Unable to add margins in iTextSharp document having images - pdf

Question

Requirement:
A large image (dynamic) needs to be split and shown in PDF pages. If image can't be accomodated in one page then we need to add another page and try to fit the remaining portion and so on.
So far I am able to split the image in multiple pages, however it appears that they are completely ignoring the margin values and so images are shown without any margins.
Please see below code:
string fileStringReplace = imageByteArray.Replace("data:image/jpeg;base64,", "");
Byte[] imageByte = Convert.FromBase64String(fileStringReplace);
iTextSharp.text.Image image = iTextSharp.text.Image.GetInstance(imageByte);
float w = image.ScaledWidth;
float h = image.ScaledHeight;
float cropHeight = 1500f;
iTextSharp.text.Rectangle page = new iTextSharp.text.Rectangle(1150f, cropHeight);
var x = page.Height;
Byte[] created;
iTextSharp.text.Document document = new iTextSharp.text.Document(page, 20f, 20f, 20f, 40f); --This has no impact
using (var outputMemoryStream = new MemoryStream())
{
PdfWriter writer = PdfWriter.GetInstance(document, outputMemoryStream);
writer.CloseStream = false;
document.Open();
PdfContentByte canvas = writer.DirectContentUnder;
float usedHeights = h;
while (usedHeights >= 0)
{
usedHeights -= cropHeight;
document.SetPageSize(new iTextSharp.text.Rectangle(1150f, cropHeight));
canvas.AddImage(image, w, 0, 0, h, 0, -usedHeights);
document.NewPage();
}
document.Close();
created = outputMemoryStream.ToArray();
outputMemoryStream.Write(created, 0, created.Length);
outputMemoryStream.Position = 0;
}
return created;
I also tried to set margin in the loop by document.SetMargins() - but that's not working.

Answer 1

You are mixing different things.
When you create margins, be it while constructing the Document instance or by using the setMargins() method, you create margins for when you let iText(Sharp) decide on the layout. That is: the margins will be respected when you do something like document.Add(image).
However, you do not allow iText to create the layout. You create a PdfContentByte named canvas and you decide to add the image to that canvas using a transformation matrix. This means that you will calculate the a, b, c, d, e, and f value needed for the AddImage() method.
You are supposed to do that Math. If you want to see a margin, then the values w, 0, 0, h, 0, and -usedHeights are wrong, and you shouldn't blame iTextSharp, you should blame your lack of insight in analytical geometrics (that's the stuff you learn in high school at the age of 16).
This might be easier for you:
iTextSharp.text.Image image = iTextSharp.text.Image.GetInstance(imageByte);
float w = image.ScaledWidth;
float h = image.ScaledHeight;
// For the sake of simplicity, I don't crop the image, I just add 20 user units
iTextSharp.text.Rectangle page = new iTextSharp.text.Rectangle(w + 20, h + 20);
iTextSharp.text.Document document = new iTextSharp.text.Document(page);
PdfWriter writer = PdfWriter.GetInstance(document, outputMemoryStream);
// Please drop the line that prevents closing the output stream!
// Why are so many people making this mistake?
// Who told you you shouldn't close the output stream???
document.Open();
// We define an absolute position for the image
// it will leave a margin of 10 to the left and to the bottom
// as we created a page that is 20 user units to wide and to high,
// we will also have a margin of 10 to the right and to the top
img.SetAbsolutePosition(10, 10);
document.Add(Image);
document.Close();
Note that SetAbsolutePosition() also lets you take control, regardless of the margins, as an alternative, you could use:
iTextSharp.text.Image image = iTextSharp.text.Image.GetInstance(imageByte);
float w = image.ScaledWidth;
float h = image.ScaledHeight;
// For the sake of simplicity, I don't crop the image, I just add 20 user units
iTextSharp.text.Rectangle page = new iTextSharp.text.Rectangle(w + 20, h + 20);
iTextSharp.text.Document document = new iTextSharp.text.Document(page, 10, 10, 10, 10);
PdfWriter writer = PdfWriter.GetInstance(document, outputMemoryStream);
// Please drop the line that prevents closing the output stream!
// Why are so many people making this mistake?
// Who told you you shouldn't close the output stream???
document.Open();
// We add the image to the document, and we let iTextSharp decide where to put it
// As there is just sufficient space to fit the image inside the page, it should fit,
// But be aware of the existence of a leading; that could create side-effects
// such as forwarding the image to the next page because it doesn't fit vertically
document.Add(Image);
document.Close();