482689 - Optimize nsDisplayBackground::IsOpaque to include solid background images

Status: RESOLVED FIXED

(Core :: Layout, defect)

Description

[Stuart Parmenter]

Attachment: v0.5

I think this patch is right, and it seems to help, although it would be nice if it could include repeat_x/repeat_y stuff that filled the whole area.  Any other optimizations to this would be helpful as well.

Comment 1

[David Baron :dbaron: (⌚️UTC-4, no longer working on Mozilla)]

Comment on attachment 366783 [details] [diff] [review]
v0.5

>+      // bottom layer's clip is used for the color
>+      bottomLayer.mClip == NS_STYLE_BG_CLIP_BORDER &&
>+      !nsLayoutUtils::HasNonZeroCorner(mFrame->GetStyleBorder()->mBorderRadius))

May as well invert the checks for these two conditions for a return false that happens before the two curent checks for them, so you don't have to check them twice.

Comment 2

[Robert O'Callahan (:roc) (email my personal email if necessary)]

This is OK other than what dbaron said.

We could improve this quite a bit by having nsDisplayBackground::GetBounds return the actual area covered by the background; then IsOpaque could return true whenever the image or color is opaque. That could easily be a followup patch though. (For simplicity you could fall back to assuming the border-box if there's more than one background.)

Comment 3

[Stuart Parmenter]

Attachment: v1.0