I went through *exactly* the same source review last month when I started
hitting it. I was quite happy to see that iText actually sets the rotation
in the page dictionary (I needed it for constructing unit tests), but I
agree that the way it happens is a bit hard to follow. If you think about
it from the way the PDF spec is written, though, you could see how this
implementation evolved:
There is a dictionary entry for the unrotated page size, plus the rotation
entry. The rectangle that the user has been working with has been in
rotated coordinates, so to set the unrotated page size, they have to
unrotate.
On the content side, iText rotates the coordinate system just to make life
easier for the user. And PDF has a complete disassociation between rotation
at the page level, and the required rotation at the content level.
Confusing as all get out.
In my parsing code, I am currently ignoring the page rotation entirely, so
rotated pages wind up with text alignment being off by 90 degrees (generally
speaking, not an issue for text extraction because all of the text rotates -
but for rendering or geometric filtering, it is an issue). At some point,
I'll have to address this - probably by applying yet another CTM when
computing user space coordinates. Oy.
- Kevin
Mark Storer-2 wrote:
>
> Looking through the Rectangle.rotate() -> Pdf-structures-in-the-output
> code, I think we might have An Issue. Woah woah woah... let me check the
> trunk instead of my red-headed-stepchild-branch of 2.0.whatever-it-was.
>
> Rectangle.rotate() { // yep, no changes
> Rectangle rect = new Rectangle(lly, llx, ury, urx);
> rect.rotation = rotation + 90;
> rect.rotation %= 360;
> return rect;
> }
>
> It swaps the x's and ys, and sets the rotation member.
>
> In PdfDocument.newPage(), we find The Following Code:
>
> // [U1] page size and rotation
> int rotation = pageSize.getRotation();
> ...
> PdfPage page = new PdfPage(new PdfRectangle(pageSize, rotation),
> thisBoxSize, resources, rotation);
>
> ----
> So rotation gets passed to the new PdfRectangle and to the new PdfPage:
>
> public PdfRectangle(float llx, float lly, float urx, float ury, int
> rotation) {
> super();
> if (rotation == 90 || rotation == 270) {
> this.llx = lly;
> this.lly = llx;
> this.urx = ury;
> this.ury = urx;
> }
> else {
> this.llx = llx;
> this.lly = lly;
> this.urx = urx;
> this.ury = ury;
> }
> super.add(new PdfNumber(this.llx));
> super.add(new PdfNumber(this.lly));
> super.add(new PdfNumber(this.urx));
> super.add(new PdfNumber(this.ury));
> }
> ----
>
> PdfRectangle swaps the coordinates *again*. It doesn't store the rotation
> value, just makes use of it.
>
> And...
> PdfPage(PdfRectangle mediaBox, HashMap<String, PdfRectangle> boxSize,
> PdfDictionary resources, int rotate) {
> super(PAGE);
> this.mediaBox = mediaBox;
> put(PdfName.MEDIABOX, mediaBox);
> put(PdfName.RESOURCES, resources);
> if (rotate != 0) {
> put(PdfName.ROTATE, new PdfNumber(rotate)); // *** This is the
> only place its used ***
> }
> for (int k = 0; k < boxStrings.length; ++k) {
> PdfObject rect = boxSize.get(boxStrings[k]);
> if (rect != null)
> put(boxNames[k], rect);
> }
> }
>
> ----
>
> So we've swapped it back, and stored the value in the PdfDictionary for
> the page ONLY. It's not retrieved anywhere in PdfPage...
>
> Ah! In PdfContent, the rotation is taken from the original Rectangle
> again and used in a transformation matrix, just like Kev(in?) said.
>
> So while swapping the rectangle coordinates twice is certainly ODD, it
> doesn't look like there's anything genuinely broken in there... just an
> "Even Number of Sign Errors". Those are fine as long as you find both of
> them. Finding one and having the "correct" output anyway is a bit
> maddening. *twitch*
>
> --Mark Storer
> Senior Software Engineer
> Cardiff.com
>
> #include <disclaimer>
> typedef std::Disclaimer<Cardiff> DisCard;
>
>
>
>> -----Original Message-----
>> From: trumpetinc [mailto:forum_...@trumpetinc.com]
>> Sent: Tuesday, January 19, 2010 9:00 PM
>> To: itext-questions@lists.sourceforge.net
>> Subject: Re: [iText-questions] Rotate Page After Adding Text
>> to Document
>>
>>
>>
>> As a point of clarification, I'm pretty sure that, in
>> addition to swapping
>> width and height, rotate() signals PdfDocument to add a
>> rotation cm entry to
>> the beginning of the content stream, and adjusts the rotation
>> dictionary
>> entry for the page.
>>
>> And I completely agree with the 'messy code for dealing with
>> it' comment.
>> As an example, ImportedPage doesn't preserve the page
>> rotation from the
>> source, which can cause all sorts of mayhem (esp because the
>> page rotation
>> implies an awkward change in origin).
>>
>> - K
>>
>>
>> Mark Storer-2 wrote:
>> >
>> > Ah. So you don't want to spin-the-pages-contents-sideways, you want
>> > landscape-vs-portrait.
>> >
>> > "Rotation" isn't the word you want. You just want to
>> change the page size
>> > from 8.5x11 to 11x8.5. By the way, Rectangle.rotate()
>> doesn't really
>> > rotate the page either, it swaps the width/height. In PDF,
>> there's a
>> > concept of page rotation indepentant of a page's physical
>> dimensions,
>> > which can lead to all manner of Interesting Confusion (and
>> messy code for
>> > dealing with it).
>> >
>> >
>>
>> --
>> View this message in context:
> http://old.nabble.com/Rotate-Page-After-Adding-Text-to-Document-tp27234067p27236838.html
> Sent from the iText - General mailing list archive at Nabble.com.
>
>
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> attendees to learn about information security's most important issues
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--
View this message in context:
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Sent from the iText - General mailing list archive at Nabble.com.
------------------------------------------------------------------------------
Throughout its 18-year history, RSA Conference consistently attracts the
world's best and brightest in the field, creating opportunities for Conference
attendees to learn about information security's most important issues through
interactions with peers, luminaries and emerging and established companies.
http://p.sf.net/sfu/rsaconf-dev2dev
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