I'm making a web-based PDF annotation tool using Angular, annotpdf library and ng2-pdf-viewer.

All the annotations work fine except when I try annotating multiple lines. So I found out, in order to annotate (underline/highlight/strike through) multiple lines, I have to pass quadPoints as a parameter into the createAnnotation() functions.

quadPoints are coordinates of rectangles that together form the selection of multiple lines. They are arrays having length multiples of 8. For example, if we select 3 lines, we need to pass the coordinates for all the 3 rectangles covered in the selection, so that it can create annotations for all of the 3 lines separately.

So my question is how do I get these quadPoints from a selection?

I think I can use the mouse click/drag/up/down event but can't figure out how. Any solutions to this?