290331 - dashes are too small when stroke-linecap="round" is used with stroke-dasharray

Status: RESOLVED WORKSFORME

(Core :: SVG, defect)

Description

[Holger Will]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8b2) Gecko/20050413 Firefox/1.0+
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8b2) Gecko/20050413 Firefox/1.0+

in the page at http://www.treebuilder.de/svg/dashc.svg there are 4 rects. the
top left rect is doted - it should be stroked width dashes with round caps.
additionaly the buttom left rect should be dotted, with the dots touching each
other. 
p.s.: the buttom right rect should not have a stroke at all i think...

Reproducible: Always

Steps to Reproduce:
1.use stroke-dasharray="0,20" stroke-width="20" on any shape. 
2.
3.

Actual Results:  
the shape is fully stroked

Expected Results:  
the shape should have a doted stroke, where dot radius = 10 and distance of
center points = 20.

Comment 1

[Holger Will]

Attachment: testfile.svg

Comment 2

[Holger Will]

Attachment: expected result

expected behaviour. though i think the buttom right rect should not have a
stroke at all.

Comment 3

[Holger Will]

possibly effecting 
https://bugzilla.mozilla.org/show_bug.cgi?id=288498

especialy the buttom right rect, which should not be stroked instead of fully
stroked.

Comment 4

[Holger Will]

this bug seems fixed by the switch to cairo.
but there are some new problems with the testcase now.

Comment 5

[Holger Will]

Attachment: testcase 1

using a length of 0 produces some screen artefacts.

Comment 6

[Holger Will]

Attachment: testcase 2

using a value slightly larger than 0 works fine.
but now half of the first dot is missing.

Comment 7

[Holger Will]

Attachment: testcase 3

if the length is too small, 0.00001 in the testcase, dots diaspear.
resize the window to see the bug in action.

Comment 8

[Holger Will]

Attachment: testcase 4

if length and space are equal ( stroke-dasharray="20,20" ), another type of
artefact is produced. again resize your window to see the bug in action.

Comment 9

[Chris Nokleberg]

Attachment: Another problematic drawing

I believe this attachments demonstrates the same problem. Resize your browser window to see the artifacts.

I've tested changing the value of stroke-dasharray from "1" to "40". The buggy values are 6, 10, 18, 22, 26, 27, 30, and 33. Some are worse than others. It would be nice (at least) to be able to calculate if a particular value will be problematic, in order to workaround this bug.

Comment 10

[Helder "Lthere" Magalhães]

Attachment: Screenshot with proper result which shows that this bug seems fixed now (in Firefox 3)

Seems to be corrected by latest cairo fixes. Attached screen shot which shows the (apparently) proper result.

Previous version (buggy):
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9b4pre) Gecko/2008021804
Minefield/3.0b4pre

Current version (fixed):
Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9b4pre) Gecko/2008022104 Minefield/3.0b4pre

Comment 11

[Jonathan Watt [:jwatt]]

Well the bug as originally reported is no longer showing, so let's close this as worksforme. There is some weirdness around the corners of the rects in the testcase though, so I've filed bug 418880 for that.