Propagate VisualElement.IsEnabled to children

src/Controls/samples/Controls.Sample/Pages/Layouts/LayoutIsEnabledPage.xaml

@@ -0,0 +1,120 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<ContentPage 
+ xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
+ xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
+ x:Class="Maui.Controls.Sample.Pages.LayoutIsEnabledPage"
+ Title="Layout IsEnabled">
+
+ <ContentPage.Resources>
+ <ResourceDictionary>
+ <Style TargetType="VerticalStackLayout">
+ <Setter Property="Padding" Value="6" />
+ </Style>
+ </ResourceDictionary>
+ </ContentPage.Resources>
+
+ <ScrollView>
+ <Grid ColumnSpacing="6" RowSpacing="6" ColumnDefinitions="*,*" RowDefinitions="Auto,Auto">
+
+ <VerticalStackLayout x:Name="MainLayout">
+
+ <Label Text="All children are enabled" />
+ <VerticalStackLayout Background="LightBlue">
+ <Button Text="Enabled" />
+ <Button Text="Enabled" />
+ </VerticalStackLayout>
+
+ <Label Text="All children are disabled" />
+ <VerticalStackLayout Background="LightBlue">
+ <Button Text="Disabled" IsEnabled="False" />
+ <Button Text="Disabled" IsEnabled="False" />
+ </VerticalStackLayout>
+
+ <Label Text="All children are disabled (because layout is disabled)" />
+ <VerticalStackLayout IsEnabled="False" Background="LightPink">
+ <Button Text="Disabled" />
+ <Button Text="Disabled" />
+ </VerticalStackLayout>
+
+ <Label Text="First item is enabled and the second one is disabled" />
+ <VerticalStackLayout Background="LightSeaGreen">
+ <Button Text="Enabled" />
+ <Button x:Name="DisabledButton" Text="Disabled" IsEnabled="False" />
+ </VerticalStackLayout>
+
+ <Label Text="Children have commands attached" />
+ <VerticalStackLayout Background="LightSeaGreen">
+ <Button Text="Enabled" Command="{Binding TheCommand}" />
+ <Button x:Name="DisabledCommandButton" Text="Disabled" IsEnabled="False" Command="{Binding TheCommand}" />
+ </VerticalStackLayout>
+
+ <Label Text="Nested layouts" />
+ <VerticalStackLayout Background="LightSkyBlue">
+ <VerticalStackLayout Background="LightGray">
+ <Button Text="Enabled" />
+ <Button Text="Disabled" IsEnabled="False" />
+ </VerticalStackLayout>
+ </VerticalStackLayout>
+
+ </VerticalStackLayout>
+
+ <VerticalStackLayout Grid.Row="1">
+ <Button Text="Disable Layout" Clicked="OnDisableLayoutBtnClicked" />
+ <Button Text="Enable Button" Clicked="OnDisableButtonBtnClicked" />
+ </VerticalStackLayout>
+
+ <VerticalStackLayout IsEnabled="{Binding IsLayoutEnabled}" Grid.Column="1">
+
+ <Label Text="All children are enabled" />
+ <VerticalStackLayout Background="LightBlue">
+ <Button Text="Enabled" />
+ <Button Text="Enabled" />
+ </VerticalStackLayout>
+
+ <Label Text="All children are disabled" />
+ <VerticalStackLayout Background="LightBlue">
+ <Button Text="Disabled" IsEnabled="False" />
+ <Button Text="Disabled" IsEnabled="False" />
+ </VerticalStackLayout>
+
+ <Label Text="All children are disabled (because layout is disabled)" />
+ <VerticalStackLayout IsEnabled="False" Background="LightPink">
+ <Button Text="Disabled" />
+ <Button Text="Disabled" />
+ </VerticalStackLayout>
+
+ <Label Text="First item is enabled and the second one is disabled" />
+ <VerticalStackLayout Background="LightSeaGreen">
+ <Button Text="Enabled" />
+ <Button IsEnabled="{Binding IsButtonEnabled}" Text="Disabled" />
+ </VerticalStackLayout>
+
+ <Label Text="Children have commands attached" />
+ <VerticalStackLayout Background="LightSeaGreen">
+ <Button Text="Enabled" Command="{Binding TheCommand}" />
+ <Button Text="Disabled" IsEnabled="{Binding IsButtonEnabled}" Command="{Binding TheCommand}" />
+ </VerticalStackLayout>
+
+ <Label Text="Nested layouts" />
+ <VerticalStackLayout Background="LightSkyBlue">
+ <VerticalStackLayout Background="LightGray">
+ <Button Text="Enabled" />
+ <Button Text="Disabled" IsEnabled="False" />
+ </VerticalStackLayout>
+ </VerticalStackLayout>
+
+ </VerticalStackLayout>
+
+ <VerticalStackLayout Grid.Row="1" Grid.Column="1">
+ <Label Text="Enable/Disable Layout" />
+ <CheckBox IsChecked="{Binding IsLayoutEnabled}" />
+ <Label Text="Enable/Disable Button" />
+ <CheckBox IsChecked="{Binding IsButtonEnabled}" />
+ <Label Text="Enable/Disable Command" />
+ <CheckBox IsChecked="{Binding IsCommandEnabled}" />
+ </VerticalStackLayout>
+
+ </Grid>
+ </ScrollView>
+
+</ContentPage>

src/Controls/samples/Controls.Sample/Pages/Layouts/LayoutIsEnabledPage.xaml.cs

@@ -0,0 +1,78 @@
+using System;
+using Microsoft.Maui.Controls;
+
+namespace Maui.Controls.Sample.Pages
+{
+ public partial class LayoutIsEnabledPage : ContentPage
+ {
+ bool isLayoutEnabled;
+ bool isButtonEnabled;
+ bool isCommandEnabled;
+
+ public LayoutIsEnabledPage()
+ {
+ InitializeComponent();
+
+ TheCommand = new Command(OnThe, OnTheCanExecute);
+ BindingContext = this;
+ }
+
+ public bool IsLayoutEnabled
+ {
+ get => isLayoutEnabled;
+ set
+ {
+ isLayoutEnabled = value;
+ OnPropertyChanged();
+ }
+ }
+
+ public bool IsButtonEnabled
+ {
+ get => isButtonEnabled;
+ set
+ {
+ isButtonEnabled = value;
+ OnPropertyChanged();
+ }
+ }
+
+ public bool IsCommandEnabled
+ {
+ get => isCommandEnabled;
+ set
+ {
+ isCommandEnabled = value;
+ OnPropertyChanged();
+ TheCommand.ChangeCanExecute();
+ }
+ }
+
+ public Command TheCommand { get; }
+
+ void OnDisableLayoutBtnClicked(object sender, EventArgs e)
+ {
+ MainLayout.IsEnabled = !MainLayout.IsEnabled;
+
+ ((Button)sender).Text = MainLayout.IsEnabled ? "Disable Layout" : "Enable Layout";
+ }
+
+ void OnDisableButtonBtnClicked(object sender, EventArgs e)
+ {
+ DisabledButton.IsEnabled = !DisabledButton.IsEnabled;
+ DisabledCommandButton.IsEnabled = !DisabledCommandButton.IsEnabled;
+
+ DisabledButton.Text = DisabledButton.IsEnabled ? "Enabled" : "Disabled";
+ DisabledCommandButton.Text = DisabledCommandButton.IsEnabled ? "Enabled" : "Disabled";
+
+ ((Button)sender).Text = DisabledButton.IsEnabled ? "Disable Button" : "Enable Button";
+ }
+
+ void OnThe()
+ {
+ System.Diagnostics.Debug.WriteLine("On THE clicked!");
+ }
+
+ bool OnTheCanExecute() => isCommandEnabled;
+ }
+}

src/Controls/samples/Controls.Sample/ViewModels/LayoutsViewModel.cs

@@ -50,6 +50,9 @@ protected override IEnumerable<SectionModel> CreateItems() => new[]
 
  new SectionModel(typeof(CustomLayoutPage), "Custom Layout",
  "Demonstrations of custom layout."),
+
+ new SectionModel(typeof(LayoutIsEnabledPage), "Layout IsEnabled",
+ "Demonstrations of enabling/disabling a layout."),
  };
  }
 }

src/Controls/src/Core/Button.cs

@@ -11,7 +11,7 @@ namespace Microsoft.Maui.Controls
  /// <summary>
  /// A button <see cref="View" /> that reacts to touch events.
  /// </summary>
- public partial class Button : View, IFontElement, ITextElement, IBorderElement, IButtonController, IElementConfiguration<Button>, IPaddingElement, IImageController, IViewController, IButtonElement, IImageElement
+ public partial class Button : View, IFontElement, ITextElement, IBorderElement, IButtonController, IElementConfiguration<Button>, IPaddingElement, IImageController, IViewController, IButtonElement, ICommandElement, IImageElement
  {
  const double DefaultSpacing = 10;
 
@@ -240,11 +240,6 @@ public double CharacterSpacing
  set { SetValue(TextElement.CharacterSpacingProperty, value); }
  }
 
- bool IButtonElement.IsEnabledCore
- {
- set { SetValueCore(IsEnabledProperty, value); }
- }
-
  /// <summary>
  /// Internal method to trigger the <see cref="Clicked"/> event.
  /// Should not be called manually outside of .NET MAUI.
@@ -439,9 +434,6 @@ void IBorderElement.OnBorderColorPropertyChanged(Color oldValue, Color newValue)
  void IImageElement.OnImageSourceSourceChanged(object sender, EventArgs e) =>
  ImageElement.ImageSourceSourceChanged(this, e);
 
- void IButtonElement.OnCommandCanExecuteChanged(object sender, EventArgs e) =>
- ButtonElement.CommandCanExecuteChanged(this, EventArgs.Empty);
-
  void IImageController.SetIsLoading(bool isLoading)
  {
  }
@@ -465,6 +457,12 @@ void ITextElement.OnTextTransformChanged(TextTransform oldValue, TextTransform n
  public virtual string UpdateFormsText(string source, TextTransform textTransform)
  => TextTransformUtilites.GetTransformedText(source, textTransform);
 
+ void ICommandElement.CanExecuteChanged(object sender, EventArgs e) =>
+ RefreshIsEnabledProperty();
+
+ internal override bool IsEnabledCore =>
+ base.IsEnabledCore && CommandElement.GetCanExecute(this);
+
  /// <summary>
  /// Represents the layout of the button content whenever an image is shown.
  /// </summary>

src/Controls/src/Core/ButtonElement.cs

@@ -7,73 +7,27 @@ namespace Microsoft.Maui.Controls
  static class ButtonElement
  {
  /// <summary>
- /// The backing store for the <see cref="IButtonElement.Command" /> bindable property.
+ /// The backing store for the <see cref="ICommandElement.Command" /> bindable property.
  /// </summary>
- public static readonly BindableProperty CommandProperty = BindableProperty.Create(nameof(IButtonElement.Command), typeof(ICommand), typeof(IButtonElement), null, propertyChanging: OnCommandChanging, propertyChanged: OnCommandChanged);
+ public static readonly BindableProperty CommandProperty = BindableProperty.Create(
+ nameof(IButtonElement.Command), typeof(ICommand), typeof(IButtonElement), null,
+ propertyChanging: CommandElement.OnCommandChanging, propertyChanged: CommandElement.OnCommandChanged);
 
  /// <summary>
- /// The backing store for the <see cref="IButtonElement.CommandParameter" /> bindable property.
+ /// The backing store for the <see cref="ICommandElement.CommandParameter" /> bindable property.
  /// </summary>
- public static readonly BindableProperty CommandParameterProperty = BindableProperty.Create(nameof(IButtonElement.CommandParameter), typeof(object), typeof(IButtonElement), null,
- propertyChanged: (bindable, oldvalue, newvalue) => CommandCanExecuteChanged(bindable, EventArgs.Empty));
-
- static void OnCommandChanged(BindableObject bo, object o, object n)
- {
- IButtonElement button = (IButtonElement)bo;
- if (n is ICommand newCommand)
- newCommand.CanExecuteChanged += button.OnCommandCanExecuteChanged;
-
- CommandChanged(button);
- }
-
- static void OnCommandChanging(BindableObject bo, object o, object n)
- {
- IButtonElement button = (IButtonElement)bo;
- if (o != null)
- {
- (o as ICommand).CanExecuteChanged -= button.OnCommandCanExecuteChanged;
- }
- }
+ public static readonly BindableProperty CommandParameterProperty = BindableProperty.Create(
+ nameof(IButtonElement.CommandParameter), typeof(object), typeof(IButtonElement), null,
+ propertyChanged: CommandElement.OnCommandParameterChanged);
 
  /// <summary>
  /// The string identifier for the pressed visual state of this control.
  /// </summary>
  public const string PressedVisualState = "Pressed";
 
- /// <summary>
- /// A method to signal that the <see cref="IButtonElement.Command"/> property has been changed.
- /// </summary>
- /// <param name="sender">The object initiating this event.</param>
- public static void CommandChanged(IButtonElement sender)
- {
- if (sender.Command != null)
- {
- CommandCanExecuteChanged(sender, EventArgs.Empty);
- }
- else
- {
- sender.IsEnabledCore = true;
- }
- }
-
- /// <summary>
- /// A method to signal that the <see cref="Command.CanExecute(object)"/> might have changed and needs to be reevaluated.
- /// </summary>
- /// <param name="sender">The object initiating this event.</param>
- /// <param name="e">Arguments associated with this event.</param>
- public static void CommandCanExecuteChanged(object sender, EventArgs e)
- {
- IButtonElement ButtonElementManager = (IButtonElement)sender;
- ICommand cmd = ButtonElementManager.Command;
- if (cmd != null)
- {
- ButtonElementManager.IsEnabledCore = cmd.CanExecute(ButtonElementManager.CommandParameter);
- }
- }
-
  /// <summary>
  /// A method to signal that this element was clicked/tapped.
- /// By calling this, the <see cref="IButtonElement.Command"/> and clicked events are triggered.
+ /// By calling this, the <see cref="ICommandElement.Command"/> and clicked events are triggered.
  /// </summary>
  /// <param name="visualElement">The element that was interacted with.</param>
  /// <param name="ButtonElementManager">The button element implementation to trigger the commands and events on.</param>

src/Controls/src/Core/CommandElement.cs

@@ -0,0 +1,58 @@
+#nullable enable
+using System;
+using System.Windows.Input;
+using Microsoft.Maui.Controls.Internals;
+
+namespace Microsoft.Maui.Controls
+{
+ static class CommandElement
+ {
+ public static void OnCommandChanging(BindableObject bo, object o, object n)
+ {
+ var commandElement = (ICommandElement)bo;
+ if (o is ICommand oldCommand)
+ oldCommand.CanExecuteChanged -= commandElement.CanExecuteChanged;
+ }
+
+ public static void OnCommandChanged(BindableObject bo, object o, object n)
+ {
+ var commandElement = (ICommandElement)bo;
+
+ if (n is ICommand newCommand)
+ {
+ newCommand.CanExecuteChanged += commandElement.CanExecuteChanged;
+ commandElement.CanExecuteChanged(bo, EventArgs.Empty);
+ }
+ }
+
+ public static void OnCommandParameterChanged(BindableObject bo, object o, object n)
+ {
+ var commandElement = (ICommandElement)bo;
+ commandElement.CanExecuteChanged(bo, EventArgs.Empty);
+ }
+
+ public static bool GetCanExecute(ICommandElement commandElement)
+ {
+ if (commandElement.Command == null)
+ return true;
+
+ return commandElement.Command.CanExecute(commandElement.CommandParameter);
+ }
+
+ public static void RefreshPropertyValue(BindableObject bo, BindableProperty property, object value)
+ {
+ var ctx = bo.GetContext(property);
+ if (ctx?.Binding is not null)
+ {
+ // support bound properties
+ if (!ctx.Attributes.HasFlag(BindableObject.BindableContextAttributes.IsBeingSet))
+ ctx.Binding.Apply(false);
+ }
+ else
+ {
+ // support normal/code properties
+ bo.SetValue(property, value);
+ }
+ }
+ }
+}