Add support for links (<a> elements)

[alafr]

I think it won't be possible because in PDFKit (and in PDF 1.3) links are only supported for a few basic shapes. And even with the polygon links supported it would be difficult to implement.
I keep this issue open because the children of the <a> tag must be rendered even without the link.

[alafr]

Children of <a> elements are rendered since commit 84064ba

[peonmodel]

could <a> be honored if the children are just text elements? i am just trying to make some simple text into a link

[alafr]

Yes it can probably be done. I see a few options:

1. Add link support for basic rectangular texts (difficulty: how to determine if a text is rectangular)
2. Add complete link support for text, with a link for each character (problem: PDFKit has no support for rotated links and text can be rotated by many different ways)
3. Add the link to the whole bounding box of the element (problem: the link will also be active outside of the non-rectangular elements)
   I think the option 3 is reasonably easy to implement but since in can have undesired results it should be offered as an option. I don't have time to try this right now but if you want you can send a pull request.

[peonmodel]

i investigated having a link in pdf with arbitrary shape and rotation, it doesnt seem possible, (it doesnt seemed to be a PDFKit limitation, rather a pdf format issue)
https://superuser.com/questions/1277302/can-a-link-rectangle-in-pdf-be-rotated

the strategy used by chrome is simply create an oversized link rectangle that covers the entire object (which is similar to your option 3)

1. if a text has no matrix transformation and is not a textpath, can it be assumed to be rectangular?

i shall try implement option 3

a related bug

commit 84064ba seems to only work for top level <a>
<a> that are children of text elements are completely ignored, <a> children are ignored

[alafr]

It would be good to do it like chrome, I had never noticed that it makes oversized links when printing as PDF. It's actually quite rare to have non-rectangular links.
I almost fixed the related bug, there is still an issue when a <textPath> is a direct child of the <a> element.

[alafr]

Support for links added in version 0.1.6