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Nested lists - Lists can directly contain another list #42

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7ec9a18
Nested lists - Lists can directly contain another list
mato7d5 Jul 22, 2026
64ea749
Unit test for nested lists
mato7d5 Jul 23, 2026
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34 changes: 34 additions & 0 deletions itext.tests/itext.layout.tests/itext/layout/renderer/ListRendererUnitTest.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -180,6 +180,40 @@ public virtual void IncorrectChildTypeDoesntThrowTest() {
}
}

[NUnit.Framework.Test]
public virtual void NestedListDirectChildDoesNotThrowOnLayoutTest() {
using (Document document = CreateDummyDocument()) {
List nestedList = new List(ListNumberingType.ENGLISH_LOWER).Add("nested-1").Add("nested-2");
List parentList = new List(ListNumberingType.DECIMAL);
parentList.Add(new ListItem("parent-1"));
parentList.Add(nestedList);
parentList.Add(new ListItem("parent-2"));
NUnit.Framework.Assert.DoesNotThrow(() => document.Add(parentList));
}
}

[NUnit.Framework.Test]
public virtual void NestedListIndentAppliedToDirectNestedListRendererTest() {
List nestedList = new List(ListNumberingType.ENGLISH_LOWER).SetMarginLeft(7).Add("nested-1");
List parentList = new List(ListNumberingType.DECIMAL).SetListIndent(15);
parentList.Add(new ListItem("parent-1"));
parentList.Add(nestedList);
parentList.Add(new ListItem("parent-2"));
ListRenderer parentRenderer = (ListRenderer)parentList.CreateRendererSubTree();
using (Document document = CreateDummyDocument()) {
parentRenderer.SetParent(document.GetRenderer());
LayoutResult result = parentRenderer.Layout(CreateLayoutContext(400, 400));
NUnit.Framework.Assert.AreNotEqual(LayoutResult.NOTHING, result.GetStatus());
}
NUnit.Framework.Assert.AreEqual(3, parentRenderer.GetChildRenderers().Count);
IRenderer nestedRenderer = parentRenderer.GetChildRenderers()[1];
NUnit.Framework.Assert.IsTrue(nestedRenderer is ListRenderer);
UnitValue nestedMarginLeft = nestedRenderer.GetProperty<UnitValue>(Property.MARGIN_LEFT);
NUnit.Framework.Assert.IsNotNull(nestedMarginLeft);
NUnit.Framework.Assert.IsTrue(nestedMarginLeft.IsPointValue());
NUnit.Framework.Assert.AreEqual(22f, nestedMarginLeft.GetValue(), 0.0001f);
}

private static ListRenderer CreateInsideListRenderer() {
List list = new List();
list.SetListSymbol(new iText.Layout.Element.Text("*"));
Expand Down
42 changes: 42 additions & 0 deletions itext/itext.layout/itext/layout/element/List.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -97,6 +97,30 @@ public virtual iText.Layout.Element.List Add(ListItem listItem) {
return this;
}

/// <summary>
/// Adds a new
/// <see cref="iText.Layout.Element.List"/>
/// (nested list) to the bottom of the List.
/// </summary>
/// <param name="list">a nested list</param>
/// <returns>this list.</returns>
public virtual iText.Layout.Element.List Add(iText.Layout.Element.List list) {
childElements.Add(list);
return this;
}

/// <summary>
/// Adds a new
/// <see cref="IBlockElement"/>
/// to the bottom of the List.
/// </summary>
/// <param name="element">a block element (e.g. Paragraph)</param>
/// <returns>this list.</returns>
public virtual iText.Layout.Element.List Add(IBlockElement element) {
childElements.Add(element);
return this;
}

/// <summary>
/// Adds a new
/// <see cref="ListItem"/>
Expand Down Expand Up @@ -234,6 +258,24 @@ public virtual iText.Layout.Element.List SetSymbolIndent(float symbolIndent) {
return this;
}

/// <summary>
/// Gets the indent (left margin) applied to nested lists that are direct children of this list.
/// </summary>
/// <returns>the nested list indent as a <c>float</c>, or <c>null</c> if not set.</returns>
public virtual float? GetListIndent() {
return this.GetProperty<float?>(Property.LIST_INDENT);
}

/// <summary>
/// Sets the indent (left margin) applied to nested lists that are direct children of this list.
/// </summary>
/// <param name="listIndent">the indent offset for nested lists.</param>
/// <returns>this list.</returns>
public virtual iText.Layout.Element.List SetListIndent(float listIndent) {
SetProperty(Property.LIST_INDENT, listIndent);
return this;
}

/// <summary>
/// Gets the piece of text that is added after the
/// <see cref="ListItem"/>
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5 changes: 5 additions & 0 deletions itext/itext.layout/itext/layout/properties/Property.cs
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Expand Up @@ -437,6 +437,11 @@ public sealed class Property {

private const int MAX_INHERITED_PROPERTY_ID = 165;

/// <summary>
/// The indent (left margin) applied to nested lists that are direct children of a parent list.
/// </summary>
public const int LIST_INDENT = 166;

static Property() {
INHERITED_PROPERTIES = new bool[MAX_INHERITED_PROPERTY_ID + 1];
INHERITED_PROPERTIES[iText.Layout.Properties.Property.APPEARANCE_STREAM_LAYOUT] = true;
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33 changes: 32 additions & 1 deletion itext/itext.layout/itext/layout/renderer/ListRenderer.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -322,6 +322,11 @@ private LayoutResult CorrectListSplitting(IRenderer splitRenderer, IRenderer ove
// Notice that placed item is a son of the first ListItemRenderer (otherwise there would be now
// FORCED_PLACEMENT applied)
IRenderer firstListItemRenderer = splitRenderer.GetChildRenderers()[0];
if (!(firstListItemRenderer is ListItemRenderer) && firstListItemRenderer is BlockRenderer) {
// If the first child is not a ListItemRenderer, fall back to default behaviour
return new LayoutResult(null == overflowRenderer ? LayoutResult.FULL : LayoutResult.PARTIAL, occupiedArea,
splitRenderer, overflowRenderer, this);
}
iText.Layout.Renderer.ListRenderer newOverflowRenderer = (iText.Layout.Renderer.ListRenderer)CreateOverflowRenderer
(LayoutResult.PARTIAL);
newOverflowRenderer.DeleteOwnProperty(Property.FORCED_PLACEMENT);
Expand Down Expand Up @@ -366,6 +371,11 @@ private LayoutResult InitializeListSymbols(LayoutContext layoutContext) {
IList<IRenderer> symbolRenderers = new List<IRenderer>();
int listItemNum = (int)this.GetProperty<int?>(Property.LIST_START, 1);
foreach (IRenderer renderer in childRenderers) {
if (!(renderer is ListItemRenderer) && (renderer is ParagraphRenderer || renderer is iText.Layout.Renderer.ListRenderer)) {
// Non-ListItem children (e.g. Paragraph, nested List) do not get list symbols
symbolRenderers.Add(null);
continue;
}
renderer.SetParent(this);
listItemNum = (renderer.GetProperty<int?>(Property.LIST_SYMBOL_ORDINAL_VALUE) != null) ? (int)renderer.GetProperty
<int?>(Property.LIST_SYMBOL_ORDINAL_VALUE) : listItemNum;
Expand Down Expand Up @@ -406,8 +416,30 @@ private LayoutResult InitializeListSymbols(LayoutContext layoutContext) {
}
}
float? symbolIndent = this.GetPropertyAsFloat(Property.LIST_SYMBOL_INDENT);
float? nestedListIndent = this.GetPropertyAsFloat(Property.LIST_INDENT);
listItemNum = 0;
foreach (IRenderer childRenderer in childRenderers) {
IRenderer symbolRenderer = symbolRenderers[listItemNum++];
if (!(childRenderer is ListItemRenderer)) {
// Non-ListItem children (e.g. Paragraph, nested List) do not get list symbols
// Apply indent to nested lists so they are visually offset from the parent list
if (childRenderer is iText.Layout.Renderer.ListRenderer) {
if (nestedListIndent != null) {
bool isRtlNested = BaseDirection.RIGHT_TO_LEFT == childRenderer.GetProperty<BaseDirection?>(Property.BASE_DIRECTION);
int nestedMarginToSet = isRtlNested ? Property.MARGIN_RIGHT : Property.MARGIN_LEFT;
UnitValue existingMargin = childRenderer.GetProperty<UnitValue>(nestedMarginToSet, UnitValue.CreatePointValue(0f));
float nestedCalculatedMargin = existingMargin.IsPointValue() ? existingMargin.GetValue() : 0f;
nestedCalculatedMargin += (float)nestedListIndent;
childRenderer.SetProperty(nestedMarginToSet, UnitValue.CreatePointValue(nestedCalculatedMargin));
}
continue;
}
else if (childRenderer is ParagraphRenderer) {
// Paragraphs - no list symbol
continue;
}
// Other non-ListItem types (e.g. DivRenderer) will fall through to the throw below
}
// Symbol indent's value should be summed with the margin's value
bool isRtl = BaseDirection.RIGHT_TO_LEFT == childRenderer.GetProperty<BaseDirection?>(Property.BASE_DIRECTION
);
Expand All @@ -426,7 +458,6 @@ private LayoutResult InitializeListSymbols(LayoutContext layoutContext) {
calculatedMargin += maxSymbolWidth + (float)(symbolIndent != null ? symbolIndent : 0f);
}
childRenderer.SetProperty(marginToSet, UnitValue.CreatePointValue(calculatedMargin));
IRenderer symbolRenderer = symbolRenderers[listItemNum++];
if (childRenderer is ListItemRenderer) {
((ListItemRenderer)childRenderer).AddSymbolRenderer(symbolRenderer, maxSymbolWidth);
}
Expand Down