Image not sequentialy added in pdf document itextsharp (wrong order of elements)

Question

i am working with iTextSharp (5.4.5) for a couple of weeks now. This week, i encountered something strangew hen it comes to the order of elements in the documents.

I am working on a pdf report that contains topics and images (charts).

The document is formatted this way:

NR. TOPIC TITLE FOR TOPIC 1

CHART IMAGE for topic 1 (from bytearray)

NR. TOPIC TITLE FOR TOPIC 2

CHART IMAGE for topic 2 ...

below is a sample of code. I know code is not completely correct but it's just to point the issue. Let's assume the loop runs 10 times, so i expect 10 topic titles all directly followed by the image.

What i noticed is, that IF the page end is reached and a new IMAGE should be added, that the image is moved to the next page and the next topic title is printed on the previous page.

So on paper we have:

page 1:

topic 1 image topic 1

topic 2 image topic 2

topic 3 topic 4

page 2:

image topic 3 image topic 4

topic 5 image topic 5

...

So the order of the elements on paper, is NOT the same as the order that i used to put the element in the document via Document.add method.

This is really strange. Anyone has any idea?

int currentQuestionNr = 0;
foreach (Topic currentTOPIC in Topics)
{
    currentQuestionNr++;

    //compose question (via table so all questions (with nr prefix) are aligned the same)
    PdfPTable questionTable = new PdfPTable(2);
    questionTable.WidthPercentage = 100;
    questionTable.SetWidths(new int[] { 4, 96 });

    PdfPCell QuestionNrCell = new PdfPCell();
    QuestionNrCell.BorderWidth = 0;
    QuestionNrCell.HorizontalAlignment = PdfPCell.ALIGN_LEFT;
    QuestionNrCell.VerticalAlignment = PdfPCell.ALIGN_TOP;
    QuestionNrCell.AddElement(new Paragraph(String.Format("{0}. ", currentQuestionNr), PdfUtility.font_10_bold));

    PdfPCell QuestionPhraseCell = new PdfPCell();
    QuestionPhraseCell.BorderWidth = 0;
    QuestionPhraseCell.HorizontalAlignment = PdfPCell.ALIGN_LEFT;
    QuestionPhraseCell.VerticalAlignment = PdfPCell.ALIGN_TOP;
    QuestionPhraseCell.AddElement(new Paragraph(currentTOPIC.Title, PdfUtility.font_10_bold));

    questionTable.addCell(QuestionNrCell);
    questionTable.addCell(QuestionPhraseCell);

    //add topic to document
    Document.add(questionTable)

    //compose image
    Image itextImage = GetImageForTopic(currentTOPIC); //let's assume this function returns an image!
    Paragraph chartParagraph = new Paragraph();
    chartParagraph.IndentationLeft = indentionForQuestionInfo;
    chartParagraph.Add(itextImage);

    //add image to document
    Document.Add(chartParagraph);
}

score 6 · Accepted Answer · answered Mar 31 '14 at 07:22

If you have a PdfWriter instance (for instance writer), you need to force iText to use strict image sequence like this:

writer.setStrictImageSequence(true);

Otherwise, iText will postpone adding images until there's sufficient space on the page to add the image.

score 0 · Answer 2 · answered Mar 28 '14 at 03:33

That is quite unintuitive...I get the same behavior. So why not add another row to the table on each iteration:

  for (int i = 1; i < 5; ++i) {
    PdfPTable questionTable = new PdfPTable(2) {
// try and keep topic & chart together on same page for each iteration    
      KeepTogether = true, 
      WidthPercentage = 100
    };
    questionTable.SetWidths(new int[] { 4, 96 });
// _defaultCell(): 
// sets BorderWidth/HorizontalAlignment/VerticalAlignment
// same as your example    
    PdfPCell QuestionNrCell = _defaultCell();
    QuestionNrCell.AddElement(new Paragraph(string.Format("{0}. ", i)));
    PdfPCell QuestionPhraseCell = _defaultCell();
    QuestionPhraseCell.AddElement(new Paragraph(string.Format("{0}", s)));

    Image itextImage = Image.GetInstance(imagePath);
// second parameter used so image is NOT scaled
    PdfPCell imageCell = new PdfPCell(itextImage, false) {
      Border = Rectangle.NO_BORDER,
      Colspan = 2, PaddingLeft = indentionForQuestionInfo
    };
    questionTable.AddCell(QuestionNrCell);
    questionTable.AddCell(QuestionPhraseCell);
    questionTable.AddCell(imageCell);
    document.Add(questionTable);
  }

Hi Kuujinbo, I first implemented it that way but if i use a table to format everything, the images are added in a table cell (in stead of using paragraph, i could add a new row). BUT if i do it that way, the images are completely scaled (downsized) to fit the page if the page end is reached. This is undesired behaviour because the images are completely unreadable than (images are graphs showing analytic data). — wim boone, Mar 31 '14 at 08:24
@user3149519 - By default images added to a `PdfPCell` **are** resized, but **if** you use the correct `PdfPCell` constructor as in the code example the image will **not** be resized. Maybe something you can use in the future. — kuujinbo, Apr 02 '14 at 16:51

Image not sequentialy added in pdf document itextsharp (wrong order of elements)

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