I am working with PDFium c# tool to create PDF document from PNG image stream.
I have an API which gets multiple image stream objects, I should combine the image streams and create a PDF document and PDF stream. I will need to hit another API to save this document.
I went through the PDFium documentation but, the examples shows how load PDF from Images but, not from stream
Do we need to create a image from Stream to load the PDF or is there any alternate?
Any help is highly appreciated
Thank you In advance
Sample Code I created based on the documentation
public void GeneratePdfFromImageStream(List<Stream> imageStreams, String pdfSaveLocation = null)
{
int pageIndex = 0;
//Initialize C# PDF Library
PdfCommon.Initialize();
//Create a PDF document
using (var doc = PdfDocument.CreateNew())
{
foreach (var imageStream in imageStreams)
{
//I am creating a Bitmap image here, is there a way I can achevie the same withrout creating the image
var image = System.Drawing.Bitmap.FromStream(imageStream, true) as System.Drawing.Bitmap;
//Create empty PdfBitmap
using (PdfBitmap pdfBitmap = new PdfBitmap(image.Width, image.Height, true))
{
using (var g = System.Drawing.Graphics.FromImage(pdfBitmap.Image))
{
//Draw image to PdfBitmap
g.DrawImage(image, 0, 0, image.Width, image.Height);
}
//Create Image object
var imageObject = PdfImageObject.Create(doc, pdfBitmap, 0, 0);
//Calculate size of image in PDF points
var size = CalculateSize(pdfBitmap.Width, pdfBitmap.Height, image.HorizontalResolution, image.VerticalResolution);
//Add empty page to PDF document
doc.Pages.InsertPageAt(pageIndex, size);
//Insert image to newly created page
doc.Pages[pageIndex].PageObjects.Add(imageObject);
//set image matrix
imageObject.Matrix = new FS_MATRIX(size.Width, 0, 0, size.Height, 0, 0);
//Generate PDF page content to content stream
doc.Pages[pageIndex].GenerateContent();
pageIndex++;
}
}
// Save PDF document as "saved.pdf" in no incremental mode
if (string.IsNullOrWhiteSpace(pdfSaveLocation))
doc.Save($"saved_{Guid.NewGuid().ToString()}.pdf", SaveFlags.NoIncremental);
}
}
I've a set of images that I'm programmatically drawing a simple watermark on them using System.Windows and System.Windows.Media.Imaging (yes, not with GDI+) by following a tutorial in here.
Most of the images are not more than 500Kb, but after applying a simple watermark, which is a text with a transparent background, the image size is drastically increasing.
For example, a 440Kb image is becoming 8.33MB after applying the watermark with the below method, and that is shocking me.
private static BitmapFrame ApplyWatermark(BitmapFrame image, string waterMarkText) {
const int x = 5;
var y = image.Height - 20;
var targetVisual = new DrawingVisual();
var targetContext = targetVisual.RenderOpen();
var brush = (SolidColorBrush)(new BrushConverter().ConvertFrom("#FFFFFF"));
brush.Opacity = 0.5;
targetContext.DrawImage(image, new Rect(0, 0, image.Width, image.Height));
targetContext.DrawRectangle(brush, new Pen(), new Rect(0, y, image.Width, 20));
targetContext.DrawText(new FormattedText(waterMarkText, CultureInfo.CurrentCulture, FlowDirection.LeftToRight,
new Typeface("Batang"), 13, Brushes.Black), new Point(x, y));
targetContext.Close();
var target = new RenderTargetBitmap((int)image.Width, (int)image.Height, 96, 96, PixelFormats.Default);
target.Render(targetVisual);
var targetFrame = BitmapFrame.Create(target);
return targetFrame;
}
I've noticed that the image quality is improved compared than the original image. The image is more smoother and colors are more lighter. But, you know I don't really want this. I want the image to be as it is, but include the watermark. No quality increases, and of course no drastic changes in image size.
Is there any settings that I'm missing in here to tell my program to keep the quality as same as source image? How can I prevent the significant change of the image size after the changes in my ApplyWatermark method?
Edit
1. This is how I convert BitmapFrame to Stream. Then I use that Stream to save the image to AmazonS3
private Stream EncodeBitmap(BitmapFrame image) {
BitmapEncoder enc = new BmpBitmapEncoder();
enc.Frames.Add(BitmapFrame.Create(image));
var memoryStream = new MemoryStream();
enc.Save(memoryStream);
return memoryStream;
}
2. This is how I get the BitmapFrame from Stream
private static BitmapFrame ReadBitmapFrame(Stream stream) {
var photoDecoder = BitmapDecoder.Create(
stream,
BitmapCreateOptions.PreservePixelFormat,
BitmapCacheOption.None);
return photoDecoder.Frames[0];
}
3. This is how I read the file from local directory
public Stream FindFileInLocalImageDir() {
try {
var path = #"D:\Some\Path\Image.png";
return !File.Exists(path) ? null : File.Open(path, FileMode.Open, FileAccess.Read, FileShare.Read);
} catch (Exception) {
return null;
}
}
The problem is that when you edit the image, the compression is gone. A 730x1108 JPG with 433kB disc size with 32bit (you mentioned transparency, so ARGB) will need at least 730 * 1108 * 4 = 3,09MB on disc. Of course you can compress it afterwards again (for disc, network stream of what else).
This is the reason why image software always needs much memory even when working with compressed data.
Conclusion: You will need the free memory to work with the image. Not possible to have it otherwise completly at hand.
The reason I asked my question in the comments earlier, is because I noticed there were several different encoders available. A bitmap usually has a significantly larger file size, due to the amount of information it's storing about your image.
I haven't tested this myself, but have you tried a different encoder?
var pngEncoder = new PngBitmapEncoder();
pngEncoder.Frames.Add(ApplyWatermark(null, null));
MemoryStream stm = File.Create(image);
pngEncoder.Save(stm);
return stm;
I have a puzzle game and I can create levels. When I save a level, it takes a snapshot of the canvas and then when I choose a level, it displays all the pictures of the levels next to their name as a thumbnail. However each image is around 1MB in size. I would like to get them to around 30KB in size. Also the file it makes cannot be edited by a photo editor to make it a smaller size even though it is a jpg. I see I have used a TiffBitmapEncoder whoops. Probably my issue with the photo editors.
Here is my code:
private void saveImage(object sender, EventArgs e)
{
string path = myImageNamePath;
FileStream fs = new FileStream(path, FileMode.Create);
RenderTargetBitmap bmp = new RenderTargetBitmap((int)myLevelDesigner.pbxMap.ActualWidth,
(int)myLevelDesigner.pbxMap.ActualHeight, 1 / 96, 1 / 96, PixelFormats.Pbgra32);
bmp.Render(myLevelDesigner.pbxMap);
BitmapEncoder encoder = new TiffBitmapEncoder();
encoder.Frames.Add(BitmapFrame.Create(bmp));
encoder.Save(fs);
fs.Close();
}
Oh my, is there a particular reason you are using the TIFF file format? I highly recommend using PNG instead, it is lossless and compressed.
Use PngBitmapEncoder instead, most graphics programs support PNG.
I would also recommend making it into an extension method that you can reuse throughout. Something like this:
public static class CanvasExtender
{
public static void SaveToImageFile(this Canvas canvas, string outputFile)
{
canvas.UpdateLayout();
var bitmap = new RenderTargetBitmap(canvas.ActualWidth, canvas.ActualHeight, 96d, 96d, PixelFormats.Pbgra32);
bitmap.Render(canvas);
var encoder = new PngBitmapEncoder();
encoder.Frames.Add(BitmapFrame.Create(bitmap));
using(var outputStream = File.Create(outputFile))
encoder.Save(outputStream);
}
}
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I am currently trying to recompress a pdf that has already been created, I am trying to find a way to recompress the images that are in the document, to reduce the file size.
I have been trying to do this with the DataLogics PDE and iTextSharp libraries but I can not find a way to do the stream recompression of the items.
I have though about looping over the xobjects and getting the images and then dropping the DPI down to 96 or using the libjpeg C# implimentation to change the quality of the image but getting it back into the pdf stream seems to always end up, with memory corruption or some other issue.
Any samples will be appreciated.
Thanks
iText and iTextSharp have some methods for replacing indirect objects. Specifically there's PdfReader.KillIndirect() which does what it says and PdfWriter.AddDirectImageSimple(iTextSharp.text.Image, PRIndirectReference) which you can then use to replace what you killed off.
In pseudo C# code you'd do:
var oldImage = PdfReader.GetPdfObject();
var newImage = YourImageCompressionFunction(oldImage);
PdfReader.KillIndirect(oldImage);
yourPdfWriter.AddDirectImageSimple(newImage, (PRIndirectReference)oldImage);
Converting the raw bytes to a .Net image can be tricky, I'll leave that up to you or you can search here. Mark has a good description here. Also, technically PDFs don't have a concept of DPI, that's for printers mostly. See the answer here for more on that.
Using the method above your compression algorithm can actually do two things, physically shrink the image as well as apply JPEG compression. When you physically shrink the image and add it back it will occupy the same amount of space as the original image but with less pixels to work with. This will get you what you consider to be DPI reduction. The JPEG compression speaks for itself.
Below is a full working C# 2010 WinForms app targeting iTextSharp 5.1.1.0. It takes an existing JPEG on your desktop called "LargeImage.jpg" and creates a new PDF from it. Then it opens the PDF, extracts the image, physically shrinks it to 90% of the original size, applies 85% JPEG compression and writes it back to the PDF. See the comments in the code for more of an explanation. The code needs lots more null/error checking. Also looks for NOTE comments where you'll need to expand to handle other situations.
using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;
using System.Windows.Forms;
using System.IO;
using iTextSharp.text;
using iTextSharp.text.pdf;
namespace WindowsFormsApplication1 {
public partial class Form1 : Form {
public Form1() {
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e) {
//Our working folder
string workingFolder = Environment.GetFolderPath(Environment.SpecialFolder.Desktop);
//Large image to add to sample PDF
string largeImage = Path.Combine(workingFolder, "LargeImage.jpg");
//Name of large PDF to create
string largePDF = Path.Combine(workingFolder, "Large.pdf");
//Name of compressed PDF to create
string smallPDF = Path.Combine(workingFolder, "Small.pdf");
//Create a sample PDF containing our large image, for demo purposes only, nothing special here
using (FileStream fs = new FileStream(largePDF, FileMode.Create, FileAccess.Write, FileShare.None)) {
using (Document doc = new Document()) {
using (PdfWriter writer = PdfWriter.GetInstance(doc, fs)) {
doc.Open();
iTextSharp.text.Image importImage = iTextSharp.text.Image.GetInstance(largeImage);
doc.SetPageSize(new iTextSharp.text.Rectangle(0, 0, importImage.Width, importImage.Height));
doc.SetMargins(0, 0, 0, 0);
doc.NewPage();
doc.Add(importImage);
doc.Close();
}
}
}
//Now we're going to open the above PDF and compress things
//Bind a reader to our large PDF
PdfReader reader = new PdfReader(largePDF);
//Create our output PDF
using (FileStream fs = new FileStream(smallPDF, FileMode.Create, FileAccess.Write, FileShare.None)) {
//Bind a stamper to the file and our reader
using (PdfStamper stamper = new PdfStamper(reader, fs)) {
//NOTE: This code only deals with page 1, you'd want to loop more for your code
//Get page 1
PdfDictionary page = reader.GetPageN(1);
//Get the xobject structure
PdfDictionary resources = (PdfDictionary)PdfReader.GetPdfObject(page.Get(PdfName.RESOURCES));
PdfDictionary xobject = (PdfDictionary)PdfReader.GetPdfObject(resources.Get(PdfName.XOBJECT));
if (xobject != null) {
PdfObject obj;
//Loop through each key
foreach (PdfName name in xobject.Keys) {
obj = xobject.Get(name);
if (obj.IsIndirect()) {
//Get the current key as a PDF object
PdfDictionary imgObject = (PdfDictionary)PdfReader.GetPdfObject(obj);
//See if its an image
if (imgObject.Get(PdfName.SUBTYPE).Equals(PdfName.IMAGE)) {
//NOTE: There's a bunch of different types of filters, I'm only handing the simplest one here which is basically raw JPG, you'll have to research others
if (imgObject.Get(PdfName.FILTER).Equals(PdfName.DCTDECODE)) {
//Get the raw bytes of the current image
byte[] oldBytes = PdfReader.GetStreamBytesRaw((PRStream)imgObject);
//Will hold bytes of the compressed image later
byte[] newBytes;
//Wrap a stream around our original image
using (MemoryStream sourceMS = new MemoryStream(oldBytes)) {
//Convert the bytes into a .Net image
using (System.Drawing.Image oldImage = Bitmap.FromStream(sourceMS)) {
//Shrink the image to 90% of the original
using (System.Drawing.Image newImage = ShrinkImage(oldImage, 0.9f)) {
//Convert the image to bytes using JPG at 85%
newBytes = ConvertImageToBytes(newImage, 85);
}
}
}
//Create a new iTextSharp image from our bytes
iTextSharp.text.Image compressedImage = iTextSharp.text.Image.GetInstance(newBytes);
//Kill off the old image
PdfReader.KillIndirect(obj);
//Add our image in its place
stamper.Writer.AddDirectImageSimple(compressedImage, (PRIndirectReference)obj);
}
}
}
}
}
}
}
this.Close();
}
//Standard image save code from MSDN, returns a byte array
private static byte[] ConvertImageToBytes(System.Drawing.Image image, long compressionLevel) {
if (compressionLevel < 0) {
compressionLevel = 0;
} else if (compressionLevel > 100) {
compressionLevel = 100;
}
ImageCodecInfo jgpEncoder = GetEncoder(ImageFormat.Jpeg);
System.Drawing.Imaging.Encoder myEncoder = System.Drawing.Imaging.Encoder.Quality;
EncoderParameters myEncoderParameters = new EncoderParameters(1);
EncoderParameter myEncoderParameter = new EncoderParameter(myEncoder, compressionLevel);
myEncoderParameters.Param[0] = myEncoderParameter;
using (MemoryStream ms = new MemoryStream()) {
image.Save(ms, jgpEncoder, myEncoderParameters);
return ms.ToArray();
}
}
//standard code from MSDN
private static ImageCodecInfo GetEncoder(ImageFormat format) {
ImageCodecInfo[] codecs = ImageCodecInfo.GetImageDecoders();
foreach (ImageCodecInfo codec in codecs) {
if (codec.FormatID == format.Guid) {
return codec;
}
}
return null;
}
//Standard high quality thumbnail generation from http://weblogs.asp.net/gunnarpeipman/archive/2009/04/02/resizing-images-without-loss-of-quality.aspx
private static System.Drawing.Image ShrinkImage(System.Drawing.Image sourceImage, float scaleFactor) {
int newWidth = Convert.ToInt32(sourceImage.Width * scaleFactor);
int newHeight = Convert.ToInt32(sourceImage.Height * scaleFactor);
var thumbnailBitmap = new Bitmap(newWidth, newHeight);
using (Graphics g = Graphics.FromImage(thumbnailBitmap)) {
g.CompositingQuality = CompositingQuality.HighQuality;
g.SmoothingMode = SmoothingMode.HighQuality;
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
System.Drawing.Rectangle imageRectangle = new System.Drawing.Rectangle(0, 0, newWidth, newHeight);
g.DrawImage(sourceImage, imageRectangle);
}
return thumbnailBitmap;
}
}
}
I don't know about iTextSharp, but you have to rewrite a PDF file if anything is changed, as it contains an xref table (index) with the exact file position of each object. This means if even one byte is added or removed, the PDF becomes corrupted.
Your best bet for recompressing the images is JBIG2 if they are B&W, or JPEG2000 otherwise, for which Jasper library will happily encode JPEG2000 codestreams for placement into PDF files at whatever quality you so desire.
If it were me I'd do it all from code without the PDF libraries. Just find all images (anything between stream and endstream after an occurance of JPXDecode (JPEG2000), JBIG2Decode (JBIG2) or DCTDecode (JPEG)) pull that out, reencode it with Jasper, then stick it back in again and update the xref table.
To update the xref table, find the positions of each object (starting 00001 0 obj) and just update the new positions in the xref table. It's not too much work, less than it sounds. You might be able to get all the offsets with a single regular expression (I'm not a C# programmer, but in PHP it would be that simple.)
Then finally update the value of the startxref tag in the trailer with the offset of the beginning of the xref table (where it says xref in the file).
Otherwise you'll end up decoding the entire PDF and rewriting it all, which will be slow, and you might lose something along the way.
There is an example on how to find and replace images in an existing PDF by the creator of iText. It's actually a small excerpt from his book. Since it's in Java, here's a simple replacement:
public void ReduceResolution(PdfReader reader, long quality) {
int n = reader.XrefSize;
for (int i = 0; i < n; i++) {
PdfObject obj = reader.GetPdfObject(i);
if (obj == null || !obj.IsStream()) {continue;}
PdfDictionary dict = (PdfDictionary)PdfReader.GetPdfObject(obj);
PdfName subType = (PdfName)PdfReader.GetPdfObject(
dict.Get(PdfName.SUBTYPE)
);
if (!PdfName.IMAGE.Equals(subType)) {continue;}
PRStream stream = (PRStream )obj;
try {
PdfImageObject image = new PdfImageObject(stream);
PdfName filter = (PdfName) image.Get(PdfName.FILTER);
if (
PdfName.JBIG2DECODE.Equals(filter)
|| PdfName.JPXDECODE.Equals(filter)
|| PdfName.CCITTFAXDECODE.Equals(filter)
|| PdfName.FLATEDECODE.Equals(filter)
) continue;
System.Drawing.Image img = image.GetDrawingImage();
if (img == null) continue;
var ll = image.GetImageBytesType();
int width = img.Width;
int height = img.Height;
using (System.Drawing.Bitmap dotnetImg =
new System.Drawing.Bitmap(img))
{
// set codec to jpeg type => jpeg index codec is "1"
System.Drawing.Imaging.ImageCodecInfo codec =
System.Drawing.Imaging.ImageCodecInfo.GetImageEncoders()[1];
// set parameters for image quality
System.Drawing.Imaging.EncoderParameters eParams =
new System.Drawing.Imaging.EncoderParameters(1);
eParams.Param[0] =
new System.Drawing.Imaging.EncoderParameter(
System.Drawing.Imaging.Encoder.Quality, quality
);
using (MemoryStream msImg = new MemoryStream()) {
dotnetImg.Save(msImg, codec, eParams);
msImg.Position = 0;
stream.SetData(msImg.ToArray());
stream.SetData(
msImg.ToArray(), false, PRStream.BEST_COMPRESSION
);
stream.Put(PdfName.TYPE, PdfName.XOBJECT);
stream.Put(PdfName.SUBTYPE, PdfName.IMAGE);
stream.Put(PdfName.FILTER, filter);
stream.Put(PdfName.FILTER, PdfName.DCTDECODE);
stream.Put(PdfName.WIDTH, new PdfNumber(width));
stream.Put(PdfName.HEIGHT, new PdfNumber(height));
stream.Put(PdfName.BITSPERCOMPONENT, new PdfNumber(8));
stream.Put(PdfName.COLORSPACE, PdfName.DEVICERGB);
}
}
}
catch {
// throw;
// iText[Sharp] can't handle all image types...
}
finally {
// may or may not help
reader.RemoveUnusedObjects();
}
}
}
You'll notice it's only handling JPEG. The logic is reversed (instead of explicitly handling only DCTDECODE/JPEG) so you can uncomment some of the ignored image types and experiment with the PdfImageObject in the code above. In particular, most of the FLATEDECODE images (.bmp, .png, and .gif) are represented as PNG (confirmed in the DecodeImageBytes method of the PdfImageObject source code). As far as I know, .NET does not support PNG encoding. There are some references to support this here and here. You can try a stand-alone PNG optimization executable, but you also have to figure out how to set PdfName.BITSPERCOMPONENT and PdfName.COLORSPACE in the PRStream.
For completeness sake, since your question specifically asks about PDF compression, here's how you compress a PDF with iTextSharp:
PdfStamper stamper = new PdfStamper(
reader, YOUR-STREAM, PdfWriter.VERSION_1_5
);
stamper.Writer.CompressionLevel = 9;
int total = reader.NumberOfPages + 1;
for (int i = 1; i < total; i++) {
reader.SetPageContent(i, reader.GetPageContent(i));
}
stamper.SetFullCompression();
stamper.Close();
You might also try and run the PDF through PdfSmartCopy to get the file size down. It removes redundant resources, but like the call to RemoveUnusedObjects() in the finally block, it may or may not help. That will depend on how the PDF was created.
IIRC iText[Sharp] doesn't deal well with JBIG2DECODE, so #Alasdair's suggestion looks good - if you want to take the time learning the Jasper library and using the brute-force approach.
Good luck.
EDIT - 2012-08-17, comment by #Craig:
To save the PDF after compressing the jpegs using the ReduceResolution() method above:
a. Instantiate a PdfReader object:
PdfReader reader = new PdfReader(pdf);
b. Pass the PdfReader to the ReduceResolution() method above.
c. Pass the altered PdfReader to a PdfStamper. Here's one way using a MemoryStream:
// Save altered PDF. then you can pass the btye array to a database, etc
using (MemoryStream ms = new MemoryStream()) {
using (PdfStamper stamper = new PdfStamper(reader, ms)) {
}
return ms.ToArray();
}
Or you can use any other Stream if you don't need to keep the PDF in memory. E.g. use a FileStream and save directly to disk.
I've written a library to do just that. It will also OCR the pdf's using Tesseract or Cuneiform and create searchable, compressed PDF files. It's a library that uses several open source projects (iTextsharp, jbig2 encoder, Aforge, muPDF#) to complete the task. You can check it out here http://hocrtopdf.codeplex.com/
I am not sure if you are considering other libraries, but you can easily recompress existing images using Docotic.Pdf library (Disclaimer: I work for the company).
Here is some sample code:
static void RecompressExistingImages(string fileName, string outputName)
{
using (PdfDocument doc = new PdfDocument(fileName))
{
foreach (PdfImage image in doc.Images)
image.RecompressWithGroup4Fax();
doc.Save(outputName);
}
}
There are also RecompressWithFlate, RecompressWithGroup3Fax, RecompressWithJpeg and Uncompress methods.
The library will convert color images to bilevel ones if needed. You can specify deflate compression level, JPEG quality etc.
I am also ask you to think twice before using approach suggested by #Alasdair. If you are going to deal with PDF files that weren't created by you than the task is far more complex that it might seem.
To start with, there is great deal of images compressed by codecs other than JPXDecode, JBIG2Decode or DCTDecode. And PDF can also contain inline images.
PDF files saved using newer versions of standard (1.5 or newer) can contain cross-reference streams. It means that reading and updating such files is more complex than just finding/updating some numbers at the end of the file.
So, please, use a PDF library.
A simple way to compress PDF is using gsdll32.dll (Ghostscript) and Cyotek.GhostScript.dll (wrapper):
public static void CompressPDF(string sInFile, string sOutFile, int iResolution)
{
string[] arg = new string[]
{
"-sDEVICE=pdfwrite",
"-dNOPAUSE",
"-dSAFER",
"-dBATCH",
"-dCompatibilityLevel=1.5",
"-dDownsampleColorImages=true",
"-dDownsampleGrayImages=true",
"-dDownsampleMonoImages=true",
"-sPAPERSIZE=a4",
"-dPDFFitPage",
"-dDOINTERPOLATE",
"-dColorImageDownsampleThreshold=1.0",
"-dGrayImageDownsampleThreshold=1.0",
"-dMonoImageDownsampleThreshold=1.0",
"-dColorImageResolution=" + iResolution.ToString(),
"-dGrayImageResolution=" + iResolution.ToString(),
"-dMonoImageResolution=" + iResolution.ToString(),
"-sOutputFile=" + sOutFile,
sInFile
};
using(GhostScriptAPI api = new GhostScriptAPI())
{
api.Execute(arg);
}
}
Wonder if this possible. Saw many posts on adding watermark after the pdf is created and saved in disk. But during creation of document how do i add a image watermark. I know how to add a image to document. But how do i position it such that it comes at the end of page.
For C#, use this code...
//new Document
Document DOC = new Document();
// open Document
DOC.Open();
//create New FileStream with image "WM.JPG"
FileStream fs1 = new FileStream("WM.JPG", FileMode.Open);
iTextSharp.text.Image JPG = iTextSharp.text.Image.GetInstance(System.Drawing.Image.FromStream(fs1), ImageFormat.Jpeg);
//Scale image
JPG.ScalePercent(35f);
//Set position
JPG.SetAbsolutePosition(130f,240f);
//Close Stream
fs1.Close();
DOC.Add(JPG);
This is essentially identical to adding a header or footer.
You need to create a class that implements PdfPageEvent, and in the OnPageEnd, grab the page's PdfContentByte, and draw your image there. Use an absolute position.
Note: You probably want to derive from PdfPageEventHelper, it has empty implementations of all the page events, so you just need to write the method you actually care about.
Note: Unless your image is mostly transparent, drawing it on top of your page will cover up Many Things. IIRC ("If I Recall Correctly"), PNG and GIF files added by iText will automatically be properly masked, allowing things under them to show through.
If you want to add an opaque image underneath everything, you should override OnStartPage() instead.
This is Java, but converting it is mostly a matter of capitalizing method names and swapping get/set calls for property access.
Image watermarkImage = new Image(imgPath);
watermarkImage.setAbsolutePosition(x, y);
writer.setPageEvent( new MyPageEvent(watermarkImage) );
public MyPageEvent extends PdfPageEventHelper {
private Image waterMark;
public MyPageEvent(Image img) {
waterMark = img;
}
public void OnEndPage/*OnStartPage*/(PdfWriter writer, Document doc) {
PdfContentByte content = writer.getContent();
content.addImage( waterMark );
}
}
This is the accepted answer's port to C#, and what worked for me. I'm using an A4 page size:
Define this BackgroundImagePdfPageEvent class:
public class BackgroundImagePdfPageEvent : PdfPageEventHelper
{
private readonly Image watermark;
public BackgroundImagePdfPageEvent(string imagePath)
{
using (var fs = new FileStream(imagePath, FileMode.Open))
{
watermark = Image.GetInstance(System.Drawing.Image.FromStream(fs), ImageFormat.Jpeg);
watermark.SetAbsolutePosition(0, 0);
watermark.ScaleAbsolute(PageSize.A4.Width, PageSize.A4.Height);
watermark.Alignment = Image.UNDERLYING;
}
}
public override void OnStartPage(PdfWriter writer, Document document)
{
document.Add(watermark);
}
}
Then, when creating your document:
var doc = new Document(PageSize.A4);
doc.SetMargins(60f, 60f, 120f, 60f);
var outputStream = new MemoryStream();
var writer = PdfWriter.GetInstance(doc, outputStream);
var imagePath = "PATH_TO_YOUR_IMAGE";
writer.PageEvent = new BackgroundImagePdfPageEvent(imagePath);