# UnderlineAnnotation Class

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

- Product: Adobe PDF Library 21
- Language: Modern C++
- Version: 21.4.0
- HTML page: https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/class/UnderlineAnnotation
- Version index: https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/llms.txt

```cpp
class UnderlineAnnotation : TextMarkupAnnotation
```

**Namespace:** `datalogics_interface`

**Inherits from:** [`TextMarkupAnnotation`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/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/ModernCPP/21.4.0/enum/AnnotationFlags.md), [`Color`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/class/Color.md), [`Form`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/class/Form.md), [`Quad`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/struct/Quad.md), [`Rect`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/struct/Rect.md)

## Constructors

### UnderlineAnnotation

```cpp
datalogics_interface::UnderlineAnnotation::UnderlineAnnotation(Page &page, const std::vector< Quad > &quads)
```

*constructor*

**Parameters**

- `page` ([`Page &`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/class/Page.md)): The page to which the UnderlineAnnotation is added.
- `quads` ([`const std::vector< Quad > &`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/struct/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.

### UnderlineAnnotation

```cpp
datalogics_interface::UnderlineAnnotation::UnderlineAnnotation(Page &page, int add_after, const std::vector< Quad > &quads)
```

*constructor*

**Parameters**

- `page` ([`Page &`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/class/Page.md)): The page to which the UnderlineAnnotation is added.
- `add_after` (`int`): A list of quads to underline. Each quad encompasses a word or group of contiguous words in the text underlying the annotation.
- `quads` ([`const std::vector< Quad > &`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/struct/Quad.md))

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.

### ~UnderlineAnnotation

```cpp
datalogics_interface::UnderlineAnnotation::~UnderlineAnnotation() override
```

*destructor*

## Methods

### clear_interior_color

```cpp
void datalogics_interface::Annotation::clear_interior_color()
```

**Returns:** `void`

Clear the interior color.

### generate_appearance

```cpp
virtual std::unique_ptr< Form > datalogics_interface::Annotation::generate_appearance() const
```

**Returns:** [`std::unique_ptr< Form >`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/class/Form.md)

A Form representing the visual appearance, or null if the appearance could not be generated.

Generate a new appearance stream with the current annotation properties.

The resulting Form can then be used to set the annotation's appearance, such as by calling SetNormalAppearance.

### get_annotated_text

```cpp
std::string datalogics_interface::TextMarkupAnnotation::get_annotated_text(bool split_lines=false)
```

**Parameters**

- `split_lines` (`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:** `std::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.

### get_annotation_feature_level

```cpp
virtual double datalogics_interface::Annotation::get_annotation_feature_level() const
```

**Returns:** `double`

The minimum PDF version level (e.g. 1.3, 1.4, or 1.5).

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

### get_color

```cpp
Color datalogics_interface::Annotation::get_color() const
```

**Returns:** [`Color`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/class/Color.md)

The annotation's color.

The color of the annotation.

### get_contents

```cpp
std::string datalogics_interface::Annotation::get_contents() const
```

**Returns:** `std::string`

The annotation's text contents.

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.

### get_flags

```cpp
AnnotationFlags datalogics_interface::Annotation::get_flags() const
```

**Returns:** [`AnnotationFlags`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/enum/AnnotationFlags.md)

The annotation's flags.

The flags for the annotation.

### get_interior_color

```cpp
std::unique_ptr< Color > datalogics_interface::Annotation::get_interior_color() const
```

**Returns:** [`std::unique_ptr< Color >`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/class/Color.md)

The interior fill color, or null if no interior color is 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.

### get_normal_appearance

```cpp
std::unique_ptr< Form > datalogics_interface::Annotation::get_normal_appearance() const
```

**Returns:** [`std::unique_ptr< Form >`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/class/Form.md)

A Form representing the annotation's normal appearance, or null if no normal appearance has been set.

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

### get_opacity

```cpp
double datalogics_interface::Annotation::get_opacity() const
```

**Returns:** `double`

The opacity value for this annotation.

The constant opacity value used in painting a Markup annotation.

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

### get_quads

```cpp
std::vector< Quad > datalogics_interface::TextMarkupAnnotation::get_quads() const
```

**Returns:** [`std::vector< Quad >`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/struct/Quad.md)

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

### get_rect

```cpp
Rect datalogics_interface::Annotation::get_rect() const
```

**Returns:** [`Rect`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/struct/Rect.md)

The annotation's bounding rectangle in user space coordinates.

The size and location of the annotation on its page.

### get_subtype

```cpp
std::string datalogics_interface::Annotation::get_subtype() const
```

**Returns:** `std::string`

The subtype string (e.g. "Circle", "Square", "Line").

The annotation's subtype.

### get_title

```cpp
std::string datalogics_interface::Annotation::get_title() const
```

**Returns:** `std::string`

The title string.

The title of the annotation.

### has_rich_text_data

```cpp
bool datalogics_interface::Annotation::has_rich_text_data() const
```

**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.

### operator==

```cpp
bool datalogics_interface::Annotation::operator==(const Annotation &other) const
```

**Parameters**

- `other` ([`const Annotation &`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/class/Annotation.md)): The annotation to compare with this annotation.

**Returns:** `bool`

true if the two annotations are equal.

Test annotations for equality (if they are the same annotation).

### set_annotation_feature_level

```cpp
virtual void datalogics_interface::Annotation::set_annotation_feature_level(double level)
```

**Parameters**

- `level` (`double`): The target PDF version level. Features requiring a higher version will be removed.

**Returns:** `void`

Removes features not supported in the supplied version number.

### set_color

```cpp
void datalogics_interface::Annotation::set_color(const Color &color)
```

**Parameters**

- `color` ([`const Color &`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/class/Color.md)): The new color to set.

**Returns:** `void`

The color of the annotation.

### set_contents

```cpp
void datalogics_interface::Annotation::set_contents(const std::string &contents)
```

**Parameters**

- `contents` (`const std::string &`): The new text contents.

**Returns:** `void`

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.

### set_flags

```cpp
void datalogics_interface::Annotation::set_flags(AnnotationFlags flags)
```

**Parameters**

- `flags` ([`AnnotationFlags`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/enum/AnnotationFlags.md)): The new annotation flags to set.

**Returns:** `void`

The flags for the annotation.

### set_interior_color

```cpp
void datalogics_interface::Annotation::set_interior_color(const Color &color)
```

**Parameters**

- `color` ([`const Color &`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/class/Color.md)): The new interior fill color. Pass null to remove the interior color.

**Returns:** `void`

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

Only RGB colors are allowed.

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

### set_normal_appearance

```cpp
void datalogics_interface::Annotation::set_normal_appearance(Form &form)
```

**Parameters**

- `form` ([`Form &`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/class/Form.md)): The Form to use as the annotation's normal appearance.

**Returns:** `void`

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

### set_opacity

```cpp
void datalogics_interface::Annotation::set_opacity(double opacity)
```

**Parameters**

- `opacity` (`double`): The new opacity value to set.

**Returns:** `void`

The constant opacity value used in painting a Markup annotation.

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

### set_quads

```cpp
void datalogics_interface::TextMarkupAnnotation::set_quads(const std::vector< Quad > &quads)
```

**Parameters**

- `quads` ([`const std::vector< Quad > &`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/struct/Quad.md)): a list of quads to mark. Each quad encompasses a word or group of contiguous words in the text underlying the annotation

**Returns:** `void`

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

### set_rect

```cpp
void datalogics_interface::Annotation::set_rect(const Rect &rect)
```

**Parameters**

- `rect` ([`const Rect &`](https://docs.datalogics.com/apdfl21/ModernCPP/21.4.0/struct/Rect.md)): The new bounding rectangle in user space coordinates.

**Returns:** `void`

The size and location of the annotation on its page.

### set_title

```cpp
void datalogics_interface::Annotation::set_title(const std::string &title)
```

**Parameters**

- `title` (`const std::string &`): The new title string.

**Returns:** `void`

The title of the annotation.

### to_string

```cpp
std::string datalogics_interface::Annotation::to_string() const
```

**Returns:** `std::string`

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

Returns a string representation of this annotation.

### try_as

```cpp
T * datalogics_interface::Annotation::try_as()
```

**Parameters**

- (unnamed) (`typename T`)

**Returns:** `T *`

Attempt to downcast this annotation to a derived type. Returns a pointer to the derived type, or nullptr if the type doesn't match.

### try_as

```cpp
const T * datalogics_interface::Annotation::try_as() const
```

**Parameters**

- (unnamed) (`typename T`)

**Returns:** `const T *`

Const overload of try_as(). Returns a const pointer, or nullptr.