/// <summary>Expected to almost never occur - this performs a full DOM scan in order to
/// find the element at the given offscreen location.</summary>
internal Element elementFromPointOffScreen(float x, float y)
{
// Get the root node:
Node node = documentElement;
if (node == null)
{
// Empty document.
return(null);
}
// We'll always return something - we don't need to check node's box (it must match the screen anyway).
// Get kids ref:
NodeList kids = node.childNodes_;
while (kids != null)
{
// Loop backwards because the 'deepest' element is the one we want.
// As soon as we find something that contains our point, we essentially stop.
for (int i = kids.length - 1; i >= 0; i--)
{
// Get the child node:
Node child = kids[i];
if (!(child is Element))
{
// Must be an element (unless it's a document).
// Ignore text, doctype, comment etc.
if (child is ReflowDocument)
{
// Step into this though!
child = (child as ReflowDocument).documentElement;
if (child == null)
{
// Not loaded yet
continue;
}
}
else
{
continue;
}
}
// Unlike on screen we can't rely on the fast screen region
// (which is only available for all on screen elements).
// We'll need to always test the boxes.
// Get the render data:
RenderableData renderData = (child as IRenderableNode).RenderData;
LayoutBox box = renderData.FirstBox;
// Must be contained in one of them.
bool notActuallyContained = true;
while (box != null)
{
if (box.Contains(x, y))
{
// Ok!
notActuallyContained = false;
break;
}
// Advance to next one:
box = box.NextInElement;
}
if (notActuallyContained)
{
// Not actually inside the element - continue as if nothing happened:
continue;
}
// The child contains our point! Step into it.
// - If it has no kids, or none of the kids are elements, we'll end up returning child.
// Note that we could trigger the event capture phase here to squeeze a tiny bit of extra performance.
node = child;
kids = child.childNodes_;
goto SteppedNode;
}
// Didn't step into anything; stop here.
break;
SteppedNode:
continue;
}
// 'Node' is our result:
return(node as Element);
}
