# TabStop

A *tab stop* is the location where the caret stops after you press the Tab key. Tab stops allow you to align text by inserting the Tab symbol. Each paragraph contains a number of tabs, which you can place wherever needed.

## TabStop Overview

The `TabStop` class is immutable, meaning you must set its properties when initializing an instance.

* `Position`: The position of the tab stop. The value is in device-independent pixels (1/96 inch).

* `Type`: The type of the tab stop. Defines the behavior of the tab stop. All possibilities are described with the [`TabStopType` enumeration](https://docs.telerik.com/devtools/document-processing/api/Telerik.Windows.Documents.Flow.Model.Styles.TabStopType.html):

  * `Left`: The text following the tab stop is left aligned with respect to the tab stop position. This is the *default* value.
  * `Center`: The text following the tab stop is centered around the tab stop position.
  * `Right`: The text following the tab stop is right aligned with respect to the tab stop position.
  * `Decimal`: Text before the decimal point is positioned to the left and text after the decimal point is positioned to the right side of the tab stop.
  * `Bar`: A vertical bar is shown at the tab position.
  * `Clear`: Clears an inherited tab stop.

* `Leader`: Specifies the character that fills the space in front of a tab. All possibilities are described with the [`TabStopLeader` enumeration](https://docs.telerik.com/devtools/document-processing/api/Telerik.Windows.Documents.Flow.Model.Styles.TabStopLeader.html):

  * `None`: The space before the tab is left empty. This is the default value.
  * `Dot`: The space before the tab is filled with dots.
  * `Hyphen`: The space before the tab is filled with hyphens.
  * `Underscore`: The space before the tab is filled with underscores.
  * `MiddleDot`: The space before the tab is filled with middle dots.

The distance between automatic tab stops is determined by the [`RadFlowDocument`](https://www.telerik.com/document-processing-libraries/documentation/libraries/radwordsprocessing/model/radflowdocument).`DefaultTabStopWidth` property. Automatic tab stops refer to the tab stop locations that occur after all custom tab stops in the current paragraph have been surpassed.

## TabStopCollection Overview

This class derives from `System.Collections.Generic.IEnumerable<T>` and represents a collection of `TabStop` objects. The collection is immutable, and it holds the tab stops in a [Paragraph](https://www.telerik.com/document-processing-libraries/documentation/libraries/radwordsprocessing/model/paragraph).

The `TabStopCollection` class exposes the following members:

* `Count`: The count of `TabStop` elements in the collection.
* `Insert()`: Returns a new instance of `TabStopCollection` with the specified tab stop inserted in it.
* `Remove()`: Returns a new instance of `TabStopCollection` with the specified tab stop removed.

## Working with TabStopCollection

### Create a TabStopCollection

Excluding the default constructor, the `TabStopCollection` class exposes an overload that allows you to directly pass a collection of `TabStop` objects:

<a name="example1"></a>

**Example 1: Create a TabStopCollection with left, center, right, and bar tab stops**

```C#
List<TabStop> tabStops = new List<TabStop>();
tabStops.Add(new TabStop(Unit.InchToDip(1), TabStopType.Left));
tabStops.Add(new TabStop(Unit.InchToDip(2), TabStopType.Center, TabStopLeader.Dot));
tabStops.Add(new TabStop(Unit.InchToDip(3), TabStopType.Right, TabStopLeader.Hyphen));
tabStops.Add(new TabStop(Unit.InchToDip(5.5), TabStopType.Bar));

TabStopCollection collection = new TabStopCollection(tabStops);
```

### Insert Item in a TabStopCollection

**Example 2** demonstrates how to insert items in the `TabStopCollection` created in [Example 1](https://www.telerik.com/document-processing-libraries/documentation/libraries/radwordsprocessing/concepts/tabstop#example1). Keep in mind that this collection is immutable, so the `Insert()` method returns a **new instance** of the class.

**Example 2: Insert two additional tab stops into the immutable TabStopCollection**

```C#
collection = collection.Insert(new TabStop(Unit.InchToDip(4)))
                           .Insert(new TabStop(Unit.InchToDip(5.5), TabStopType.Right));
```

### Remove Item from a TabStopCollection

The following snippet shows how to remove an item from the `TabStopCollection` created in [Example 1](https://www.telerik.com/document-processing-libraries/documentation/libraries/radwordsprocessing/concepts/tabstop#example1). Keep in mind that this collection is immutable, so the `Remove()` method returns a new instance of the class.

**Example 3: Remove the first tab stop from the TabStopCollection**

```C#
TabStop tabStopToRemove = collection.First();
collection = collection.Remove(tabStopToRemove);
```

## Working with TabStop

In RadWordsProcessing, the tab stops are stored as a collection in the [Paragraph](https://www.telerik.com/document-processing-libraries/documentation/libraries/radwordsprocessing/model/paragraph). This section shows how to work with the `TabStop` element.

### Create a TabStop

The code from **Example 4** demonstrates how to create a tab stop.

<a name="example4"></a>

**Example 4: Create a centered tab stop positioned at two inches**

```C#
TabStop tabStop = new TabStop(Unit.InchToDip(2), TabStopType.Center);
```

### Add a TabStop

**Example 5** shows how to add the tab stop created in [Example 1](https://www.telerik.com/document-processing-libraries/documentation/libraries/radwordsprocessing/concepts/tabstop#example1) to an existing `Paragraph` through the `TabStops` property of type `TabStopCollection`.

**Example 5: Insert the tab stop into a paragraph TabStops collection**

```C#
paragraph.TabStops = paragraph.TabStops.Insert(tabStop);
```

### Remove a TabStop

The following code-snippet shows how to remove the tab stop created in [Example 4](https://www.telerik.com/document-processing-libraries/documentation/libraries/radwordsprocessing/concepts/tabstop#example4):

**Example 6: Remove the tab stop from the paragraph TabStops collection**

```C#
paragraph.TabStops = paragraph.TabStops.Remove(tabStop);
```

### Use a TabStop in the Content

Once you have applied the desired tab stops to a paragraph, insert tabs (\t) so that the content aligns to the specified tab stops. The code in **Example 7** inserts tab stops at three positions with different properties. It then aligns three words on the tab stop positions using tabs.

**Example 7: Define three tab stops and align left, center, and right text with tab characters**

```C#
private RadFlowDocument CreateDocumentWithTabStops()
        {
RadFlowDocument document = new RadFlowDocument();
RadFlowDocumentEditor editor = new RadFlowDocumentEditor(document);

List<TabStop> tabStops = new List<TabStop>();
tabStops.Add(new TabStop(Unit.InchToDip(1), TabStopType.Left));
tabStops.Add(new TabStop(Unit.InchToDip(3), TabStopType.Center, TabStopLeader.Dot));
tabStops.Add(new TabStop(Unit.InchToDip(5), TabStopType.Right, TabStopLeader.Hyphen));

TabStopCollection tabStopCollection = new TabStopCollection(tabStops);

Paragraph paragraph = editor.InsertParagraph();
paragraph.TabStops = tabStopCollection;
paragraph.Inlines.AddRun("\tleft\tcenter\tright");

return document;
        }
```

## See Also

* [Paragraph](https://www.telerik.com/document-processing-libraries/documentation/libraries/radwordsprocessing/model/paragraph)