Input Controls Truly ReadOnly

5 comments

March 14, 2025 - Maui, Hawaii

A discussion of how to show readonly controls in user interface and ensuring that they are not UI activated. This post discusses readonly and disabled behavior and how you can make readonly behave better if you choose to use it over disabled.

Accessing Windows Settings Dialogs from Code via Shell Commands

March 13, 2025 - Maui, Hawaii

Windows has support for an `ms-setting:` Protocol Handler/Uri Scheme that allows you to directly open most Windows settings dialogs directly via simple Url based shell commands.

Resolving Paths To Server Relative Paths in .NET Code

March 08, 2025 - Maui, Hawaii

ASP.NET Core has support for resolving Urls in Controllers and Razor Pages via embedded `~/` links in Views and via `Url.Content()`. But, these features are tied to Controllers or Razor Pages - what if you need to resolve Urls elsewhere, in middleware or even inside of business logic? In this post I describe how you can build a couple of helpers that are more flexible and also provide some additional functionality of resolving site root and relative paths to full site root paths.

Inline Confirmations in JavaScript UI

2 comments

February 26, 2025 - Maui, Hawaii

Confirmation dialogs or modal popups can be annoying in HTML applications. What if you could instead use an inline UI to confirm an operation? In this post I describe a simple way you can use an inline UI to confirm an operation that can be easily implemented with a few lines of code and a couple of binding directives.

Retrieving Images from the Clipboard Reliably in WPF Revisited

February 21, 2025 - Maui, Hawaii

The WPF Clipboard is notoriously bad for retrieving image data, mainly because of the funky behavior of the ImageSource control into which clipboard data is loaded. WPF cuts a lot of corners when retrieving images and there are many scenarios where Clipboard.GetImage() either crashes or doesn't render the supposedly successfully retrieved image. In this post I review some of the challenges and how you can work around the retrieving an ImageSource with an intermediary load of a bitmap in between to provide reliable image retrieval from the clipboard in WPF.

Comparing Raw ASP.NET Request Throughput across Versions: 8.0 to 9.0 Edition

January 19, 2025 - Maui, Hawaii

Once again I'm taking a look at the newish .NET release and how it compares to the previous release - this time .NET 9.0 from .NET 8.0. I'll run my simple load tests to compare performance and also discuss a number of anecdotes from running .NET 9.0 in production apps for the last couple of months.

Back to Basics: Using the Parallel Library to Massively Boost Loop Performance

8 comments

December 27, 2024 - Maui, Hawaii

I recently had another occasion to add Parallel.ForEachAsync() into an application to improve performance of an Http look up operation drastically. When I tweeted a note on X there was quite a bit of response, so I thought I follow up and discuss Parallel use in this use case and when it makes sense to use Parallel in applications.

Getting the Current TabItem when the Tab is not selected in WPF

3 comments

November 08, 2024 - Hood River, Oregon

There's no direct support in WPF to find the control that the mouse is hovering over in Items controls like the TabControl, so if you need to bring up context sensitive information like a context menu or tooltip it takes a little extra effort to get the correct item to work with in this case ContextMenuOpening.

Using SQL Server on Windows ARM

17 comments

October 24, 2024 - Hood River, Oregon

I recently got a SnapDragon X Elite ARM device to play with and while I've been impressed with all things that work very well on it, one thing did not install easily: SQL Server. There's no ARM version of SQL Server and the x64 versions don't run on ARM devices. Docker images are also amd64 so that didn't work well either. Turns out you can use LocalDb onin emulation mode, but setting it up is anything but intuitive. In this post I discuss how to get SQL Server to run on a Windows ARM device.

Getting the ASP.NET Core Server Hosting Urls at Startup and in Requests

4 comments

September 03, 2024 - Hood River, Oregon

Ever need to retrieve an ASP.NET application's hosting Urls? There are million ways to set these URLs but there's no easy fixed location where you can pick the addresses up from. Instead you have to go through a bit of a dance, and use one of two approaches depending on whether you need the addresses during startup or inside of a request.

Nuking Local Nuget Package Sources to show newly Published Packages

1 comment

August 04, 2024 - Hood River, Oregon

Every once in while when I publish a NuGet package and then try to use the published package in another project I end up with a situation where the new package simply is not recognized. Most of the time it shows up after a few minutes, but on more than a few occasions I've stuck waiting for quite a while waiting for the package cache to refresh. Luckily there's a way to nuke the cache and force Nuget to re-read local packages and while that is the nuclear option that requires downloading a lot of packages it works to make your project compile - right now!

Create a .NET PlantUML Markdown Render Extension

2 comments

July 29, 2024 - Hood River, Oregon

PlantUML is a Web based diagramming markup language that can be used to create diagrams using text descriptions that are rendered into images via a PlantUML server. In this post I describe how you can integrate PlantUML image rendering into your .NET application, specifically from a Markdown rendering perspective as Markdown documents are the most common mechanism that PlantUML output is delivered.

Back to Basics: Await a Task with a Timeout

8 comments

July 25, 2024 - Hood River, Oregon

Sometimes it's useful to call async methods and be able to stop waiting after a given timeout period. Unfortunately there's no native support on Task to provide this. In this short post I show how you can simulate timeouts and provide a couple of helper methods to make the process generically available.

Work around the WebView2 NavigateToString() 2mb Size Limit

4 comments

July 22, 2024 - Hood River, Oregon

The WebView2 control's NavigateToString() method has a limit for the string size of 2mb, which can be a problem especially for HTML pages with embedded content. In this post I'll describe how this problem can show up and show a couple of ways to work around the issue.

Dealing with Platform Specific Classes and Methods in CrossPlatform .NET

July 18, 2024 - Hood River, Oregon

If you deal with old .NET library code that is sprinkled with some Windows specific code in places you've likely run into places where the Windows specific code is throwing up unwanted compiler warnings. Sometimes that matters, but often times these warnings are annoyances as these methods are highly unlikely to get called from x-platform code. In this post I describe some annoyances, how you can work around them and eventually fix the issues without throwing everything out the window.

C# Version String Formatting

9 comments

June 13, 2024 - Hood River, Oregon

I'm tired of trying to format versions for user facing interfaces after fumbling with it again and again. In this short post I show a small helper extension method that lets you configure how to form user friendly version strings to display to end users.

Mime Base64 is a Thing?

3 comments

May 26, 2024 - Hood River, Oregon

Ran into an old legacy application recently that required that attached data was preformatted to Mime Base64 which I never even heard of before. Turns out it's a 'url-safe' version of base64 that replaces certain characters that can be present in base64 with 'safe' characters. In this short post I show a small helper that handles several Base64 Mime operations.

Speed up your Start Menu by disabling Web Search

2 comments

May 03, 2024 - Hood River, Oregon

If you're like me, you've probably cursed the Windows Start menu from time to time, when it's either very slow to pop up, or in some instances fails to pop up at all when you press the Windows key. This simple tip can drastically improve performance of your Windows Start Menu by simply disabling Web search.

ASP.NET Core Hosting Module with Shadow Copy Not Starting: Separate your Shadow Copy Folders!

4 comments

April 28, 2024 - Hood River, Oregon

I recently ran into a major failure related to Shadow Copying for an ASP.NET Web app on IIS which was caused by corruption of the Shadow Copy directories. The app starts with the dreaded white ANCM Error page and event log entries that point at missing application folders. It turns out that this is caused by interference of multiple applications using the same shadow copy folder. In this post I describe the problem and how to work around it.

Programmatic Html to PDF Generation using the WebView2 Control with .NET

11 comments

March 26, 2024 - Maui, Hawaii

In this post I describe how to use the Microsoft WebView2 control to automate HTML to PDF generation generically for any kind of Windows application, including services. We'll look at the WebView and it's printing functionality and some of the intricacies that are involved in hosting the WebView control outside of a desktop application context to provide unattended mode even in service context.

Comparing Raw ASP.NET Request Throughput across Versions

2 comments

March 08, 2024 - Maui, Hawaii

When I set up a new machine I usually use a small ASP.NET test project to get a feel of performance of the machine and when that happens I also take a moment to compare performance across recent versions of .NET to see how things are improving - and improved they have. Both due to the new hardware I'm using but also ASP.NET continues to bump up performance in every new version that comes out. In this post I describe a simple project with minimal do nothing requests to test the ASP,.NET pipeline locally and how to test these request as well as discussing the results.

Reading Raw ASP.NET Request.Body Multiple Times

4 comments

February 20, 2024 - Maui, Hawaii

Some time ago I wrote about accessing raw request body content in ASP.NET Core which ended up being one of the most popular posts on this blog. But I failed to mention one major caveat: By default Request.Body can only be read once. In this post I discuss why frequently when you need raw Request.Body access you actually need to read the body more than once, and you can enable that functionality and deal with the caveats of doing so.

Sharing Tab Missing in Windows 11 Folder Properties

1 comment

January 10, 2024 - Maui, Hawaii

For some unfathomable reason, Windows 11 has removed the Sharing Tab on the Explorer Properties Context menu by default. The Sharing Tab allows you to shared folders and drives for remote access. In this post I discuss how to get the Sharing Tab back and also touch on how to make sure your machine can actually accept remote connections so you can share your folders and drives.

Working around the WPF ImageSource Blues

2 comments

January 03, 2024 - Maui, Hawaii

The WPF Image control and its ImageSource property can be problematic if you are loading a lot of images in a list. Depending on where you load images from, and how, you can very easily get bogged down with slow, blocking load operations, and memory leaks when the controls are released. In this post I describe a couple of specific problems I ran into loading a sizable list of images from files and show a few ways how to avoid the potential pitfalls related to ImageSource peculiarities.

Integrating OpenAI Image Generation into a .NET Application

December 21, 2023 - Maui, Hawaii

Image Generation AIs are proving to be very good at creating images that can be used for all sorts of purposes. In this article I discuss how you can integrate image generation right into your own .NET applications using the OpenAI REST API. In addition I'll show how you can integrated this functionality into a larger application and discuss some general thoughts on image AI usage based on some of the experiences from a developer/non-designer user perspective.

Embedding a minimal ASP.NET Web Server into a Desktop Application

3 comments

November 27, 2023 - Maui, Hawaii

Did you ever need to embed a Web Server into a non-Web application? In this post I describe how you can use host ASP.NET in a non-Web application and specifically in a WPF desktop app. What do you need, how is it different and some of the issues that you need to consider if you want to use ASP.NET in your non-Web applications.

Save Files With Elevated Permissions on UnauthorizedAccessException

November 03, 2023 - Maui, Hawaii

If you have an application that generically allows you to edit and save files, you might on rare occasions need to save files in locations that where a regular user account does not have permissions to save. Rather than failing wouldn't it be nice to let the user know and optionally allow saving with elevated permissions? In this post I describe the workflow and implementation on how to do just that.

Caching your WebView Environment to manage multiple WebView2 Controls

2 comments

October 31, 2023 - Maui, Hawaii

I've been struggling with rare WebView initialization errors in one of my applications, that have been difficult to debug and track down. After a lot of trial and error I discovered that the problem is related to WebView Environment instantiations that might be stepping on each other. In this post I describe the problem and a solution that involves creating a single WebView Environment and reusing it for all WebView initialization.

Rolling Forward to Major Versions in .NET

2 comments

October 02, 2023 - Hood River, Oregon

.NET Core has sophisticated policies that allows your applications that are compiled to specific versions of the .NET Runtime can roll forward to newer versions. You can specify what part of the version to roll forward and that generally works well, except for preview releases which require an extra step.

IIS Error 500.19 with ASP.NET Core Application

September 19, 2023 - Hood River, Oregon

Running on IIS locally is pretty rare, but if for some odd reason you decide to run IIS locally on your dev machine you might find yourself getting a 500.19 error which relates to an issue in the web.config configuration. The solution is simple enough: Make sure the ASP.NET Core Hosting Module is installed. In this post I describe in more detail what the problem is and why you need a seemingly superfluous extra install to get IIS and ASP.NET Core to cooperate on local dev machine.

Dotnet Tool Component not found on the Mac

September 11, 2023 - Hood River, Oregon

I've run into this problem a few times: I install a new Mac OS and then install the .NET SDK. A bit later I install a dotnet tool using `dotnet tool install -g` and then try to run it, only to find out that the SDK is not able find it. This post is a note to self on how to fix the pathing for .NET tools to be found correctly and to be able to run your dotnet tools.

Map Physical Paths with an HttpContext.MapPath() Extension Method in ASP.NET

1 comment

August 15, 2023 - Hood River, Oregon

ASP.NET Core doesn't have a Server.MapPath() method as classic ASP.NET had, and getting at the root path in Core is a little bit more involved than in those older versions. In this post I describe how to find the application Content and Web root folders and describe a MapPath() helper that simulates the old behavior.

A WPF Statusbar Control

1 comment

August 08, 2023 - Hood River, Oregon

Statusbar controls are boring, but because of the way that they are used there are a number of caveats like ensuring the UI updates even in linear code, allowing for timeouts of status messages and resetting to default, and to provide some visual clues to draw attention to the status messages displayed. In this post I talk about a custom status bar control and helper that make it super easy to use a new status bar control or attach additional functionality to an existing status bar.

Getting the .NET Desktop Runtime Installed with a Custom Runtime Checker and Installer

June 21, 2023 - Hood River, Oregon

I've recently moved my Markdown Monster Desktop Application to .NET 7.0 and I had to make a decision on how to get the Runtime installed or packaged with my application. In this post I review the different deployment modes, the plus's and cons and the solution I ended up with which was to build a custom install wrapper that can check and install the runtime if not already present from an Installer or interactively.,

Getting .NET Library Projects to Output Dependent Assemblies

May 29, 2023 - Hood River, Oregon

Recent .NET Core versions have changed how .NET Core Library projects output dependencies into the build folder. The new behavior doesn't output depdencies, unlike full framework .NET projects which always automatically dumped dependencies into the build output folder. This isn't a common requirement, but when you need it, the options are sufficiently obscure and this post discusses how you can make your dependencies output into the build folder

Implementing Two-Factor Auth using an Authenticator App in ASP.NET

8 comments

May 17, 2023 - Hood River, Oregon

Two factor authentication using Authenticator apps is getting more popular. One advantage of Authenticator 2FA is that you don't need to use a service nor do users have to provide additional bits of personal information. It's easy to implement, doesn't cost anything and also very secure as it uses one-time codes that can't easily be corrupted short of physical take over of a device. In this article I describe how Authenticator based 2FA works in the context of an application without using ASP.NET Identity.

Removing the IIS Server Request Header from ASP.NET Core Apps (any version)

4 comments

May 08, 2023 - Maui, Hawaii

ASP.NET Core applications that run on IIS as InProcess output an Server name for IIS into the HTTP headers. If you want to remove the server header, you'll find that the process for IIS is different than for the internally created Kestrel header and you can't use the same approach to remove the header as with Kestrel applications. In this post I discuss why the header behaves differently in IIS and how to remove it regardless of ASP.NET version.

Sending and Receiving GMail Email Attachments that contain Code or Binaries

5 comments

April 30, 2023 - Maui, Hawaii

As a developer, you're likely to occasionally send an email with attachments that are either code or binary executable files either as straight files or in a zipped up collection of code or binary files. You'll find that you can't actually send certain types of files or even files embedded in archives and even encrypted archives as most mail servers these days scan file content both before sending and when receiving email. In this post I discuss what works and what doesn't and how you can work around those files that don't work. It ain't pretty...

Setting an Absolute Output Path for .NET SDK Projects

1 comment

April 21, 2023 - Maui, Hawaii

By default .NET SDK project dump their final build output into a deeply nested folder structure that describes the build configuration, target, platform and sometimes additional package folders. While that's useful especially for multi-targeted projects. Sometimes you just want your output to go to specific folder without all that noise. In this short post I show you what you need to set in your project file to put your files exactly where you tell them to,

Preventing iOS Textbox Auto Zooming and ViewPort Sizing

6 comments

April 17, 2023 - Maui, Hawaii

If you've build mobile Web applications that need to run on iOS Safari and on an iPhone you might have run into the problem of input fields 'auto-zooming' the display when the input field and popup keyboard get focus. The view zooms and doesn't return back to the unzoomed even after exiting the input field. In this post I describe why this happens in some scenarios, and a couple of ways you can work around this annoying iOS Web browser behavior.