Bug 120327 - Overlapping "dashed" lines appear as solid line
Summary: Overlapping "dashed" lines appear as solid line
Status: RESOLVED WORKSFORME
Alias: None
Product: LibreOffice
Classification: Unclassified
Component: Draw (show other bugs)
Version:
(earliest affected)
6.0.6.2 release
Hardware: All All
: medium normal
Assignee: Not Assigned
URL:
Whiteboard:
Keywords:
Depends on:
Blocks:
 
Reported: 2018-10-04 21:50 UTC by Damian Hofmann
Modified: 2019-10-10 18:41 UTC (History)
3 users (show)

See Also:
Crash report or crash signature:


Attachments
Example of overlapping dashed lines appearing as a single solid line (13.65 KB, application/vnd.oasis.opendocument.graphics)
2018-10-04 21:50 UTC, Damian Hofmann
Details

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Description Damian Hofmann 2018-10-04 21:50:16 UTC
Created attachment 145400 [details]
Example of overlapping dashed lines appearing as a single solid line

In diagrams, when there are multiple connectors from multiple boxes, going into a single target box, I like to "group" them together into a single "lane". This reduces visual noise and communicates, that all these connections are similar.

If these connectors have the "dashed" line style, the "common" part that goes into the target box, appears as a single solid line, because of the overlap of multiple dashed lines.

In many diagrams there's a semantic distiction between solid an dashed lines. Where multiple "dashed" lines overlap, that section should still be displayed as a single dashed line.
Comment 1 Telesto 2018-10-05 17:54:55 UTC
Repro with
Version: 6.2.0.0.alpha0+
Build ID: 52cb73911e661fb636085337374e09845f07783b
CPU threads: 4; OS: Windows 6.3; UI render: default; 
TinderBox: Win-x86@42, Branch:master, Time: 2018-10-02_01:05:50
Locale: nl-NL (nl_NL); Calc: CL

and with
LibreOffice 3.3.0 
OOO330m19 (Build:6)
tag libreoffice-3.3.0.4

Sounds like a bug, but adding UX-advise to be sure
Comment 2 Heiko Tietze 2018-10-07 08:47:25 UTC
Yes, definitely a bug.
Comment 3 Regina Henschel 2018-10-07 11:00:12 UTC
Dashes are drawn starting from the start of a line. If you draw your connectors with the common part as start, then the dashed will be at the same place in all connectors and do not overlap.

But I can imagine a new attribute 'stroke-dashoffset' as defined in SVG to fine-tune the position of the dashes. That would be an enhancement request.
Comment 4 Damian Hofmann 2018-10-07 12:35:28 UTC
Allow me to argue that this is still a (user experience) bug, not an enhancement.

Having to draw connectors in a certain direction, just to have dashes line up, isn't intuitive.

More so, because the connectors palette offers connectors with arrows. These connectors must be drawn in a certain direction, to make the arrow appear at the correct end. In my example (attachment), that direction is the opposite to what would be required to make the dashes line up. From a usability point of view, Draw gives no indications, at best, that the connector must be drawn in a certain direction. At worst (as with arrow line ends) it gives counter-intuitive indications.

Even if the user realizes that (unlikely), he then has to manually set the arrows at the end of the connectors. If he starts with solid lines (default) - using the "wrong" direction because of arrow heads" - and then changes the stile to "dashed", the connectors would have to be completely redrawn. That's poor UX.

IMHO it can't be expected of users to consider/anticipate all these aspects when drawing connectors between boxes. Practically, as of now, it is impossible for users to correctly draw that diagram. Technically, a workaround might exists, but it's very much unlikely that users will figure that one out.

My conclusion: Still a bug, not an enhancement.

Maybe a simple rule would work: The gluepoint with the most connectors is the start point. Would that work?
Comment 5 Regina Henschel 2018-10-07 13:06:23 UTC
A similar problem exists, if two not filled, dashed rectangles touch another.

And what do you expect, if your lines have different colors? Should only the top most color be visible?

Therefore I suggest to allow the user to set an individual offset. Such option does not exist yet, and therefore would be an enhancement.
Comment 6 Heiko Tietze 2018-10-08 05:45:00 UTC
(In reply to Regina Henschel from comment #5)
> ...
> Therefore I suggest to allow the user to set an individual offset. Such
> option does not exist yet, and therefore would be an enhancement.

Too many options for my taste. Simplicity first means the lines are merged and one (ideally the last drawn) takes the properties into the result.
Comment 7 Damian Hofmann 2018-10-08 16:45:40 UTC
(In reply to Heiko Tietze from comment #6)

I tend to agree with Heiko. I have not considered the scenario with multiple colors yet. But the idea to have the style of the frontmost shape take precedence is quite appealing.

It's predictable and fits well with the concept of layers. Using the "Arrange" commands ("Bring to Front", "Send to Back", ...) I can controll the outcome easily. It's a mechanism that most Draw users should be familiar with, which is a big plus.
Comment 8 QA Administrators 2019-10-09 02:29:24 UTC Comment hidden (obsolete)
Comment 9 Damian Hofmann 2019-10-10 18:41:23 UTC
Going to close my old bug report. I since have found a usable workaround:

As already said by Regina Henschel (#c3), dashes are drawn from the start of the line. If drawn, starting from the common/overlapping section, the dashes do not overlap. But the (default) connectors palette only offers connectors with arrows at the end. These often must be drawn the opposite direction to make the arrow appear at the correct end.

Since reporting this bug, I discovered that connectors with arrows at the start of the line are available, but hidden by default.

1. Go to "Tools" > "Customize..." > "Toolbars"
2. For the "Scope" pull down, select "Draw"
3. For the "Target" pull down, select "Connectors"
4. In the "Function" list, enable all the "... connector Starts with Arrow" options

The new connector types are now available in the connectors palette. With the additional connector types available, it's less cumbersome to control the outcome of both the dashes and where the arrows appear. Works for me.


Tested with:

Version: 6.2.5.2 (x64)
Build-ID: 1ec314fa52f458adc18c4f025c545a4e8b22c159
CPU-Threads: 8; BS: Windows 10.0; UI-Render: Standard; VCL: win; 
Gebietsschema: de-CH (de_CH); UI-Sprache: de-DE
Calc: threaded