layout/base/nsStyleChangeList.cpp

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 /*
   8  * a list of the recomputation that needs to be done in response to a
   9  * style change
  10  */
  11
  12 #include "nsStyleChangeList.h"
  13
  14 #include "mozilla/dom/ElementInlines.h"
  15
  16 #include "nsCSSFrameConstructor.h"
  17 #include "nsIContent.h"
  18 #include "nsIFrame.h"
  19
  20 void nsStyleChangeList::AppendChange(nsIFrame* aFrame, nsIContent* aContent,
  21                                      nsChangeHint aHint) {
  22   MOZ_ASSERT(aFrame || (aHint & nsChangeHint_ReconstructFrame),
  23              "must have frame");
  24   MOZ_ASSERT(aHint, "No hint to process?");
  25   MOZ_ASSERT(!(aHint & nsChangeHint_NeutralChange),
  26              "Neutral changes do not need extra processing, "
  27              "and should be stripped out");
  28   MOZ_ASSERT(aContent || !(aHint & nsChangeHint_ReconstructFrame),
  29              "must have content");
  30   // XXXbz we should make this take Element instead of nsIContent
  31   MOZ_ASSERT(
  32       !aContent || aContent->IsElement() ||
  33           // display:contents elements posts the changes for their children:
  34           (aFrame && aContent->GetFlattenedTreeParentElementForStyle() &&
  35            Servo_Element_IsDisplayContents(
  36                aContent->GetFlattenedTreeParentElementForStyle())) ||
  37           (aContent->IsText() && aContent->HasFlag(NODE_NEEDS_FRAME) &&
  38            aHint & nsChangeHint_ReconstructFrame),
  39       "Shouldn't be trying to restyle non-elements directly, "
  40       "except if it's a display:contents child or a text node "
  41       "doing lazy frame construction");
  42   MOZ_ASSERT(!(aHint & nsChangeHint_AllReflowHints) ||
  43                  (aHint & nsChangeHint_NeedReflow),
  44              "Reflow hint bits set without actually asking for a reflow");
  45
  46   if (aHint & nsChangeHint_ReconstructFrame) {
  47     // If Servo fires reconstruct at a node, it is the only change hint fired at
  48     // that node.
  49
  50     // Note: Because we check whether |aHint| is a reconstruct above (which is
  51     // necessary to avoid debug test timeouts on certain crashtests), this check
  52     // will not find bugs where we add a non-reconstruct hint for an element
  53     // after adding a reconstruct. This is ok though, since
  54     // ProcessRestyledFrames will handle that case via mDestroyedFrames.
  55 #ifdef DEBUG
  56     for (size_t i = 0; i < Length(); ++i) {
  57       MOZ_ASSERT(aContent != (*this)[i].mContent ||
  58                      !((*this)[i].mHint & nsChangeHint_ReconstructFrame),
  59                  "Should not append a non-ReconstructFrame hint after \
  60                  appending a ReconstructFrame hint for the same \
  61                  content.");
  62     }
  63 #endif
  64   }
  65
  66   if (!IsEmpty() && aFrame && aFrame == LastElement().mFrame) {
  67     LastElement().mHint |= aHint;
  68     return;
  69   }
  70
  71   AppendElement(nsStyleChangeData{aFrame, aContent, aHint});
  72 }