[net11.0] Use ElementHandlerAttribute instead of DI for built-in visual elements #29952

simonrozsival · 2025-06-12T07:43:43Z

This is a follow-up to #28357

I modified all built-in controls to use [ElementHandler<THandler>] instead of DI. This allowed me to remove all of AppHostBuilderExtensions.AddControlsHandlers().

I needed to add a new [ElementHandlerWithAndroidContext<THandler>] + interface IElementHandlerWithAndroidContext<THandler> which allows us to create handlers that need injecting the Android context in the constructor. This works perfectly well for our internal use, but I'm not sure if this will be an acceptable API to expose to our customers. This attribute is currently needed for 3 compatibility handlers: FrameRenderer (deprecated in .NET 9), ListViewRenderer (deprecated in .NET 10), TableViewRenderer (deprecated in .NET 10). I might revisit this before I mark this PR as ready for review.

It was necessary to make changes to MauiHandlerFactory to correctly resolve handlers when they were explicitly registered via DI. This is tricky because our handler resolution algorithm is pretty complicated. I wonder if we should revisit and simplify this part (it's not clear to me how much of a breaking change this could be for our customers).

TODO:

meassure the final app difference for the template app and for the sample content app (it won't be too dramatic, the default styles + the custom marking logic for NSObjects/Java objects will keep most of the platform handlers in the app anyway.. for now)
meassure startup time difference (there's less setup

Copilot

Pull Request Overview

This PR transitions built-in controls from DI registration to using [ElementHandler] attributes, introduces IElementHandlerWithAndroidContext<T> for Android renderers, and adds a new MSBuild property to toggle CSS support.

Apply [ElementHandler] to core controls and cells instead of DI
Introduce IElementHandlerWithAndroidContext<T> and CreateHandler(Context) on Android renderers
Add MauiCssEnabled MSBuild property and corresponding runtime host configuration

Reviewed Changes

Copilot reviewed 120 out of 120 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/Controls/src/Core/ContentPage/ContentPage.Mapper.cs	Added static ctor calling `RemapForControls` and `VisualElement.RemapIfNeeded`
src/Controls/src/Core/Compatibility/Handlers/TableView/Android/TableViewRenderer.cs	Implemented `IElementHandlerWithAndroidContext<TableViewRenderer>` and `CreateHandler`
src/Controls/src/Core/Compatibility/Handlers/ListView/Android/ListViewRenderer.cs	Implemented `IElementHandlerWithAndroidContext<ListViewRenderer>` and `CreateHandler`
src/Controls/src/Core/Compatibility/Handlers/Android/FrameRenderer.cs	Implemented `IElementHandlerWithAndroidContext<FrameRenderer>` and `CreateHandler`
src/Controls/src/Core/Cells/*.cs	Added `[ElementHandler<...>]` attributes for compatibility cell renderers
src/Controls/src/Core/Button/Button.cs	Added `[ElementHandler<ButtonHandler>]`
src/Controls/src/Core//.Mapper.cs	Added static ctors calling `RemapForControls` / `RemapIfNeeded`
src/Controls/src/Build.Tasks/nuget/.../Microsoft.Maui.Controls.targets	Added `MauiCssEnabled` property and runtime host configuration option
src/Compatibility/Core/src/{iOS,Android}/Platform.cs	Updated `GetHandler` calls to pass `MauiContext`

Comments suppressed due to low confidence (1)

src/Controls/src/Build.Tasks/nuget/buildTransitive/netstandard2.0/Microsoft.Maui.Controls.targets:240

Added the MauiCssEnabled build property but no corresponding public documentation under /docs/; please update the XML docs to describe this new feature.

<MauiCssEnabled Condition="'$(MauiCssEnabled)' == '' and '@(MauiCss->Count())' == '0'">false</MauiCssEnabled>

Copilot · 2025-06-12T07:44:44Z

src/Controls/src/Core/Compatibility/Handlers/TableView/Android/TableViewRenderer.cs

 {
 #pragma warning disable CS0618 // Type or member is obsolete
-	public class TableViewRenderer : ViewRenderer<TableView, AListView>
+	public class TableViewRenderer : ViewRenderer<TableView, AListView>, IElementHandlerWithAndroidContext<TableViewRenderer>


Implementing IElementHandlerWithAndroidContext introduces a new public interface on this renderer, which is a breaking API change; please assess version impact.

Copilot · 2025-06-12T07:44:45Z

src/Controls/src/Core/Compatibility/Handlers/ListView/Android/ListViewRenderer.cs

 {
 #pragma warning disable CS0618 // Type or member is obsolete
-	public class ListViewRenderer : ViewRenderer<ListView, AListView>
+	public class ListViewRenderer : ViewRenderer<ListView, AListView>, IElementHandlerWithAndroidContext<ListViewRenderer>


Implementing IElementHandlerWithAndroidContext introduces a new public interface on this renderer, which is a breaking API change; please assess version impact.

Copilot · 2025-06-12T07:44:45Z

src/Controls/src/Core/Compatibility/Handlers/Android/FrameRenderer.cs

 {
 	[Obsolete("Frame is obsolete as of .NET 9. Please use Border instead.")]
-	public class FrameRenderer : CardView, IPlatformViewHandler
+	public class FrameRenderer : CardView, IPlatformViewHandler, IElementHandlerWithAndroidContext<FrameRenderer>


Implementing IElementHandlerWithAndroidContext introduces a new public interface on this renderer, which is a breaking API change; please assess version impact.

src/Core/src/RuntimeFeature.cs

mattleibow · 2025-06-17T15:11:42Z

/azp run

azure-pipelines · 2025-06-17T15:11:49Z

Azure Pipelines will not run the associated pipelines, because the pull request was updated after the run command was issued. Review the pull request again and issue a new run command.

simonrozsival · 2025-11-25T16:24:08Z

@copilot there are merge conflicts in this branch. please resolve them. When you're done, write summary of what this PR does and what functionality is missing to fully convert the "old" way of implementing handlers to the "new" way.

Copilot · 2025-11-25T16:24:20Z

@simonrozsival I've opened a new pull request, #32861, to work on those changes. Once the pull request is ready, I'll request review from you.

simonrozsival · 2025-11-25T16:25:08Z

@copilot oops, try now!

Copilot · 2025-11-25T16:25:24Z

@simonrozsival I've opened a new pull request, #32862, to work on those changes. Once the pull request is ready, I'll request review from you.

simonrozsival · 2025-12-01T10:54:02Z

@copilot there are several errors popping up:

src\Controls\src\Core\Shell\Shell.cs(29,25): Error CS0246: The type or namespace name 'ShellHandler' could not be found (are you missing a using directive or an assembly reference?)
src\Controls\src\Core\Shell\ShellItem.cs(18,25): Error CS0246: The type or namespace name 'ShellItemHandler' could not be found (are you missing a using directive or an assembly reference?)
buildtasks/Microsoft.Maui.Controls.Build.Tasks.After.targets(15,3): error MSB4024: The imported project file "/mnt/vss/_work/1/s/.buildtasks/Microsoft.Maui.Controls.targets" could not be loaded. Name cannot begin with the '<' character, hexadecimal value 0x3C. Line 325, position 2. [/mnt/vss/_work/1/s/src/BlazorWebView/tests/DeviceTests/MauiBlazorWebView.DeviceTests.csproj]

Fix them and make sure the product can be built.

Copilot · 2025-12-01T10:54:15Z

@simonrozsival I've opened a new pull request, #32933, to work on those changes. Once the pull request is ready, I'll request review from you.

…ameRenderer and TableViewRenderer

…al elements (#32862) * Initial plan * Resolve merge conflicts from main branch Co-authored-by: simonrozsival <[email protected]> * Change ElementHandlerAttribute from generic to Type parameter Co-authored-by: simonrozsival <[email protected]> * Remove unnecessary suppression details and simplify Co-authored-by: simonrozsival <[email protected]> * Improve ElementHandelrAttribute error handling * Fix ElementHandlerAttribute --------- Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: simonrozsival <[email protected]> Co-authored-by: Simon Rozsival <[email protected]>

…onflicts (#32933) * Initial plan * Fix build errors: fully qualify ShellHandler/ShellItemHandler and resolve merge conflicts Co-authored-by: simonrozsival <[email protected]> --------- Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: simonrozsival <[email protected]>

…ement (#33138) * Initial plan * Fix build failures in HostBuilderHandlerTests by adding IMauiContext parameter Co-authored-by: simonrozsival <[email protected]> --------- Co-authored-by: copilot-swe-agent[bot] <[email protected]> Co-authored-by: simonrozsival <[email protected]>

…ndler attributes

…Enabled to RuntimeFeature

Copilot AI review requested due to automatic review settings June 12, 2025 07:43

simonrozsival requested a review from a team as a code owner June 12, 2025 07:43

simonrozsival requested review from jfversluis and mattleibow June 12, 2025 07:43

Copilot AI reviewed Jun 12, 2025

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simonrozsival commented Jun 12, 2025

View reviewed changes

src/Core/src/RuntimeFeature.cs Outdated Show resolved Hide resolved

simonrozsival marked this pull request as draft June 12, 2025 08:06

PureWeen added this to the .NET 10.0-preview6 milestone Jun 17, 2025

PureWeen added this to MAUI SDK Ongoing Jun 17, 2025

github-project-automation bot moved this to Todo in MAUI SDK Ongoing Jun 17, 2025

PureWeen moved this from Todo to In Progress in MAUI SDK Ongoing Jun 17, 2025

simonrozsival force-pushed the dev/simonrozsival/net10.0-use-element-handler-attributes branch from 33afe18 to c49e57e Compare June 18, 2025 11:53

PureWeen modified the milestones: .NET 10.0-preview6, .NET 11 Planning Jul 2, 2025

PureWeen added platform/macos macOS / Mac Catalyst platform/windows platform/android platform/ios area-architecture Issues with code structure, SDK structure, implementation details labels Aug 7, 2025

Copilot AI mentioned this pull request Nov 25, 2025

[WIP] Use ElementHandlerAttribute for built-in visual elements #32861

Closed

Copilot AI mentioned this pull request Nov 25, 2025

[net11.0] Use ElementHandlerAttribute instead of DI for built-in visual elements #32862

Merged

Copilot AI mentioned this pull request Dec 1, 2025

[net11.0] Fix build errors: qualify handler types and resolve merge conflicts #32933

Merged

simonrozsival and others added 23 commits January 16, 2026 16:30

Pass Android context to the ctor

ed7e977

Migrate Android's Frame to the new handler registration pattern

4cac230

Move Android's TableView to the new handler registration pattern

ed4a5e9

Fixups

16af8dc

Add missing implementation of IElementHandlerWithAndroidContext to Fr…

465bca5

…ameRenderer and TableViewRenderer

Remove unnecessary setup code

6271904

Update tests

1c7aa38

Fix TemplatedView element handler

d566790

Fix IContentView scenario

c7ebb38

Cleanup

80d2ea9

Update Compatibility

dbe813d

Fix ambiguous match of attributes

d59c689

Update Element.TrySetValue

26eefc0

Update ViewHandler.PreventGestureBubbling on Windows

ca36a6b

Make CSS trimmable

09c1b22

WIP

0451c75

Disable the CSS feature if there are no CSS items in the project

ec435d7

Fix merge conflicts: restore inline docs from net11.0, keep ElementHa…

69a3652

…ndler attributes

Fix platform conditionals for ElementHandler attributes and add IsCss…

05b6b45

…Enabled to RuntimeFeature

Add TrySetValue override to Editor

820c96d

simonrozsival force-pushed the dev/simonrozsival/net10.0-use-element-handler-attributes branch from d4f1219 to 820c96d Compare January 16, 2026 16:38

simonrozsival added 2 commits January 16, 2026 17:44

Remove CSS trimming code (moved to separate PR)

2310e0e

Split GetHandlerType and (annotated) GetConstructibleHandlerType

e504d1c

simonrozsival force-pushed the dev/simonrozsival/net10.0-use-element-handler-attributes branch 2 times, most recently from 6ced46a to fd782a0 Compare January 16, 2026 17:24

Restore XML doc comments and fix TextCell command implementation

7c7d0f8

simonrozsival force-pushed the dev/simonrozsival/net10.0-use-element-handler-attributes branch from fd782a0 to 7c7d0f8 Compare January 16, 2026 17:34

[net11.0] Use ElementHandlerAttribute instead of DI for built-in visual elements #29952

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[net11.0] Use ElementHandlerAttribute instead of DI for built-in visual elements #29952

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simonrozsival commented Jun 12, 2025 •

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