Closed
Bug 1359248
Opened 7 years ago
Closed 7 years ago
Float/percentage color rounding is unfairly distributed/wrong
Categories
(Core :: CSS Parsing and Computation, defect)
Core
CSS Parsing and Computation
Tracking
()
RESOLVED
DUPLICATE
of bug 1340484
People
(Reporter: manishearth, Unassigned)
References
Details
Attachments
(1 file, 1 obsolete file)
15.45 KB,
image/png
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Details |
When parsing colors like rgb(10%, 10%, 10%), or `rgba(0,0,0,0.1)`, Gecko multiplies by 255 and rounds. http://searchfox.org/mozilla-central/rev/313e5199bf58200f158c6fcbe193e41b88ed58a6/layout/style/nsCSSValue.cpp#3189 Servo and Chrome multiply by 256 and floor (and then clamp to 255, so that the input of 1.0 produces a result within bounds). This is more correct: The function has an equal distribution of values in the range to the domain. On the other hand, Gecko's function has fewer numbers mapping to 0 and 255 and the numbers in between get a larger domain each. This means that `rgb(10%, 10%, 10%)` is `rgb(25,25,25)` in servo and chrome, but `rgb(26, 26,26)` in gecko. Similarly, `rgba(0,0,0,0.1)` maps to different alpha values. (As a result, in Stylo, `rgba(0,0,0,0.1)` computes to `rgba(0,0,0,0.098)` since we still use nscolor but map the correct values into it, but Gecko's serialization assumes the flawed mapping) Try at https://treeherder.mozilla.org/#/jobs?repo=try&revision=4708b2339447d70af11f20d7e4bca3369df82380 This is a behavioral change, not sure if I should email dev.tech.layout.
Reporter | ||
Comment 1•7 years ago
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Interestingly, Chrome serializes without truncation here. 0.0980392, instead of trying to reproduce 0.1, which is what gecko does. <div id=f style="background-color: rgba(10%, 10%, 10%, 0.1)">aaa</div> <script type="text/javascript"> document.write( getComputedStyle(document.getElementById('f')).backgroundColor) </script>
Summary: Float/percentage color rounding is unfair and wrong → Float/percentage color rounding is unfairly distributed/wrong
Comment hidden (mozreview-request) |
Comment 3•7 years ago
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Manish, could you move your patch to Bug 1340484? Thanks.
Status: NEW → RESOLVED
Closed: 7 years ago
Resolution: --- → DUPLICATE
Reporter | ||
Updated•7 years ago
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Attachment #8861210 -
Attachment is obsolete: true
Attachment #8861210 -
Flags: review?(cam)
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Description
•