List marker pseudo elements.

Source/core/dom/MarkerPseudoElement.cpp

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "config.h"
+#include "core/dom/MarkerPseudoElement.h"
+
+#include "core/layout/LayoutBlockFlow.h"
+#include "core/layout/LayoutListItem.h"
+#include "core/layout/LayoutListMarker.h"
+
+namespace blink {
+
+MarkerPseudoElement::MarkerPseudoElement(Element* parent)
+    : PseudoElement(parent, MARKER)
+{
+}
+
+MarkerPseudoElement::~MarkerPseudoElement()
+{
+}
+
+LayoutObject* MarkerPseudoElement::parentOfFirstLineBox(LayoutBlockFlow* curr, const LayoutObject* marker)
+{
+    LayoutObject* firstChild = curr->firstChild();
+    if (!firstChild)
+        return nullptr;
+
+    bool inQuirksMode = curr->document().inQuirksMode();
+    for (LayoutObject* currChild = firstChild; currChild; currChild = currChild->nextSibling()) {
+        if (currChild == marker)
+            continue;
+
+        if (currChild->isInline() && (!currChild->isLayoutInline() || curr->generatesLineBoxesForInlineChild(currChild)))
+            return curr;
+
+        if (currChild->isFloating() || currChild->isOutOfFlowPositioned())
+            continue;
+
+        if (!currChild->isLayoutBlockFlow() || (currChild->isBox() && toLayoutBox(currChild)->isWritingModeRoot()))
+            break;
+
+        if (curr->isListItem() && inQuirksMode && currChild->node()
+            && (isHTMLUListElement(*currChild->node()) || isHTMLOListElement(*currChild->node())))
+            break;
+
+        if (LayoutObject* lineBox = parentOfFirstLineBox(toLayoutBlockFlow(currChild), marker))
+            return lineBox;
+    }
+
+    return nullptr;
+}
+
+PassRefPtr<ComputedStyle> MarkerPseudoElement::customStyleForLayoutObject()
+{
+    if (!layoutObject())

[esprehn, 2015/04/22 07:45:45]

This isn't right, you should never look at the layout tree from inside
customStyleForLayoutObject.

[dsinclair, 2015/04/22 20:00:38]

Removed customStyleForLayoutObjects and did calls from ::attach as the marker
style needs me to know the list item styling.

+        return nullptr;
+
+    LayoutObject* parent = layoutObject()->parent();

[esprehn, 2015/04/22 07:45:45]

You need to call LayoutTreeBuilderTraversal::parent here and return the right
value always.

[dsinclair, 2015/04/22 20:00:38]

Removed.

+    if (!parent)
+        return nullptr;
+
+    return styleForListMarkerLayoutObject(*parent, layoutObject()->style());
+}
+
+PassRefPtr<ComputedStyle> MarkerPseudoElement::styleForListMarkerLayoutObject(LayoutObject& parent, const ComputedStyle* style)

[esprehn, 2015/04/22 07:45:45]

styleForListMarker(...) no need for LayoutObject in the name.

[dsinclair, 2015/04/22 20:00:38]

Done.

+{
+    RefPtr<ComputedStyle> newStyle = ComputedStyle::create();
+
+    // The marker always inherits from the list item, regardless of where it might end
+    // up (e.g., in some deeply nested line box). See CSS3 spec.
+    newStyle->inheritFrom(*parent.style());
+    if (style) {
+        // Reuse the current margins. Otherwise resetting the margins to initial values
+        // would trigger unnecessary layout.
+        newStyle->setMarginStart(style->marginStart());
+        newStyle->setMarginEnd(style->marginRight());

[esprehn, 2015/04/22 07:45:45]

This code should just be inlined in the above method.

[dsinclair, 2015/04/22 20:00:38]

It can be in the future when we remove the old code paths, but at the moment
this is called through them and needs to be separate. Added a FIXME.

+    }
+    return newStyle;
+}
+
+LayoutObject* MarkerPseudoElement::firstNonMarkerChild(LayoutObject* parent)
+{
+    LayoutObject* result = parent->slowFirstChild();
+    while (result && result->isListMarker())
+        result = result->nextSibling();
+    return result;
+}
+
+LayoutObject* MarkerPseudoElement::createLayoutObject(const ComputedStyle& style)
+{
+    ASSERT(parentElement()->layoutObject());
+    LayoutListMarker* marker = new LayoutListMarker(this, toLayoutListItem(parentElement()->layoutObject()));
+    marker->setStyle(ComputedStyle::clone(style));

[esprehn, 2015/04/22 07:45:45]

Don't clone the style, you never need to do that in createLayoutObject.

[dsinclair, 2015/04/22 20:00:38]

Done.

+    return marker;
+}
+
+void MarkerPseudoElement::attachListMarkerLayoutObject()
+{
+    LayoutListItem* parentLayoutObject = toLayoutListItem(parentElement()->layoutObject());
+    ASSERT(parentLayoutObject);
+    ASSERT(layoutObject());
+
+    LayoutListMarker* marker = toLayoutListMarker(layoutObject());
+    LayoutObject* markerParent = marker->parent();
+
+    LayoutObject* insertionLayoutObject = MarkerPseudoElement::parentOfFirstLineBox(parentLayoutObject, marker);
+
+    // We didn't find any line boxes so make the insertion point the LI layoutObject.
+    if (!insertionLayoutObject)
+        insertionLayoutObject = parentLayoutObject;
+    ASSERT(insertionLayoutObject);
+
+    // Check if we're already inserted into the right parent as the first child.
+    if (markerParent && marker == markerParent->slowFirstChild()
+        && (markerParent == insertionLayoutObject || markerParent == insertionLayoutObject->slowFirstChild()))
+        return;
+
+    marker->remove();
+    insertionLayoutObject->addChild(marker, MarkerPseudoElement::firstNonMarkerChild(insertionLayoutObject));
+    marker->updateMarginsAndContent();

[esprehn, 2015/04/22 07:45:45]

Layout calls this for isImage(), make it call it every time and remove this.

[dsinclair, 2015/04/22 20:00:38]

That will mean we'll do it on every layout, where this will just do it when the
marker is attached.

+
+    // If markerParent is an anonymous block with no children, destroy it.
+    if (markerParent && markerParent->isAnonymousBlock() && !toLayoutBlock(markerParent)->firstChild() && !toLayoutBlock(markerParent)->continuation())
+        markerParent->destroy();
+
+    if (marker->isInside())
+        parentLayoutObject->containingBlock()->updateLogicalWidth();

[esprehn, 2015/04/22 07:45:45]

You can't update logical widths inside style recalc. You can only mark dirty
bits.

[dsinclair, 2015/04/22 20:00:38]

Done.

+}
+
+void MarkerPseudoElement::attach(const AttachContext& context)
+{
+    PseudoElement::attach(context);
+    ASSERT(layoutObject());
+
+    LayoutListMarker* marker = toLayoutListMarker(layoutObject());
+
+    RefPtr<ComputedStyle> newStyle = MarkerPseudoElement::styleForListMarkerLayoutObject(*(marker->mutableListItem()), marker->style());
+    marker->setStyle(newStyle.release());

[esprehn, 2015/04/22 07:45:45]

::attach went through the customStyleForLayoutObject code, that thing needs to
always return the right style. You shouldn't set the style sometimes there when
updating and sometimes here when attaching.

[dsinclair, 2015/04/22 20:00:38]

Style is set here only now.

+
+    attachListMarkerLayoutObject();
+}
+
+void MarkerPseudoElement::didRecalcStyle(StyleRecalcChange)
+{
+    attachListMarkerLayoutObject();
+}
+
+} // namespace blink