third_party/WebKit/Source/core/frame/FrameViewAutoSizeInfo.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 "core/frame/FrameViewAutoSizeInfo.h"

#include "core/frame/FrameView.h"
#include "core/frame/LocalFrame.h"
#include "core/layout/LayoutBox.h"
#include "core/layout/LayoutView.h"
#include "core/layout/api/LayoutViewItem.h"
#include "wtf/AutoReset.h"

namespace blink {

FrameViewAutoSizeInfo::FrameViewAutoSizeInfo(FrameView* view)
    : m_frameView(view), m_inAutoSize(false), m_didRunAutosize(false) {
  ASSERT(m_frameView);
}

DEFINE_TRACE(FrameViewAutoSizeInfo) {
  visitor->trace(m_frameView);
}

void FrameViewAutoSizeInfo::configureAutoSizeMode(const IntSize& minSize,
                                                  const IntSize& maxSize) {
  ASSERT(!minSize.isEmpty());
  ASSERT(minSize.width() <= maxSize.width());
  ASSERT(minSize.height() <= maxSize.height());

  if (m_minAutoSize == minSize && m_maxAutoSize == maxSize)
    return;

  m_minAutoSize = minSize;
  m_maxAutoSize = maxSize;
  m_didRunAutosize = false;
}

void FrameViewAutoSizeInfo::autoSizeIfNeeded() {
  if (m_inAutoSize)
    return;

  AutoReset<bool> changeInAutoSize(&m_inAutoSize, true);

  Document* document = m_frameView->frame().document();
  if (!document || !document->isActive())
    return;

  Element* documentElement = document->documentElement();
  if (!documentElement)
    return;

  // If this is the first time we run autosize, start from small height and
  // allow it to grow.
  if (!m_didRunAutosize)
    m_frameView->resize(m_frameView->frameRect().width(),
                        m_minAutoSize.height());

  IntSize size = m_frameView->frameRect().size();

  // Do the resizing twice. The first time is basically a rough calculation
  // using the preferred width which may result in a height change during the
  // second iteration.
  for (int i = 0; i < 2; i++) {
    // Update various sizes including contentsSize, scrollHeight, etc.
    document->updateStyleAndLayoutIgnorePendingStylesheets();

    LayoutViewItem layoutViewItem = document->layoutViewItem();
    if (layoutViewItem.isNull())
      return;

    int width = layoutViewItem.minPreferredLogicalWidth().toInt();

    LayoutBox* documentLayoutBox = documentElement->layoutBox();
    if (!documentLayoutBox)
      return;

    int height = documentLayoutBox->scrollHeight().toInt();
    IntSize newSize(width, height);

    // Check to see if a scrollbar is needed for a given dimension and
    // if so, increase the other dimension to account for the scrollbar.
    // Since the dimensions are only for the view rectangle, once a
    // dimension exceeds the maximum, there is no need to increase it further.
    if (newSize.width() > m_maxAutoSize.width()) {
      Scrollbar* localHorizontalScrollbar = m_frameView->horizontalScrollbar();
      if (!localHorizontalScrollbar)
        localHorizontalScrollbar =
            m_frameView->createScrollbar(HorizontalScrollbar);
      if (!localHorizontalScrollbar->isOverlayScrollbar())
        newSize.setHeight(newSize.height() +
                          localHorizontalScrollbar->height());

      // Don't bother checking for a vertical scrollbar because the width is at
      // already greater the maximum.
    } else if (newSize.height() > m_maxAutoSize.height()) {
      Scrollbar* localVerticalScrollbar = m_frameView->verticalScrollbar();
      if (!localVerticalScrollbar)
        localVerticalScrollbar =
            m_frameView->createScrollbar(VerticalScrollbar);
      if (!localVerticalScrollbar->isOverlayScrollbar())
        newSize.setWidth(newSize.width() + localVerticalScrollbar->width());

      // Don't bother checking for a horizontal scrollbar because the height is
      // already greater the maximum.
    }

    // Ensure the size is at least the min bounds.
    newSize = newSize.expandedTo(m_minAutoSize);

    // Bound the dimensions by the max bounds and determine what scrollbars to
    // show.
    ScrollbarMode horizonalScrollbarMode = ScrollbarAlwaysOff;
    if (newSize.width() > m_maxAutoSize.width()) {
      newSize.setWidth(m_maxAutoSize.width());
      horizonalScrollbarMode = ScrollbarAlwaysOn;
    }
    ScrollbarMode verticalScrollbarMode = ScrollbarAlwaysOff;
    if (newSize.height() > m_maxAutoSize.height()) {
      newSize.setHeight(m_maxAutoSize.height());
      verticalScrollbarMode = ScrollbarAlwaysOn;
    }

    if (newSize == size)
      continue;

    // While loading only allow the size to increase (to avoid twitching during
    // intermediate smaller states) unless autoresize has just been turned on or
    // the maximum size is smaller than the current size.
    if (m_didRunAutosize && size.height() <= m_maxAutoSize.height() &&
        size.width() <= m_maxAutoSize.width() &&
        !m_frameView->frame().document()->loadEventFinished() &&
        (newSize.height() < size.height() || newSize.width() < size.width()))
      break;

    m_frameView->resize(newSize.width(), newSize.height());
    // Force the scrollbar state to avoid the scrollbar code adding them and
    // causing them to be needed. For example, a vertical scrollbar may cause
    // text to wrap and thus increase the height (which is the only reason the
    // scollbar is needed).
    m_frameView->setVerticalScrollbarLock(false);
    m_frameView->setHorizontalScrollbarLock(false);
    m_frameView->setScrollbarModes(horizonalScrollbarMode,
                                   verticalScrollbarMode, true, true);
  }
  m_didRunAutosize = true;
}

}  // namespace blink