2023-03-28 12:24 BST

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IDProjectCategoryView StatusLast Update
0002121NetSurfLayoutpublic2014-07-19 10:34
ReporterChris Young 
Assigned ToMichael Drake 
PlatformAmigaOSAmigaOSOS Version4.1
Product Version3.2 
Target VersionFixed in Version 
Summary0002121: CSS alpha support
DescriptionThe lack of CSS (plotter?) alpha channel support is causing some pages to be unreadable without highlighting text.
Steps To ReproduceThe Eurovision results pages (eg. http://www.eurovision.tv/page/results?event=1893&voter=UA) have all the information in boxes above a background image. On other web browsers these boxes are largely transparent, however on NetSurf they are opaque. Without the alpha channel they consist of black or white boxes with white text on top of them.
Additional InformationI believe it is things like this in the CSS causing the problem:

The two screenshots show the Amiga and GTK frontends display the page the same way.
TagsNo tags attached.
Fixed in CI build #
Reported in CI build #1862
URL of problem pagehttp://www.eurovision.tv/page/results?event=1893&voter=UA
Attached Files


Michael Drake


Michael Drake (administrator)

The plotter interface could be extended to support rgba() backgrounds and colours. It would be a backwards incompatible change that would need all core and frontend code's handling of NS_TRANSPARENT changed. I may look at doing this.

If the issue comes from the use of the CSS opacity property we can't do anything about it with the current layout engine. CSS opacity affects the descendants of a box as well as the box itself, so there would need to be some compositing of the rendering in a memory buffer, before plotting the result with opacity applied.

-Issue History
Date Modified Username Field Change
2014-05-11 15:45 Chris Young New Issue
2014-05-11 15:45 Chris Young File Added: css_alpha.png
2014-05-11 15:51 Chris Young File Added: eu.png
2014-05-11 15:52 Chris Young Additional Information Updated View Revisions
2014-05-11 16:30 Vincent Sanders Assigned To => Michael Drake
2014-05-11 16:30 Vincent Sanders Status new => confirmed
2014-05-11 16:30 Vincent Sanders Description Updated View Revisions
2014-05-11 16:30 Vincent Sanders Steps to Reproduce Updated View Revisions
2014-05-11 16:30 Vincent Sanders Additional Information Updated View Revisions
2014-07-19 10:34 Michael Drake Note Added: 0000416
+Issue History