> For the complete documentation index, see [llms.txt](https://docs.apryse.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.apryse.com/xamarin/guides/android/bookmark/outline.md).

# Outline tree (Android)

Learn how to work with an outline tree in Xamarin.Android using a UI component or API guide. Display outlines & bookmarks, set bookmarks, and navigate PDF documents programmatically. The Apryse Xamari

There are two options to working with an outline tree. First is using a UI component that provides tools to set a bookmark or display the outline. Second is an API guide to programmatically read outline items.

{% tabs %}
{% tab title="UI component" %}

## Display outlines & bookmarks in Android

{% hint style="info" %}
**This tutorial only applies to Xamarin.Android. See Xamarin.iOS equivalent here .**
{% endhint %}

The [`OutlineDialogFragment`](https://sdk.apryse.com/api/xamarinandroid/tools/api/pdftron.PDF.Controls.OutlineDialogFragment.html) displays a document outline (containing PDF `Bookmarks` that can be used to navigate the PDF document by selecting a bookmark item.

![](https://653871032-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FgjsBtuYmcKhWOdM9VCg4%2Fuploads%2Fgit-blob-70d682efd843654067aaa1eda10edfa72af76763%2Fcf7d5120d7c199b14fec80aefd804b573704dac8-810x1710.png?alt=media)

## Show outline dialog

To show an outline dialog fragment in your activity, create a new instance of [`OutlineDialogFragment`](https://sdk.apryse.com/api/xamarinandroid/tools/api/pdftron.PDF.Controls.OutlineDialogFragment.html) by calling `newInstance()` and setting the [`PDFViewCtrl`](https://sdk.apryse.com/api/xamarinandroid/pdfnet/api/pdftron.PDF.PDFViewCtrl.html):

{% code lineNumbers="true" %}

```csharp
fun showBookmarksDialog(fragmentManager: FragmentManager, pdfViewCtrl: PDFViewCtrl): BookmarksDialogFragment {
    var bookmarksDialog = pdftron.PDF.Dialog.BookmarksDialogFragment.NewInstance();
    bookmarksDialog.SetPdfViewCtrl(pdfViewCtrl);
    List<DialogFragmentTab> tabs = new List<DialogFragmentTab>();
    var outlineDialog = new DialogFragmentTab(
        Java.Lang.Class.FromType(typeof(OutlineDialogFragment)), BookmarksTabLayout.TagTabOutline, null, "Outline", "Bookmarks Dialog", null);
    tabs.Add(outlineDialog);
    bookmarksDialog.SetDialogFragmentTabs(tabs);
    bookmarksDialog.SetStyle((int)DialogFragmentStyle.NoTitle, Resource.Style.PDFTronAppTheme);
    bookmarksDialog.Show(fragmentManager, "bookmarks_dialog");
    return bookmarksDialog;
}
```

{% endcode %}

You can also set the current bookmark using `setCurrentBookmark(Bookmark)`.

## Listener

You can set a listener to be notified when an item in an [`OutlineDialogFragment`](https://sdk.apryse.com/api/xamarinandroid/tools/api/pdftron.PDF.Controls.OutlineDialogFragment.html) is clicked by calling `setOutlineDialogListener(OutlineDialogListener)`.
{% endtab %}

{% tab title="API guide" %}

## API to programmatically read, edit & create outlines / bookmarks

To navigate an outline tree and print its result.

{% code lineNumbers="true" %}

```csharp
void PrintIdent(Bookmark item)
{
  int ident = item.GetIdent() - 1;
  for (int i=0; i < ident; ++i) {
    Console.Write("  ");
  }
}
void PrintOutlineTree(Bookmark item)
{
  for (; item.IsValid(); item=item.GetNext()) {
    PrintIdent(item);
    Console.Write("{0:s}{1:s} ACTION -> ", (item.IsOpen() ? "- " : "+ "), item.GetTitle());
    if (item.HasChildren()) {
      PrintOutlineTree(item.GetFirstChild());
    }
  }
}
PDFDoc doc = new PDFDoc(filename);
Bookmark root = doc.GetFirstBookmark();
PrintOutlineTree(root);
```

{% endcode %}

[Read, add, edit PDF outlines and bookmarks](/xamarin/get-started/samples.md#bookmarks) Full code sample which illustrates how to read and edit existing outline items and create new bookmarks using the high-level API.

## About outline tree

A PDF document may display a document outline on the screen, allowing the user to navigate interactively from one part of the document to another. The outline consists of a tree-structured hierarchy of Bookmarks (sometimes called outline items), which serve as a "visual table of contents" to display the document's structure to the user.

Each Bookmark has a title that appears on screen, and an Action that specifies what happens when a user clicks on the Bookmark. The typical Action for a user-created Bookmark is to move to another location in the current document — although any Action can be specified.
{% endtab %}
{% endtabs %}


---

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