Bug 88772

Summary: Viewbox Scaling Exposes Incorrect Transformations on Text Gradient Fills
Product: WebKit Reporter: Dominik Röttsches (drott) <d-r>
Component: SVGAssignee: Nobody <webkit-unassigned>
Status: NEW    
Severity: Normal CC: ahmad.saleem792, eae, krit, zimmermann
Priority: P2    
Version: 528+ (Nightly build)   
Hardware: Unspecified   
OS: Unspecified   
Attachments:
Description Flags
RefTests none

Dominik Röttsches (drott)
Reported 2012-06-11 03:03:11 PDT
When using a viewbox attribute that results in upscaling, text gradient fills are rendered incorrectly.
Attachments
RefTests (2.41 KB, patch)
2012-06-11 04:11 PDT, Dominik Röttsches (drott) 		no flags
DetailsFormatted DiffDiff
View All Add attachment proposed patch, testcase, etc.
Dominik Röttsches (drott)
Comment 1 2012-06-11 04:11:02 PDT
Created attachment 146825 [details] RefTests
Dominik Röttsches (drott)
Comment 2 2012-06-11 04:14:12 PDT
Comment on attachment 146825 [details] RefTests This reftest shows the issue. The gradient should scale from red over green to blue over the size of the text, same in both cases - with viewbox and without.
Dominik Röttsches (drott)
Comment 3 2012-06-18 07:51:39 PDT
The issue seems to be with identifying the bounding box of small-scale text. Origin of bounding box for the text in LayoutTests/svg/transforms/viewbox-text-fill-gradient.html is 0,0 - extents are 1,1 - while these should be precise float values.
Dominik Röttsches (drott)
Comment 4 2012-06-18 09:07:07 PDT
In my understanding, the rounding happens in void SVGRootInlineBox::layoutRootBox(). Using LayoutUnits here, would only improve the results but not fix the issue completely - we need higher precision for the text bounding boxes.
Dominik Röttsches (drott)
Comment 5 2012-06-18 09:11:03 PDT
Probably same root cause as bug 75781.
Dominik Röttsches (drott)
Comment 6 2013-01-25 05:31:37 PST
This issue persists even after landing patch from bug 107771.
Ahmad Saleem
Comment 7 2023-01-21 06:44:24 PST
I took the test case from the attached patch and turned into JSFiddle and also added missing </rect>: JSFiddle - https://jsfiddle.net/9z4Ljr7y/show Safari 16.2, Safari Technology Preview 161, Chrome Canary 111 and Firefox Nightly 111 are matching other, do we need to track anything else? Thanks!
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