Rick Strahl's Weblog
Wind, waves, code and everything in between...
- The Markdown Editor for Windows
WebLog Posts in Category WPF
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Async and Async Void Event Handling in WPF
April 22, 2022 - Maui Time, Hawaii
When running WPF and WinForms applications with async operations, I've run into a number of issues with event handling 'hanging' the UI thread in unexpected ways, where the UI hangs until the mouse is moved or a key is pressed. A lot of times these issues are associated with events that fire async code, and in this post I take closer look at one scenario that can cause these hang ups along with a workaround that has proven useful in a number of occasions for me.
Using the WebView control to capture HTTP Request Content
August 18, 2021 - Hood River, Oregon
Need to capture requests when navigating the new Edge WebView2 control? The control supports this but the way that you do this is a little less obvious than you might be used to from other browser controls. Here's how to do it.
WebView and Modal Dialogs in WPF Async Code
August 16, 2021 - Hood River, Oregon
Another day another problem with the WebView control - this time dealing with certain Windows dialogs crashing the WebView control and making it unresponsive so that the control has to be reloaded or - more commonly the application has to be restarted.
Thoughts on Async/Await Conversion in a Desktop App
July 07, 2021 - Hood River, Oregon
I spent the last month or so working through Markdown Monster's code to switch from mostly sync code to async code. This change was forced on me by an Async Cascade triggered by a third party dependency of a component (the WebView2 control) and ended up requiring massive changes throughout the app. In this post I go over some of the issues I ran into converting from sync to async along with some thoughts on the pitfalls.
WebView2 Home and End Key Problems inside of WPF TabControl Containers
May 25, 2021 - Hood River, Oregon
Another day another WebView2 quirk to work around: This time running into issues with the WebView2 not processing Home and End keys properly as they are being hijacked by a parent TabControl and its TabNavigation keystroke handling.
WebView2: Forwarding Alt Keys to a Host WPF Window
April 15, 2021 - Maui, Hawaii
I've been puzzling over how to reliably integrate keyboard forwarding from the WebView2 control into WPF host forms. Unlike the IE WebBrowser control the WebView2 doesn't automatically forward Alt keys to the host form so special handling is required. In this post I describe why this is a problem and show the workaround to make this work.
January 26, 2021 - Maui, Hawaii
Taking the new Chromium WebView2 Control for a Spin in .NET - Part 1
January 14, 2021 - Maui, Hawaii
Window Activation Headaches in WPF
October 12, 2020 - Maui, Hawaii
Ran into a problem with properly activating a WPF when launching from Explorer and indirectly trying to activate an already running instance 'from within itself'. It seems simple, but windows focus-stealing restrictions can cause problems with actually getting focus into an application window. Here's how.
Wrestling with Clipboard Images in WPF
September 16, 2020 - Maui, Hawaii
Retrieving images from the clipboard with WPF seems so simple, but once you get into it you'll find that there are lots of problems with reliable image retrieval that works for all images. In this post I talk about the different issues you're likely to run into and one hacky but flexible solution to better image support by selectively sniffing image formats and using different clipboard retrievals based on the image format.
WPF Window Closing Errors
September 02, 2019 - Maui, Hawaii
I've recently had a large uptick of errors in my Markdown Monster logs that complain about `Cannot set Visibility to Visible or call Show, ShowDialog, Close, or WindowInteropHelper.EnsureHandle while a Window is closing`. This error can crop up with nested or parallel window closing operations, which might not always be obvious when they happen. I'll show some of the issues and the hacky by easy to implement work around.
First Steps in porting Markdown Monster WPF App to .NET Core 3.0
April 24, 2019 - Maui, Hawaii
I spent a good part of the day today getting Markdown Monster to run on .NET Core 3.0 and in this post I packaged up my notes into a lengthy post with how went through this process. It wasn't exactly quick to make this happen but MM has a few peculiarities that made this process a little bit more trying than it could have been. I'll summarize some thoughts at the end on both the process and the relevance of this process.
WPF Hanging in Infinite Rendering Loop
February 14, 2019 - Maui, Hawaii
Ran into a nasty WPF bug this week with Markdown Monster that caused MM to hang during startup in certain scenarios. Several users reported issues that I could not duplicate until I started playing around with my screen resolution and scaling. An obscure but insidious WPF bug can cause an application to go into an infinite loop which effectively locks up the application's UI and the app overall. Here's more info on what the problem is and how to work around it.
Creating a WPF ItemSource Length Filter Converter
June 23, 2018 - Hood River, Oregon
In this short post I show you you can create a simple Value Converter to limit the max number of items in an ItemsSource value binding in WPF.
WPF Slow Window Loading due to Invalid SpellChecking Dictionaries
September 25, 2017 - Maui, Hawaii
I ran into a nasty problem with spell checking on WPF, which caused any form that uses spell checking to load extremely slow. It turns out the problem was caused by errant entries in the global Windows dictionary key in the registry. This post describes the problem and how to find and fix your global Windows dictionary settings.
Updating Windows Applications and Installers for non-Admin Installation
July 17, 2017 - Hood River, OR
I recently updated Markdown Monster to run as a non-admin installation even when running the full installer. There have been many requests for this functionality and in this post I describe several of the updates required in order to make this work.
July 06, 2017 - Hood River, OR
Debouncing and Throttling Dispatcher Events
July 02, 2017 - Hood River, OR
In UI applications it's not uncommon for a number of UI events to fire more events than your application can handle. In order to limit the number of events it's often a good idea to throttle or 'debounce' events so that only a single event is fire for a given period. In this post I describe a Dispatcher based implementation for debouncing and throttling UI events in WPF applications.
Dragging and Dropping Images and Files into the Web Browser Control
March 10, 2017 - Maui, Hawaii
Dragging content into the Web Browser control and capturing the content dropped can be tricky. The Web Browser Control is based on Internet Explorer and is actually an ActiveX control hosted inside of a container and because of that is difficult to deal with. In this post I describe how you can get around this issue and still capture images and files dropped on the control and handle the drop operations.
Debugging the Web Browser Control with FireBug
March 08, 2017 - Maui, Hawaii
Video Rendering Issues for WPF Windows
February 13, 2017 - Maui, Hawaii
Recently I ran into a few reports of black screen of death rendering of Markdown Monster when starting up from a very few users of the application. They reported the screen just shows black, while actually being responsive to moving and showing menus etc. Also moving to another screen often fixes the problem. It turns out this is a hardware related issue with WPF with certain video hardware/monitor combinations. In this post I describe the problem and the workaround to get the application to render properly even on compromised hardware.
Faking out the .NET Runtime Version
January 09, 2017 - Maui, Hawaii
I've been struggling with DPI Scaling issues in WPF in Markdown Monster and .NET 4.6.2 has a few fixes that address the problems I've been working on. However, requiring 4.6.2 is a problem due to lowish adoption rates and skittishness about installing new versions of .NET. In this post I show a little hack that allows me to compile my app to .NET 4.6.2 but don't require user to have that version installed so those that have it can take advantage of the updates.
Downgrading a .NET Applications from 64 bit to 32 bit for the WebBrowser Control
December 23, 2016 - Maui, Hawaii
Recently while working on Markdown Monster I ran into some odd crashes and behaviors when interacting with the Web Browser control in this WPF application. It turns out that some of these inconsistent behaviors are apparently caused by running hte application in 64 bit mode. Switching to 32 bit mode has made the application and Web Browser interaction much more responsive and has stopped the nagging unexplainable crashes. In this post I look at 32 and 64 bit applications in .NET and outline some of the issues I ran into and how I fixed the problem by switching to building a 32 bit app.
WPF Rendering DUCE.Channel Crashes due to Image Loading
December 15, 2016 - Maui, Hawaii
I ran into a nasty WPF rendering bug that affected only a few select machines. Rendering problems in WPF can be terribly difificult to debug because there often is no additional information on what failed and the exceptions that occur are not trappable but fall back to application wide error handling. In this post I describe a specific failure caused by a 'bad' image WPF can't deal with and how I tracked it down and fixed it.
Capturing Zoom Operations in the WPF Web Browser Control
September 05, 2016 - Portland, Oregon
If you need to capture Zoom operations in the Web Browser control - either to avoid letting hte user zoom or to capture the zoom operation and take action on it - you need to dig into the Web Browser's DOM events to capture the scroll wheel and key events. In this post I describe how you can do just that by looking at an application that captures scrolling and rather than zooming adjusts the font size of the content.
Detecting and Setting Zoom Level in the WPF WebBrowser Control
August 22, 2016 - Reykjavik, Iceland
Zoom level detection in the Web Browser control is a pain and in this article I describe one approach I used to both capture the current Zoom level in order to adjust font sizes, and then also explicitly set the Zoom level in the Web Browser control of a WPF application.
Creating Single Instance WPF Applications that open multiple Files
May 13, 2016 - Maui, HI
If you're building document centric applications, Singleton style EXE applications are pretty common. Rather than creating new windows for each opened file, a more common scenario is to open new tabs in a single instance. In this post I'll describe how to create a WPF application that allows only a single instance to run and passes command line arguments passed in secondary instances to the primary instance and I'll describe some pitfalls that you might have to watch out for.
WPF Localization Guidance Paper Posted on CodePlex
July 01, 2009 - Hood River, Oregon
I’m happy to announce that my WPF Localization paper went live a couple of days ago on CodePlex. This document provides an overview of localization in .NET in general as well as specifically to WPF. It covers localization with the rigid LocBaml approach, as well as using Resx resources for binding using markup extensions and attached properties respectively.
WPF Bindings and CurrentCulture Formatting
June 14, 2009 - Hood River, Oregon
WPF doesn't apply the CurrentCulture to bindings by default, which is a little... unexpected to say the least. As it turns out there's an easy solution to this problem, but it does require using code to apply the culture specifically in every document.
Getting the App’s Startup Assembly in WPF Designer?
June 09, 2009 - Maui, Hawaii
I've run into a vexing problem with a Markup Extension for localization. In this extension I have the need to get a reference to the parent application (the WPF EXE basically) inside the WPF designer/Blend. Due to the runtime environment of the designer I've not been able to make this work short of running the markup extension in the same assembly as the main application.
Resx and BAML Resources in WPF
June 04, 2009 - Maui, Hawaii
Resource loading in WPF applications that mix BAML and Resx resources can be very confusing as BAML resources require that all BAML resources are stored in external satellite assemblies.
Rendering a WPF Container to Bitmap
September 10, 2007 - Hood River, Oregon
One of WPF's nicer features is its ability to render any visual into a bitmap easily, and so I thought I'd create a simple little tool that would create rounded corner bitmap bars with transparent backgrounds. It's actually quite easy to do, but I ran into a few pitfalls and inconsistencies that make WPF coding oh so much fun.
Hosting a WCF Service in a non-.NET Client
June 15, 2007 - Hood River, Oregon
I'm still screwing around Web Connection and trying out a quick proof of concept tonight and thought I'd share a few steps on how to host a WCF in a non .NET client via COM Interop client like Visual FoxPro. This article discusses WCF server and client creation in general terms and in addition covers the interop issues to make it work in these clients.
WPF: How hard could it be to get a SelectedItemTemplate?
May 23, 2007 - Hood River, Oregon
Here's a fun one to do in WPF. Say you have a ListBox or ListView that is databound and you want to get at the content of the data template used for binding of the items in the list. In my case I want to trigger an animation when the item is selected to indicate the change. It's quite easy to get a...
Fumblings and Thoughts on WPF DataBinding
May 20, 2007 - Hood River, Oregon
So I spent the evening today experimenting with databinding in WPF. Overall I'm very excited about that data binding capabilities in WPF which finally has produced a powerful and reasonably user friendly way to do data binding of just about any type to anything else. WPF makes this easily available...
WPF Experiments: Changing a Live Writer Plug-in to use WPF
May 14, 2007 - Hood River, Oregon
Ok so I had a little free time on my hands this weekend and was looking for a simple something to use WPF on. A few weeks back I'd been playing with an Justin Brown's Amazon book plug in for Live Writer, which is part of the Windows Live Writer Plugins on CodePlex. Back when I first looked at his...
Great WPF Book
April 22, 2007 - Maui, Hawaii
As I've mentioned off and on I've been boning up on WPF for about a month now. I'd though I'd pass on my thoughs on the book I've enjoyed reading and working through: Windows Presentation Foundation Unleashed (WPF) (Unleashed)by Adam Nathanpublished Dec. 2006Read more... This book rocks -...
Beyond HTML: Rich Internet Applications
April 15, 2007 - Maui, Hawaii
Rich Internet Applications (RIA) is a term used to describe non HTML based, low impact Internet applications. RIA’s typically run in the browser (although they don’t have to) and get their data from the Web server over HTTP. One of the big selling points of RIA’s is that they provide many of the...