I know we can insert text into pdf with rotation using itext. But I want to rotate the text which is already present in the pdf.

CodePudding user response：

_{First of all, in your question you only talk about how to rotate a specific text but in your example you additionally rotate a red rectangle. This answer focuses on rotating text. The process of guessing which graphics might be related to the text and, therefore, probably should be rotated along, is a topic in its own right.}

_{You also mention you are looking for a solution using itext or pdfbox and used the tags}

As you can see the text is rotated. In contrast to your After.pdf, though, the red rectangle is not rotated. The reason is - as already mentioned at the start - that that rectangle in no way is part of the text.

Some Ideas

First of all, there are ports of the PdfCanvasEditor to iText 5 (the PdfContentStreamEditor in this answer) and PDFBox (the PdfContentStreamEditor in this answer). Thus, if you eventually prefer to switch to either of these PDF libraries, you can create equivalent implementations.

Then, if the assumption that the text to rotate is drawn in a consecutive sequence of text showing instructions in a text object in the page content stream framed by instructions that are not text showing ones does not hold for you, you can generalize the implementation here somewhat. Have a look at the SimpleTextRemover in this answer for inspiration which is based on the PdfContentStreamEditor for iText 5. Here also texts that start somewhere in one text showing instruction and end somewhere in another one are processed which requires some more detailed data keeping and splitting of existing text drawing instructions.

Also, if you want to rotate graphics along with the text that a human viewer might consider associated with it (like the red rectangle in your example file), you can try and extend the example accordingly, e.g. by also extracting the coordinates of the rotated text and in a second run trying to guess which graphics around those coordinates are related and rotating the graphics along. This is not trivial, though.

Finally note that the Matrix provided in the constructor is not limited to rotations, it can represent an arbitrary affine transformation. So instead of rotating text you can also move it or scale it or skew it, ...