126262 2013-12-27 07:07:58 -0800 Graphics buffer issue with clip-path and fixed positioned element 2014-02-17 11:08:29 -0800 1 1 1 Unclassified WebKit CSS 528+ (Nightly build) Unspecified Unspecified RESOLVED FIXED InRadar P2 Normal --- 126207 1 krit simon.fraser commit-queue dino esprehn+autocc glenn kondapallykalyan rniwa simon.fraser webkit-bug-importer oldest_to_newest 963114 0 220059 krit 2013-12-27 07:07:58 -0800 Created attachment 220059 Example In the attached example there is a small example where a fixed positioned element is clipped with the clip-path property. It seems like the fixed positioned element is drawn on a graphics buffer and this buffer is not cleared. This leads to artifacts on areas that are clipped away. Reload the example multiple times to see the issue. In Safari stable the background is always black. In nightlies the background is not stable. It even happened that a video playing in another application show through. This just happens with "position: fixed". 963356 1 simon.fraser 2013-12-30 11:15:43 -0800 Hmm, we probably think it's opaque when it isn't. 963358 2 webkit-bug-importer 2013-12-30 11:16:26 -0800 <rdar://problem/15732905> 981541 3 224397 simon.fraser 2014-02-17 11:02:48 -0800 Created attachment 224397 Patch 981547 4 simon.fraser 2014-02-17 11:08:29 -0800 https://trac.webkit.org/r164232 220059 2013-12-27 07:07:58 -0800 2013-12-27 07:07:58 -0800 Example clip-buffer-error-2.html text/html 396 krit PHN0eWxlPgojcGFyZW50IHsKCWhlaWdodDogMjAwcHg7CgltYXJnaW46IDIwcHg7CglwYWRkaW5n OiAyMHB4OwoJYmFja2dyb3VuZDogYmx1ZTsKCWJvcmRlcjogc29saWQgcmVkIDIwcHg7Cgktd2Vi a2l0LWNsaXAtcGF0aDogY2lyY2xlKDUwJSwgNTAlLCA1MCUpOwoJLXdlYmtpdC1jbGlwLXBhdGg6 IGNpcmNsZSg1MCUgYXQgNTAlIDUwJSkgY29udGVudC1ib3g7Cgl0b3A6IDEwMHB4OwoJbGVmdDog MTAwcHg7Cglwb3NpdGlvbjogZml4ZWQ7Cn0KI2NoaWxkIHsKCXdpZHRoOiAxMDAlOwoJaGVpZ2h0 OiAxMDAlOwoJcGFkZGluZzogMDsKCW1hcmdpbjogMDsKCWJhY2tncm91bmQ6IGdyZWVuOwp9Cjwv 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