#17 highlighter should be below text

J Sieber

Typically, one first writes some text and then highlights it using the highlighter. Currently, this obscures the text rather than highlights it because the highlighter is
(slightly transparently) above the text, making it less readable.
"Highlighter always below text" would at least be a very sensible option, probably even a good default setting.

This may not qualify as a bug but it reduces the usefulness of highlighting drastically.

PS: I have used xournal a lot recently and enjoyed it: a reliable tool with good graphical quality and ergonomic user interface.


  • Denis Auroux

    Denis Auroux - 2007-10-09

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    Good idea - however it won't work when annotating PDF or other backgrounds, in those cases the highlighter has to be on top of the background anyway.

    In the meantime: in the latest versions you can modify the transparency of your highlighter in the config file (~/.xournal/config), making it less opaque / more transparent should help the readability of the text underneath.


  • J Sieber

    J Sieber - 2007-10-09

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    This applies only to text written by strokes NOT for PDF background text/images.

  • Michael Wayne Goodman

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    Yes! I avoid the highlighter because of this very problem. And going over the same area twice makes it even more faded/colored. It might not be appropriate to put the highlighter below the writing since (I think) this wouldn't work with background stuff like editing PDFs (unless you can put it under PDF text as well... But then what do you do for graphics/tables in pdfs? etc..)

    It might be more appropriate to simply (hah!) allow all markings (or perhaps just those within a certain contrast threshold) to show through 100%. I uploaded a sample pdf at http://www.goodmami.org/temp/highlight-test.pdf (this file is temporary... I'll see if i can't attach it to this bug page). Ideally, for me, the highlighter would allow all text, table-borders and shape-outlines to show through, but background colors would appear 'below'. Note that it would still be the case if the text/lines were a color other than black. Given that, it seems like we'd need something that looks for high-contrast lines (perhaps with a width smaller than the highlighter). This solution looks potentially complex, and maybe processor heavy.

    Any thoughts?

  • Denis Auroux

    Denis Auroux - 2008-04-06

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    No, you can't put highlighter strokes under PDF text or any kind of PDF items. In fact, on screen, pretty much the only option available is to put highlighter strokes under the other annotations, and that's it.

    When exporting to PDF, I think there are ways to modify how the compositing is done (i.e., how the highlighter color and the color of whatever it's writing over are combined) to make the output more reasonable. However, there is no way to make the highlighter be "under contents and over background", or "looking for high-constrast lines" as you suggest - the PDF language doesn't allow for such distinctions.
    And in any case, this would not apply to how things look on screen while drawing in xournal - libgnomecanvas doesn't allow any finetuning of transparency effects (alpha channel compositing) in line objects.


  • mudd1

    mudd1 - 2012-08-30

    I just wanted to add that for the PDF export a "multiply" or "darken only" blend mode would work pretty well ( http://en.wikipedia.org/wiki/Blend_modes#Multiply ). This would destroy WYSIWYG though since all libgnomecanvas seems to be capable of is simple alpha blending. I would gladly accept this difference in screen and PDF rendering if only the PDF looks better in the end.


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