Rotation on a previously rotated page on PDF-lib not correctly handled
Normally we rotate a page using setRotation like this on PDF-lib
const newDegree = 90 //for example const page = pages[pageIndex] const newRotationAngle = degrees(parseInt(newDegree)) page.setRotation(newRotationAngle)
We pass the newDegree to the setRotation.
But I found a case, where a PDF, that has been rotated before, not correctly handled. It treated as if the PDF start from 0deg. But that’s not always the case, sometimes the PDF has already been rotated before.
Here is how I solved it
const page = pages[pageIndex] const rotationAngle = page.getRotation().angle const newRotationAngle = degrees( rotationAngle + parseInt(newDegree) ) page.setRotation(newRotationAngle)
By getting the original previous rotation angle using
page.getRotation().angle I then add this info to our newDegree.
Now our rotation correctly handled.