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Fixes TextBox measure logic for MaxLines scenario #12589

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merged 2 commits into from
Aug 19, 2023
Merged

Fixes TextBox measure logic for MaxLines scenario #12589

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41bef0e
Fix for TextBox not accounting for space between ScrollViewer and Tex…
billhenn Aug 18, 2023
932b40b
Added unit tests for TextBox to verify MaxLines property assigns the …
boydpatterson Aug 18, 2023
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34 changes: 33 additions & 1 deletion src/Avalonia.Controls/TextBox.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -1879,6 +1879,37 @@ private string GetSelection()
return text.Substring(start, end - start);
}

/// <summary>
/// Returns the sum of any vertical whitespace added between the <see cref="ScrollViewer"/> and <see cref="TextPresenter"/> in the control template.
/// </summary>
/// <returns>The total vertical whitespace.</returns>
private double GetVerticalSpaceBetweenScrollViewerAndPresenter()
{
var verticalSpace = 0.0;
if (_presenter != null)
{
Visual? visual = _presenter;
while ((visual != null) && (visual != this))
{
if (visual == _scrollViewer)
{
// ScrollViewer is a stopping point and should only include the Padding
verticalSpace += _scrollViewer.Padding.Top + _scrollViewer.Padding.Bottom;
break;
}

var margin = visual.GetValue<Thickness>(Layoutable.MarginProperty);
var padding = visual.GetValue<Thickness>(Decorator.PaddingProperty);

verticalSpace += margin.Top + padding.Top + padding.Bottom + margin.Bottom;

visual = visual.VisualParent;
}
}

return verticalSpace;
}

/// <summary>
/// Raises both the <see cref="TextChanging"/> and <see cref="TextChanged"/> events.
/// </summary>
Expand Down Expand Up @@ -2032,8 +2063,9 @@ protected override Size MeasureOverride(Size availableSize)
var typeface = new Typeface(FontFamily, FontStyle, FontWeight, FontStretch);
var paragraphProperties = TextLayout.CreateTextParagraphProperties(typeface, fontSize, null, default, default, null, default, LineHeight, default);
var textLayout = new TextLayout(new MaxLinesTextSource(MaxLines), paragraphProperties);
var verticalSpace = GetVerticalSpaceBetweenScrollViewerAndPresenter();

maxHeight = Math.Ceiling(textLayout.Height);
maxHeight = Math.Ceiling(textLayout.Height + verticalSpace);
}

_scrollViewer.SetCurrentValue(MaxHeightProperty, maxHeight);
Expand Down
79 changes: 78 additions & 1 deletion tests/Avalonia.Controls.UnitTests/TextBoxTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@
using Avalonia.Rendering;
using Avalonia.Rendering.Composition;
using Avalonia.UnitTests;
using Avalonia.VisualTree;
using Moq;
using Xunit;

Expand Down Expand Up @@ -916,6 +917,82 @@ public void Should_Fullfill_MaxLines_Contraint()
}
}

[Theory]
[InlineData(1)]
[InlineData(2)]
[InlineData(3)]
public void MaxLines_Sets_ScrollViewer_MaxHeight(int maxLines)
{
using (UnitTestApplication.Start(Services))
{
var target = new TextBox
{
Template = CreateTemplate(),
MaxLines = maxLines,

// Define explicit whole number line height for predictable calculations
LineHeight = 20
};

var impl = CreateMockTopLevelImpl();
var topLevel = new TestTopLevel(impl.Object)
{
Template = CreateTopLevelTemplate(),
Content = target
};
topLevel.ApplyTemplate();
topLevel.LayoutManager.ExecuteInitialLayoutPass();

var textPresenter = target.FindDescendantOfType<TextPresenter>();
Assert.Equal("PART_TextPresenter", textPresenter.Name);
Assert.Equal(new Thickness(0), textPresenter.Margin); // Test assumes no margin on TextPresenter

var scrollViewer = target.FindDescendantOfType<ScrollViewer>();
Assert.Equal("PART_ScrollViewer", scrollViewer.Name);
Assert.Equal(maxLines * target.LineHeight, scrollViewer.MaxHeight);
}
}

[Theory]
[InlineData(1)]
[InlineData(2)]
[InlineData(3)]
public void MaxLines_Sets_ScrollViewer_MaxHeight_With_TextPresenter_Margin(int maxLines)
{
using (UnitTestApplication.Start(Services))
{
var target = new TextBox
{
Template = CreateTemplate(),
MaxLines = maxLines,

// Define explicit whole number line height for predictable calculations
LineHeight = 20
};

var impl = CreateMockTopLevelImpl();
var topLevel = new TestTopLevel(impl.Object)
{
Template = CreateTopLevelTemplate(),
Content = target
};
topLevel.ApplyTemplate();
topLevel.LayoutManager.ExecuteInitialLayoutPass();

var textPresenter = target.FindDescendantOfType<TextPresenter>();
Assert.Equal("PART_TextPresenter", textPresenter.Name);
var textPresenterMargin = new Thickness(horizontal: 0, vertical: 3);
textPresenter.Margin = textPresenterMargin;

target.InvalidateMeasure();
target.Measure(Size.Infinity);

var scrollViewer = target.FindDescendantOfType<ScrollViewer>();
Assert.Equal("PART_ScrollViewer", scrollViewer.Name);
Assert.Equal((maxLines * target.LineHeight) + textPresenterMargin.Top + textPresenterMargin.Bottom, scrollViewer.MaxHeight);
}
}

[Fact]
public void CanUndo_CanRedo_Is_False_When_Initialized()
{
Expand Down Expand Up @@ -1125,7 +1202,7 @@ private IControlTemplate CreateTemplate()
return new FuncControlTemplate<TextBox>((control, scope) =>
new ScrollViewer
{
Name = "Part_ScrollViewer",
Name = "PART_ScrollViewer",
Template = new FuncControlTemplate<ScrollViewer>(ScrollViewerTests.CreateTemplate),
Content = new TextPresenter
{
Expand Down