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LibWeb: Avoid layout in Element.client{Width,Height} if possible

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When querying the HTML element (in strict mode) or the BODY element
(in quirks mode), we return the viewport dimensions.

Layout doesn't change the size of the viewport, so we can actually
reorder the steps here and avoid performing layout in some cases.

This removes a bunch of synchronous layouts on pages with reCAPTCHA.
This commit is contained in:
Andreas Kling 2022-09-09 11:44:42 +02:00
parent 3f960781fd
commit 67b3af8025
1 changed files with 16 additions and 12 deletions
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28
Userland/Libraries/LibWeb/DOM/Element.cpp
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@ -629,12 +629,7 @@ int Element::client_left() const
// https://drafts.csswg.org/cssom-view/#dom-element-clientwidth
int Element::client_width() const
{
// NOTE: Ensure that layout is up-to-date before looking at metrics.
const_cast<Document&>(document()).update_layout();
// 1. If the element has no associated CSS layout box or if the CSS layout box is inline, return zero.
if (!paint_box())
return 0;
// NOTE: We do step 2 before step 1 here since step 2 can exit early without needing to perform layout.
// 2. If the element is the root element and the element’s node document is not in quirks mode,
// or if the element is the HTML body element and the element’s node document is in quirks mode,
@ -644,6 +639,13 @@ int Element::client_width() const
return document().browsing_context()->viewport_rect().width();
}
// NOTE: Ensure that layout is up-to-date before looking at metrics.
const_cast<Document&>(document()).update_layout();
// 1. If the element has no associated CSS layout box or if the CSS layout box is inline, return zero.
if (!paint_box())
return 0;
// 3. Return the width of the padding edge excluding the width of any rendered scrollbar between the padding edge and the border edge,
// ignoring any transforms that apply to the element and its ancestors.
return paint_box()->absolute_padding_box_rect().width();
@ -652,12 +654,7 @@ int Element::client_width() const
// https://drafts.csswg.org/cssom-view/#dom-element-clientheight
int Element::client_height() const
{
// NOTE: Ensure that layout is up-to-date before looking at metrics.
const_cast<Document&>(document()).update_layout();
// 1. If the element has no associated CSS layout box or if the CSS layout box is inline, return zero.
if (!paint_box())
return 0;
// NOTE: We do step 2 before step 1 here since step 2 can exit early without needing to perform layout.
// 2. If the element is the root element and the element’s node document is not in quirks mode,
// or if the element is the HTML body element and the element’s node document is in quirks mode,
@ -667,6 +664,13 @@ int Element::client_height() const
return document().browsing_context()->viewport_rect().height();
}
// NOTE: Ensure that layout is up-to-date before looking at metrics.
const_cast<Document&>(document()).update_layout();
// 1. If the element has no associated CSS layout box or if the CSS layout box is inline, return zero.
if (!paint_box())
return 0;
// 3. Return the height of the padding edge excluding the height of any rendered scrollbar between the padding edge and the border edge,
// ignoring any transforms that apply to the element and its ancestors.
return paint_box()->absolute_padding_box_rect().height();