RESOLVED FIXED 24726
hit testing doesn't work right when the click is on anonymous content 
https://bugs.webkit.org/show_bug.cgi?id=24726
Summary hit testing doesn't work right when the click is on anonymous content
Darin Adler
Reported 2009-03-20 14:23:17 PDT
When looking at a bug affecting Apple’s Mail application I discovered that hit testing doesn’t work when the item hit (or the nearest item) is anonymous content. While I can’t share the Mail test case here, we can make other test cases.
Attachments
first cut at a test, made by Eric (196 bytes, text/html)
2009-03-20 14:54 PDT, Darin Adler 		no flags
Details
patch (19.27 KB, patch)
2009-03-20 15:48 PDT, Darin Adler 		adele: review+
DetailsFormatted DiffDiff
Show Obsolete (1) View All Add attachment proposed patch, testcase, etc.
Darin Adler
Comment 1 2009-03-20 14:54:57 PDT
Created attachment 28802 [details] first cut at a test, made by Eric
Darin Adler
Comment 2 2009-03-20 15:22:55 PDT
rdar://problem/6696992
Darin Adler
Comment 3 2009-03-20 15:48:56 PDT
Created attachment 28805 [details] patch
Ojan Vafai
Comment 4 2009-03-20 16:28:44 PDT
Comment on attachment 28805 [details] patch > Index: WebCore/rendering/RenderObject.cpp > =================================================================== > --- WebCore/rendering/RenderObject.cpp (revision 41868) > +++ WebCore/rendering/RenderObject.cpp (working copy) > +VisiblePosition RenderObject::createVisiblePosition(int offset, EAffinity affinity) > +{ > + // If is is a non-anonymous renderer, then it's simple. > + if (Node* node = this->node()) > + return VisiblePosition(node, offset, affinity); > + > + // Find a nearby non-anonymous renderer. > + RenderObject* child = this; > + while (RenderObject* parent = child->parent()) { I think you need to check here that the parent is of the same editability as the child like in positionForPointRespectingEditingBoundaries. > + // Find non-anonymous content after. > + RenderObject* renderer = child; > + while ((renderer = renderer->nextInPreOrder(parent))) { > + if (Node* node = renderer->node()) > + return VisiblePosition(node, 0, DOWNSTREAM); > + } Maybe add the following test cases to test the rest of this? -Editable element with generated content only at the beginning -Editable element with only generated content inside > + // Find non-anonymous content before. > + renderer = child; > + while ((renderer = renderer->previousInPreOrder())) { > + if (renderer == parent) > + break; > + if (Node* node = renderer->node()) > + return VisiblePosition(node, numeric_limits<int>::max(), DOWNSTREAM); > + } > + > + // Use the parent itself unless it too is anonymous. > + if (Node* node = parent->node()) > + return VisiblePosition(node, 0, DOWNSTREAM); > + > + // Repeat at the next level up. > + child = parent; > + } > + Is this actually possible? If so, would be good to have a test case. Maybe this even deserves an ASSERT(false)? > + // Everything was anonymous. Give up. > + return VisiblePosition(); > +} > + > +VisiblePosition RenderObject::createVisiblePosition(const Position& position) > +{ > + if (position.container) > + return VisiblePosition(position); > + > + ASSERT(!node()); > + return createVisiblePosition(0, DOWNSTREAM); > +} > Index: LayoutTests/editing/selection/hit-test-anonymous.html > =================================================================== > --- LayoutTests/editing/selection/hit-test-anonymous.html (revision 0) > +++ LayoutTests/editing/selection/hit-test-anonymous.html (revision 0) > @@ -0,0 +1,74 @@ > +<head> > +<style> > +span:before { > + content: "<before> "; > +} > +span:after { > + content: " <after>"; > +} > +</style> > +<script> Not a big deal, but LayoutTests/editing/selection/resources/js-test-selection-shared.js already has equivalents to the first three of these methods. Although it's DOM-based in it's asserts rather than string-based and it assumes you pull in js-test-pre.js. > + function nodeAsString(node) > + { > + if (node && node.nodeType == Node.TEXT_NODE) > + return "text in " + nodeAsString(node.parentNode); > + if (node && node.nodeType == Node.ELEMENT_NODE) { > + var id; > + if (id = node.getAttribute("id")) > + return id; > + } > + return node; > + } > + function selectionAsString() > + { > + return "(" + nodeAsString(getSelection().anchorNode) > + + ", " + getSelection().anchorOffset > + + "), (" + nodeAsString(getSelection().focusNode) > + + ", " + getSelection().focusOffset + ")"; > + } > + function checkSelection(step, expected) > + { > + if (selectionAsString() !== expected) { > + document.getElementById("result").innerHTML = "FAIL: After step " + step + " selection was " + selectionAsString(); > + return true; > + } > + return false; > + }
Darin Adler
Comment 5 2009-03-20 16:41:20 PDT
(In reply to comment #4) > I think you need to check here that the parent is of the same editability as > the child like in positionForPointRespectingEditingBoundaries. I don't think I do in practice. Everything has to be anonymous. I think you’ll have some non-anonymous nodes anywhere you’d have an editability transition. By the way, what do you think we’d do when the parent’s editability differed from the child? > Maybe add the following test cases to test the rest of this? > -Editable element with generated content only at the beginning > -Editable element with only generated content inside We’d have to add tons more test cases to test all of these. I can try to make more, but I think this fix can go in before we add tests to cover every single one of the cases. > > + // Find non-anonymous content before. > > + renderer = child; > > + while ((renderer = renderer->previousInPreOrder())) { > > + if (renderer == parent) > > + break; > > + if (Node* node = renderer->node()) > > + return VisiblePosition(node, numeric_limits<int>::max(), DOWNSTREAM); > > + } > > + > > + // Use the parent itself unless it too is anonymous. > > + if (Node* node = parent->node()) > > + return VisiblePosition(node, 0, DOWNSTREAM); > > + > > + // Repeat at the next level up. > > + child = parent; > > + } > > Is this actually possible? If so, would be good to have a test case. Maybe this > even deserves an ASSERT(false)? Sure, I have no idea which of these pathological cases really exist and which don’t. Making test cases for these are extremely challenging. We can add more test cases after I land the initial patch. > Not a big deal, but > LayoutTests/editing/selection/resources/js-test-selection-shared.js already has > equivalents to the first three of these methods. Although it's DOM-based in > it's asserts rather than string-based and it assumes you pull in > js-test-pre.js. And these exact three function came from yet another test. I’d be happy to see lots of other high-quality tests and refactoring to include this test. But at the moment I’m satisfied having at least one test to demonstrate the need for this fix.
Ojan Vafai
Comment 6 2009-03-20 16:49:29 PDT
Yeah, it occurred to me afterwards that we probably can't cross an editability boundary here since we stop at the first non-anonymous node we see. Maybe it's worth adding a comment to that effect for the next guy who messes with this code?
Darin Adler
Comment 7 2009-03-20 16:55:22 PDT
(In reply to comment #6) > Yeah, it occurred to me afterwards that we probably can't cross an editability > boundary here since we stop at the first non-anonymous node we see. Maybe it's > worth adding a comment to that effect for the next guy who messes with this > code? Will do.
Darin Adler
Comment 8 2009-03-23 17:51:42 PDT
http://trac.webkit.org/changeset/41928
Simon Fraser (smfr)
Comment 9 2009-03-24 14:18:30 PDT
Do we know which commit originally caused this regression?
Darin Adler
Comment 10 2009-03-24 14:23:45 PDT
(In reply to comment #9) > Do we know which commit originally caused this regression? I don't know which one. The cause was presumably indirect. We had this latent bug for a long time and I think it was changes to higher levels of the editing code that made it start to matter.
Eric Seidel (no email)
Comment 11 2009-03-24 14:25:32 PDT
Yes http://trac.webkit.org/changeset/41191 was the commit which would have exposed this latent bug to these more common circumstances.
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