third_party/WebKit/Source/core/layout/LayoutPagedFlowThread.cpp

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "config.h"
   6 #include "core/layout/LayoutPagedFlowThread.h"
   7
   8 #include "core/layout/LayoutMultiColumnSet.h"
   9
  10 namespace blink {
  11
  12 LayoutPagedFlowThread* LayoutPagedFlowThread::createAnonymous(Document& document, const ComputedStyle& parentStyle)
  13 {
  14     LayoutPagedFlowThread* pagedFlowThread = new LayoutPagedFlowThread();
  15     pagedFlowThread->setDocumentForAnonymous(&document);
  16     pagedFlowThread->setStyle(ComputedStyle::createAnonymousStyleWithDisplay(parentStyle, BLOCK));
  17     return pagedFlowThread;
  18 }
  19
  20 int LayoutPagedFlowThread::pageCount()
  21 {
  22     if (LayoutMultiColumnSet* columnSet = firstMultiColumnSet())
  23         return columnSet->actualColumnCount();
  24     return 1;
  25 }
  26
  27 bool LayoutPagedFlowThread::needsNewWidth() const
  28 {
  29     return progressionIsInline() != pagedBlockFlow()->style()->hasInlinePaginationAxis();
  30 }
  31
  32 void LayoutPagedFlowThread::updateLogicalWidth()
  33 {
  34     // As long as we inherit from LayoutMultiColumnFlowThread, we need to bypass its implementation
  35     // here. We're not split into columns, so the flow thread width will just be whatever is
  36     // available in the containing block.
  37     LayoutFlowThread::updateLogicalWidth();
  38 }
  39
  40 void LayoutPagedFlowThread::layout()
  41 {
  42     ASSERT(firstMultiColumnBox() == lastMultiColumnBox()); // There should either be zero or one of those for paged layout.
  43     setProgressionIsInline(pagedBlockFlow()->style()->hasInlinePaginationAxis());
  44     LayoutMultiColumnFlowThread::layout();
  45
  46     LayoutMultiColumnSet* columnSet = firstMultiColumnSet();
  47     if (!columnSet)
  48         return;
  49     LayoutUnit pageLogicalHeight = columnSet->pageLogicalHeightForOffset(LayoutUnit());
  50     if (!pageLogicalHeight)
  51         return; // Page height not calculated yet. Happens in the first layout pass when height is auto.
  52     // Ensure uniform page height. We don't want the last page to be shorter than the others,
  53     // or it'll be impossible to scroll that whole page into view.
  54     LayoutUnit paddedLogicalBottomInFlowThread = pageLogicalHeight * pageCount();
  55     ASSERT(paddedLogicalBottomInFlowThread >= columnSet->logicalBottomInFlowThread());
  56     columnSet->endFlow(paddedLogicalBottomInFlowThread);
  57 }
  58
  59 } // namespace blink