WPF community is filled with so many passionate individuals with truly amazing experiences and this post aims to highlight what has been done in the dotnet/wpf repo in past few months and thanking the amazing people behind all this. We are really grateful for the contributors who have consistently worked towards improving WPF. Here is a quick recap of what was accomplished in the past few months in the dotnet/wpf repository.
Performance
WPF in .NET 7 ships with number of improvements in the areas not just limited to unnecessary boxing/unboxing, use of Span for string manipulation, better allocation/deallocation of objects, memory improvements, font rendering etc. but also code cleanup and making way for future readiness.
Boxing/Unboxing
Boxing and Unboxing are computationally expensive processes. When a value type is boxed, a new object must be allocated and constructed. To a lesser degree, the cast required for unboxing is also expensive computationally.
- Avoid boxing when setting DependencyObject properties (Thanks Ilya)
- Stop boxing WeakReferenceListEnumerator in PresentationSource use
- Reuse bool box objects in UncommonField.SetValue
- Stop boxing in Visual.SetDpiScaleVisualFlags
- Avoid enumerator boxing in XamlSchemaContext.UpdateNamespaceByUriList
- Avoid boxing list/array enumerator in CreateTextLSRuns
- Avoid boxing list enumerator in XamlObjectWriter.Logic_ConvertPositionalParamsToArgs
Allocations
The more objects allocated on the heap, more is GC overhead in reclaiming those object post their lifetimes. Reducing such allocations in memory lowers GC overhead.
- Avoid Hashtable-related allocations in AccessorTable
- Avoid Hashtable-related allocations in DataBindEngine
- Remove closure/delegate allocation in ItemContainerGenerator
- Avoid delegate allocation to call ListCollectionView.PrepareComparer
- Avoid unnecessary byte[] allocation in Baml2006Reader.Process_Header
- Avoid allocating
Stack<BranchNode>just to peek at it - Stop allocating unnecessary StringBuilders in ParsePropertyComments
- Avoid unnecessary StringBuilder reallocation in LookupAndSetLocalizabilityAttribute
- Avoid exceptional string allocation in StaticExtension.ProvideValue
- Remove unnecessary string and string[] allocations from MS.Internal.ContentType
- Remove some unnecessary StringBuilders
- Remove substring allocation from Baml2006Reader.Logic_GetFullXmlns
- Don’t allocate fallback name in XamlNamespace.GetXamlType unless it’s needed
- Avoid unnecessary enumerator allocations in XamlDirective.GetHashCode
Miscellaneous
- Avoid excessive calls to the PropertyValues index getter. (Thanks paulozemek)
- Harden events against race conditions (Thanks Bruno Martinez )
- Eliminate memory copy when reading font data (Thanks Bradley Grainger)
- Small performance improvement of PathParser (Thanks ThomasGoulet73)
- Use span slice instead of substring in AbbreviatedGeometryParser.ReadNumber
- Avoid unnecessary duplication of fields in NullableBooleanBoxes
- Change most non-generic sorts to be generic
- Some improvements to FrugalList
- Avoid unnecessary
Collection<T>wrapper in CombineSources - Avoid unnecessary
List<>wrapper in GetTextRunSpans
Special thanks to Stephen Toub for contributing many other performance fixes.
Accessibility
With a commitment to ensure WPF controls are accessible, below are the product improvements that made its way to WPF.
- WPF DataGrid/GridView column width can be changed using the keyboard shortcut ALT+left or right arrow key – Datagrid column width can be adjusted using keyboard shortcut Alt + Left arrow / Right arrow.
- Sort Datagrid Column by Keyboard F3 – Datagrid columms can now be sorted (if sorting is enabled for a column) using keyboard shortcut F3.
- Narrator announcement for Checkable Menuitems – Onscreen narrators can correctly announce the presence of checkable menuitems.
Bug fixes
While WPF remains fully supported and serviced on .NET Framework, most fixes and all new features will go only into .NET Core, where we have the opportunity to make bigger changes. Our community helped address some long-standing bugs in this release.
- FocusVisualStyle can’t be overwritten globally (Thanks Bastian Schmidt)
- CommandParameter invalidates CanExecute by miloush (Thanks Jan Kučera)
- Tooltip issues
- ContextMenu stops working if its owner is removed from the visual tree
- Fixes rounding error while glyphrun serialization
The above list is NOT exhaustive and many more bug fixes went thanks to our community contributors for their efforts in fixing them.
Infrastructure upgrades
One of the major areas for improvement voiced by community is the rate at which community contributions were accepted. With the below infrastructure upgrades, we intend to address the rate at which we accept community contributions.
| Title | Description |
|---|---|
| Test repository migration | WPF codebase has more than 30K integration tests. These tests ensure sanity of the build with various OS and .NET framework combination matrix. As part of open sourcing the test infrastructure, we aim at moving all the tests from internal to Github. This would also enable community to add their own tests to the test repo.
We have open-sourced most of the basic regression tests that enables the community contributors to run those tests locally and debug them, in case there’s an issue with any of the PR submissions . |
| Running basic tests on each incoming PR | Basic regression tests, (aka Daily Regression Tests or DRT(s)) that validates the basic behavior of controls, need to be run on each submitted PR to ensure that the changes do not cause any regressions. The end goal of this exercise is to make sure that we have a framework in place that allows running tests on incoming PRs. This would reduce the turn-around times on PRs, thereby increasing the velocity at which new changes / fixes can be merged into the repository.
We are now running these tests as a part of build on every incoming PR. In upcoming months, we plan to enhance these pipelines in terms of the reporting the status if test execution, to avoid manual lookup in logs for failures. |
Ongoing activities
- Tests repository migration still has a larger subset of tests that are yet to be ported.
- Enabling running the bigger suite of test cases on community submitted PRs which would improve the turnaround time for feedback on PRs.
- Clearing the backlog of PRs and issues.
Community
The community run-project started with the intent to enable developers in making big difference in shaping WPF going forward. To all the WPF developers, your work is invaluable. We’d like to thank the below contributors for their efforts in fixing long standing issues and contributing performance and functional improvements.
- lindexi
- Fix the stream do not be closed in ImageSourceTypeConverter
- Fix GetStreamCore in ContentFilePart
- Fix create BitmapDecoder with async file stream.
- Using the
Clonemethod to fast clone the array in StylusPoint - Using ArrayPool in RenderData
- Using
Array.Copyto make array copy faster in StylusPointCollection - Use pattern matching in TaskExtensions
-
- Small performance improvement of PathParser
- Use params and char overload
- Inline VerifyAccess
- Fix Invalid_IInputElement resource
- Disable Indeterminate animation when hiding ProgressBar
- Replace IsAssignableFrom with is in converters
- Use generic Marshal.StructureToPtr
- Migrate DPI awareness initialization to managed
- Use generic Marshal.PtrToStructure
Summary
We’d encourage you to try out WPF on .NET 7 and let us know how these improvements have helped. We are always looking for feedback on how to improve the product and look forward to your contributions. We would like to thank everyone that is committed to making WPF better as a product. Our goal is to continue improving WPF, while growing our community so that we can bring you the best developer experience possible. Your help and input is very much required. Whether that is through triaging issues, updating documentation, participating in discussions or writing code, we appreciate all of your help!
After all these years still not working in .NET7. When will this be solved? https://github.com/dotnet/wpf/issues/3546
(see https://github.com/dotnet/runtime/issues/78629 )
Hey WPF team, see: https://github.com/dotnet/wpf/discussions/6542#discussioncomment-4320804 and https://github.com/dotnet/runtime/issues/78629
We’ve been waiting since the first .net core release for some of the fixes.
We are getting frustrated and agry.
Thanks,
the WPF community.
16 years later and that nasty
and
bug has been fixed. Without a doubt the best change in .NET 7 for people using XAML styling/cleanup/reordering.
Please add windows 11 like ui option for us to truly make our apps shine, add new ui and ux from maui fluent ui
Hello,
Is there a bug in .NET 7 WPF, with the ItemsControl ?
The override of “PrepareContainerForItemOverride()” is only called for the first item in my CustomControl, deriving from ItemsControl.
When using .NET 6 WPF, it was called for every items.
Could anything has changed related to VirtualizingPanel.IsVirtualizingWhenGrouping ?
Thank you
There is a commit pertaining to ItemsControl, but that is performance related. Could you please register an issue with the sample repro at wpf github repo?
https://github.com/dotnet/wpf/
A Sample could be difficult to create.
What I can see is that attached property VirtualizingPanel.IsVirtualizingWhenGrouping should be set to false when VirtualizingStackPanel.IsVirtualizing is false.
If VirtualizingPanel.IsVirtualizingWhenGrouping is true while VirtualizingStackPanel.IsVirtualizing is false, my panel is only displying the first item.
I think there is something different between .NET 6 and .NET 7 related to this. But any way, if I set VirtualizingPanel.IsVirtualizingWhenGrouping based on VirtualizingStackPanel.IsVirtualizing, my custom panel is working.
Thanks
Is it possible to resolve the airspace issue thoroughly? There always are some problems in most of the existed solutions.
@Roy Lai – You can file an issue here – http://github.com/dotnet/wpf
Can WPF support AOT?Can the dependency of COM be cancelled?
@shusong lu – We are working on the plan to support such features. Here is one such issue that would enable us to support AOT (https://github.com/dotnet/wpf/issues/5305)
Is it possible to create, say, generic StyleSelector to avoid casting?
@Eugene Ivanoff – You can file a feature request here – http://github.com/dotnet/wpf
Good to see that WPF is still alive in .Net 7.
I have lost my time with UWP platform in the past and I don’t want lost my time again with MAUI.
So I realy expect that WPF will receive new features like style update to match Windows 10 and 11 UI in near futur.
It definitely will. 🙂
Any chance you backport improvements to WPF for .NET Framework? Despite your optimistic work on raw .NET Core, A LOT of people still stays on stable .NET FW and we NEED improvements. We heard a lot about how WPF is fast, but IT IS NOT. Improvements can change situation when modern 4GHz CPU cannot handle simplistic grid in WPF.
You knew what the answer to that question was going to be.
No, any improvements to WPF will be solely focused on .NET Core only. And yes, (aligned with entire .NET Core charter) performance improvements will be a major investment area in upcoming releases as well.