Summary: | [Qt][32 bit] Child div overlay on parent div results in image diff when it shouldn't | ||||||||||||||||
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Product: | WebKit | Reporter: | Dave Tharp <dtharp> | ||||||||||||||
Component: | CSS | Assignee: | Nobody <webkit-unassigned> | ||||||||||||||
Status: | RESOLVED INVALID | ||||||||||||||||
Severity: | Normal | CC: | allan.jensen, ossy | ||||||||||||||
Priority: | P2 | Keywords: | Qt, QtTriaged | ||||||||||||||
Version: | 528+ (Nightly build) | ||||||||||||||||
Hardware: | Unspecified | ||||||||||||||||
OS: | Linux | ||||||||||||||||
Bug Depends on: | |||||||||||||||||
Bug Blocks: | 87008 | ||||||||||||||||
Attachments: |
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Description
Dave Tharp
2012-05-09 15:38:42 PDT
Created attachment 141030 [details]
testcase
Created attachment 141031 [details]
ref test for testcase
Created attachment 141032 [details]
actual output (png)
Created attachment 141033 [details]
expected output (png)
Created attachment 141034 [details]
diff output (png)
More research on this issue: I have analyzed the actual vs expected output with "compare -verbose -identify". The interesting part is the histogram and the resultant diff.png. The relevant part of the histograms: == actual == Histogram: 296: ( 0, 0, 0,255) #000000 black 29700: ( 0,128, 0,255) #008000 green 4: ( 1, 1, 1,255) #010101 rgba(1,1,1,1) 300: ( 1,127, 0,255) #017F00 rgba(1,127,0,1) 1: ( 2, 2, 2,255) #020202 rgba(2,2,2,1) == expected == Histogram: 296: ( 0, 0, 0,255) #000000 black 30000: ( 0,128, 0,255) #008000 green 4: ( 1, 1, 1,255) #010101 rgba(1,1,1,1) 1: ( 2, 2, 2,255) #020202 rgba(2,2,2,1) Note that expected has 30,000 green pixels as expected (300 * 100). Now the actual has only 29700 green pixels. There are 300 missing, as if the child div is missing an entire line. Where are these 300 pixels? Well, there are 300 pixels that are *almost* green (1,127,0) present. This line of pixels is off by 1 bit in red and green. The diff png (attached) shows this line as the very bottom line of the rectangle. Created attachment 141183 [details]
diff output png from "compare -verbose -identify"
A similar bug: https://bugs.webkit.org/show_bug.cgi?id=86130 === Bulk closing of Qt bugs === If you believe that this bug report is still relevant for a non-Qt port of webkit.org, please re-open it and remove [Qt] from the summary. If you believe that this is still an important QtWebKit bug, please fill a new report at https://bugreports.qt-project.org and add a link to this issue. See http://qt-project.org/wiki/ReportingBugsInQt for additional guidelines. |