198454 2019-06-01 10:55:22 -0700 Optimize for negative z children on the root 2019-06-01 10:59:49 -0700 1 1 1 Unclassified WebKit Compositing WebKit Nightly Build Unspecified Unspecified NEW P2 Normal --- 1 simon.fraser simon.fraser koivisto simon.fraser zalan oldest_to_newest 1540971 0 371114 simon.fraser 2019-06-01 10:55:22 -0700 Created attachment 371114 Testcase It's pretty common to have negative z-index children in the root stacking context. Currently, we'll pop in to adding a foreground layer, which will become tiled and double our tiled backing store memory use. We could, in some cases, use the page tiles for the foreground, and just have a solid color background behind the negative z-index child. 371114 2019-06-01 10:55:22 -0700 2019-06-01 10:55:22 -0700 Testcase paint-order-non-stacking-negative-z-child.html text/html 1733 simon.fraser PCFET0NUWVBFIGh0bWw+CjxodG1sPgo8aGVhZD4KICAgIDxzdHlsZT4KICAgICAgICAuY29udGFp bmVyIHsKICAgICAgICAgICAgcG9zaXRpb246IHJlbGF0aXZlOwogICAgICAgICAgICBtYXJnaW46 IDMwcHg7CiAgICAgICAgICAgIHdpZHRoOiAzMDBweDsKICAgICAgICAgICAgaGVpZ2h0OiAzMDBw eDsKICAgICAgICAgICAgYm9yZGVyOiAxcHggc29saWQgYmxhY2s7CiAgICAgICAgICAgIGJveC1z aGFkb3c6IDAgMCAxMHB4IGJsYWNrOwogICAgICAgIH0KICAgICAgICAKICAgICAgICAubmVnYXRp dmV6IHsKICAgICAgICAgICAgcG9zaXRpb246IGFic29sdXRlOwogICAgICAgICAgICB0b3A6IDQw cHg7CiAgICAgICAgICAgIGxlZnQ6IDIwcHg7CiAgICAgICAgICAgIHotaW5kZXg6IC0xOwogICAg ICAgICAgICB3aWR0aDogMTAwcHg7CiAgICAgICAgICAgIGhlaWdodDogMTAwcHg7CiAgICAgICAg ICAgIGJhY2tncm91bmQtY29sb3I6IGdyZWVuOwogICAgICAgICAgICB0cmFuc2Zvcm06IHRyYW5z bGF0ZVooMCk7CiAgICAgICAgfQogICAgICAgIAogICAgICAgIC50cmlnZ2VyIHsKICAgICAgICAg ICAgcG9zaXRpb246IGFic29sdXRlOwogICAgICAgICAgICB0b3A6IDEwcHg7CiAgICAgICAgICAg IGxlZnQ6IDEwcHg7CiAgICAgICAgICAgIHdpZHRoOiA1MHB4OwogICAgICAgICAgICBoZWlnaHQ6 IDUwcHg7CiAgICAgICAgICAgIGJhY2tncm91bmQtY29sb3I6IGdyYXk7CiAgICAgICAgICAgIHRy YW5zZm9ybTogdHJhbnNsYXRlWigwKTsKICAgICAgICB9CiAgICAgICAgCiAgICA8L3N0eWxlPgog ICAgPHNjcmlwdD4KICAgICAgICBpZiAod2luZG93LnRlc3RSdW5uZXIpCiAgICAgICAgICAgIHRl c3RSdW5uZXIuZHVtcEFzVGV4dCgpOwoKICAgICAgICB3aW5kb3cuYWRkRXZlbnRMaXN0ZW5lcign bG9hZCcsICgpID0+IHsKICAgICAgICAgICAgaWYgKHdpbmRvdy50ZXN0UnVubmVyKQogICAgICAg ICAgICAgICAgZG9jdW1lbnQuZ2V0RWxlbWVudEJ5SWQoJ2xheWVycycpLmlubmVyVGV4dCA9IHdp bmRvdy5pbnRlcm5hbHMubGF5ZXJUcmVlQXNUZXh0KGRvY3VtZW50KTsKICAgICAgICB9LCBmYWxz ZSk7CiAgICA8L3NjcmlwdD4KPC9oZWFkPgo8Ym9keT4KICAgIDxkaXYgY2xhc3M9InRyaWdnZXIi PjwvZGl2PgogICAgPGRpdiBjbGFzcz0iY29udGFpbmVyIj4KICAgICAgICA8cD5Mb3JlbSBpcHN1 bSBkb2xvciBzaXQgYW1ldCwgY29uc2VjdGV0dXIgYWRpcGlzaWNpbmcgZWxpdCwgc2VkIGRvIGVp dXNtb2QgdGVtcG9yIGluY2lkaWR1bnQgdXQgbGFib3JlIGV0IGRvbG9yZSBtYWduYSBhbGlxdWEu IFV0IGVuaW0gYWQgbWluaW0gdmVuaWFtLCBxdWlzIG5vc3RydWQgZXhlcmNpdGF0aW9uIHVsbGFt Y28gbGFib3JpcyBuaXNpIHV0IGFsaXF1aXAgZXggZWEgY29tbW9kbyBjb25zZXF1YXQuIER1aXMg YXV0ZSBpcnVyZSBkb2xvciBpbiByZXByZWhlbmRlcml0IGluIHZvbHVwdGF0ZSB2ZWxpdCBlc3Nl IGNpbGx1bSBkb2xvcmUgZXUgZnVnaWF0IG51bGxhIHBhcmlhdHVyLiBFeGNlcHRldXIgc2ludCBv Y2NhZWNhdCBjdXBpZGF0YXQgbm9uIHByb2lkZW50LCBzdW50IGluIGN1bHBhIHF1aSBvZmZpY2lh IGRlc2VydW50IG1vbGxpdCBhbmltIGlkIGVzdCBsYWJvcnVtLjwvcD4KICAgICAgICA8ZGl2IGNs YXNzPSJuZWdhdGl2ZXogY2hpbGQiPjwvZGl2PgogICAgPC9kaXY+CjxwcmUgaWQ9ImxheWVycyI+ PC9wcmU+CjwvYm9keT4KPC9odG1sPgo=