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PDF Rendering
Convert PDF to Image (.NET)
Convert PDF to image on Android (Xamarin)
Convert PDF to image on iOS (Xamarin)
Convert PDF to image in Windows Store apps (.NET)
Convert PDF to image in Windows Phone apps (.NET)
PDF to image in Universal Windows Store apps (.NET)
Free PDF Viewer control for Windows Forms (.NET)
How to integrate PDF Viewer control in WPF app (.NET)
Creating WPF PDF Viewer supporting bookmarks (.NET)
Cross-platform PDF Viewer using GTK# (MONO)
Silverlight PDF viewer control (Silverlight 5)
Multithreaded PDF rendering (.NET)
Convert pdf to image in Silverlight app (C# sample)
How to set fallback fonts for PDF rendering (C#)
Avoiding the out-of-memory exception on rendering (C#)
PDF viewer single page application (WebAPI, AngularJS)
PDF viewer control for Windows 10 universal applications
Use custom ICC profile for CMYK to RGB conversion
PDF layers - separate images, text, annotations, graphics

PDF Forms Creation PDF Security
Conversion to PDF/A
Other topics
PDF Document Manipulation PDF Content Generation
Fixed and Flow layout document API (.NET)
Creation of grids and tables in PDF (C# sample)
How to create interactive documents using Actions (C# sample)
Text flow effects in PDF (C# sample)
How to generate ordered and bulleted lists in PDF (C# sample)
Convert HTML to PDF using flow layout API (C# sample)
How to use custom fonts for PDF generation (.NET)
Create document with differently sized pages (C#)
Create PDF documents using MONO (C#/MONO/Windows/OSX)
How to use background images for content elements (C#/PDF Kit/FlowLayout)
Add transparent images to PDF document (C#)
Draw round rect borders in PDF documents(C#)
ICC color profiles and and ICC based colors in PDF (C#)
How to use bidirectional and right to left text in PDF (C#)
Create PDF documents from XML templates (C# sample)
How to resize PDF pages and use custom stamps (C#)
Add header and footer to PDF page (.NET sample)
How to use clipping mask for drawing on PDF page
Fill graphics path with gradient brushes in PDF (Shadings)
Apitron PDF Kit and Rasterizer engine settings
Add layers to PDF page (optional content, C# sample)
How to create free text annotation with custom appearance
PDF Content Extraction PDF Navigation
PDF to TIFF conversion
Contact us if you have a PDF related question and we'll cover it in our blog.

2015-10-21

Convert and view PDF documents in Xamarin Forms applications

Introduction


Xamarin.Forms offers you a flexible cross-platform alternative to create data entry applications targeting multiple platforms at once. Sometimes you might need to create PDF file based on entered data, or show the existing PDF document to user. In this article we’ll demonstrate how to render existing PDF documents in a Xamarin.Forms app targeting iOS and Android using Apitron PDF Rasterizer component.


Form layout and code


We’ll use very simple layout – a button to trigger rendering and an image to display the result. See the XAML and code behind below:

<?xml version="1.0" encoding="UTF-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms" 
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" 
x:Class="XamarinFormsSample.MyPage">
    <ContentPage.Content>    
         <StackLayout Orientation="Vertical" Spacing="10" 
          VerticalOptions="FillAndExpand"
          HorizontalOptions="FillAndExpand">
             <StackLayout Padding="0,10,0,10">
                <Button x:Name="btnRenderPDF" Clicked="OnRenderPdfClicked" 
                Text="Render"/>
            </StackLayout>
            <ScrollView Orientation="Horizontal">
            <ScrollView Orientation="Vertical">
                 <Image x:Name="myImage" Aspect="Fill" VerticalOptions="StartAndExpand" 
                 HorizontalOptions="StartAndExpand"/>                
            </ScrollView>
            </ScrollView>
        </StackLayout>
    </ContentPage.Content>
</ContentPage>

public partial class MyPage : ContentPage
{
    public MyPage ()
    {
        InitializeComponent ();
    }

    void OnRenderPdfClicked(object sender, EventArgs args)
    {
        Assembly currentAssembly = typeof(MyPage).GetTypeInfo().Assembly;

        using (Stream resourceStream = 
currentAssembly.
               GetManifestResourceStream("XamarinFormsSample.Data.testfile.pdf")) 
 {                
            byte[] buffer = new byte[resourceStream.Length];
            resourceStream.Read (buffer, 0, buffer.Length);

            var renderer = DependencyService.Get<IRenderer>();
            myImage.Source = ImageSource.FromStream (()=>
                {                        
                    return renderer.RenderToStream(buffer,0);
                });
        }                
    }
}

We read the PDF document from resources and pass it to platform dependent renderer implementation requested using the dependency service. It returns an image stream used as image source. 


Android implementation


using System;
using Xamarin.Forms;
using XamarinFormsSample;
using Apitron.PDF.Rasterizer;
using Android.Graphics;
using System.IO;
using XamarinFormsSample.Droid;
using Java.Nio;

[assembly: Dependency(typeof(Renderer))]

namespace XamarinFormsSample.Droid
{
    /// <summary>
    /// Android specific implementation of <see cref="XamarinFormsSample.IRenderer"/>
    /// interface.
    /// </summary>
    public class Renderer:IRenderer
    {
        public Renderer ()
        {
        }

        #region IRenderer implementation
        public System.IO.Stream RenderToStream (byte[] documentData, int pageIndex)
        {
            using (MemoryStream ms = new MemoryStream (documentData))
            {
                // open document
                using (Document doc = new Document (ms)) 
                {
                    // prepare for rendering
                    int width = (int)doc.Pages [pageIndex].Width;
                    int height = (int)doc.Pages [pageIndex].Height;
                    // render as ints array
                    int[] renderedPage =doc.Pages[pageIndex].RenderAsInts(width,height,
                        new Apitron.PDF.Rasterizer.Configuration.RenderingSettings ());

                    // create bitmap and save it to stream
                    Bitmap bm = Bitmap.CreateBitmap (renderedPage, width, height,
                        Bitmap.Config.Argb8888);

                    MemoryStream outputStream = new MemoryStream ();
                    bm.Compress (Bitmap.CompressFormat.Png, 100, outputStream);
                    outputStream.Position = 0;

                    return outputStream;
                }
            }
        }
        #endregion
    }
}


iOS implementation


using …

[assembly: Dependency(typeof(Renderer))]

namespace XamarinFormsSample.iOS
{
    // iOS specific implementation of <see cref="XamarinFormsSample.IRenderer"/> 
    // interface.
    public class Renderer:IRenderer
    {
        public Renderer ()
        {
        }
        public System.IO.Stream RenderToStream (byte[] documentData, int pageIndex)
        {
            using (MemoryStream ms = new MemoryStream (documentData))
            {
                // open document
                using (Document doc = new Document (ms)) 
                {
                    // prepare for rendering
                    int width = (int)doc.Pages [pageIndex].Width;
                    int height = (int)doc.Pages [pageIndex].Height;

                    // render the page to a raw bitmap data represented by byte array
                    byte[] imageData=ConvertBGRAtoRGBA(
                    doc.Pages[pageIndex].RenderAsBytes(width, height,
                        new RenderingSettings(), null));

                    // create CGDataProvider which will serve CGImage creation
                    CGDataProvider dataProvider =new CGDataProvider(imageData,0,
                        imageData.Length);

                    // create core graphics image using data provider created above, 
                    // note that we use CGImageAlphaInfo.Last(ARGB) pixel format
                    CGImage cgImage = new CGImage(width,height,8,32,width*4,
                        CGColorSpace.CreateDeviceRGB(), CGImageAlphaInfo.Last, 
                        dataProvider, null, false, CGColorRenderingIntent.Default);

                    // create UIImage and save it to gallery
                    UIImage finalImage = new UIImage (cgImage);                                
                    return finalImage.AsPNG ().AsStream();
                }
            }                        
        }

        /// <summary>
        /// Converts the BGRA data to RGBA.
        /// </summary>
        /// <returns>Same byte array but with RGBA color dara.</returns>
        /// <param name="bgraData">Raw bitmap data in BGRA8888 format .</param>
        byte[] ConvertBGRAtoRGBA(byte[] bgraData)
        {
            // implemented simple conversion, swap 2 bytes.
            byte tmp;
            for(int i=0,k=2;i<bgraData.Length;i+=4,k+=4)
            {
                tmp = bgraData [i]; 
                bgraData [i] = bgraData [k];
                bgraData [k] = tmp;
            }
            return bgraData;
        }
    }
}


Results


The source PDF file rendered on both platforms is shown on the images below:

Pic. 1 Render PDF in Xamarin.Forms App ( Android

Pic.
1 Render PDF in Xamarin.Forms App ( Android) 


Pic. 2 Render PDF in Xamarin.Forms app ( iOS )

Pic. 2 Render PDF in Xamarin.Forms app ( iOS )

Conclusion


In this article we’ve shown how to convert to image and view PDF documents in Xamarin Forms applications. We used Apitron PDF Rasterizer .NET component for that, but if you need to create PDF documents or manipulate them you can use Apitron PDF Kit and do whatever you want with PDF files. Text extraction, context generation, adding signatures and many other features are wrapped by the easy to use API for your convenience. Contact us if you need any help and we’ll be happy to assist you. 

Downloadable version of this article can be found by the following link [PDF].

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