# UnderlineAnnotation Class

> A type of text markup annotation, for underlining text.

- Product: Adobe PDF Library 21
- Language: .NET Framework
- Version: APDFL21.0.0PlusP1e
- HTML page: https://docs.datalogics.com/apdfl21/DotNetFramework/APDFL21.0.0PlusP1e/class/UnderlineAnnotation
- Version index: https://docs.datalogics.com/apdfl21/DotNetFramework/APDFL21.0.0PlusP1e/llms.txt

```csharp
class UnderlineAnnotation : TextMarkupAnnotation
```

**Namespace:** `Datalogics::PDFL`

**Inherits from:** [`TextMarkupAnnotation`](https://docs.datalogics.com/apdfl21/DotNetFramework/APDFL21.0.0PlusP1e/class/TextMarkupAnnotation.md)

## Description

A type of text markup annotation, for underlining text.

Text markup annotations added to a PDF file appear as highlights, underlines, or strikeouts. The Underline Annotation appears PDF document as underlined text when the documnent is opened in a PDF Viewer.

**Uses types:** [`AnnotationFlags`](https://docs.datalogics.com/apdfl21/DotNetFramework/APDFL21.0.0PlusP1e/enum/AnnotationFlags.md), [`Color`](https://docs.datalogics.com/apdfl21/DotNetFramework/APDFL21.0.0PlusP1e/class/Color.md), [`Form`](https://docs.datalogics.com/apdfl21/DotNetFramework/APDFL21.0.0PlusP1e/class/Form.md), [`OptionalContentContext`](https://docs.datalogics.com/apdfl21/DotNetFramework/APDFL21.0.0PlusP1e/class/OptionalContentContext.md), [`OptionalContentMembershipDict`](https://docs.datalogics.com/apdfl21/DotNetFramework/APDFL21.0.0PlusP1e/class/OptionalContentMembershipDict.md), [`PDFDict`](https://docs.datalogics.com/apdfl21/DotNetFramework/APDFL21.0.0PlusP1e/class/PDFDict.md), [`Page`](https://docs.datalogics.com/apdfl21/DotNetFramework/APDFL21.0.0PlusP1e/class/Page.md), [`Quad`](https://docs.datalogics.com/apdfl21/DotNetFramework/APDFL21.0.0PlusP1e/class/Quad.md), [`Rect`](https://docs.datalogics.com/apdfl21/DotNetFramework/APDFL21.0.0PlusP1e/class/Rect.md)

## Constructors

### UnderlineAnnotation

```csharp
Datalogics.PDFL.UnderlineAnnotation.UnderlineAnnotation(Page page, int addAfter, System.Collections.Generic.IList< Quad > quadList)
```

*constructor*

**Parameters**

- `page` ([`Page`](https://docs.datalogics.com/apdfl21/DotNetFramework/APDFL21.0.0PlusP1e/class/Page.md)): The page to which the UnderlineAnnotation is added.
- `addAfter` (`int`): Where to add the annotation in the page's annotation array. To add the annotation to the end of the array, pass a value of -2 or use the alternate version of this constructor that does not take an index (this is generally what you should do unless you have a need to place the annotation at a special location in the array). Passing a value of -1 adds the annotation to the beginning of the array. Passing other negative values produces undefined results.
- `quadList` ([`System.Collections.Generic.IList< Quad >`](https://docs.datalogics.com/apdfl21/DotNetFramework/APDFL21.0.0PlusP1e/class/Quad.md)): A list of quads to underline. Each quad encompasses a word or group of contiguous words in the text underlying the annotation.

Create a new UnderlineAnnotation at a specific index in the page's annotation array.

### UnderlineAnnotation

```csharp
Datalogics.PDFL.UnderlineAnnotation.UnderlineAnnotation(Page page, System.Collections.Generic.IList< Quad > quadList)
```

*constructor*

**Parameters**

- `page` ([`Page`](https://docs.datalogics.com/apdfl21/DotNetFramework/APDFL21.0.0PlusP1e/class/Page.md)): The page to which the UnderlineAnnotation is added.
- `quadList` ([`System.Collections.Generic.IList< Quad >`](https://docs.datalogics.com/apdfl21/DotNetFramework/APDFL21.0.0PlusP1e/class/Quad.md)): A list of quads to underline. Each quad encompasses a word or group of contiguous words in the text underlying the annotation.

Create a new UnderlineAnnotation at the end of a page's annotation array. To create a FreeTextAnnotation and place it elsewhere in the page's annotation array, use the version of the constructor that takes an array position.

## Properties

### AnnotationFeatureLevel

```csharp
double Datalogics.PDFL.Annotation.AnnotationFeatureLevel { get; set; }
```

The minimum PDF version necessary to support the features used in this annotation.

### Color

```csharp
Color Datalogics.PDFL.Annotation.Color { get; set; }
```

The color of the annotation.

### Contents

```csharp
string Datalogics.PDFL.Annotation.Contents { get; set; }
```

The text contents of the annotation.

The text to be displayed for the annotation or, if this type of annotation does not display text, an alternate description of the annotation's contents in human-readable form.

### Flags

```csharp
AnnotationFlags Datalogics.PDFL.Annotation.Flags { get; set; }
```

The flags for the annotation.

### InteriorColor

```csharp
Color Datalogics.PDFL.Annotation.InteriorColor { get; set; }
```

The interior color with which to fill the annotation's rectangle or circle.

The color of the border itself can be retrieved from Annotation.Color.

### NormalAppearance

```csharp
Form Datalogics.PDFL.Annotation.NormalAppearance { get; set; }
```

The normal appearance of the annotation, represented as a Form XObject.

### Opacity

```csharp
double Datalogics.PDFL.Annotation.Opacity { get; set; }
```

The constant opacity value used in painting a Markup annotation.

Opacity is a range from 0.0 (fully transparent) to 1.0 (fully opaque).

### OptionalContentMembershipDict

```csharp
OptionalContentMembershipDict Datalogics.PDFL.Annotation.OptionalContentMembershipDict { get; set; }
```

The OptionalContentMembershipDict property for this Annotation.

Setting this property will attach the Annotation to an OptionalContentMembershipDict; it will then be associated with the OptionalContentGroups and be subject to the VisibilityPolicy and VisibilityExpression of that MembershipDict.

By setting this property to null, the Annotation is detached from any OptionalContentMembershipDict.

### PDFDict

```csharp
PDFDict Datalogics.PDFL.Annotation.PDFDict { get; }
```

The underlying PDF dictionary for this annotation.

Retrieves the PDFDict representation of this annotation object.

### Quads

```csharp
System.Collections.Generic.IList<Quad> Datalogics.PDFL.TextMarkupAnnotation.Quads { get; set; }
```

A list of quads to mark. Each quad encompasses a word or group of contiguous words in the text underlying the annotation.

### Rect

```csharp
Rect Datalogics.PDFL.Annotation.Rect { get; set; }
```

The size and location of the annotation on its page.

### Subtype

```csharp
string Datalogics.PDFL.Annotation.Subtype { get; }
```

The annotation's subtype.

### Title

```csharp
string Datalogics.PDFL.Annotation.Title { get; set; }
```

The title of the annotation.

## Methods

### Dispose

```csharp
void Datalogics.PDFL.Annotation.Dispose()
```

**Returns:** `void`

### Equals

```csharp
override bool Datalogics.PDFL.Annotation.Equals(object obj)
```

**Parameters**

- `obj` (`object`)

**Returns:** `override bool`

### GenerateAppearance

```csharp
override Form Datalogics.PDFL.UnderlineAnnotation.GenerateAppearance()
```

**Returns:** `override Form`

A new Form object representing the underline appearance. The caller takes ownership of the returned object.

Generate a new appearance stream for this underline annotation.

Creates a Form containing stroked line paths for each quad in the annotation. The underline width is based on the font size of the text found within each quad, and the annotation's color is used as the stroke color.

### GetAnnotatedText

```csharp
string Datalogics.PDFL.TextMarkupAnnotation.GetAnnotatedText(bool splitLines)
```

**Parameters**

- `splitLines` (`bool`): If true, text corresponding to each quadrilateral will be separated by CRLF characters. If false, text corresponding to each quadrilateral will be separated by spaces.

**Returns:** `string`

The text marked by the annotation.

The text that is marked by the annotation. Marked text is defined as text which falls within one or more of the quadrilaterals specified by the annotation's QuadPoints entry. If the annotation marks partial words, only those portions of the word that are bounded within the QuadPoints array will be returned. If the annotation marks partial characters, the characters that fall partially within the annotation bounds may not be returned.

### HasRichTextData

```csharp
bool Datalogics.PDFL.Annotation.HasRichTextData()
```

**Returns:** `bool`

true if the annotation contains Rich Text String content.

Checks the annotation for Rich Text String content (PDFReference 1.7 Section 8.6.2). Annotations that contain Rich Text String content and do not have a normal appearance set will not be visible when rendering the page.

### IsCurrentlyVisible

```csharp
bool Datalogics.PDFL.Annotation.IsCurrentlyVisible(OptionalContentContext occ)
```

**Parameters**

- `occ` ([`OptionalContentContext`](https://docs.datalogics.com/apdfl21/DotNetFramework/APDFL21.0.0PlusP1e/class/OptionalContentContext.md)): The optional content context in which to check visibility.

**Returns:** `bool`

true if the annotation is currently visible.

Tests whether an annotation is visible in a given optional content context, considering the current ON-OFF states of the optional-content groups in the optional-content dictionary (OCMD) and the dictionary's visibility policy.

If the annotation occurs more than once within the content, this method only checks the visibility of the first occurrence of the annotation.

This method determines visibility without considering the visbility of the Content object that the annotation belongs to. To determine the visibility of an annotation while taking the Content's visibility into consideration, use the alternate version of this method.

### ToString

```csharp
override string Datalogics.PDFL.Annotation.ToString()
```

**Returns:** `override string`

A string describing this annotation, including its type and rectangle.

Returns a string representation of this annotation.