Images rotated when added to PDF in itext7 - pdf

Question

I'm using the following extension method I built on top of itext7's com.itextpdf.layout.Document type to apply images to PDF documents in my application:
fun Document.writeImage(imageStream: InputStream, page: Int, x: Float, y: Float, width: Float, height: Float) {
val imageData = ImageDataFactory.create(imageStream.readBytes())
val image = Image(imageData)
val pageHeight = pdfDocument.getPage(page).pageSize.height
image.scaleAbsolute(width, height)
val lowerLeftX = x
val lowerLeftY = pageHeight - y - image.imageScaledHeight
image.setFixedPosition(page, lowerLeftX, lowerLeftY)
add(image)
}
Overall, this works -- but with one exception! I've encountered a subset of documents where the images are placed as if the document origin is rotated 90 degrees. Even though the content of the document is presented properly oriented underneath.
Here is a redacted copy of one of the PDFs I'm experiencing this issue with. I'm wondering if anyone would be able to tell me why itext7 is having difficulties writing to this document, and what I can do to fix it -- or alternatively, if it's a potential bug in the higher level functionality of com.itextpdf.layout in itext7?
Some Additional Notes
I'm aware that drawing on a PDF works via a series of instructions concatenated to the PDF. The code above works on other PDFs we've had issues with in the past, so com.itextpdf.layout.Document does appear to be normalizing the coordinate space prior to drawing. Thus, the issue I describe above seems to be going undetected by itext?
The rotation metadata in the PDF that itext7 reports from a "good" PDF without this issue seems to be the same as the rotation metadata in PDFs like the one I've linked above. This means I can't perform some kind of brute-force fix through detection.
I would love any solution to not require me to flatten the PDF through any form of broad operation.

Answer 1

I can talk only about the document you`ve shared.
It contains 4 pages.
/Rotate property of the first page is 0, for other pages is 270 (defines 90 rotation counterclockwise).
IText indeed tries to normalize the coordinate space for each page.
That`s why when you add an image to pages 2-4 of the document it is rotated on 270 (90 counterclockwise) degrees.
... Even though the content of the document is presented properly oriented underneath.
Content of pages 2-4 looks like
q
0 -612 792 0 0 612 cm
/Im0 Do
Q
This is an image with applied transformation.
0 -612 792 0 0 612 cm represents the composite transformation matrix.
From ISO 32000
A transformation matrix in PDF shall be specified by six numbers,
usually in the form of an array containing six elements. In its most
general form, this array is denoted [a b c d e f]; it can represent
any linear transformation from one coordinate system to another.
We can extract a rotation from that matrix.
How to decompose the matrix you can find there.
https://math.stackexchange.com/questions/237369/given-this-transformation-matrix-how-do-i-decompose-it-into-translation-rotati
The rotation is defined by the next matrix
0 -1
1 0
This is a rotation on -90 (270) degrees.
Important note: in this case positive angle means counterclockwise rotation.
ISO 32000
Rotations shall be produced by [rc rs -rs rc 0 0], where rc = cos(q)
and rs = sin(q) which has the effect of rotating the coordinate system
axes by an angle q counter clockwise.
So the image has been rotated on the same angle in the counter direction comparing to the page.