LibWeb: Do paint-order traversal in Document::element_from_point()

Specify callback for hit-test function to identify closest DOM element,
excluding text nodes. Add a previously failing test case.
This commit is contained in:
Aliaksandr Kalenik 2024-02-13 23:39:22 +01:00 committed by Andreas Kling
parent 9d2809146f
commit 88ad871e2b
Notes: sideshowbarker 2024-07-17 02:38:39 +09:00
3 changed files with 48 additions and 4 deletions

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@ -0,0 +1 @@
hello <DIV id="c" >

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@ -0,0 +1,36 @@
<!DOCTYPE html>
<style>
.box {
width: 100px;
height: 100px;
position: absolute;
}
#a {
background-color: magenta;
z-index: 1;
transform: translate(110px, 10px);
}
#b {
background-color: mediumaquamarine;
z-index: 2;
transform: translate(120px, 20px);
}
#c {
background-color: greenyellow;
z-index: 3;
transform: translate(130px, 30px);
}
</style>
<div id="a" class="box"></div>
<div id="b" class="box"></div>
<div id="c" class="box">hello</div>
<script src="../include.js"></script>
<script>
test(() => {
const element = document.elementFromPoint(150, 50);
printElement(element);
});
</script>

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@ -3793,12 +3793,19 @@ Element const* Document::element_from_point(double x, double y)
// 2. If there is a box in the viewport that would be a target for hit testing at coordinates x,y, when applying the transforms
// that apply to the descendants of the viewport, return the associated element and terminate these steps.
Optional<Painting::HitTestResult> hit_test_result;
if (auto const* paintable_box = this->paintable_box(); paintable_box) {
if (auto result = paintable_box->hit_test(position, Painting::HitTestType::Exact); result.has_value()) {
if (auto* dom_node = result->dom_node(); dom_node && dom_node->is_element())
return static_cast<Element const*>(dom_node);
}
(void)paintable_box->hit_test(position, Painting::HitTestType::Exact, [&](Painting::HitTestResult result) {
auto* dom_node = result.dom_node();
if (dom_node && dom_node->is_element()) {
hit_test_result = result;
return Painting::TraversalDecision::Break;
}
return Painting::TraversalDecision::Continue;
});
}
if (hit_test_result.has_value())
return static_cast<Element*>(hit_test_result->dom_node());
// 3. If the document has a root element, return the root element and terminate these steps.
if (auto const* document_root_element = first_child_of_type<Element>(); document_root_element)