> 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/uwp/basic-operations/open.md).

# Open a PDF in UWP

Learn how to open a PDF document from a memory buffer with full source code examples. Explore how to read and write PDF files efficiently using Apryse SDK. The Apryse uwp SDK streamlines secure docume

To open a PDF document.

{% tabs %}
{% tab title="C#" %}
{% code lineNumbers="true" %}

```csharp
// open document from the filesystem
PDFDoc doc = new PDFDoc(fileName);

// optionally read a PDF document from a stream
MappedFile file = new MappedFile(fileName);
PDFDoc documentStream = new PDFDoc(file);

// or pass-in a memory buffer
ulong fileSize = file.WinRTGetFileSize();
FilterReader fileReader = new FilterReader(file);
byte[] memoryBuffer = new byte[(int)fileSize];
long bytesRead = fileReader.Read(memoryBuffer);
PDFDoc documentMemory = new PDFDoc(memoryBuffer);

// load from a URL
Uri url = new Uri("https://myserver.com/myfile.pdf");
HttpClient client = new HttpClient();
var file_content = client.GetByteArrayAsync(url);
PDFDoc doc = new PDFDoc(new MemoryStream(file_content));
```

{% endcode %}
{% endtab %}
{% endtabs %}

[Read & write a PDF file from/to memory buffer](/uwp/get-started/samples.md#pdfdocmemory) Full source code which illustrates how to read/write a PDF document from/to memory buffer. This is useful for applications that work with dynamic PDF documents that don't need to be saved/read from a disk.

## About opening a document

The PDFDoc constructor creates a PDF document from scratch:

{% hint style="warning" %}
**PDFDoc.Close()**

When you are finished with a PDFDoc object, the PDFDoc.Close() method should be called to clean up memory, file handles, and resources.
{% endhint %}

{% tabs %}
{% tab title="C#" %}
{% code lineNumbers="true" %}

```csharp
PDFDoc new_doc = new PDFDoc();
```

{% endcode %}
{% endtab %}
{% endtabs %}

A newly-created document does not yet contain any pages. See the [accessing pages](/uwp/basic-operations/pages.md) section for details on creating new pages and working with existing pages.

Using Apryse SDK, you can open a document from a serialized file, from a memory buffer, or from a Filter stream.

To open an existing PDF document from a file, specify its file path in the PDFDoc constructor:

{% tabs %}
{% tab title="C#" %}
{% code lineNumbers="true" %}

```csharp
PDFDoc new_doc = new PDFDoc(filename);
```

{% endcode %}
{% endtab %}
{% endtabs %}

Here's how to open an existing PDF document from a memory buffer:

{% tabs %}
{% tab title="C#" %}
{% code lineNumbers="true" %}

```csharp
MappedFile file = new MappedFile(filename);
ulong fileSize = file.WinRTGetFileSize();
FilterReader fileReader = new FilterReader(file);
byte[] memoryBuffer = new byte[(int)fileSize];
long bytesRead = fileReader.Read(memoryBuffer);
PDFDoc doc = new PDFDoc(memoryBuffer);
```

{% endcode %}
{% endtab %}
{% endtabs %}

It's also easy to open a PDF document from a [MemoryFilter or a custom Filter ](/uwp/low-level-pdf-api/filters.md).

After creating a PDFDoc object, it's good practice to call `InitSecurityHandler()` on it. If the document is encrypted, calling the method will decrypt it. If the document is not encrypted, calling the method is harmless.

{% tabs %}
{% tab title="C#" %}
{% code lineNumbers="true" %}

```csharp
PDFDoc doc = new PDFDoc(filename);
if (!doc.InitSecurityHandler())
{
  Console.WriteLine("Document authentication error...");
  return;
}
```

{% endcode %}
{% endtab %}
{% endtabs %}


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