Author Topic: Confusing Layers Result with Opacity.  (Read 77 times)

December 06, 2018, 08:25:14 AM
Read 77 times

Agrajag

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Attached is one of our card SVGs. It behaves in a way I'm left to think is a bug unless there's some normal reason for this behavior that I'm overlooking.

The card has a few layers:

Text - The main layer where most everything on the card ended up so it's not so much text as really what's become "the top layer".

Poison - A special layer unrelated to this card and blank here.

Background - A critical layer to this issue. It generally contains just an image of a moon and I applied an Opacity of 80% to it when later we felt the moon was too dark in printing and this became an easy way to adjust it over various test print runs. It also provides the white background that is not there when this layer is off that, without it, results in a see-through card as you see below. Necessary for printing onto white card stock, but not desired for non-printing previews.

Border - A layer that is 99% of the time turned off that contains a white-filled, rounded corner rectangle with a black stroke. We turn this on to give the image the look of the shape of a card, but keep it off for printing as the cutting process creates that "border" and so the black stroke border is not desired. However, this is also a major part of the trouble. This layer is BELOW the Background layer, but if we turn it on it results in the moon in the layer above it to vanish entirely. I can't explain this.

Base Template - This layer is off almost always after the initial setup and is just the image of the printing guidelines for spacing and edge limits, etc.

We've just recently worked around this anomaly by setting the PNG of the moon to a lighter shade that matches the 80% Opacity look and then returning the Background layer to 100% Opacity which then results in the Border layer working as anticipated. I can turn it on, see the black border around the card, with the moon, and then export a PNG to use this anywhere it's needed. I still want to know why this is happening though for future us as this approach was so darned useful.
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December 06, 2018, 08:58:04 AM
Reply #1

Moini

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There is no white background in the Background layer, just a semi-transparent moon with a Blend filter.

I suspect that removing the Blend filter (as already suggested elsewhere, I think - stackoverflow? stackexchange? some other forum? Must have been weeks ago. Or maybe the question was just very similar, at least it was about that same moon, and I think I mentioned the filter.), will fix it.

Select moon, Filters > Remove filters, at the bottom.

December 06, 2018, 09:22:29 AM
Reply #2

Agrajag

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There is no white background in the Background layer, just a semi-transparent moon with a Blend filter.

That's correct as the white background is in the Border layer which the Background layer should see through to. Turn On the Border layer and Export a PNG. It will be no longer be transparent, but will show a white card background. However, the moon will be inexplicably gone. That's the confusing part.

FWIW, any question I'd have posed about this moon would have been here. I don't post to Stack Exchange or Stack Overflow.

I'll also see what the removing of the filter will do as well. I'm assuming the DESIRED effect will end up the same which is really all that matters in the end, however, as a quality assurance pro from way back, I would absolutely argue that this behavior as noted above is quite unintuitive.

UPDATE: It does indeed work as Moini suggested so, noobie question: Why did this filter get applied at all? What's it really doing?
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December 06, 2018, 03:55:26 PM
Reply #3

Moini

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I suspect you have once had a layer with that filter (I think that's a question where we met before). The filter is a so-called blend mode, which makes layers interact with layers below. It's easy to accidentally (or intentionally) apply a blend mode to a layer.

When an object is moved to another layer, it will keep all the filters that the layer (=group) it was in has.

So I guess you moved the moon from an old layer that appeared broken to you to another layer, but the problem persisted.


December 07, 2018, 12:36:20 AM
Reply #4

brynn

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Yes, I've been worried about this behavior where objects moved from a layer with a blend mode, acquire a new filter when they're moved.  I don't understand the logic behind that behavior, and I fear it will continue to be troublesome.

I wonder if this behavior could be made optional?  Is it worth a feature request?  Or do I just not see what makes it useful?
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December 07, 2018, 08:33:05 AM
Reply #5

Agrajag

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To me it could very easily be handled the way a copy and paste is handled in apps like Word and Excel. You get the option of the depth of the Paste and choose what elements you want pasted. 90% of the time you want just a raw, no-nonsense paste of the object in question and not everything associated with it.
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December 07, 2018, 10:10:10 AM
Reply #6

Moini

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It's that Inkscape doesn't treat layers different from groups in this respect. Probably it should.

December 08, 2018, 10:35:09 AM
Reply #7

brynn

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Oh, so you mean Inkscape thinks you're moving an object from one group to another, and it thinks the first group has the filter applied to it?

Maybe I'll make the request.  I nothing else, maybe I'll learn something.  Actually, now that I think of it.....there might already be a report for this.  Let's see....  Hhm, I didn't find it, but that's not too surprising.  But if it's already there, someone will figure it out, and link them together.  I think it's worth risking a bug manager wasting a couple of minutes for this, just in case it's not reported.

https://bugs.launchpad.net/inkscape/+bug/1807524
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December 08, 2018, 01:23:52 PM
Reply #8

Moini

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The first group really has the filter applied to it. It's a blend filter, and it is applied to a layer - which is the same thing as a group.

December 08, 2018, 03:10:16 PM
Reply #9

brynn

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Oh yes, I realize that.  But users think of it as a layer, and most of them don't know that Inkscape implements layers as special groups.  So they don't think of the layer as a group.  They don't think that "layer blend mode" equals "filter".

And plus, to me, having a filter applied to a group, I might expect that taking one object out of that group, maybe it ought to leave the filter behind.  That might not be technically correct, but I still might expect it not to have the filter.
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December 09, 2018, 07:01:53 AM
Reply #10

Moini

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What about dissolving a group that has, say, blur on it? Would you say it should not keep the blur filters?

December 10, 2018, 02:49:18 AM
Reply #11

brynn

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Well, for that after thought, I qualified it heavily with "mights" and "maybes".  I haven't thought through every possibility.  But for the feature request/bug, I'm not suggesting something that would apply to all groups.  Whatever solution might be used would apply only to the special groups which are called layers (or only the blend filters, although with my extremely limited understanding of programming, it doesn't seem like a solution could be applid to specific filters).
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December 10, 2018, 05:32:17 AM
Reply #12

Agrajag

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I once again argue that the way to handle this is to put info in the hands of the user. When copying make it clear (with the menus) that there are other options to copying. Copy Raw (nothing but the object). Copy with Properties (whatever the group/layer has), etc...
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December 10, 2018, 06:51:09 AM
Reply #13

brynn

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Exactly how developers might solve this is over my head.  But if you'd like to discuss it with them, you're welcome to reply to that bug report.
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December 10, 2018, 09:16:48 AM
Reply #14

Agrajag

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But if you'd like to discuss it with them, you're welcome to reply to that bug report.

Link?
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December 10, 2018, 09:29:11 AM
Reply #15

Moini

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