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* Add BringIntoView pass to the LayoutManager * Make ProcessBringIntoViewRequests part of the standard layout pass * Clarify why TryScrollIntoViewNow's result is ignored --------- Co-authored-by: grokys <grokys@users.noreply.github.com>pull/22095/head
Julien Lebosquain
1 month ago
committed by
GitHub
GitHub
12 changed files with 695 additions and 80 deletions
@ -0,0 +1,22 @@ |
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namespace Avalonia.Layout |
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{ |
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/// <summary>
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/// A bring-into-view request, processed by the <see cref="IBringIntoViewLayoutManager"/> at the end of a layout pass.
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/// </summary>
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internal abstract class BringIntoViewRequest(Layoutable target) |
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{ |
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/// <summary>
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/// Gets the control this request is associated with.
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/// </summary>
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public Layoutable Target { get; } = target; |
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/// <summary>
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/// Attempts to execute the request.
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/// </summary>
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/// <returns>
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/// true if the request has been executed (or abandoned) and should be removed from the queue;
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/// false if the target isn't ready yet and the request should be retained for a following layout pass.
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/// </returns>
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public abstract bool TryExecute(); |
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} |
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} |
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@ -0,0 +1,18 @@ |
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namespace Avalonia.Layout; |
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/// <summary>
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/// A <see cref="ILayoutManager"/> that handles <see cref="BringIntoViewRequest"/>.
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/// </summary>
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internal interface IBringIntoViewLayoutManager : ILayoutManager |
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{ |
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/// <summary>
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/// Gets whether a layout pass is currently running.
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/// </summary>
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bool IsInLayoutPass { get; } |
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/// <summary>
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/// Enqueues a bring-into-view request to be processed at the end of the current or next layout pass,
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/// replacing any previously enqueued request for the same target.
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/// </summary>
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void EnqueueBringIntoView(BringIntoViewRequest request); |
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} |
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@ -0,0 +1,265 @@ |
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using System; |
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using Avalonia.Controls; |
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using Avalonia.Layout; |
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using Avalonia.UnitTests; |
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using Xunit; |
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namespace Avalonia.Base.UnitTests.Layout; |
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public class LayoutManagerTests_BringIntoView : ScopedTestBase |
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{ |
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[Fact] |
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public void Request_Is_Executed_At_End_Of_Layout_Pass() |
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{ |
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var control = new LayoutTestControl(); |
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var root = new LayoutTestRoot { Child = control }; |
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root.LayoutManager.ExecuteInitialLayoutPass(); |
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var request = new TestRequest(control); |
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GetLayoutManager(root).EnqueueBringIntoView(request); |
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Assert.Equal(0, request.ExecuteAttempts); |
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root.LayoutManager.ExecuteLayoutPass(); |
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Assert.Equal(1, request.ExecuteAttempts); |
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Assert.Equal(1, request.Executions); |
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root.LayoutManager.ExecuteLayoutPass(); |
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// Should not have been executed twice.
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Assert.Equal(1, request.ExecuteAttempts); |
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Assert.Equal(1, request.Executions); |
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} |
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[Fact] |
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public void Request_Is_Executed_Before_LayoutUpdated_Is_Raised() |
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{ |
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var control = new LayoutTestControl(); |
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var root = new LayoutTestRoot { Child = control }; |
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root.LayoutManager.ExecuteInitialLayoutPass(); |
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var layoutUpdatedRaised = false; |
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var executedBeforeLayoutUpdated = false; |
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root.LayoutManager.LayoutUpdated += (_, _) => layoutUpdatedRaised = true; |
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var request = new TestRequest(control) |
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{ |
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OnExecute = () => executedBeforeLayoutUpdated = !layoutUpdatedRaised, |
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}; |
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GetLayoutManager(root).EnqueueBringIntoView(request); |
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root.LayoutManager.ExecuteLayoutPass(); |
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Assert.Equal(1, request.Executions); |
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Assert.True(executedBeforeLayoutUpdated); |
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} |
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[Fact] |
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public void Request_Is_Retained_Until_It_Can_Execute() |
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{ |
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var control = new LayoutTestControl(); |
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var root = new LayoutTestRoot { Child = control }; |
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root.LayoutManager.ExecuteInitialLayoutPass(); |
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var canExecute = false; |
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var request = new TestRequest(control) { CanExecute = () => canExecute }; |
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GetLayoutManager(root).EnqueueBringIntoView(request); |
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root.LayoutManager.ExecuteLayoutPass(); |
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Assert.Equal(1, request.ExecuteAttempts); |
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Assert.Equal(0, request.Executions); |
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root.LayoutManager.ExecuteLayoutPass(); |
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Assert.Equal(2, request.ExecuteAttempts); |
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Assert.Equal(0, request.Executions); |
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canExecute = true; |
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root.LayoutManager.ExecuteLayoutPass(); |
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Assert.Equal(3, request.ExecuteAttempts); |
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Assert.Equal(1, request.Executions); |
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} |
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[Fact] |
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public void Requests_Are_Coalesced_By_Target() |
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{ |
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var control = new LayoutTestControl(); |
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var root = new LayoutTestRoot { Child = control }; |
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root.LayoutManager.ExecuteInitialLayoutPass(); |
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var first = new TestRequest(control); |
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var second = new TestRequest(control); |
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var layoutManager = GetLayoutManager(root); |
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layoutManager.EnqueueBringIntoView(first); |
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layoutManager.EnqueueBringIntoView(second); |
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root.LayoutManager.ExecuteLayoutPass(); |
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Assert.Equal(0, first.ExecuteAttempts); |
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Assert.Equal(1, second.Executions); |
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} |
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[Fact] |
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public void Request_Is_Dropped_When_Target_Is_Detached() |
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{ |
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var control = new LayoutTestControl(); |
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var root = new LayoutTestRoot { Child = control }; |
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root.LayoutManager.ExecuteInitialLayoutPass(); |
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var request = new TestRequest(control); |
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GetLayoutManager(root).EnqueueBringIntoView(request); |
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root.Child = null; |
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root.LayoutManager.ExecuteLayoutPass(); |
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Assert.Equal(0, request.ExecuteAttempts); |
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root.Child = control; |
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root.LayoutManager.ExecuteLayoutPass(); |
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Assert.Equal(0, request.ExecuteAttempts); |
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} |
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[Fact] |
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public void Layout_Invalidated_By_Request_Converges_Within_Same_Pass() |
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{ |
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var control = new LayoutTestControl(); |
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var root = new LayoutTestRoot { Child = control }; |
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root.LayoutManager.ExecuteInitialLayoutPass(); |
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control.Measured = control.Arranged = false; |
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var request = new TestRequest(control) { OnExecute = control.InvalidateMeasure }; |
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GetLayoutManager(root).EnqueueBringIntoView(request); |
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root.LayoutManager.ExecuteLayoutPass(); |
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// The layout invalidated by the request (e.g. a scroll offset change) has been
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// re-run before ExecuteLayoutPass returned, so the frame is rendered fully scrolled.
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Assert.Equal(1, request.Executions); |
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Assert.True(control.Measured); |
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Assert.True(control.Arranged); |
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} |
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[Fact] |
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public void LayoutUpdated_Is_Not_Raised_Until_All_Requests_Have_Been_Processed() |
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{ |
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var first = new LayoutTestControl(); |
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var second = new LayoutTestControl(); |
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var root = new LayoutTestRoot { Child = new StackPanel { Children = { first, second } } }; |
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root.LayoutManager.ExecuteInitialLayoutPass(); |
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var layoutManager = GetLayoutManager(root); |
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var layoutUpdatedRaised = false; |
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var secondExecutedBeforeLayoutUpdated = false; |
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root.LayoutManager.LayoutUpdated += (_, _) => layoutUpdatedRaised = true; |
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// The second request can only execute once the layout invalidated by the first one has
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// been re-run, so it is executed by a following pass of the processing loop.
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first.Measured = false; |
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var secondRequest = new TestRequest(second) |
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{ |
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CanExecute = () => first.Measured, |
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OnExecute = () => secondExecutedBeforeLayoutUpdated = !layoutUpdatedRaised, |
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}; |
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var firstRequest = new TestRequest(first) { OnExecute = first.InvalidateMeasure }; |
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layoutManager.EnqueueBringIntoView(firstRequest); |
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layoutManager.EnqueueBringIntoView(secondRequest); |
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root.LayoutManager.ExecuteLayoutPass(); |
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Assert.Equal(1, secondRequest.Executions); |
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Assert.True(secondExecutedBeforeLayoutUpdated); |
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} |
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[Fact] |
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public void LayoutUpdated_Is_Raised_Once_When_Request_Invalidates_Layout() |
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{ |
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var control = new LayoutTestControl(); |
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var root = new LayoutTestRoot { Child = control }; |
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root.LayoutManager.ExecuteInitialLayoutPass(); |
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var layoutUpdated = 0; |
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root.LayoutManager.LayoutUpdated += (_, _) => ++layoutUpdated; |
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var request = new TestRequest(control) { OnExecute = control.InvalidateMeasure }; |
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GetLayoutManager(root).EnqueueBringIntoView(request); |
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root.LayoutManager.ExecuteLayoutPass(); |
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Assert.Equal(1, request.Executions); |
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Assert.Equal(1, layoutUpdated); |
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} |
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[Fact] |
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public void Request_Enqueued_While_Processing_Is_Attempted_By_The_Same_Pass() |
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{ |
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var first = new LayoutTestControl(); |
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var second = new LayoutTestControl(); |
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var root = new LayoutTestRoot { Child = new StackPanel { Children = { first, second } } }; |
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root.LayoutManager.ExecuteInitialLayoutPass(); |
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var layoutManager = GetLayoutManager(root); |
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var canExecuteSecond = false; |
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var secondRequest = new TestRequest(second) { CanExecute = () => canExecuteSecond }; |
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// Executing a request can enqueue another one (as ControlExtensions.BringIntoViewCore does):
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// the new request must be attempted by the same pass, and retained if it can't execute yet.
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var firstRequest = new TestRequest(first) |
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{ |
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OnExecute = () => |
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{ |
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layoutManager.EnqueueBringIntoView(secondRequest); |
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first.InvalidateMeasure(); |
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} |
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}; |
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layoutManager.EnqueueBringIntoView(firstRequest); |
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root.LayoutManager.ExecuteLayoutPass(); |
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Assert.Equal(1, firstRequest.Executions); |
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// Attempted first during the same pass as the first request, then retried once after a new layout pass.
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Assert.Equal(2, secondRequest.ExecuteAttempts); |
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Assert.Equal(0, secondRequest.Executions); |
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// The second request couldn't execute despite having been through an extra layout pass.
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// We can't retry forever (nothing has changed). The request will be retried again on the next "natural" pass.
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canExecuteSecond = true; |
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root.LayoutManager.ExecuteLayoutPass(); |
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Assert.Equal(3, secondRequest.ExecuteAttempts); |
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Assert.Equal(1, secondRequest.Executions); |
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} |
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private static LayoutManager GetLayoutManager(TestRoot root) |
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=> Assert.IsType<LayoutManager>(root.LayoutManager, exactMatch: false); |
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private sealed class TestRequest(Layoutable target) : BringIntoViewRequest(target) |
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{ |
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public int ExecuteAttempts { get; private set; } |
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public int Executions { get; private set; } |
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public Func<bool>? CanExecute { get; init; } |
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public Action? OnExecute { get; init; } |
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public override bool TryExecute() |
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{ |
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++ExecuteAttempts; |
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var canExecute = CanExecute?.Invoke() ?? true; |
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if (!canExecute) |
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return false; |
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++Executions; |
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OnExecute?.Invoke(); |
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return true; |
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} |
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} |
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} |
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@ -0,0 +1,86 @@ |
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using Avalonia.UnitTests; |
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using Xunit; |
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namespace Avalonia.Controls.UnitTests; |
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public class BringIntoViewTests : ScopedTestBase |
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{ |
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[Fact] |
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public void BringIntoView_On_Laid_Out_Control_Raises_RequestBringIntoView_Synchronously() |
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{ |
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using var app = UnitTestApplication.Start(TestServices.MockPlatformRenderInterface); |
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var child = new Border { Width = 50, Height = 50 }; |
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var root = new TestRoot(child); |
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root.LayoutManager.ExecuteInitialLayoutPass(); |
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var raised = false; |
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root.AddHandler(Control.RequestBringIntoViewEvent, (_, _) => raised = true); |
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child.BringIntoView(); |
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Assert.True(raised); |
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} |
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[Fact] |
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public void BringIntoView_Before_Layout_Is_Deferred_Until_End_Of_Layout_Pass() |
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{ |
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using var app = UnitTestApplication.Start(TestServices.MockPlatformRenderInterface); |
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var child = new Border { Width = 50, Height = 50 }; |
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var root = new TestRoot(child); |
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var raised = 0; |
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var targetRect = default(Rect); |
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root.AddHandler(Control.RequestBringIntoViewEvent, (_, e) => |
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{ |
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++raised; |
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targetRect = e.TargetRect; |
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}); |
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child.BringIntoView(); |
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Assert.Equal(0, raised); |
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root.LayoutManager.ExecuteInitialLayoutPass(); |
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Assert.Equal(1, raised); |
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Assert.Equal(new Rect(0, 0, 50, 50), targetRect); |
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} |
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[Fact] |
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public void Deferred_BringIntoView_Is_Abandoned_When_Control_Becomes_Invisible() |
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{ |
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using var app = UnitTestApplication.Start(TestServices.MockPlatformRenderInterface); |
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var child = new Border { Width = 50, Height = 50 }; |
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var root = new TestRoot(child); |
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var raised = false; |
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root.AddHandler(Control.RequestBringIntoViewEvent, (_, _) => raised = true); |
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child.BringIntoView(); |
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child.IsVisible = false; |
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root.LayoutManager.ExecuteInitialLayoutPass(); |
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Assert.False(raised); |
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} |
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[Fact] |
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public void BringIntoView_On_Invisible_Control_Is_Ignored() |
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{ |
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using var app = UnitTestApplication.Start(TestServices.MockPlatformRenderInterface); |
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var child = new Border { Width = 50, Height = 50, IsVisible = false }; |
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var root = new TestRoot(child); |
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root.LayoutManager.ExecuteInitialLayoutPass(); |
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var raised = false; |
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root.AddHandler(Control.RequestBringIntoViewEvent, (_, _) => raised = true); |
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child.BringIntoView(); |
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root.LayoutManager.ExecuteLayoutPass(); |
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Assert.False(raised); |
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} |
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} |
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