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      1 /*
      2  * Copyright (C) 2009, 2010 Apple Inc. All rights reserved.
      3  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  *
     14  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
     15  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     17  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
     18  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     19  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     20  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     21  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
     22  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     24  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     25  */
     26 
     27 #include "config.h"
     28 #include "core/rendering/RenderObjectChildList.h"
     29 
     30 #include "core/accessibility/AXObjectCache.h"
     31 #include "core/rendering/RenderCounter.h"
     32 #include "core/rendering/RenderObject.h"
     33 #include "core/rendering/RenderView.h"
     34 #include "core/rendering/style/RenderStyle.h"
     35 
     36 namespace WebCore {
     37 
     38 void RenderObjectChildList::destroyLeftoverChildren()
     39 {
     40     while (firstChild()) {
     41         if (firstChild()->isListMarker() || (firstChild()->style()->styleType() == FIRST_LETTER && !firstChild()->isText())) {
     42             firstChild()->remove();  // List markers are owned by their enclosing list and so don't get destroyed by this container. Similarly, first letters are destroyed by their remaining text fragment.
     43         } else {
     44             // Destroy any anonymous children remaining in the render tree, as well as implicit (shadow) DOM elements like those used in the engine-based text fields.
     45             if (firstChild()->node())
     46                 firstChild()->node()->setRenderer(0);
     47             firstChild()->destroy();
     48         }
     49     }
     50 }
     51 
     52 RenderObject* RenderObjectChildList::removeChildNode(RenderObject* owner, RenderObject* oldChild, bool notifyRenderer)
     53 {
     54     ASSERT(oldChild->parent() == owner);
     55 
     56     if (oldChild->isFloatingOrOutOfFlowPositioned())
     57         toRenderBox(oldChild)->removeFloatingOrPositionedChildFromBlockLists();
     58 
     59     // So that we'll get the appropriate dirty bit set (either that a normal flow child got yanked or
     60     // that a positioned child got yanked). We also repaint, so that the area exposed when the child
     61     // disappears gets repainted properly.
     62     if (!owner->documentBeingDestroyed() && notifyRenderer && oldChild->everHadLayout()) {
     63         oldChild->setNeedsLayoutAndPrefWidthsRecalc();
     64         // We only repaint |oldChild| if we have a RenderLayer as its visual overflow may not be tracked by its parent.
     65         if (oldChild->isBody())
     66             owner->view()->repaint();
     67         else
     68             oldChild->repaint();
     69     }
     70 
     71     // If we have a line box wrapper, delete it.
     72     if (oldChild->isBox())
     73         toRenderBox(oldChild)->deleteLineBoxWrapper();
     74 
     75     // If oldChild is the start or end of the selection, then clear the selection to
     76     // avoid problems of invalid pointers.
     77     // FIXME: The FrameSelection should be responsible for this when it
     78     // is notified of DOM mutations.
     79     if (!owner->documentBeingDestroyed() && oldChild->isSelectionBorder())
     80         owner->view()->clearSelection();
     81 
     82     if (!owner->documentBeingDestroyed() && notifyRenderer)
     83         oldChild->willBeRemovedFromTree();
     84 
     85     // WARNING: There should be no code running between willBeRemovedFromTree and the actual removal below.
     86     // This is needed to avoid race conditions where willBeRemovedFromTree would dirty the tree's structure
     87     // and the code running here would force an untimely rebuilding, leaving |oldChild| dangling.
     88 
     89     if (oldChild->previousSibling())
     90         oldChild->previousSibling()->setNextSibling(oldChild->nextSibling());
     91     if (oldChild->nextSibling())
     92         oldChild->nextSibling()->setPreviousSibling(oldChild->previousSibling());
     93 
     94     if (firstChild() == oldChild)
     95         setFirstChild(oldChild->nextSibling());
     96     if (lastChild() == oldChild)
     97         setLastChild(oldChild->previousSibling());
     98 
     99     oldChild->setPreviousSibling(0);
    100     oldChild->setNextSibling(0);
    101     oldChild->setParent(0);
    102 
    103     // rendererRemovedFromTree walks the whole subtree. We can improve performance
    104     // by skipping this step when destroying the entire tree.
    105     if (!owner->documentBeingDestroyed())
    106         RenderCounter::rendererRemovedFromTree(oldChild);
    107 
    108     if (AXObjectCache* cache = owner->document().existingAXObjectCache())
    109         cache->childrenChanged(owner);
    110 
    111     return oldChild;
    112 }
    113 
    114 void RenderObjectChildList::insertChildNode(RenderObject* owner, RenderObject* newChild, RenderObject* beforeChild, bool notifyRenderer)
    115 {
    116     ASSERT(!newChild->parent());
    117     ASSERT(!owner->isRenderBlockFlow() || (!newChild->isTableSection() && !newChild->isTableRow() && !newChild->isTableCell()));
    118 
    119     while (beforeChild && beforeChild->parent() && beforeChild->parent() != owner)
    120         beforeChild = beforeChild->parent();
    121 
    122     // This should never happen, but if it does prevent render tree corruption
    123     // where child->parent() ends up being owner but child->nextSibling()->parent()
    124     // is not owner.
    125     if (beforeChild && beforeChild->parent() != owner) {
    126         ASSERT_NOT_REACHED();
    127         return;
    128     }
    129 
    130     newChild->setParent(owner);
    131 
    132     if (firstChild() == beforeChild)
    133         setFirstChild(newChild);
    134 
    135     if (beforeChild) {
    136         RenderObject* previousSibling = beforeChild->previousSibling();
    137         if (previousSibling)
    138             previousSibling->setNextSibling(newChild);
    139         newChild->setPreviousSibling(previousSibling);
    140         newChild->setNextSibling(beforeChild);
    141         beforeChild->setPreviousSibling(newChild);
    142     } else {
    143         if (lastChild())
    144             lastChild()->setNextSibling(newChild);
    145         newChild->setPreviousSibling(lastChild());
    146         setLastChild(newChild);
    147     }
    148 
    149     if (!owner->documentBeingDestroyed() && notifyRenderer)
    150         newChild->insertedIntoTree();
    151 
    152     if (!owner->documentBeingDestroyed()) {
    153         RenderCounter::rendererSubtreeAttached(newChild);
    154     }
    155 
    156     newChild->setNeedsLayoutAndPrefWidthsRecalc();
    157     if (!owner->normalChildNeedsLayout())
    158         owner->setChildNeedsLayout(); // We may supply the static position for an absolute positioned child.
    159 
    160     if (AXObjectCache* cache = owner->document().axObjectCache())
    161         cache->childrenChanged(owner);
    162 }
    163 
    164 } // namespace WebCore
    165